MCQ in Communications Engineering PDF

MULTIPLE CHOICE QUESTIONS in COMPREHENSIVE REVIEWER IN COMMUNICATIONS ENGINEERING Philander U. Lomboy, ECE Benedetto D. Villanueva, ECE dB/NOISE Multiple choice. Encircle the letter which corresponds to your answer. 1. A current change that is equal to twice its original value will correspond to a change of a. 3 dB b. 9 dB c. 10 dB d. 6 dB 2. What does a power difference of -3dB mean? a. A loss of one third of the power b. A loss of one-half of the power c. A loss of 3 watts of power d. No significant change 3. A gain of 60 dB is the same as a gain of a. 10 volts/volt b. 100 volts/volt c. 1000 volts/volt d. 10,000 volts/volt 4. ______ is mathematically equal to the logarithm to the base ten of the power ratio P1 over P2. a. bel b. dB c. bel/10 d. dB/2 5. Noise that is produced by the active components within the receiver. a. Thermal b. External c. Internal d. White 6. Noise due to random variation in the arrival of charge carriers at the output electrode of an active device a. Shot b. Impulse c. Thermal d. Dynamic 7. A network has a loss of 20 dB. What power ratio corresponds to this loss a. 0.01 b. 0.1 c. 10 d. 100 8. A receiver connected to an antenna whose resistance is 60 ohms has an equivalent noise resistance of 40 ohms. Calculate the receiver’s noise figure in decibels and its equivalent noise temperature. a. 1.67 & 194°K b. 2.23 & 194°K c. 1.67 & 174°K d. 2.23 & 194°K 9. _____ Noise is the most prevalent noise found in urban areas and is normally caused by the arc discharge from automobile or aircraft ignition systems, induction motors, switching gears, high voltage lines and the like. a. Industrial b. Johnson c. Flicker d. Mixer 10. The noise figure of a totally noiseless device is a. Unity b. Infinity c. Zero d. 100 11. Indicate the noise whose source is in a category different from that of the other three. a. Solar b. Cosmic c. Atmospheric d. Galactic 12. The ratio(in dB) of the power of a signal at point to the power of the same signal at the reference point. a. Transmission Level Point b. Noise Figure c. S/N Ratio d. Neper 13. A network has a power gain of -3dB. If the input power is 100 watts, the output power is a. 50 watts b. 55 watts c. 60 watts d. 62 watts 14. Which of the following types of noise becomes of great importance at high frequencies? a. Shot b. Random c. Impulse d. Transmit time 15. The input current of a network is 190 uA and the output is 1.3 uA. The loss in decibels is a. 20.2 b. 21.6 c. 28.6 d. 43.3 16. If a network connected in series have a gain of -0.5 dB, -0.3dB, -2dB and 6.8dB, the overall gain is a. 2 dB b. -2dB c. 4 dB d. -4dB 17. What is the gain, in dB, if the output to input ratio is 1000. a. 20 b. 30 c. 40 d. 10 18. The following characteristics of noise exept a. Unwanted energy b. Predictable in character c. Present in the channel d. Due to any cause 19. The equivalent noise temperature of the amplifier is 25 °K what is the noise figure? a. 10.86 b. 1.086 c. 0.1086 d. 1.86 20. A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? a. 464°K b. 754°K c. 400°K d. 174°K 21. A theoretical antenna has a gain of 1dB. Its gain in nepers is a. 8.686 b. 0.1151 c. 6.868 d. 0.5111 22. What is the equivalent output of a circuit in dBm, if it has an output of 10 watts? a. 10 dBm b. 30dBm c. 20dBm d. 40dBm 23. An amplifier with an input resistance of 1000 ohms is operating over a 4 MHz bandwidth. Calculate the rms voltage if the amplifier is operating at 27 °C. a. 8.14 nV b. 8.14 uV c. 6.6 nV d. 6.6 uV 24. The value of a resistor creating thermal noise is doubled. The noise power generated is therefore a. Halved b. Quadrupled c. Doubled d. Unchanged 25. One of the following is not a useful quantity for comparing the noise performance of receivers. a. Input noise voltage b. Equivalent noise resistance c. Noise temperature d. Noise figure 26. Any unwanted form of energy that tends to interfere with the wanted signal is called a. Noise b. Spectrum c. Radiation d. Absorption 27. The correct symbol for decibel is a. DB b. dB c. Db d. db 28. _____ is the noise created outside the receiver. a. Internal b. External c. Shot d. Industrial 29. _____ is the noise created by man. a. Solar b. Industrial c. Extraterrestrial d. Galactic 30. A voltage change that is equal to twice its original value correspond to a change of a. 3dB b. 6dB c. 9dB d. 10dB 31. Indicate the voltage level in dB with reference to one volt. This unit is used in video or TV measurement a. dBW b. dBk c. dBm d. dBV 32. which of the following is not an actual amount of power? a. dB b. dBm c. dBw d. dBk 33. In noise analysis, the reference temperature is a. 75 K b. 250 K c. 290 K d. 300 K 34. Noise from distant panels, stars, galaxies and other celestial objects are called a. Cosmic b. Extraterrestrial c. Galactic d. Black body 35. Indicate which one of the following types of noise does not occur in transistors a. Shot noise b. Flicker noise c. Partition noise d. Resistance noise 36. Which of the following is not a source of space noise a. Sun b. Star c. Lightning d. Black body 37. Noise that is due to the random and rapid motion of the charge carriers inside a resistive component. a. Johnson b. Thermal Agitation c. White d. All of the above 38. Indicate the false statement. The square of the thermal noise voltage generated by a resistor is proportional to a. Its resistance b. Its temperature c. Boltzmann’s Constant d. The bandwidth over which it is measured 39. In a communication system, noise is likely to affect the signal a. At the transmitter b. In the channel c. In the information source d. At the destination 40. The noise power generated by a resistor is proportional to a. Temperature b. Bandwidth c. a and b d. NOTA 41. Thermal noise is also known as a. Gaussian Noise b. White Noise c. Johnson noise d. All of the above 42. This type of noise has a power spectrum which decreases with increasing frequency. It is most important at low frequencies from 0 to about 100 Hz). a. Shot noise b. Flicker noise c. Diode noise d. BJT noise 43. Industrial noise extends up to what frequency? a. 500 MHz b. 500 GHz c. 500 THz d. 500 KHz 44. Impulse Noise is a. A function of current b. A shot duration pulse c. Dependent of frequency d. Dependent of temperature 45. When the power ratio of the output to input of a circuit is 200. What is the gain in dB? a. 23 b. 46 c. -23 d. -46 46. What is the reference level for random noise measurement, FIA weighted? a. -82 dBm b. -90 dBm c. -85 dBm d. -77 dBm 47. A 10 dB pad has an output level of -3 dBm. The level at the input is: a. 13 dBm b. -7 dBm c. 1 dBm d. 7 dBm 48. The sum of three signals of 45dBm each is ______ dBm. a. 45 b. 135 c. 20 d. 50 49. It is characterized by high amplitude peaks of short duration in the total noise spectrum a. Intermodulation voice b. Impulse noise c. Dropout d. Phase hits 50. Originally was determined by measuring the interfering effect of noise in a Type 144 handset. A tone of 1 kHz, having a power level of 90dBm was selected as the reference level. a. Noise figure b. S/N ratio c. Signal Figure d. Figure of Merit 51. A power level of 50 uW could be expressed as: a. 1.39 dBm b. -4.3 dBm c. 1 dBm d. -13 dBm 52. If a power of 0.25mW is launched into a fiber system with an overall loss of 15 dB the output power would be: a. 250 u/W b. 31.6 uW c. 7.9 uW d. 15 dBm 53. A system having an input power of 2 mW an output power of 0.8mW has a loss of: a. 2.98 dBm b. 3.98 dB c. 3.98 uW d. 1.98 mW 54. An output of -10 dB means that the power has been a. Halved in value b. Increased by a factor of 10 c. Reduced by a factor of 10 d. Doubled 55. Any unwanted form of energy interfering the reception of wanted signal is called a. Noise b. Sideband c. Harmonics d. Modulation 56. Is the reduction of signal amplitude as it passed over the transmission medium. a. Noise b. Distortion c. Attenuation d. Interference 57. Signal waveform perturbation or deviation caused by imperfect response of the system to the desired signal a. Noise b. Aliasing c. Distortion d. Interference 58. Signal attenuation can be corrected by a. Filtering b. Modulation c. Equalization d. Amplification 59. Distortion in a waveform can be corrected by a. Filtering b. Modulation c. Equalization d. Amplification 60. Signal contamination by extraneous or external sources, such as, other transmitters, power lines, and machinery. a. Noise b. Distortion c. Harmonics d. Interference 61. Man-made or industrial noise is also known as a. Noise b. Distortion c. Interference d. Thermal Noise 62. The noise performance of a receiver or circuit. It is expressed as ratio of the S/N power at the output. a. Noise figure b. S/N ratio c. Signal figure d. Figure of merit 63. Noise that is caused by natural disturbances such as lightning discharge. a. Static noise b. Space noice c. Atmospheric noise d. A or C 64. Atmospheric or static noise becomes less severe at frequencies a. Below 30 KHz b. Between 30 KHz and 300 KHz c. Between 300 KHz and 30 MHz d. Above 30 MHz 65. Considered as space noise or extraterrestrial noise a. Solar noise b. Cosmic noise c. Black-body noise d. All of the above 66. Which statement is true a. Industrial noise is usually of impulse type b. Distant stars produce atmospheric noise c. Active switches are sources of man-made noise d. Static noise is due to lightning discharges and other natural electric disturbances occurring in the atmosphere. 67. Noise performance of microwave system is usually expressed in terms of a. Noise voltage, Vn= b. Noise power, Pn = KTB c. Noise temperature, Te = (F – 1)290 d. Noise figure, F = (S/N)I / (S/N)o 68. Which circuit contributes most to the noise at the receiver? a. RF amplifier b. Mixer c. Detector d. Local Oscillator 69. Which noise figure represents the lowest noise? a. 1.5 dB b. 2.0 dB c. 3.7 dB d. 4.1 dB 70. Denote the interference of noise in dB above an adjusted reference noise. The adjusted reference noise level was a 1 kHz tone, set at -85 dBm a. dBa b. dBm c. dBa0 d. pWp 71. The extent of noise referred to a test tone level of zero dBm. a. dBa b. dBm c. dBa0 d. pWp 72. An amplifier operating over a 4 MHz bandwidth has a 100 input resistance and is operating at 300°K. Determine the noise power generated. a. 1.656 x 10-14 Watts b. 1656 nW c. 1.656 pW d. 1.656 uW 73. Generally used when noise readings are measured using the C-message weighting network. The reference level was 1 kHz tone, set at -90 dBm a. dBa b. dBm c. dBaO d. dBmC 74. The measurement of noise was made with a C-message filter, and the reading is taken at a test point where the level is zero dBm. a. dBaO b. dBmCo c. dBa d. dBmC 75. Which of the following is not an important cause of distortion in DC signaling a. line resistance b. line inductance c. line capacitance d. all of the above 76. There are a number of different sources of radio noise, the most important being a. Galactic noise b. Man-made noise c. Atmospheric noise d. All f the above 77. The amount of noise power is measured using a psophometric weighting network. This unit of measurement is generally used in Europe where the standard reference tone is 800 hertz, 1 picowatt. a. dBa b. dBm c. dBaO d. pWp 78. Noise produced mostly by lightning discharges in thunderstorms. a. White noise b. Industrial noise c. Atmospheric noise d. Extraterrestrial noise 79. Propagation of man made noise is chiefly by a. Transmission over power lines and by ground wave b. Space wave c. Sky wave d. None of these 80. A more precise evaluation of the quality of a receiver as far as noise is concerned a. S/N b. VSWR c. Noise factor d. Noise margin 81. NIF stands for a. Non-intrinsic figure b. Noise interference figure c. Noise improvement factor d. Narrow intermediate frequency 82. External noise fields are measured in terms of a. Dc values b. Rms values c. Peak values d. Average values 83. Form of interference caused by rain, hail, snow or dust storms a. Shot noise b. Galactic noise c. Impulse noise d. Precipitation static 84. Extra-terrestrial noise is observable at frequencies from a. 0 to 20KHz b. 8 MHz to 1.43 GHz c. 5 to 8 GHz d. 15 to 160 MHz 85. Industrial noise is observable from a. 15 to 160 MHz b. 200 to 3000 MHz c. 0 to 10 kHz d. 8 Mhz to 1.43 GHz 86. Noise that becomes significant at VHF range and above a. Atmospheric b. Transit-time c. Galactic d. White 87. Noise figure for an amplifier with noise is always a. 0 dB b. Infinite c. Less than 1 d. Greater than 1 88. The noise generated by the tube, transistor or integrated circuit in an amplifier. a. White noise b. Amplification noise c. Active noise d. Dynamic Noise 89. Electrical noise inherent to a particular device, circuit or system that remains when no other signal is present. a. Shot noise b. Thermal noise c. Background noise d. Static noise 90. A wideband form of impulse noise generated by the electric arc in the spark plugs of an internal combustion engine. This noise is a common problem in mobile radio system. a. Thermal noise b. Shot noise c. Amplification noise d. Ignition noise 91. The amount of power in dB referred to one Kilowatt a. dBW b. dBk c. dBm d. Dbv 92. Noise in any form of electromagnetic interference that can be traced to non-natural causes. a. Man-made noise b. Distortion c. External noise d. Internal noise 93. The frequency range wherein noise is said to be intense. a. Noise equivalent bandwidth b. Spectral response c. Cut-off frequency d. Noise cut-off frequency 94. Refers to the temperature that corresponds to the spectral energy distribution of a noise.\ a. Absolute temperature b. Temperature band c. Noise-equivalent temperature d. Critical temperature 95. A passive circuit, usually consisting of capacitance and/or inductance, that I inserted in series with the a-c power cord of an electronic device which will allow the 60-Hz current to pass and suppressed high frequency noise components. a. Noise filter b. Noise limiter c. Noise floor d. Noise quieting 96. What do you call the level of background noise, relative to some reference signal. a. Noise figure b. Minimum noise c. Reference noise d. Noise floor 97. A circuit often used in radio receivers that prevents externally generated noise from exceeding amplitude. They are also called noise clippers a. Noise floor b. Noise filter c. Noise limiter d. Noise clamper 98. It is referred to as a short burst of electromagnetic energy. a. Pulse b. Noise pulse c. Spike d. Noise floor 99. The reduction of internal noise level in a frequency-modulated (FM) receiver as a result of an incoming signal. a. Noise quieting b. Noise limiting c. Noise suppression d. Noise degredation 100. Noise generated within electronic equipment by either passive or active components. a. Shot noise b. Thermal noise c. Circuit noise d. External noise Modulation Multiple choice. Encircle the letter which corresponds to your answer. 1. Having an information signal change some characteristic of a carrier signal is called a. Multiplexing b. Modulation c. Duplexing d. Linear mixing 2. Which of the following is not true about AM? a. The carrier amplitude varies. b. The carrier frequency remains constant. c. The carrier frequency changes. d. The information signal amplitude changes the carrier amplitude. 3. The opposite of modulation is a. Reverse modulation b. Downward modulation c. Unmodulation d. Demodulation 4. The circuit used to produce modulation is called a. Modulator b. Demodulator c. Variable gain amplifier d. Multiplexer 5. A modulator circuit performs what mathematical operation on its two inputs? a. Addition b. Multiplication c. Division d. Square root 6. The ratio of the peak modulating signal voltage to the peak carrier voltage is referred to as a. The voltage ratio b. Decibels c. The modulation index d. The mix factor 7. If m is greater than 1, what happens? a. Normal operation b. Carrier drops to zero c. Carrier frequency shifts d. Information signal is distorted 8. For ideal AM, which of the following is true? a. m = 0 b. m = 1 c. m < 1 d. m > 1 9. The outline of the peaks of a carrier has the shape of the modulating signal and is called the a. Trace b. Waveshape c. Envelope d. Carrier variation 10. Overmodulation occurs when a. Vm > Vc b. Vm < Vc c. Vm = Vc d. Vm = Vc = 0 11. The values of Vmax and Vmin as read from an AM wave on oscilloscope are 2.8 and 0.3. the percentage of modulation is a. 10.7 % b. 41.4 % c. 80.6 % d. 93.3 % 12. The new signals produced by modulation are called a. Spurious emissions b. Harmonics c. Intermodulation products d. Sidebands 13. A carrier of 880 kHz is modulated by a 3.5 kHz sine wave. The LSB and USB are, respectively, a. 873 and 887 kHz b. 876.5 and 883.5 kHz c. 883.5 and 876.5 kH d. 887 and 873 kHz 14. A display of signal amplitude versus frequency is called the a. Time domain b. Frequency Spectrum c. Amplitude Spectrum d. Frequency Domain 15. Most of the power in an AM signal is in the a. Carrier b. Upper sideband c. Lower sideband d. Modulating signal 16. An AM signal has a carrier power of 5 W. the percentage of modulation is 80% the total sideband power is a. 0.8 W b. 1.6 W c. 2.5 W d. 4.0 W 17. For 100 % modulation, what percentage of power is in each sideband? a. 25 % b. 33.3 % c. 50 % d. 100 % 18. An AM transmitter has a percentage of modulation of 88. The carrier power is 440 W. The power is 440W. The power in one sideband is a. 85 W b. 110 W c. 170 W d. 610 W 19. An AM transmitter antenna current is measured with no modulation and found to be 2.6 amperes. With modulation, the current rises to 2.9 amperes. The percentage of modulation is a. 35 % b. 70 % c. 42 % d. 89 % 20. What is the carrier power in the problem above if the antenna resistance is 75 ohms? a. 195 W b. 631 W c. 507 W d. 792 W 21. In an AM signal, the transmitted information is contained within the a. Carrier b. Modulating signal c. Sidebands d. Envelope 22. An AM signal without the carrier is called a(n) a. SSB b. Vestigial sideband c. FM signal d. DSB 23. What is the minimum AM signal needed to transmit information? a. Carrier plus sidebands b. Carrier only c. One sideband d. Both sideband 24. The main advantage of SSB over standard AM or DSB is a. Less spectrum space is used b. Simpler equipment is used c. Less power is consumed d. A higher modulation percentage 25. In SSB, which sideband is the best to use? a. Upper b. Lower c. Neither d. Depends upon the use 26. The typical audio modulating frequency range used in radio and telephone communication is a. 50 Hz to 5 kHz b. 50 Hz to 15 kHz c. 100Hz to 10kHz d. 300 Hz to 3 kHz 27. An AM signal with a maximum modulating signal frequency of 4.5 kHz has a total bandwidth of a. 4.5 kHz b. 6.75 kHz c. 9 kHz d. 18 kHz 28. The modulation system used for telegraphy is a. Frequency-shift keying b. Two-tone modulation c. Pulse-code modulation d. Single-tone modulation 29. The process of translating a signal, with or without modulation, to a higher or lower frequency for processing is called a. Frequency multiplication b. Frequency division c. Frequency shift d. Frequency conversion 30. Frequency translation is carried out by a circuit called a a. Translator b. Convertor c. Balanced modulator d. Local oscillator 31. An input signal of 1.8 MHz is mixed with a local oscillator of 5 MHz. A filter selects the difference signal. The output is a. 1.8 MHz b. 3.2 MHz c. 5 MHz d. 6.8 MHz 32. One type of pulse communications system uses pulse that appear as a group, and which vary in number according to the loudness of the voice. This type of pulse modulation is called a. Pulse duration modulation b. Pulse amplitude modulation c. Pulse code modulation d. Pulse position modulation 33. An SSB transmitter produces a 400-V peak to peak signal across a 52-Ω antenna load. The PEP output is a. 192.2 W b. 384.5 W c. 769.2 W d. 3077 W 34. The output power of an SSB transmitter is usually expressed in terms of a. Average power b. RMS power c. Peak-to-peak power d. Peak envelope power 35. The letter-number designation B8E is a form of modulation also known as a. Pilot-carrier system b. Independent sideband emission c. Lincomlex d. Vestigal sideband transmission 36. Amplitude modulation is the same as a. Linear mixing b. Analog multiplication c. Signal summation d. Inductor 37. In a diode modulator, the negative half of the AM wave is supplied by a(n) a. Tuned circuit b. Transformer c. Capacitor d. Inductor 38. Amplitude modulation can be produced by a. Having the carrier vary a resistance b. Having the modulating signal vary a capacitance c. Varying the carrier frequency d. Varying the gain of an amplifier 39. Amplitude modulators that vary the carrier amplitude with the modulating signal by passing it through an attenuator work on the principle of a. Rectification b. Resonance c. Variable resistance d. Absorption 40. The component used to produce AM at very high frequencies is a a. Varactor b. Thermistor c. Cavity resonator d. PIN diode 41. Amplitude modulation generated at a very low voltage or power amplitude is known as a. High-level modulation b. Low-level modulation c. Collector modulation d. Minimum modulation 42. A collector modulator has a supply voltage of 48 V. The peak-to-peak amplitude of the modulating signal for 100 percent modulation is a. 24 V b. 48 V c. 96 V d. 120 V 43. A collector modulated transmitter has a supply voltage of 24 V and collector current of 0.5 A. The modulator power for 100 percent modulation is a. 6 W b. 12 W c. 18 W d. 24 W 44. The circuit that recovers the original modulating information from an AM signal is known as a a. Modulator b. Demodulator c. Mixer d. Crystal set 45. The most commonly used amplitude demodulator is the a. Diode mixer b. Balanced modulator c. Envelope detector d. Crystal filter 46. A circuit that generates the upper and lower sidebands but no carrier is called a(n) a. Amplitude modulator b. Diode detector c. Class C amplifier d. Balanced modulator 47. The inputs to a balance modulator are 1 MHz and a carrier of 1.5 MHz. The outputs are a. 500 kHz b. 2.5 MHz c. 1.5 MHz d. Both a and b 48. A widely used balanced modulator is called the a. Diode bridge circuit b. Full-wave bridge rectifier c. Lattice Modulator d. Balanced bridge modulator 49. In a diode ring modulator, the diodes act like a. Variable resistors b. Switches c. Rectifiers d. Variable capacitors 50. The output of a balanced modulator is a. AM b. FM c. SSB d. DSB 51. The principal circuit in the popular 1496/1596 IC balanced modulator is a a. Differential amplifier b. Rectifier c. Bridge d. Constant current source 52. The most commonly used filter in SSB generators uses a. LC network b. Mechanical resonators c. Crystals d. RC networks and op amps 53. The equivalent circuit of a quartz crystal is a a. Series resonant circuit b. Parallel resonant circuit c. Neither a nor b d. Both a and b 54. A crystal lattice filter has crystal frequencies of 27.5 and 27.502 MHz. The bandwidth is approximately a. 2 kHz b. 3kHz c. 27.501 MHz d. 55.502 MHz 55. An SSB generator has a sideband filter centered at 3.0 MHz. The modulating signal is 3kHz. To produce both upper and lower sidebands, the following carrier frequencies must be produced: a. 2.7 and 3.3 MHz b. 3.3 and 3.6 MHz c. 2997 and 3003 kHz d. 3000 and 3003 kHz 56. In the phasing method of SSB generation, one sideband is canceled due to a. Phase shift b. Sharp selectivity c. Carrier suppression d. Phase inversion 57. A balanced modulator used to demodulate a SSB signal is called a(n) a. Transporter b. Product detector c. Converter d. Modulator 58. Frequency translation is done with a circuit called a a. Summer b. Multiplier c. Filter d. Mixer 59. The inputs to a mixer are fo and fm. In down conversion, which of the following mixer output signals is selected? a. Fo b. Fm c. Fo – fm d. Fo + fm 60. Mixing for frequency conversion is the same as a. Rectification b. AM c. Linear summing d. Filtering 61. Which of the following can be used as a mixer? a. Balanced modulator b. FET c. Diode modulator d. All the above 62. The desired output from a mixer is usually selected with a a. Phase-shift circuit b. Crystal filter c. Resonant circuit d. Transformer 63. The amount of frequency deviation from the carrier center frequency in an FM transmitter is proportional to what characteristic of the modulating signal? a. Amplitude b. Phase c. Angle d. Duty Cycle 64. Both FM and PM are types of what kind of modulation? a. Amplitude b. Phase c. Angle d. Duty Cycle 65. If the amplitude of the modulating signal decreases, the carrier deviation a. Increases b. Decreases c. Remains constant d. Both b and c 66. In PM, a frequency shift occurs while what characteristic of the modulating signal is changing? a. Shape b. Phase c. Frequency d. Amplitude 67. Maximum frequency deviation of a PM signal occurs at a. Zero crossing points b. Peak positive amplitude c. Peak negative amplitude d. Peak positive or negative amplitudes 68. A 100-MHz carrier is deviated 50 KHz by a 4 kHz signal. The modulation index is a. 5 b. 8 c. 12.5 d. 40 69. The maximum deviation of an FM carrier is 2 kHz by a maximum modulating signal of 400 Hz. The deviation ratio is a. 0.2 b. 5 c. 8 d. 40 70. According the Nyquist theorem, the sampling rate that can be used in a PCM system is _____ the highest audio frequency a. Once b. Eight times c. Twice d. Thrice 71. SSB transmission requires only _______ of the bandwidth for a DSBFC a. ¼ b. 2/3 c. ½ d. ¾ 72. Which of the following pulse modulation systems is analog? a. Delta b. Differential PCM c. PWM d. PCM 73. Which of the following is not a major benefit of FM over AM? a. Greater efficiency b. Noise immunity c. Capture Effect d. Lower Complexity and Cost 74. The primary disadvantage of FM is it a. Higher cost and complexity b. Excessive use of spectrum space c. Noise susceptibility d. Lower efficiency 75. The phenomenon of a strong FM signal dominating weaker signal on a common frequency is referred to as the a. Capture effect b. Blot out c. Quieting factor d. Dominating syndrome 76. If the plate supply voltage for a plate-modulated class C amplifier is E, the maximum plate-cathode voltage could be almost as high as a. 4E b. 3E c. 2E d. E 77. In a low-level AM system, amplifiers following the modulated stage must be a. Linear devices b. Harmonic devices c. Class C amplifiers d. Nonlinear devices 78. If the carrier of a 100 percent modulated AM wave is suppressed, the percentage power saving will be a. 50 b. 150 c. 100 d. 66.66 79. Leak-type bias is used in a plate-modulated class C amplifier to a. Prevent tuned circuit damping b. Prevent excessive grid current c. Prevent overmodulation d. Increase the bandwidth 80. The output stage of a television transmitter is most likely to be a a. Plate-modulated class C amplifier b. Grid-modulated class C amplifier c. Screen-modulated class C amplifier d. Grid-modulated class A amplifier 81. The modulation index of an AM wave is changed from 0 to 1. The transmitted power is a. Unchanged b. Halved c. Doubled d. Increased by 50 percent 82. One of the advantages of base modulation over collector modulation of a transistor class C amplifier is a. The lower modulating power required b. Higher power output per transistor c. Better efficiency d. Better linearity 83. A carrier simultaneously modulated by two sine waves with modulation indices of 0.3 and 0.4; the total modulation index a. 1 b. Cannot be calculated unless the phase relations are known c. 0.5 d. 0.7 84. In the stabilized reactance modulator AFC system, a. The discriminator must have a fast time constant to prevent demodulation b. The higher the discriminator frequency, the better the oscillator frequency stability c. The discriminator frequency must not be too low, or the system will fail d. Phase modulation is converted into FM by the equalizer circuit 85. In the spectrum of a frequency of a frequency-modulated wave a. The carrier frequency disappears when the modulation index is large b. The amplitude of any sideband depends on the modulation index c. The total number of sidebands depends on the modulation index d. The carrier frequency cannot disappear 86. The difference between phase and frequency modulation a. Is purely theoretical because they are the same in practice b. Is too great to make the two systems compatible c. Lies in the poorer audio response of phase modulation d. Lies in the different definitions of the modulation index 87. Indicate the false statement regarding the Armstrong modulation system. a. The system is basically phase, not frequency, modulation b. AFC is not needed, as a crystal oscillator is used c. Frequency multiplication must be used d. Equalization is unnecessary 88. An FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of a. mf/3 b. mf c. 3 mf d. 9mf 89. An FM signal with a deviation δ is passed through a mixer, and has its frequency reduced fivefold. The deviation in the output of the mixer is a. 5 δ b. Indeterminate c. δ/5 d. δ 90. A pre-emphasis circuit provides extra noise immunity by a. Boosting the bass frequencies b. Amplifying the higher audio frequencies c. Pre-amplifying the whole audio band d. Converting the phase modulation to FM 91. Since noise phase modulates the FM wave, as the noise sideband frequency approaches the carrier frequency, the noise amplitude a. Remains constant b. Decreased c. Increased d. Equalized 92. When the modulating frequency is doubled, the modulation index is halved, and the modulating voltage remains constant. The modulating system is a. Amplitude modulation b. Phase modulation c. Frequency modulation d. Any of the three 93. Indicate which one of the following is not an advantage of FM over AM a. Better noise immunity is provided b. Lower bandwidth is required c. The transmitted power is more useful d. Less modulating power is required 94. One of the following is an indirect way of generating FM. This is the a. Reactance FET modulator b. Varactor diode modulator c. Armstrong modulator d. Reactance bipolar transistor modulator 95. Indicate the false statement regarding the advantages of SSB over double-sideband, full- carrier AM. a. More channel space is available b. Transmitter circuits must be more stable, giving better reception c. The signal is more noise resistance d. Much less power is required for the same signal strength 96. When the modulation index of an AM wave is doubled, the antenna current is also doubled. The AM system being used is a. A3H b. A5C c. A3J d. A3 97. Indicate which of the following advantages of the phase cancellation method of obtaining SSB over the filter method is false a. Switching from one sideband to the other is simpler b. It is possible to generate SSB at any requency c. SSB with lower audio frequencies present can be generated d. There are more balanced modulators; therefore the carrier is suppressed better 98. The most commonly used filter in SSB generation are a. Mechanical b. RC c. LC d. Low- pass 99. Indicate in which one of the following only one sideband is transmitter a. A3H b. A3 c. A3B d. A5C 100. A3A modulation is sometimes used to a. Allow the receiver to have a frequency synthesizer b. Simplify the frequency stability problem in reception c. Reduce the power that must be transmitted d. Reduce the bandwidth required for transmission. Transmission Lines Multiple choice. Encircle the letter which corresponds to your answer. 1. In practice, the transmission lines are almost connected to antennas that have a _____. a. Resistive load whose resistance is greater than the characteristic impedance of the line b. Resistive load whose resistance is less than the characteristic impedance of the line c. Resistive load at the resonant frequency d. Capacitive load 2. When the transmission line is matched to the load, it a. Transfers maximum current to the load b. Transfers maximum voltage to the load c. Transfers maximum power to the load d. Reduces the load current 3. Conventional transmission media include a. Twisted cable pair b. Waveguide c. Fiber optic cable d. All of these 4. To couple a coaxial line to a parallel wire line, it is best to use a _____ a. Slotted line b. Directional coupler c. Balun d. All of these 5. Impedance inversion may be obtained with a. An open circuited stub b. A short circuited stub c. A quarterwave line d. A half-wave line 6. To be properly matched, the ratio of maximum to minimum voltage along a transmission line should be equal to a. 50 b. 10 c. 2 d. 1 7. When ZL ≠ Zo, the powersent down the line toward the load is called the a. The incident power b. The reflected power c. The power dissipation d. The carrier power 8. For transmission line load matching over a range of frequencies, it is best to use a a. Balun b. Broadband directional coupler c. Double stub d. Single adjustable stub 9. A short section of a transmission line, open or shorted that is used to match the impedance of the line to that of an antenna or transmitter. a. Slotted line b. Stub c. Wavetrap d. Lecher wire 10. The property of a material that determines how much electrostatic energy can be stored per unit volume when voltage is applied a. Permeability b. Magnetic effect c. Capacitance d. Permittivity 11. The value of the total opposition of the transmission media to the flow of electromagnetic field energy is called a. Characteristic impedance b. Velocity factor c. Standing waves d. Reflected waves 12. When mismatch is great, this power actually cause damage to the transmitter or the line itself. a. The incident power b. The reflected power c. The power dissipation d. The carrier power 13. What is the velocity factor for non-foam dielectric 50 or 75 ohm flexile coaxial cable such as RG 8, 11, 58 and 59? a. 270 b. 0.10 c. 0.66 d. 0.30 14. The measure of the superiority of a material over a vacuum as a path for magnetic lines of force is a. Permittivity b. Permeability c. Conductivity d. Resistivity 15. The number of standing waves on the wire is equal to the length of the wire divided by a half wavelength. The principle which allows antennas to operate at different frequencies which are integral multiples of the fundamental frequency is called_______. a. Harmonic operation b. Decimonic operation c. Electromagnetic reverberation d. Asynchronous operation 16. A coax line has an attenuation of 2.4 dB per 100 ft. the attenuation for 2.75 ft. is _____ dB. a. 2.4 b. 4.8 c. 3.3 d. 6.6 17. When a quarter wave stub is used to match a 600 ohm antenna to aline of 52 ohms, the impedance of the matching stub must be ____ ohms. a. 176 b. 200 c. 150 d. 300 18. The characteristic impedance of a transmission line is determined by a. Its length b. Its height above ground c. Its physical construction d. The operating frequency 19. When the diameter of two conductors of a two-wire transmission line is held constant, the effect of decreasing the distance between the conductors is to a. Decrease the impedance b. Increase the surge impedance c. Increase the radiation resistance d. Decrease SWR 20. Considering a coaxial transmission line, maximum voltage on the line divided by the minimum voltage equals the a. Characteristic impedance b. ISWR c. VSWR d. Inductive reactance 21. In a transmission line, if the SWR or maximum current to a minimum current ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is a. 1:4 b. 4:1 c. 1:2 d. 2:1 22. Transmission lines are either balanced or unbalanced with respect to a. Negative terminal b. Input c. Ground d. Positive terminal 23. The load is properly matched with the transmission line if the standing wave ratio is equal to a. 50 b. 10 c. 5 d. 1 24. The radiation resistance of a quarterwave antenna is a. 49 ohms b. 288 ohms c. 72 ohms d. 144 ohms 25. A radio transmission line of 500 ohms impedance is to be connected to an antenna having an imepedance of 200 ohms. What is the impedance of a quarter wave matching line? a. 300 b. 316 c. 316.5 d. 361 26. The VSWR for a line terminated in its Zo is a. 0 b. 1 c. 1.5 d. Infinity 27. Which of the following is used to measure SWR? a. Multimeter b. Reflectometer c. Spectrum analyzer d. Oscilloscope 28. A 75 – j50 ohm load is connected to a coaxial transmission line of Zo = 75 ohms at 10 GHz. The best method of matching consists in connecting a. A short circuited stub at the load b. A capacitance at some specific distance from the load c. An inductance at the load d. A short-circuited stub at some specific distance from the load 29. For a two-wire line, Zo is higher when a. The wire size is small with respect to the spacing of the conductors b. The spacing is varied in accordance with the frequency c. The D:d ratio is smaller d. The wire is large with respect to the spacing of the conductors 30. A resultant wave due to the combination of incident and reflected wave a. Electromagnetic wave b. Sine wave c. Standing wave d. Current 31. For transmission line load matching over a range of frequencies, it is best to use a a. Balun b. Broadband directional coupler c. Double stub d. Single stub 32. If the load impedance matches the characteristic impedance of the line, there are _____ standing waves. a. More b. Less c. No d. Ten(10) 33. VSWR stands for a. Voltage sending wave ratio b. Voltage receiving wave ratio c. Very small wave radiation d. Voltage standing wave ratio 34. Reflections on a transmission line can occur when a. Impedance of the source and load are matched b. Impedance of the source and the load are mismatched c. Resonance conditions are obtained d. Power transfer between source and load is maximum 35. A transmission line with characteristic impedance (Zo) of 300 ohms is terminated in a resistance load (RI). If by measurement, the minimum and maximum voltage through the load are 12 and 20 micro volts, respectively, what is the SWR? a. 1.67 b. 0.6 c. 6.7 d. 3.67 36. A measure of the mismatched between line and load impedance is called as a. Reflection coefficient b. Standing wave ratio c. Loss d. Standing waves 37. Transmission lines when connected to antenna have a. Capacitive load b. Resistive load whose resistance is less than characteristic impedance c. Resistive load at the resonant frequency d. Resistive load whose resistance is greater than the characteristic impedance of the line 38. At matched condition, SWR is equal to a. Zero b. One c. 100 d. Infinite 39. An HF transmission line has a characteristic impedance of 600 ohms and is terminated by an antenna. The SWR along the line when the antenna impedance is 500 ohms is a. 1.2:1 b. 1:2.1 c. 2:1 d. 1:2 40. A characteristic of an infinite transmission line is that a. The impedance in equals impedance out b. It carries waves at the velocity of light c. It can be connected to mismatched loads d. The impedance varies with the length of the line 41. A quarter wave transmission line shorted at the end: a. Has the characteristics of parallel tuned circuit b. Has the characteristics of a series tuned circuit c. Has a minimum current at the end d. Reflects a low impedance to the supply 42. The outer conductor of a coaxial transmission line is usually grounded at the: a. Input and output b. Output only c. Input only d. Point of infinite resistance 43. A certain feedline has a high SWR. It can be caused by: a. An impedance mismatched b. Use of non-resonant line c. Matching the load to the line d. Excessive transmitter output 44. If the input impedance of an antenna is 300 ohms and it is fed with a 600 ohm balanced transmission line, the SWR on the line is a. 4 b. 3 c. 2 d. 0.5 45. A radio transmission line of 300 ohms impedance to be connected to an antenna having an input impedance of 150 ohms. The impedance if a quarter wave matching line is ___ ohms a. 212 b. 450 c. 600 d. 150 46. The ratio of the reflected voltage to the incident voltage on the transmission line is termed as a. Reflection coefficient b. Standing wave ratio c. Loss d. Standing waves 47. Indicate the three types of transmission line energy losses a. Radiation, I(squared) R and dielectric Heating b. Conductor heating, dielectric heating and radiation resistance c. I(squared)R, RL and temperature d. Dielectric separation insulation breakdown and radiation 48. Termination means a. Load connected to the output end of a transmission line b. Result of disconnecting a line from a transmitter c. Looking back impedance of a line with no load d. Result of cutting both ends of a conductor 49. When transmission line uses ground return, it is called a/n _____ line. a. Ungrounded b. Unbalanced c. Grounded d. Balanced 50. Permeability is the measure of superiority of a material over a vacuum as a path of magnetic lines of force. The permeability of free space is equal to _____ henry/meter a. 1.257 x 10-6 b. 1.527 x 10-6 c. 7.251 x 10-6 d. 5.217x10-6 51. The most commonly used transmission line is a a. Two-wire balanced line b. Single line c. Three-wire line d. Coax 52. The characteristic impedance of a transmission line does not depend upon its a. Length b. Conductor diameter c. Conductor spacing d. Thickness of armor 53. What is the impedance of a balance 4-wire with a diameter of 0.25cm and spaced 2.5 cm apart using an insulator with a dielectric constant of 2.56? a. 100 ohms b. 65 ohms c. 75 ohms d. 50 ohms 54. It is required to match a 73-ohm antenna to a 600 ohm polyethylene coaxial feeder line, with a velocity factor of 0.66 by means of a quarter wave matching a transformer. At a frequency of 150MHz, the impedance of the matching section is____ ohms. a. 209.28 b. 310.5 c. 150.28 d. 450.82 55. If the terminating impedance is exactly equal to the characteristic impedance of the transmission line, the return loss is____ a. Zero b. Infinity c. One d. Negative 56. The characteristic impedance of a transmission line is the impedance measured at the ____ when its length is infinite. a. Shorted end of the line b. Midsection c. Input d. Output 57. The characteristic impedance of a transmission line is 70 ohms and has a load of 35 ohms. The SWR and reflection coefficient are _____ and _____ respectively a. 2 and 0.333 b. 1 and 0.666 c. 2 and 0.666 d. 1 and 0.333 58. It is required to match a 200 ohm load to a 300 ohm transmission line to reduce the SWR and attain resonace. A quarter wave transformer used, directly connected to the load has a Zo of ____ ohms. a. 245 b. 425 c. 524 d. 254 59. What quarter wave transformer will match a 100 ohm-lne to an antenna whose value is 175 ohms? a. 150 ohms b. 137.5 ohms c. 132.29 ohms d. 16.58 ohms 60. The mismatch between antenna and transmission line impedance cannot be corrected by a. Using an LC network b. Adjusting antenna length c. Using a balun d. Adjusting the length of the transmission line 61. A pattern of voltage and current variation along a transmission line not terminated in ints characteristic impedance is called a. An electric field b. Radio waves c. Standing waves d. Magnetic field 62. The most desirable value of SWR on a transmission line is a. 0 b. 1 c. 2 d. Infinity 63. In transmission lines, the most desisrable reflection coefficient is a. Zero b. 0.5 c. 1 d. Infinity 64. At very high frequencies, transmission lines are used as _____. a. Tuned circuits b. Antennas c. Insulators d. Resistors 65. What is the reflection coefficient of a 100 ohm characteristic impedance line and a 300 ohm load? a. 0.25 b. 0.3 c. 0.5 d. 0.75 66. The minimum voltage along a transmission line is 260 volts, while the maximum is 390 volts. The SWR is a. 0.67 b. 1.0 c. 1.2 d. 1.5 67. A single conductor running from the transmitter to the antenna a. RG-8/U b. Single line wire c. Twin-lead d. Microstrip 68. What characteristic impedance is needed to match a 50-ohm line to a 300 ohm-load? a. 221 ohms b. 122 ohms c. 212 ohms d. 112 ohms 69. Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in a. Short circuit b. A complex impedance c. An open circuit d. A pure reactance 70. A (75 – j50) Ω load is connected to a coaxial transmission line of Zo = 75 Ω at 10 GHz. The best method of matching consists in connecting a. A short circuited stub b. An inductance at the load c. A capacitance at some specific distance from the load d. A short circuited stub at some specific distance from the load 71. The velocity factor of a transmission line a. Depends on the dielectric constant of the material used b. Increases the velocity along the transmission line c. Is governed by the skin effect d. Is higher for a solid dielectric than for air 72. What is the characteristic impedance of a single wire with diameter d=0.25mm placed at the center between grounded parallel planes separated by 1mm apart. The wire is held by a material with a velocity factor of 0.75 a. 85 ohms b. 63 ohms c. 50 ohms d. 75 ohms 73. Coaxial lines are used on those system operating ________. a. Below 2 GHz b. At 300 MHz c. Above 10 KHz d. Above 10 GHz 74. Referred to the dielectric constant of a transmission line material a. Inductance and capacitance b. Velocity factor c. Characteristic impedance d. Propagation velocity 75. The main advantage of the two-hole directional coupler is a. Low directional coupling b. Poor directivity c. High SWR d. Narrow bandwidth 76. To couple a coaxial line to a parallel-wire line, it is best to use a a. Slotted line b. Balun c. Directional coupler d. Quarter-wave transformer 77. What is the meaning of the term velocity factor of a transmission line? a. The index of shielding for coaxial cable b. The velocity of the wave on the transmission line multiplied by the velocity of light in a vacuum c. The ratio of the characteristic impedance of the line to the terminating impedance d. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum 78. A transmission line consisting of two conductors that have equal resistance per unit length. a. Unbalance line b. Open-wire line c. Balanced line d. Coaxial line 79. Which if the following is not a common transmission line impedance? a. 50 Ω b. 75 Ω c. 120 Ω d. 300 Ω 80. For a maximum absorption of power at the antenna, the relationship between the characteristic impedance of the line Zo and the load impedance Zl should be a. Zo = ZL b. Zo > ZL c. Zo < ZL d. Zo = 0 81. Which of the following determines the characteristics of a transmission line? a. Inductance b. Capacitance c. Physical dimensions d. Length 82. In the study of transmission cable, twin lead is also referred to as a ______. a. Twisted pair b. Double cable c. Ribbon cable d. Open pair 83. A 50 Ω coax is connected to a 73 Ω the SWR is a. 0.685 b. 1 c. 1.46 d. 2.92 84. A ratio expressing the percentage of incident voltage reflected on a transmission line is known as the a. Velocity factor b. Standing-wave ratio c. Reflection coefficient d. Line efficient 85. Three feet is one wavelength at a frequency of a. 100 MHz b. 164 MHz c. 300 MHz d. 328 MHz 86. An open quarter-wave line at the operating frequency acts like a(n) a. Series resonant circuit b. Parallel resonant circuit c. Capacitor d. Inductor 87. A shorted half-wave line at the operating frequency acts like a(n) a. Capacitor b. Inductor c. Series resonant circuit d. Parallel resonant circuit 88. At UHF and microwave frequencies, transmission lines are commonly used as a. Antenna b. Coupler c. Resonant circuit d. Transformer 89. The transmission medium subjects the transmitted signal to be a. Modulated b. Amplified c. Attenuated d. Boosted 90. Transmission line is a two-wire cable that connects the transmitter to the antenna or the antenna to the receiver. The purpose of the transmission line is to a. Amplify the RF signal b. Modulate the signal c. Carry the RF energy for the desired distance d. All of the above 91. These conductors are uniformly spaced by insulators. They have low losses at low medium frequencies and are economical to construct and maintained a. Coaxial cables b. Open-wire transmission lines c. Optical cables d. Waveguides 92. To prevent radiation losses and interference from external sources, the inner conductor of this transmission line is completely enclosed with a metal sheath or braid a. Coaxial cable b. Open-wire transmission lines c. Optical cables d. Waveguides 93. The term “balanced line” means that a. Both conductors carry currents that flow in opposite directions b. Conductors present equal capacitance to ground c. One conductor is connected to ground d. Both A and B 94. The characteristic impedance of a transmission line is determined by: a. Its operating frequency b. Its length c. Its physical size and arrangement d. The signal applied at the input terminal 95. The disturbance parameters of the transmission line are: the series resistance; the series inductance; the shunt capacitance and the shunt conductance. What parameter was determined due to dielectric losses? a. Series resistance b. Series inductance c. Shunt capacitance d. Shunt conductance 96. Shunt capacitance was determined due to: a. Conductors were closed to each other b. The length and diameter of the conductors c. Dielectric loses d. Flux linkages 97. Series resistances was determined due to: a. Conductors were closed to each other b. The length and diameter of the conductors c. Dielectric losses d. Flux linkages 98. At radio frequencies was determined due to: a. Characteristic b. Inductive reactance is much larger than the shunt conductance c. Capacitive reactance is much larger than the shunt conductance d. Both b and c 99. Determine the characteristic impedance of a transmission line which has a capacitance of 30 pF/m and an inductance of 75 nH/m a. 5 Ω b. 50 Ω c. 500 Ω d. 5 K Ω 100. If a charge in the dielectric material decreases the capacitance, the characteristic impedance is a. Kept constant b. Decreased c. Increased d. Halved Wave Propagation Multiple choice. Encircle the letter which corresponds to your answer. 1. Whether or not polarization of an antenna is linear depends on changes in direction in which: a. The direction in which the electric plane is radiated. b. The horizontal or vertical plane of the electric wave. c. The direction in which magnetic wave is radiated. d. None of these 2. The D, E and F layers of the ionosphere are called a. Mark-Space Layers b. Davidson-Miller Layers c. Kenelly Heaviside Layers d. Maxwell Layer 3. ________ refers to the ratio of an electric field component to a magnetic field component at the same point of the wave. a. Characteristics impedance b. Load impedance c. Intrinsic impedance d. Wave impedance 4. The field strength of a radio signal varies according to the output or transmitted power and the distance of the receiver from the transmitter. This wave behavior is described by a. The field strength b. Huygen’s Principle c. Faraday’s Law d. Inverse Square Law 5. The antenna theory states that reception and transmission functions are interchangeable is a. Poynting Theorem b. Snell’s Law c. Huygen’s Principle d. Law of Reciprocity 6. The frequency band where electromagnetic waves travel in straight path or in a direct line of sight between the transmitter and receiver antenna is a. ELF b. HF c. VLF d. VHF and above 7. This mode of electromagnetic wave propagation uses the earth’s surface or curvature as a guide to transmit vertically polarized waves a. Sky wave b. Tropospheric wave c. Transionospheric wave d. Ground wave 8. Frequencies in the UHF range propagate by means of a. Ground waves b. surface waves c. sky waves d. space waves 9. the ground wave eventually disappear as it moves farther away from the transmitter, because of a. tilting b. reflection c. refraction d. diffraction 10. as electromagnetic waves travel in free space, only one of the following can happen a. absorption b. attenuation c. refraction d. reflection 11. In polarization diversity, two signals are a. Both polarized at one specific loacation b. Vertically and horizontally polarized separately c. Polarized in the same manner d. Vertically and horizontally polarized using a common antenna 12. If the direction of the electric field of a radio wave is horizontal. That wave is known to be _____ polarized. a. Negatively b. Vertically c. Positively d. Horizontally 13. The property of a material that determines how much change electrostatic energy can be stored per unit volume when voltage is applied a. Miller effect b. Permeability c. Capacitance d. Permitivity 14. According to this law or principle, a wavefront may be considered to consist of an infinite number of isotropic radiators, each one sending out wavelets, always away from the source. a. Snell’s Law b. Maxwell’s Law c. Huygen’s Principle d. Archimedes Principle 15. A number, which when multiplied by the speed of light in free space gives the speed of light in the medium in question is a. Fibonacci number b. Fermat’s number c. Velocity factor d. K-factor 16. The ability of a radio wave to be bent slightly over the edge of a sharp obstacle such as a steep hill or mountain top is a. Diffraction b. Reflection c. Refraction d. Attenuation 17. A space wave is a. Sky wave b. Radio wave c. Surface wave d. Line of sight propagation wave 18. It is a diagram indicating the intensity in volts/meter, in all directions, of the radiated filed of an antenna as it would occur under actual operating conditions. a. Constellation diagram b. Argand diagram c. Funicular diagram d. Radiation pattern 19. Equivalent to capacitance in electrical circuits a. Inductance b. Permittivity c. Permeability d. Power density 20. All of these cause attenuation except a. Tilting b. Ground absorption c. Atmospheric absorption d. Surface wave propagation 21. The transmission of radio waves far beyond line of sight distances by using high power and large transmitting antennas to beam the signal upward into the atmosphere and a similar large receiving antenna to pick up a small portion of the signal scattered by the atmosphere is called a. Forward scatter propagation b. Beyond the horizon propagation c. Either a or b d. Meteoric Scatter Propagation 22. The apparent height of an ionized layer of the atmosphere; as determined from the time interval between the transmitted signal and the ionospheric echo at vertical incidence. This height is the maximum height reached if the actual paths are projected forming straight lines from the ascent to the descent of waves. a. Optimum height b. Virtual height c. Complex height d. Critical height 23. The highest frequency whereby a wave will be returned back to earth by an ionospheric layer having been beamed up at it and ranges from 5 to 12 MHz. For F2 layers. This frequency is directly proportional to the secant function of the smallest angle, which allows reflection of sky waves. a. Apex frequency b. Critical frequency c. Carrier frequency d. Baseband frequency 24. The distant at which sky-wave signals are reflected back to earth depend on a. Height of the reflecting layer b. The takeoff angle of the waves c. Both a and b d. Conductivity of the soil 25. Perfect reflection of waves occur when a. The magnitude of the incident is equal to the reflected waves b. The magnitude of the incident is less than the reflected waves c. The magnitude of incident is greater than reflected waves d. Both and b 26. The process by which a radio wave is bent and returned to earth from one medium to another after striking them is a. Reflection b. Refraction c. Diffraction d. Absorption 27. An incident, traveling obliquely from one medium to another, will undergo a change in direction if the velocity of the wave in one medium is different from that in the other and the ratio of the sine of the angle of incidence to the sine of the angle of refraction is the same ratio of respectively wave velocities in these media. This law is called a. Snell’s Law b. Fisher’s Law c. Hooke’s Law d. Newton’s Law 28. The lowest layer of the ionosphere which exists between 50 to 90 km from the earth’s surface and reflects VLF and LF waves while absorbing MF and HF waves during daytime is the a. D layer b. E layer c. F layer d. Vantress layer 29. This phenomenon occurs when the thicker air is on top instead of being at the bottom when the temperature of water vapor gradient is lesser or greater than the standard rate. a. Thermal inversion b. Horizontal ducting c. Elevated ducting d. Sporadic E 30. An ionospheric layer, which exists between 90 to 120 km above the earth’s surface and is about 25km thick. It aids MF surface propagation while reflecting some HF during daytime a. D-layer b. E-layer c. F layer d. Vantress layer 31. Atmospheric condition is controlled by a. Pressure b. Temperature c. Humidity d. All of these 32. This ionospheric layer forms at night at about 300 km from the earth’s surface and is responsible for long distance HF wave propagation due to reflection and refraction. It splits during daytime due to the ionizing energy from ultraviolet rays of the sun. a. D layer b. E layer c. F layer d. Vantress layer 33. When the transmitting and receiving antennas are line-of-sight of each other, the mode of propagation is _____ wave. a. Space or direct b. Sky c. surface d. ground 34. Power density is inversely proportional to the square of the distance from the source or transmitter to the destination or receiver. This law is called: a. Coulomb’s law b. Law of Universal Gravitation c. Inverse Square Law d. Lenz’s Law 35. A one-hop, full duplex, microwave system is in a space diversity arrangement. Determine how many receivers in all are used? a. 6 b. 2 c. 8 d. 4 36. ________ is the extra ionization of the E-layer resulting to irregular and intermittent reflection of frequencies of up to 80 MHz in temperate and lower latitudes of frequencies of up to 80MHz in temperate and lower latitudes. It is variable in time of occurrence, height. Geographical distribution, penetration frequency and ionization density. a. Sporadic E b. Dillinger Effect c. Faraday rotation d. Scintillations 37. The decrease in signal strength as a result of absorption or scattering of energy along a transmission path is called: a. Attenuation b. Microbending c. Dispersion d. Multipath fading 38. The transfer of electromagnetic waves or acoustical energy from one place to another through a suitable transmission medium is a. Wave propagation b. RF induction c. Radio Frequency Interference d. Forward Scatter 39. The upper limit of frequencies that can be used at a specified time for radio transmission between two points and involving propagation by reflection from regular ionized layers of the ionosphere is a. Maximum usable frequency b. Optimum traffic frequency c. Minimum usable frequency d. Carrier frequency 40. Waves whose oscillations are perpendicular to the direction of propagation are called a. Huygen’s waves b. Transverse waves c. Longitudinal waves d. Fraunhoffer waves 41. Indicate which one of the following terms applies to troposcatter propagation: a. SIDs b. Fading c. Atmospheric storms d. Faraday rotation 42. VLF waves are used for some types of services because a. Of the low power required b. The transmitting antennas are of convenient size c. They are very reliable d. They penetrate the ionosphere easily 43. High frequency waves are a. Absorbed by the F2 layer b. Reflected by the D layer c. Capable of use for long-distance communications on the moon d. Affected by the solar cycle 44. Distances near the skip distance should be used for sky-wave propagation a. To avoid tilting b. To prevent sky-wave and upper ray interference c. To avoid the faraday effect d. So as not to exceed the critical frequency 45. The ground wave ecentually disappears, as one moves away from the transmitter, because of a. Interference from the sky wave b. Loss of line of sight conditions c. Maximum single-hop distance limitation d. Tilting 46. In electromagnetic waves, polarization a. Is caused by reflection b. Is due to the transverse nature of the waves c. Results from the longitudinal nature of the waves d. Is always vertical in an isotropic medium 47. Radio fading resulting from obstruction losses. a. Log normal fading b. Rayleigh Fading c. Multi-path fading d. None of these 48. The absorption of radio waves by the atmosphere depends on a. Their frequency b. Their distance from the transmitter c. The polarization of the waves d. The polarization of the atmosphere 49. Electromagnetic waves are refracted when they a. Pass into a medium of different dielectric constant b. Are polarized at right angles to the direction of propagation c. Encounter a perfectly conducting surface d. Pass through a small slot in a conducting plane 50. Diffraction of electromagnetic waves a. Is caused by reflection from the ground b. Arises only with spherical wavefronts c. Will occur when the waves pass through a large slot d. May occur around the edge of a sharp obstacle 51. What do you call of the travel of electromagnetic waves through a medium at the speed of light? a. RF propagation b. Radio propagation c. Wave propagation d. All of these 52. Electromagnetic waves are a. Consist of electric and magnetic component that are parallel to each other b. Oscillations that propagate through free space c. Irregular oscillations d. Oscillations that are produced by an oscillating circuit 53. The region around an electrically charged body in which other charged bodies are acted by an attracting or repelling force. a. Electric field b. Radiation field c. Magnetic field d. Electromagnetic field 54. What are the two components of electromagnetic field? a. Ray and wavefront b. Magnet and electricity c. Polar electrons and magnetic field d. Electric field (E-field) and magnetic field 55. Shows a surface of constant phase of a wave and is formed when points of equal phase on rays propagated from the source are joined together. a. Ray b. Wavefront c. Point source d. Isotropic source 56. It is a line drawn along the direction of propagation of an electromagnetic wave used to show the relative direction of electromagnetic wave propagation. a. Ray b. Wavefront c. Point source d. Isotropic source 57. Refers to the rate at which energy passes through a given surface area in free space a. Field intensity b. Power density c. Refractive index d. Absorption coefficient 58. It it’s the intensity of the electric and magnetic fields of an electromagnetic wave propagating in free space a. Field intensity b. Power density c. Refractive index d. Absorption coefficient 59. In a lossless transmission medium, _______ of free space is equal to the square root of the ratio of its magnetic permeability to its electric permittivity a. Resistance b. Field intensity c. Characteristic impedance d. A or C is correct 60. Electromagnetic wave measures all except a. Inductance b. Power density c. Magnetic field intensity d. Permittivity of the medium 61. A reduction in power density due to the inverse square law presumes free-space propagation is called a. Absorption b. Wave attenuation c. Space attenuation of the wave d. B or C is correct 62. Which of the following are optical effects of radio waves? a. Refraction and reflection b. Diffraction and interence c. Induction and diffraction d. A and B 63. What is diffraction? a. Is the change in direction of a ray as it passes obliquely from one medium to another with different velocities or propagation b. Refers to the modulation or redistribution of energy within a wavefront when it passes near the edge of an opaque object c. Is the phenomenon that allows light or radio waves to travel(peek) around corners of an obstacle. d. A or C is right 64. A rare refracting medium has a. Smaller value of dielectric constant b. Higher value of dielectric constant c. Variable value for dielectric constant d. A dielectric constant dependent on the medium 65. Refractive index refers to a. The ratio of velocity of light in free space to the velocity of light in a given material b. The ratio of the light in free space towards the light in a given medium c. The ratio of the angle of refraction d. The amount of bending or refraction that occurs at the interface of two material of different densities 66. Why is it that rays traveling near the top of the medium travel faster than those at the bottom? a. The medium is more dense near the bottom b. The medium is less dense at the top c. A and B are incorporated d. The medium is less dense near the bottom and more dense at the top 67. When does reflection if wave occur? a. When an incident wave strikes a boundary of two media, and some of the incident power does not enter the second material b. When the reflective surface is irregular or rough c. When two or more electromagnetic waves combine in such a way that the system performance is degraded. d. A and B 68. What is meant by specular reflection? a. Is a reflection from a perfectly smooth surface b. Is an incident wavefront striking an irregular surface, randomly scattered in many directions c. Reflection of surfaces that fall between smooth and irregular d. Is a combination of diffused and semirough surfaces 69. ________ states that a semirough surface will reflect as if it were a smooth surface whenever the cosine of he angle of incidence is greater than 1/8d, where d is the depth of the surface irregularity and I is the wavelength of the incident wave. a. Rayleigh criterion b. Huygen’s principle c. Linear superposition d. Reflection coefficient 70. Energy that has neither been radiated into space nor completely transmitted a. Modulated waves b. Captured waves c. Standing waves d. Incident waves 71. What property of radio waves occurs whenever two or more waves simultaneously occupy the same point in space? a. Reflection b. Refraction c. Diffraction d. Interference 72. Pertains to a source which radiates equally in all directions a. Isobaric source b. Isotropic source c. Isentropic source d. Isothermal source 73. Electromagnetic waves travel at _____ in free space a. 300,000 km/sec b. 200 km/sec c. 400,000 km/sec d. 100,000 km/sec 74. Any space or region wherein a magnetic force is exerted on moving electric charges a. Electric field b. Radiation field c. Magnetic field d. Electromagnetic field 75. Which of the following is a characteristic of electromagnetic wave? a. Measures power, voltage, capacitance and impedance of a system b. Measures power density, voltage, and inductance c. Measures power density, magnetic field intensity, and electric field intensity d. All of the above 76. Reflection waves a. Should take place at one medium b. Does not necessarily take place at one medium c. Occurs at any other medium at the same time d. Is not possible 77. Way(s) of propagating electromagnetic waves: a. Ground-wave propagation b. Space wave propagation c. Sky-wave propagation d. All of these 78. At frequencies below 1.5 MHz, what propagation provides the best coverage? a. Ground wave b. Space wave c. Sky wave d. All of these 79. Which of these causes the wavefront to tilt progressively forward? a. Gradient density b. Electric field intensity c. Absorption coefficient d. Magnetic field intensity 80. Which of following of must be taken into consideration to ensure proper ground-wave propagation? a. Power b. Terrain c. Frequency d. B and C 81. What are the applications of ground–wave propagation? a. Ship-to-ship and ship-to-shore communications b. Maritime mobile communications c. Radio navigation d. All of these 82. The curvature of the earth presents a horizon to space wave propagation which is approximately 4/3 that of the optical horizon a. Standard atmosphere b. Optical horizon c. Radio horizon d. All of these 83. Refraction is caused by what factors? a. Changes in troposphere’s density and temperature b. Water vapor content c. Relative conductivity d. All of the above 84. Any of the flowing can be caused to lengthen radio horizon: a. Elevating the transmit or receive antennas above Earth’s surface b. Elevating both antennas c. Installing the transmit and/or receive antennas on top of mountains or high buildings d. All of these 85. A special condition which occurs when the density of the lower atmosphere is such that electromagnetic waves are trapped between it and earth’s surface a. Duct propagation b. Sky wave propagation c. Space wave propagation d. Ground wave propagation 86. The vibrating electrons at the ionosphere decrease current which is equivalent to reducing the dielectric constant, which in turn, will also cause the velocity of propagation to______. a. Increase b. Decrease c. Remain constant d. Decrease by a factor of 2 87. Increasing the velocity of propagation causes a/an _____ of the electromagnetic waves. a. Increasing refraction b. Decreasing reflection c. Increasing diffraction d. Decreasing interference 88. What layer has its maximum density at approximately 70 mi a noon, when the sun is at its highest point? a. D layer b. E layer c. Kennelly-Heaviside layer d. B or C 89. The sporadic E layer is a thin layer with a very high ionization density. It is considered separately from the other layers and when it appears, gives an unexpected improvement in long distance radio transmissions. What cause(s) its unpredictable appearance? a. Sunspot activity b. Sunspot cycle c. Solar flares d. A and C 90. The region in the ionosphere with a very high ionization density at roughly 55 to 90 miles and is used for frequencies up to about 20 MHz. It is gone completely at midnight. a. D layer b. E layer c. F layer d. G layer 91. A layer in the ionosphere which is the most important reflecting medium fir HF radio waves. It has 2 sublayers, at 90 to 250 mi height a. A layer b. D layer c. E layer d. F layer 92. The apparent height og the ionized layer and is always greater than the actual height a. Critical height b. Virtual height c. Maximum height d. Imaginary height 93. Refers to the shortest distance in which a sky-wave signal will be returned to the earth. It includes the maximum ground-wave range and the width of the skip zone. a. Hop b. Skip distance c. Actual distance d. Critical distance 94. Concerns to the highest frequency that is able to return to earth when beamed at a certain angle of incidence a. Relative frequency b. Optimum frequency c. Resonant frequency d. Maximum usable frequency, muf 95. In ________, the distant of each succeeding hop from earth to ionosphere and back is also the skip distance. a. Hop transmission b. Single transmission c. Unihop transmission d. Multihop transmission 96. Concerns to the single reflection of a radio wave form the ionosphere back to earth. a. Jog b. Hop c. Skip d. Fading 97. The fluctuation of signal strength at the receiver that are caused by changes in the transmission medium a. Fading b. Hopping c. Skipping d. Diversity 98. Gradual variation in the field strength of a radio signal is compensated by a. Fading techniques b. Diversity techniques c. Transverse techniques d. Transmission techniques 99. A modulation of two different RF carrier frequencies with the same IF intelligence, then transmitting both RF signals to a given destination. a. Diversity b. Space diversity c. Frequency diversity d. Polarization diversity 100. To increase the availability of the system, a method in which the output of a transmitter is fed to two or more antennas that are physically separated by an appreciable number of wavelengths. a. Space diversity b. Frequency diversity c. Polarization diversity d. Space wave propagation COMMUNICATIONS ENGINEERING PART 6 ANTENNAS 1. An ungrounded antenna near the ground a. Acts as a single antenna of twice the height b. Is unlikely to need an earth mat c. Acts as an antenna array d. Must be horizontally polarized 2. One of the following consists of nonresonant antennas: a. The rhombic antenna b. The folded dipole c. The end-fire array d. The broadside array 3. One of the following is very useful as a multiband HF receiving antenna. This is the: a. Conical horn b. Folded dipole c. Log-periodic d. Square loop 4. Which of the following antennas is best excited from a waveguide? a. Biconical b. Horn c. Helical d. Discone 5. Indicate which of the following reasons for using a counterpoise with antennas is false: a. Impossibility of a good ground connection b. Protection of personnel working underneath c. Provision of an earth for the antenna d. Rockiness of the ground itself 6. One of the following is not a reason for the use of an antenna coupler: a. To make the antenna look resistive b. To provide the output amplifier with the correct load impedance c. To discriminate against harmonics d. To prevent reradiation of the local oscillator 7. Indicate the antenna that is not wideband a. Discone b. Folded dipole c. Helical d. Marconi 8. Indicate which one of the following reasons for the use of an earth mat with antennas is false: a. Impossibility of a good ground connection b. Provision of an earth for the antenna c. Protection of personnel working underneath d. Improvement of the radiation pattern of the antenna 9. Show which of the following terms does not apply to the Yagi-Uda array a. Good bandwidth b. Parasitic elements c. Folded dipole d. High gain 10. An antenna that is circularly polarized is the a. Helical b. Small circular loop c. Parabolic reflector d. Yagi-Uda 11. The standard reference antenna for the directive gain is the a. Infinitesimal dipole b. Isotropic antenna c. Elementary doublet d. Half-wave dipole 12. Top loading is sometimes used with an antenna in order to increase its a. Effective height b. Bandwidth c. Beamwidth d. Input capacitance 13. Cassegrain feed is used with a parabolic reflector to a. Increase the gain of the system b. Increase the beamwidth of the system c. Reduce the size of the main reflector d. Allow the feed to be places at a convenient point 14. Zoning is used with a dielectric antenna in order to a. Reduce the bulk of the lens b. Increase the bandwidth of the lens c. Permit pin-point focusing d. Correct the curvature of the wavefront from a horn that is too short 15. A helical antenna is used for satellite tracking because of its a. Circular polarization b. Maneuverability c. Broad bandwidth d. Good front-to-back ratio 16. The discone antenna is a. A useful direction-finding antenna b. Used as a radar receiving antenna c. Circularly polarized like other circular antennas d. Useful as a UHF receiving antenna 17. One of the following is not omnidirectional antenna a. Half-wave dipole b. Log-periodic c. Discone d. Marconi 18. The polarization of a discone antenna is ______________. a. Horizontal b. Vertical c. Omni d. Directional 19. _____________ is the horizontal pointing angle of an antenna. a. Right angle b. Angle of elevation c. Bandwidth d. Azimuth 20. Which is a properly terminated antenna? a. Rhombic b. Hertz c. Marconi d. Dipole 21. ____________ is a device that detects both vertically and horizontally polarized signals simultaneously. a. Crystal b. Orthomode transducer c. Light transducer d. Optoisolator 22. How much does the radiated power of an antenna increases if its current increased by 3.3 times? a. 6.6 times b. 3.3 times c. 10.89 times d. 9.9 times 23. What do you call the energy that was not radiated into space or completely transmitted? a. Incident waves b. Captured waves c. Standing waves d. Modulated waves 24. What is the estimated medium wind loading in the Philippines for antenna tower design? a. 200 kph b. 250 kph c. 300 kph d. 100 kph 25. The minimum number of turns a helix antenna must have a. 4 b. 5 c. 3 d. 6 26. When testing transmitter to prevent interfering with other stations, which type of antenna must be used? a. Dummy antenna b. Herztian antenna c. None d. Void antenna 27. A device that radiates electromagnetic energy and/or intercepts electromagnetic radiation a. Antenna b. Transmitter c. Transmission line d. Transceiver 28. Determine the gain of a 6 ft parabolic dish operating at 1800 MHz a. 15.5 dB b. 30 dB c. 11.2 dB d. 28.17 dB 29. Radiation characteristic of a dipole a. figure of eight b. omnidirectional c. bi-directional d. unidirectional 30. An antenna which is not resonant at particular frequencies and so can be used over a wide band of frequencies is called a. Aperiodic b. Cassegrain c. Top-loaded d. Boresight 31. Two wires that are bent 90 degrees apart. a. Rhombic b. Hertz c. Dipole d. Log-periodic 32. Harmonic suppressor connected to an antenna a. Tank circuit b. M-derived filter c. Low-pass filter d. High-pass filter 33. Theoretical gain of a Herztian dipole a. 0 dB b. 1.76 dB c. 2.15 dB d. 3 dB 34. A helical antenna is used for satellite tracking because of a. Maneuverability b. Good front-to-back c. Circular polarization d. Broad bandwidth 35. A convenient method of determining antenna impedance a. Reactance circle b. Stub matching c. Smith chart d. Trial and error 36. Unity gain antenna. a. Half-wave dipole b. Rhombic c. Dummy d. Isotropic 37. EIRP stands for ______________________. a. Effective isotropic reflected power b. Effective isotropic refracted power c. Efficient and ideal radiated power d. Effective isotropic radiated power 38. Which of the following refers to the smallest beam of satellite antenna’s radiation pattern? a. Global beam b. Zoom beam c. Spot beam d. Hemispheric beam 39. A region in front of a parabolic antenna a. Transmission zone b. Fraunhofer c. Fresnel d. All of these 40. An antenna that can only receive a television signal. a. Isotropic antenna b. Reference antenna c. TVRO d. Yagi antenna 41. Radiation pattern of a discone a. Figure of eight b. Bi-directional c. Omnidirectional d. Unidirectional 42. Radio wave concentration in the direction of the signal emitted by a directional antenna. a. Back lobe radiation b. Transmitted signal c. Side lobe radiation d. Major lobe radiation 43. The reflector and director of an antenna array are considered as: a. Transcendental elements b. Feed-points c. Driven elements d. Parasitic elements 44. An electronic equipment used to measure standing wave ratio: a. Altimeter b. Multimeter c. Reflectometer d. Wavemeter 45. The product of the power supplied to the antenna and its gain relative to a half-wave dipole in a given direction. a. Rated power b. ERP c. Peak envelope power d. Carrier power 46. What makes an antenna physicaly long electronically short? a. Adding C in series b. Top loading c. Adding L in series d. All of these 47. The capture area of an antenna is directly proportional to the a. Distance between transmitter and receiver b. Power density of the signal c. Gain of the antenna d. Frequency of the received signal 48. A type of an underfrounded antenna is a/an ________________. a. Hertz b. Isotropic c. Parabolic d. Marconi 49. What is meant by antenna gain? a. The ratio of the signal in the forward direction to the signal in the backward direction b. The ratio of the amount of power produced by the antenna compared to the output power of the transmitter c. The final amplifier gain minus the transmission line losses (including any phasing lines present) d. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna 50. It consists of a number of dipoles of equal size, equally spaces along a straight line with all dipoles fed in the same phase from the same source. a. End-fire array b. Yagi antenna c. Log-periodic antenna d. Broadside array 51. A type of array antenna which consists of one half-wave driven dipole, one reflector and one director. a. Log periodic dipole array b. Yagi-uda c. Herztian dipole d. Broadside collinear 52. It is measure of the microwave power radiated from an antenna as a function of angular direction from the antenna axis. a. Polarization b. Sidelobes c. Beamwidth d. Antenna pattern 53. What is the gain of four identically polarized antennas stacked one above the other fed in phase? a. 4 dB over the gain of one antenna b. 10 dB over the gain of one antenna c. 3 dB over the gain of one antenna d. 6 dB over the gain of one antenna 54. Gain of an isotropic antenna. a. 1 dB b. -1 dB c. 0 dB d. 2 dB 55. A dipole antenna requires to be fed with 20 kW of power to produce a given signal strength to a particular distant point. If the addition of a reflector makes the same field strength available with an input power of 11 kW, what is the gain in dB obtained by the use of the reflector? (Gain referred to this particular dipole) a. 4. 75 b. 1.81 c. 4.24 d. 2.6 56. Top loading is used in an antenna in order to increase its __________________. a. Bandwidth b. Beamwidth c. Input capacitance d. Effective height 57. A horizontal antenna is a. Perpendicularly polarized b. Centrally polarized c. Horizontally polarized d. Vertically polarized 58. The frequency of operation of a dipole antenna cut to length of 3.4 m. a. 42.9 MHz b. 53.3 MHZ c. 38.5 MHz d. 61.3 MHz 59. Two or more antennas separated by 9 wavelengths are used. a. Frequency diversity b. Space diversity c. Hybrid diversity d. Polarized diversity 60. A convenient method of determining antenna impedance. a. Trial and error b. Stub matching c. Smith chart d. Reactance circle 61. Width measured in degrees of a major lobe between end of the lobe at which the relative power is one half (-3 dB) its value from the peak of the lobe. a. Radiation b. Wavelength c. Bandwidth d. Beamwidth 62. An increase in the effective power radiated by an antenna in a certain desired direction at the expense of power radiated in other directions. a. Antenna gain b. Antenna efficiency c. Antenna total ratio d. Antenna back lobe ratio 63. Where does the maximum current and minimum voltage value on a resonant Hertz dipole exist? a. Center of the antenna b. Ends of the antenna c. Near the center of the antenna d. Near the end of the antenna 64. How can the antenna efficiency of a HF grounded vertical antenna be made comparable to that of a half-wave antenna? a. By isolating the coax shield from ground b. By installing a good ground radial system c. By shortening the vertical d. By isolating the coax shield from ground 65. Known as the technique for adding a series inductor at or near the center of an antenna element in order to cancel the capacitive reactance of an antenna. a. Reflector b. Center loading c. Dipole d. Loading coil 66. What is meant by the term antenna bandwidth? a. The angle between the half-power radiation points b. The angle formed between two imaginary lines drawn through the ends of the elements c. The frequency range over which an antenna can be expected to perform well d. Antenna length divided by the number of elements 67. Where does the voltage node of a half-wave antenna exist? a. At feed point b. Near the feed point c. Near the center d. At center 68. This is a flexible vertical rod antenna commonly used on mobiles. a. Hertz b. Ground plane c. Whip d. Marconi 69. What is a dummy antenna? a. A non-directional transmitting antenna b. An antenna used for hand-held ratio c. One which is used as a reference for gain measurements d. A non-radiating load for a transmitter used for testing 70. Best description of a collinear and broadside antenna radiation pattern. a. Bidirectional b. Omnidirectional c. Unidirectional d. Perfect circle 71. What is a driven element of an antenna? a. Always the forwardmost element b. Always the rearmost element c. The element fed by the transmission line d. The element connected to the rotator 72. Antenna which is not properly terminated a. Whip b. Non-resonant c. Isotropic d. Resonant 73. At the ends of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna? a. Minimum voltage and maximum current b. Maximum voltage and minimum current c. Minimum voltage and minimum current d. Equal voltage and current 74. Refers to a type of beam antenna which uses two or more straight elements arranged in line with each other. a. Whip antenna b. Yagi antenna c. Rhombic antenna d. Dipole antenna 75. What is meant by the term radi

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