ECEN 30124 Quiz #2 PDF

# Polytechnic University of the Philippines ## Electronics Engineering Department ### ECEN 30124: Transmission Media and Antenna Systems & Design **Prepared By:** Engr. Christian P. Enoval **Quiz #2** **Name:** Frinh Quadrac P. Orillos **Date:** Nov. 20, 2024 **Score:** 42.5 / 112.50 **Checked...

# Polytechnic University of the Philippines ## Electronics Engineering Department ### ECEN 30124: Transmission Media and Antenna Systems & Design **Prepared By:** Engr. Christian P. Enoval **Quiz #2** **Name:** Frinh Quadrac P. Orillos **Date:** Nov. 20, 2024 **Score:** 42.5 / 112.50 **Checked By:** Katrina Diann P. Fernandez **Instructions:** No looking at either side. Erasures and misspelled words are considered wrong. Anybody caught cheating will automatically drop the subject. ### I. **Multiple Choice:** (1 pt each) 1. Which of the following is not a common application of fiber-optic cable? a. Computer networks b. Long-distance telephone systems c. Closed circuit TV d. Consumer TV 2. Total internal reflection takes place if the light ray strikes the interface at an angle with what relationship to the critical angle? a. Less than b. Greater than c. Equal to d. Zero 3. The operation of a fiber-optic cable is based on the principle of: a. Refraction b. Reflection c. Dispersion d. Absorption 4. Which of the following is not a common type of fiber-optic cable? a. Single-mode step-index b. Multimode graded-index c. Single-mode graded-index d. Multimode step-index 5. Cable attenuation is usually expressed in terms of: a. Loss per foot b. dB/km c. Intensity per mile d. Voltage drop per inch 6. The upper pulse rate and information-carrying capacity of a cable is limited by: a. Pulse shortening b. Attenuation c. Light leakage d. Modal dispersion 7. The core of a fiber-optic cable is made of: a. Air b. Glass c. Diamond d. Quartz 8. The core of a fiber-optic cable is surrounded by: a. Wire braid shield b. Kevlar c. Cladding d. Plastic insulation 9. The speed of light in plastic compared to the speed of light in air is: a. Less b. More c. The same d. Zero 10. Which of the following is not a major benefit of fiber-optic cable? a. Immunity from interference b. Excellent data security c. No electrical safety problems d. Lower cost 11. The main benefit of microwaves or any light-wave communications over microwaves or any other communications media are: a. Lower cost b. Better security c. Wider bandwidth d. Freedom from interference 12. Which of the following is not part of the optical spectrum? a. Infrared b. Ultraviolet c. Visible color d. X-rays 13. The wavelength of visible light extends from: a. 0.8 to 1.6 µm b. 200 to 660 nm c. 400 to 750 nm d. 700 to 1200 nm 14. Refraction is the: a. Bending of light waves b. Reflection of light waves c. Distortion of light waves d. Diffusion of light waves 15. The ratio of the speed of light in air to the speed of light in another substance is called the: a. Speed factor b. Index of refraction c. Index of reflection d. Speed gain 16. Which type of fiber-optic cable is the most widely used? a. Single-mode step-index b. Multimode step-index c. Single-mode graded-index d. Multimode graded-index 17. Which type of fiber-optic cable is best for very high speed data? a. Single-mode step-index b. Single-mode graded-index c. Multimode step-index d. Multimode graded-index 18. Which type of fiber-optic cable has the least modal dispersion? a. Single-mode step-index b. Single-mode graded-index c. Multimode step-index d. Multimode graded-index 19. Which of the following is not a factor in cable light loss? a. Reflection b. Absorption c. Scattering d. Dispersion 20. Which light emitter is preferred for high-speed data in a fiber-optic system? a. Incandescent b. LED c. APDS d. Laser 21. Most fiber-optic light sources emit light in which spectrum? a. Visible b. Infrared c. Ultraviolet d. X-ray 22. Both LEDs and ILDS operate correctly with: a. Forward bias b. Reverse bias c. Neither a or b d. Either a or b 23. Single-frequency light is called: a. Pure b. Intense c. Coherent d. Monochromatic 24. Laser light is very bright because it is: a. Pure b. White c. Coherent d. Monochromatic 25. Which of the following is not a common light detector? a. PIN photodiode b. Photovoltaic diode c. Photodiode d. Avalanche photodiode 26. Which of the following is the fastest light sensor? a. PIN photodiode b. Photovoltaic diode c. Phototransistor d. Avalanche photodiode 27. The product of the bit rate and distance of a fiber-optic system is 2 Gbits km/s. What is the maximum rate at 5 km? a. 100 Mbits/s b. 200 Mbits/s c. 400 Mbits/s d. 1000 Gbits/s ### II. **Identification** (1.5 points each) 1. **Jean Daniel Colladon** is the true grandfather of fiber-optics. 2. **Kopany** coined the term fiber optics in 1956. 3. **Planck's Law** states that "When visible light or high frequency electromagnetic radiation illuminates a metallic surface, electrons are emitted." 4. **Photometry** is the science of measuring only light waves that are visible to the human eye. 5. **Critical angle** is the minimum angle of incidence at which a light ray may strike the interface of two media and result in an angle of refraction of 90° or greater. 6. **Prismatic Diffraction** is the spectral separation of white light and the phenomenon that causes rainbow, where water droplets in the atmosphere act as a small prisms that splits white sunlight into various wavelengths, creating a visible spectrum of color. 7. **Radiometry** is the rate at which electromagnetic waves transfer light energy; the flow of light energy past a given point in a specified time. 8. **Acceptance angle** is the maximum angle in which external light rays may strike the air/glass interface and still propagate down the fiber. 9. **Numerical Aperture** is the measure of the magnitude of the acceptance angle. Also used to describe the light-gathering or light-collecting ability of an optical fiber (the ability to couple light into the cable from an external source). 10. **Power Loss** in an optical fiber cable is probably the most important characteristic of the cable. Power loss is often called attenuation and results in a reduction in the power of the light wave as it travels down the cable. 11. **Coupling Loss** occurs as a result of differences in the thermal contraction rates between the core and the cladding material. A geometric imperfection along the axis of the fiber and represents discontinuity in the fiber material. 12. **Refraction** is simply the ratio of the velocity of propagation of a light ray in free space to the velocity of propagation of a light ray in a given material. 13. **The first laser was developed by Maiman** who directed a beam of light into ruby crystals with a xenon flashlamp and measured emitted radiation from the ruby. 14. **Absorption Loss** is loss incurred by an electromagnetic wave as it propagates in a straight line through a vacuum with no absorption or reflection of energy from nearby objects. 15. **Huygen's Principle** states that every point source of electromagnetic waves from which other secondary waves are radiated outward. 16. **Attenuation** is the reduction in signal strength at the receiver or a random variation in the received signal. The variation of signal loss and can be caused by natural weather and manmade disturbances. 17. **Critical Frequency** is the highest frequency that can be propagated directly upward and still returned to Earth by the ionosphere. 18. **Critical angle** is the maximum vertical angle of a frequency at which it can be propagated and still be refracted by the ionosphere. 19. **Maximum Useable Frequency** is the highest frequency that would permit acceptable operation of a radio service between given terminals at a given time under specific working conditions. 20. **Skip distance** is the minimum distance from a transmit antenna that the sky wave at a given frequency will be returned to Earth. 21. **Skip Zone** is the area where the Surface or Ground waves are completely dissipated and the point where the first sky wave returns to the Earth. 22. **Working frequency (LUF)** is defined as the frequency at below which the signal falls below the minimum strength required for satisfactory reception. 23. **Solar Wind Flares** are sudden explosions of energy caused by tangling, crossing, or reorganizing of magnetic field lines near sunspots. 24. **Sudden Ionospheric Disturbance** is a blackout of HF sky wave communications that occurs after a solar flare. 25. In cell phone systems, these circuits are called **Received Signal Strength Indicator.** They determine the signal with the greatest strength and switch that signal to the remainder of the receiver circuits. ### III. **Enumeration** (1 pt each) 1. The **light frequency spectrum** is divided into three general bands as follow: * Infrared * Visible Light * Ultraviolet 2. Give at least (5) Losses In optical fiber cables: * Absorption Loss * Chromatic Dispersion * Radiation Loss * Modal Dispersion * Coupling Loss 3. Two Types of Optical Sources: * Light-emitting Diode * Injection Laser Diode 4. Two (2) devices commonly used Light Detectors in Fiber optics: * PIN Diode * Avalanche photodiode 5. Types of LASER: * Gas Laser * Liquid laser * Solid laser * Semiconductor Laser 6. Most Important Characteristics of Light Detectors: * Responsivity * Dark current * Transit Time * Spectral Response * Light sensitivity 7. Fading Solutions: * Frequency Diversity * Spatial Diversity ### IV. Problem Solving (5pts each) 1. Determine the power density for a radiated power of 1000 W at a distance 20km from an isotropic antenna. 2. Light travels from air into an optical fiber with an index of refraction of 1.44. If the angle of incidence on the end of the fiber is 22°, what is the angle of refraction inside the fiber? 3. Determine the maximum radio horizon distance for a transmit antenna that is 100 ft high and a receiving antenna that is 50 ft high. 4. Determine the optimum working frequency for a critical frequency of 10MHz and an angle of incident of 45°. 5. For a carrier frequency of 5GHz and a distance of 60,000 meters, determine the free space path loss. # Polytechnic University of the Philippines ## Electronics Engineering Department ### ECEN 30124: Transmission Media and Antenna Systems & Design **Prepared By:** Engr. Christian P. Enoval **Quiz #3** **Name:** Frinh Quadrac P. Orillos **Date:** Jan 14, 2025 **Score:** 40/60 **Checked By:** SAR P. PERMED **Instructions:** No looking at either side. Erasures and misspelled words are considered wrong. Anybody caught cheating will automatically drop the subject. ### I. **Multiple Choice:** (1 pt each) 1. A popular half-wavelength antenna is the: a. Ground plane b. End fire c. Collinear d. Dipole 2. A popular vertical antenna is the a. Collinear b. Dipole c. Ground plane d. Broadside 3. The magnetic field of an antenna is the ________ to the antenna's polarization: a. Is vertical b. Is horizontal c. Is circular d. Cannot be determined from the information given 4. An antenna that transmits or receives equally well in all directions is said to be: a. Omnidirectional b. Bidirectional c. Unidirectional d. Quasidirectional 5. The horizontal radiation pattern of a dipole is a: a. Circle b. Figure eight c. Clover leaf d. Narrow beam 6. The impedance of a dipole is about: a. 50 Ω b. 73 Ω c. 93 Ω d. 300 Ω 7. A directional antenna with two or more elements is known as a(n): a. Ground plane b. Loop c. Array d. Folded dipole 8. The horizontal radiation pattern of a vertical dipole is a: a. Figure eight b. Circle c. Narrow beam d. Clover leaf 9. In a Yagi antenna, maximum direction of radiation is toward the: a. Director b. Driven element c. Reflector d. Sky 10. Conductors in multielement antennas that do not receive energy directly from the transmission line are known as: a. Parasitic elements b. Driven elements c. The boom d. Receptors 11. A coax has an attenuation of 2.4 dB per 100 ft. The attenuation for 275 ft. is: a. 2.4 dB b. 3.3 dB c. 4.8 dB d. 6.6 dB 12. An antenna has a power gain of 15. The power applied to the antenna is 32 W. The effective radiated power is: a. 2.13 W b. 26.81 W c. 120 W d. 480 W 13. Which beam width represents the best antenna directivity? a. 7° b. 45° c. 19° d. 28° 14. The radiation pattern of collinear and broadside antennas is: a. Omnidirectional b. Bidirectional c. Unidirectional d. Clover-leaf shape 15. Which antenna has a unidirectional radiation pattern and gain? a. Dipole b. Ground plane c. Yagi d. Collinear 16. A wide-bandwidth multiplexement driven array is the: a. End-fire b. Log-periodic c. Yagi d. Collinear 17. Ground-wave communications is most effective in what frequency range? a. 300 kHz to 3 MHz b. 3 to 30 MHz c. 30 to 300 MHz d. Above 300 MHz 18. The ionosphere causes the radio signal to be: a. Diffused b. Absorbed c. Refracted d. Reflected 19. The ionosphere has its greatest effect on signals in what frequency range? a. 300 kHz to 3 MHz b. 3 to 30 MHz c. 30 to 300 MHz d. Above 300 MHz 20. The type of radio wave responsible for long-distance communications by multiple skips is the: a. Ground wave b. Direct wave c. Surface wave d. Sky wave 21. Microwave signals propagate by way of the: a. Direct wave b. Sky wave c. Surface wave d. Standing wave 22. Line-of-sight communications is not a factor in which frequency range? a. VHF b. UHF c. HF d. Microwave 23. A microwave-transmitting antennas is 550 ft. high. The receiving antenna is 200 ft. high. The maximum transmission distance is: a. 20 mi. b. 33.2 mi. c. 38.7 mi. d. 53.2 mi. 24. To increase the transmission distance of UHF signal, which of the following should be done? a. Increase antenna gain b. Increase antenna height c. Increase transmitter power d. Increase receiver sensitivity 25. A coax has a velocity factor of 0.68. What is length of a half-wave at 30 MHz? a. 11.2 ft. b. 12.9 ft. c. 15.6 ft. d. 16.4 ft. 26. A receiver-transmitter station used to increase the communications range of VHF, UHF a microwave signals is called a (n): a. Transceiver b. Remitter c. Repeater d. Amplifier 27. EIRP stands for: a. Effective Isotropic Reflected Power b. Effective Isotropic Refracted Power c. Efficient and Ideal Radiated Power d. Effective Isotropic Radiated Power 28. It consists of a number of dipoles of equal size, equally spaced 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. Breadside array 29. A type of antenna which consists of one half-wave driven dipole, one reflector, and one director. a. Log-periodic antenna b. Yagi uda c. Hertzian Dipole d. Broadside Collinear 30. It is a 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 31. It is the horizontal pointing angle of an antenna. a. Bandwidth b. Beamwidth c. Angle of elevation d. Azimuth 32. A device that radiates electromagnetic energy and/or intercepts electromagnetic radiation. a. Antenna b. Transceiver c. Transmission Line d. Transmitter 33. The reflector and director of an antenna array are considered as: a. Parasitic elements b. Driven elements c. Feed-points d. Transcendental elements 34. A convenient method of determining antenna impedance. a. Trial and error b. Stub matching c. Smith Chart d. Reactance Circle 35. This is a flexible vertical rod antenna commonly used on mobiles: a. Hertz b. Ground plane c. Whip d. Marconi 36. 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 37. The ration of the radiation resistance of an antenna to the total resistance of the system: a. Antenna efficiency b. Radiation conversion loss c. Beamwidth d. Effective radiated power 38. How do you compare the length of the reflector element of a parasitic beam antenna with that of its driven element? a. Same length b. Reflector element is 5% longer c. Reflector element is half shorter d. Reflector element is 5% shorter 39. Which of the following is taken as the standard reference antenna for directive gain? a. Half-wave dipole b. Infinitesimal dipole c. Elementary doublet d. Isotropic 40. A non resonant antenna used in skywave propagation that uses 2 obtuse angles V antenna placed side by side producing unidirectional pattern. a. Broadside Array Antenna b. Marconi c. Rhombic Antenna d. Dipole Antenna 41. Gain of a folded halfwave dipole antenna: a. 6.54 dB b. 5.64 dB c. 4.65 dB d. 6.45 dB 42. Beamwidth of a folded halfwave dipole antenna: a. 35° b. 45° c. 55° d. 65° 43. Input Impedance of a folded halfwave dipole antenna: a. 1000 b. 500 c. 300 d. 3000 44. Gain of a loop antenna: a. 4.13 dB b. 3.75 dB c. 4.65 dB d. 3.14 dB 45. Beamwidth of a folded halfwave dipole antenna: a. 300° b. 200° c. 500° d. 45° 46. Input Impedance of a turnstile antenna: a. 360 b. 730 c. 372 d. 632 47. The only antenna used in Groundwave Propagation: a. Broadside Array Antenna b. Marconi c. Rhombic Antenna d. Dipole Antenna 48. Gain of a Yagi Uda antenna: a. 3.14 dB b. 3.75 dB c. 4.65 dB d. 7.14 dB 49. Beamwidth of a Yagi Uda antenna: a. 55° b. 45° c. 35° d. 25° 50. Input Impedance of a marconi antenna: a. 362 b. 632 c. 372 d. 500 51. Gain of a halfwave dipole antenna: a. 3.15 dB b. 5.64 dB c. 2.15 dB d. 6.45 dB 52. Beamwidth of a halfwave antenna: a. 55° b. 45° c. 35° d. 25° 53. It is a polar diagram or graph representing field strengths or power densities at various angular positions relative to an antenna: a. Radiation pattern b. Beamwidth c. Bandwidth d. Polarization 54. A nonradiating antenna that dissipates rather than radiates the power supplied to it when the main transmitter is being adjusted while the antenna is being excited: a. Counterpoise b. Isotropic Antenna c. Elementary Doublet d. Dummy Antenna 55. A hypothetical resistance which if placed by an equivalent resistor, would dissipate exactly the same amount of power that the antenna would radiate. a. Actual Resistance b. Resistance c. Radiation Resistance d. Ohmic Resistance 56. Arrays are used to increase the antenna's: a. Radiation resistance b. Directivity c. Beamwidth d. Radiation Pattern 57. Radio signals are made up of: a. Voltages and currents. b. Electric and magnetic fields. c. Electrons and protons. d. Noise and data 58. Another name for signals in the HF range is: a. Microwaves. b. RF waves. c. Shortwaves. d. Millimeter waves. 59. Television broadcasting occurs in which ranges? a. HF b. EHF c. VHF d. UHF 60. Electromagnetic waves produced primarily by heat are called: a. Infrared rays b. Microwaves c. Shortwaves d. X-rays ### **Problem Solving:** 1. For a transmit antenna with a radiation resistance Rr = 72 Ω, an effective antenna resistance Re = 8 Ω, a directive gain D = 20, and an input power Pin = 100W, determine: a. Antenna Efficiency b. Antenna Gain (absolute and dB) c. Radiate power in W, dBm, dBW d. EIRP in W, dBm, dBW.