Microwave Engineering Past Paper PDF

 ‫صح وخطأ‬ 1. Microwaves don't need to be treated differently from low-frequency circuits. 2. In microwaves, antenna gain is proportional to the electrical size of the antenna. 3. Waveguides have more losses compared to two lines and coaxial lines. 4. waveguides have cutoff frequencies below which...

 ‫صح وخطأ‬ 1. Microwaves don't need to be treated differently from low-frequency circuits. 2. In microwaves, antenna gain is proportional to the electrical size of the antenna. 3. Waveguides have more losses compared to two lines and coaxial lines. 4. waveguides have cutoff frequencies below which propagation is possible. 5. Microwave signals travel by line of sight and are not bent by the ionosphere. 6. The dominant mode is the mode with highest cutoff frequency. 7. In TE modes, the electric field is transverse to the direction of propagation. 8. Klystron and Magnetron are microwave active devices. 9. For the TE mode, if n or m is zero, all fields are zero. 10. More bandwidth (information-carrying capacity) can be realized at higher frequencies. 11. For microwaves, the wavelengths are between 1mm and 1000 mm. 12. The order of the mode is not refer to the field configuration in the waveguide. 13. Microwave communications systems began to be developed soon after the birth of radar. 14. Rectangular waveguides have cutoff frequencies below which propagation is not possible. 15. Waveguides are not effected by the surrounding electromagnetic waves 16. The dominant mode is the mode with lowest cutoff frequency. 17. In TM modes, the magnetic field is transverse to the direction of propagation. 18. The design of the waveguide depends on the frequency and the power of the transmitted signals. 19. The order of the modes change depending on the dimensions of the waveguide. 20. The order of the next modes change depending on the dimensions of the waveguide. 21. More bandwidth (information-carrying capacity) can be realized at lower frequencies. 22. For the TE mode n and m cannot be both zero. 23. Rectangular waveguides have cutoff frequencies below which the propagation is possible. 24. As per IEEE, electromagnetic waves between 30 and 300 GHz are called millimeter waves (MW). 25. In TE modes, the magnetic field is transverse to the direction of propagation. 26. A particular mode is only supported above its cutoff frequency. 27. For microwaves, the Frequencies are between 3x106 Hz and 3x109 Hz. 28. Microwaves need to be treated differently from low-frequency circuits. 29. Waveguide can't support TE or TM modes. 30. Rectangular waveguides have cutoff frequencies above which propagation is possible. 31. The attenuator can pass the signal coming from any port to the next port in a circular direction. 32. For the waveguide, the dominant mode is the mode with lowest cutoff frequency. 33. The echo of radar is only affected by the shape and size of the target. 34. Repeaters can be placed at regular intervals to extend the range of the link. 35. Diversity is used to increase the reliability of the system by decreasing its availability. 36. The receiver threshold is not depending on the wideband noise power. 37. For Transverse Electromagnetic (TEM) Waves, ( Ez  0 , but H z  0 ). 38. As per IEEE, electromagnetic waves between 300MHz and 300 GHz are called millimeter waves (MW). 39. The order of the modes is not depending on the dimensions of the waveguide. 40. Over the horizon radar has (high power, low resolution). 41. For the TM mode, if n or m is zero, all fields are zero. 42. Diversity is used to increase the capacity of the system 43. Attenuator passes the signal coming from any port to the next port in a circular direction. 44. Rectangular waveguides has more attenuation than the circular waveguides. 45. Propagation losses are due to Earth's atmosphere and terrain. 46. Diversity is used to increase the capacity of the system by increasing its availability. 47. The Airborne radar has (high power, low resolution)  ‫أسئلة الحفظ‬ 1. What is the function of: Attenuator, Isolator, and Filter 2. Explain the phennomeon of skin effect at microwaves ? 3. What is a microwave communication system? 4. What is a waveguide? 5. What is the difference between the cutoff frequency of the mode and the cutoff frequency of the Waveguide.? 6. In microwave engineering, what is the difference between the cutoff frequency of the waveguide and the cutoff mode. 7. What is the cutoff frequency of the waveguide and the cutoff frequency of the mode? 8. What is the cutoff frequency of the waveguide? 9. Why the lumped circuits components such as the carbon resistors, mica capacitors, and small inductors cannot be used with microwaves. 10. Give a brief definition for the term "Microwave. 11. In microwave system, what is the function of : circulator, magnetron and filter Which of them is an Active device? 12. Which special techniques are used to insert/eject the power to/from the waveguides. Explain the probe Method briefly. 13. In microwave system, what is the function of : klystron, terminator and isolator Which of them is an Active device? 14. What is the function of Isolator. Attenuator and Filter. 15. Give a brief definition for: link budget, Diversity and waveguide. 16. What is the function of: Repeater station, Circulator and Radar? 17. In microwave systems, what is the function of: isolator, circulator and magnetron. 18. Explain briefly the main applications of mirowave systems. 19. In microwave systems, what is the function of: isolator, circulator and magnetron. 20. In microwave communication, what is the diversity?. Mention the types of diversity. 21. What is the main function of microwave repeater ?.Mention the types of repeaters. 22. What is the basic operation of the radar?. And mention the factors that affect the received echo? 23. Mention some advantages and disadvantages of waveguides. 24. Which special techniques are used to insert/eject the power to/from the-waveguides I Method briefly. 25. What is the function of: Isolator, Attenuator and Filter. 26. What is the main function of repeater station.? 27. What is the main function of a radar system and how does it works? 28. In microwave systems, give a brief definition for: circulator, filter, and Triac. 29. Why the microwave repeaters are needed? 30. For microwave Communication, what is the Link Budget? 31. What is the main function of repeater station?. Mention the types of repeaters. 32. Mention the types of diversity in microwave communications. Why diversity is used. 33. What do you know about waveguide in terms of (definition. Function and shape). 34. What is the dominant mode of a waveguide? and how to prevent the propagation of higher order modes in the waveguide. 35. Give a brief explanation for: a) Microwave communications system. b) Waveguides.  ‫املسائل‬ For an air-filled circular waveguide with a diameter D = 3.28 cm. Calculate the cutoff frequency for the modes TE12, TE11, Tm01 and TM21. A rectangular waveguide with dimensions: a = 2b and b = 0.622 inch, a) Calculate cutoff frequency of the waveguide. b) Calculate the cutoff frequency for the first six modes of this waveguide. c) Determine the dominant mode for the waveguide. d) Which modes will be propagated in this waveguide for the frequency range (4.85-6.20) GHz ? Calculate the cutoff frequency for the first 6 modes of air-filled rectangular waveguide. The waveguide dimensions are a=1.52 inches and b=0. 643 inches. a) Determine the dominant mode for this waveguide. b) Determine the cutoff frequency of the wavegude. c) Which modes will be propagated in this waveguide for the frequency range (5.85-8.20) GHz ? Calculate the cutoff frequency for the first 6 modes of air-filled rectangular waveguide. The waveguide dimensions are a=2.84 inches and b=1.42 inches. a) Determine the dominant mode for this waveguide. b) Determine the cutoff frequency of the wavegude. c) Which modes will be propagated in this waveguide for the frequency range (2.60-5.35) GHz ? Calculate the dimensions(a,b when a 2b) of the rectangular waveguide to fit the cutoff frequency of 6.56 GHz Is it possible for a signal with the frequency 6 GHz to propagate through this waveguide? Calculate the cutoff frequency for the first 5 modes of air-filled WR90 waveguide. The guide dimensions are a=0.9 inches and b-0.450 inches, Determine the dominant mode of this waveguide. For an air-filled circular waveguide with a diameter D=3 cm. Calculate the cutoff frequency for the Modes TE01 TE11, TE02 and TE13. Calculate the dimensions(a,b when a 2b) of the rectangular waveguide to fit the cutoff frequency of 1.375 GHz Is it possible for a signal with the frequency 2 GHz to propagate through this waveguide? Calculate the cutoff frequency for the first 5 modes of air-filled WR187 waveguide. The guide dimensions are a=1.872 inches and b=0.872 inches, Determine the dominant mode of this waveguide. For an air-filled circular waveguide with a diameter D=5.08 cm. Calculate the cutoff frequency for the Modes TE01 TE11, TE02 and TE13.  For an air-filled circular waveguide with a diameter D=2.8 cm. Calculate the cutoff frequency for the modes TE01 TE11, TE02 and TE13. A rectangular waveguide has cutoff frequency of 6.25 GHz a) Calculate the dimensions of the waveguide (a , b when b=0.47a). b) Calculate the cutoff frequency for the first five modes of this waveguide. c) Which modes will be propagated in this waveguide for the frequency range (10.85-15.20) GHz ? For an air-filled circular waveguide with a diameter D=3.2 cm. Calculate the cutoff frequency for the modes TE01 TE11, TE02 and TE13. A rectangular waveguide has cutoff frequency of 7.5 GHz a) Calculate the dimensions of the waveguide (a , b when b=0.47a). b) Calculate the cutoff frequency for the first five modes of this waveguide. c) Which modes will be propagated in this waveguide for the frequency range (10.85-15.20) GHz ? For an air-filled rectangular waveguide, the cutoff frequency of the TE 02 mode is 40.76 GHz, calculate: a) the dimensions of the waveguide (a and b when b=0.46a). b) The cutoff frequency of the dominant mode. c) Suggest the suitable frequency range for this waveguide. d) Is it possible for a signal with the frequency 9.35 GHz to propagate in this waveguide? For a monostatic radar system operating at the frequency 11.53 GHz with an antenna gain of The target distance is 3.4 km and the received echo is -93.94 dBm, calculate: a) The time needed for the received echo.. b) The radar transmitted power when the radar cross section (RCS) is 1.32 m². c) The maximum detection range, when the minimum detectable signal (MDS) is -112 dBm? d) The free space loss for the radar signal in dB. Explain why: a) The lumped circuit's components can't be used with microwave frequencies? b) Waveguides are not suitable for low frequencies? c) The reflected wave is generally smaller in amplitude than the direct wave? d) The fade margin is needed for the communication link? e) The rain attenuation is significant for frequencies above 15 GHz? Q: a) Calculate the cutoff frequency for the first 5 modes of air-filled rectangular waveguide. The waveguide dimensions are a=0.622 inches and b=0.311 inche. b) Determine the dominant mode for this waveguide. c) Is it possible for a signal with the frequency 9.4 GHz to propagate through this waveguide For a LOS microwave link operating at 10.4 GHz, the distance between the transmitter and receiver is 20 km. The Transmitter antenna gain is 25 dBi and the receiver antenna gain is 17-dBi The loss between the transmitter and antenna is 1.5 dB and the loss between the receiver and antenna is 2.5 dB. When the transmitter output power Po, is 5.5 kW and the receiver threshold is - 63 dBm, calculate: a) The received signal level (in dBm and in watts) b) The free space loss. c) The fade margin d) The input noise power in dBm, when the noise bandwidth is 3MHz for receiver temperature of 290K. e) Is this link suitable for rain attenuation about 15 dB ? For an air-filled circular waveguide with a diameter D=2.6 cm. Calculate the cutoff frequency for modes TE01 TE11, TE02 and TE13. For a monostatiq radar system operating at 2.5vGHz with transmitted power 2.4 kw and antenna gain of 18 dBI. When the time needed for the receiving echo is 0.15 ms and the received power is -126.66 dBm calculate: a) The target distance from the radar. b) The radar cross section (RCS) of the target. c) The free space loss in dB. d) The maximuni radar range, when the minimum detectable signal (MDS) is -130 dBm? For a rectangular waveguide with the cutoff frequency of 4.29 GHz, calculate: a) The dimensions of the waveguide (a,b, when a = 2b). b) The cutoff frequency for the first four modes. A 12 km microwave communication link operating at 10 GHz, The Transmitter antenna gain And the receiver antenna gain is 20 dB. The loss between the transmitter and antenn is 3 dB Loss between the receiver and antenna is also 3 dB, When the received signal level is - 45 dBm Fade margin is 15 dB, calculate: a. The free space loss. b. The transmitter output power Po. c. The antenna height above the Earth. d. The receiver threshold. e. The noise bandwidth. When the input noise power is -130 dBm and the receivet temperature 300. For monostatic radar system operating at 8.6 GHz with transmitted power 2.6 kw and antenna gain of 23 dBi. When the target distance from the radar is 3.65 km and the received power is - 111.86 dBm, calculate: a) The time needed for the receiving echo. b) The radar cross section (RCS) of the target. c) The free space loss between the radar and the target in dB. d) The maximum radar range, when minimum detectable signal (MDS) is -136 dBm? A 15.6 km LOS microwave communication link operating at 6.25 GHz, The Transmitter antenna gain is 17dB and the receiver antenna gain is 24 dB. The loss between the transmitter and antenna is 3.5 dB and the loss between the receiver and antenna is also 3.5 dB. When the received signal level is -43 dBm and the fade margin is 13 dB, calculate: a) The free space loss. b) The transmitter output power P, in watts. c) The antenna height above the Earth. d) The receiver threshold. e) The noise bandwidth, when the input noise power is -137 dBm and the receiver temperature is 310K. For an air-filled rectangular waveguide, the cutoff frequency of the TE02 mode is 26.25 GHz, calculate: a) The dimensions of the waveguide (a and b, when b= 0.5a). b) The cutoff frequency of the waveguide. c) Suggest the suitable frequency range for this waveguide. d) Is it possible for a signal with the frequency 6.35 GHz to propagate in this waveguide A18 km LOS microwave communication link operating at 8.25 GHz. The Transmitter antenna gain is 18 dB and the receiver antenna gain is 20 dB. The loss between the transmitter and antenna is 3 dB and the loss between the receiver and antenna is also 3 dB. When the received signal level is -48 dBm and the fade margin is 15 dB, Calculate: a. The free space loss. b. The transmitter output power Po. c. The antenna height above the Earth. d. The receiver threshold. e. The noise bandwidth. When the input noise power is -120 dBm and the receivet temperature 300.  Calculate the dimensions(a,b when a 2b) of the rectangular waveguide to fit the cutoff frequency of 9.49 GHz. Calculate the cutoff frequency for the first four modes of this waveguide. For a LOS microwave link operating at 12 GHz, the distance between the transmitter and receiver is 18 km. The Transmitter antenna gain is 17 dBi and the receiver antenna gain is 15 dBi The loss between the transmitter and antenna is 2 dB and the loss between the receiver and antenna is also 2 dB. When the transmitter output power Po, is 6.5 kW and the receiver threshold is - 63 dBm, calculate: a) The received signal level. b) The antenna height above the Earth c) The fade margin d) The noise bandwidth, when the input noise power is -130 dBm and the receiver temperature 300K. Calculate the cutoff frequency for the first 5 modes of air-filled rectangular waveguide. The waveguide Dimensions are a= 14 inches and b 1.42 inch. Determine the dominant mode. For a LOS microwave link operating at 12.4 GHz. The distance between the transmitter and receiver is 11 km. The Transmitter antenna-gain is 15 dBi and the receiver untenna gain is 18 dBi. The loss between the transmiter and antenna is 15-dB and the loss between the receiver and antenna is also 1.3 dB. When the transmitter output power P., is 3.5 kW and the receiver threshold is -70 dBm. Calculate: a) The free space loss. b) The received signal level (in dBm and in watts). c) The antenna height above the Earth. d) The fade margin. e) The input noise power in dBm, when the noise bandwidth is 6MHz for receiver temperature of 300K. For a monostatic radar system operate at.7.5 GHz with transmitted power 2.5 kw and antenna gain. of 16 dBi calculate: a) The radar range when the time needed for the received echo is 20 ms. b) The radar cross section (RCS) of the target when the received power is -128dBm. For an air-filled circular waveguide with a diameter D= 1.8 cm. a) Calculate the cutoff frequencies for the first 6 modes. b) Determine the dominant mode in this waveguide. c) Suggest the suitable frequency range for this waveguide. For a monastatic radar system operating at 5.25 GHz with transmitted power 1.8 kw and antenna gain of 23 dBi When the target distance from the radar is 1.95 km and the received power is - 81.86 Bm Calculate : a) The time needed for the receiving echo. b) The radar cross section(RCS) of the target. c) The free space loss between the radar and the target in (dB). d) The minimum detectable signal (MDS) in dBm, when the maximum radar range is 12km ? For a rectangular waveguide, the cutoff frequency of the TE21 mode is 14.14 GHz, calculate: a) The dimensions of the waveguide (a,b when a=2b). b) The cutoff frequency for the first four modes. For an air-filled rectangular waveguide, the cutoff frequency of the TM mode is 11.83 GHz, calculate: a) The dimensions of the waveguide b) The cutoff frequency for the first four modes. c) Suggest the suitable frequency range for this waveguide. For an air-filled circular waveguide with a diameter D= 2.4 cm. a. Calculate the cutoff frequencies for the first 6 modes. b. Determine the dominant mode in this waveguide. For a monostatic radar system operating at 8.4 GHz with transmitted power 2.6 kw and antenna gain of 25 dBi When the target distance from the radar is 3.65 km and the received power is -111.86 dBm calculate: a) The time needed for the received echo.. b) The radar cross section (RCS) of the target. c) The free space loss between the radar and the target in dB. d) The maximum detection range, when minimum detectable signal (MDS) is -136 dBm?