MICRO WAVE - QUESTIONS AND ANSWERS - PREPARED BY T. UPPILI, SDE, RTTC, CHENNAI MICROWAVE COMMUNICATION MULTIPLE CHOICE QUESTIONS 1. __________ is the progressive decrease of signal strength with increasing distance. • A. Radiation • B. Attenuation • C. Modulation • D. Propagation 2. Calculate the effective earth’s radius if the surface refractivity is 301. • A. 8493 km • B. 8493 mmi • C. 6370 km • D. 6370 mi 3. If k-factor is greater than 1, the array beam is bent • A. Away from the earth • B. towards the ionosphere, • C. towards the earth • D. towards the outer space 4. the antenna separations (in meters) required for optimum operation of a space diversity system can be calculated from: • A. S = 2λR/L • B. S = 3λR/L • C. S = λR/RL • D. S = λR/L where R = effective earth radius (m) and L = path length (m) 5. Rainfall is an important factor for fading of radio waves at frequencies above • A. 10 GHz • B. 100 GHz • C. 1 GHz • D. 100 MHz 6. Theoretically electromagnetic radiation field strength varies in inverse proportion to the square of the distance, but when atmospheric attenuation effects and the absorption of the terrain are taken into account the attenuation can be as high as the inverse _______ power of the distance. • A. Third • B. Fourth • C. Fifth • D. Sixth 7. What do you call an attenuation that occurs over many different wavelengths of the carrier? • A. Rayleigh fading • B. Rician fading • C. Wavelength fading • D. Slow fading 8. Which of the reception problems below that is not due to multipath? • A. Delayed spreading • B. Rayleigh fading • C. Random Doppler shift • D. Slow fading 9. Which causes multipath or frequency-selective fading? • A. Small reflector • B. Nearer reflector • C. Further reflector • D. Large reflector 10. In microwave transmission using digital radio, what causes most intersymbol interference? • A. Delayed spreading • B. Rayleigh fading • C. Random Doppler shift • D. Slow fading 11. A shipboard equipment which measures the distance between the ship’s bottom and the ocean floor. • A. Fathometer • B. Echosounder • C. LORAN • D. SONAR 12. The cavity resonator • A. Is equivalent to an LC resonant circuit • B. In a reflect klystron has its output taken from the reflector plate • C. Produces a frequency which is independent of the cavity size. • D. Has a low Q factor for narrow operation. 13. At what position is the input signal inserted into a traveling-wave tube? • A. At the cathode end of the helix • B. At the collector • C. At the collector end of the helix • D. At the control grid of the electron gun 14. Coupling into and out of a traveling-wave tube can be accompanied by a • A. Waveguide match • B. Cavity match • C. Direct coax-helix match • D. All of the above 15. a high-power microwave pulse of the order of megawatts can be generated by a • A. traveling-wave tube • B. magnetron • C. reflex klystron • D. Gunn diode 16. A traveling-wave tube (TWT) amplifies by virtue of • A. The absorption of energy by the signal from an electron stream • B. The effect of an external magnetic field • C. The energy contained the cavity resonators • D. The energy liberated form the collector 17. What is the purpose of the electromagnetic field which surrounds a traveling-wave tube? • A. To accelerate the electron • B. To velocity modulate the electron beam • C. To keep the electrons from spreading out • D. To slow down the signal on the helix 18. Which of the following is used as an oscillator device in the SHF band? • A. Thyratron tube • B. Tunnel diode • C. Klystron tube • D. Both B and C 19. Microwave frequencies are normally regarded as those in the range of • A. 1 to 500 MHz • B. 1000 to 10,000 GHz • C. 1 to 100 GHz • D. 10 to 1000 GHz 20. The highest frequency which a conventional vacuum-tube oscillator can generate is not limited by the • A. Electron transit time • B. Distributed lead inductance • C. Inter-electrode capacitance • D. Degree of emission from the cathode 21. As the electron beam moves through a klystron’s intercavity drift space • A. Frequency modulation at the input cavity creates velocity modulation at the output cavity • B. Velocity modulation at the input cavity creates density modulation at the output cavity • C. Density modulation at the input cavity creates velocity modulation at the output cavity • D. Phase modulation at the input cavity creates velocity modulation at the output cavity. 22. The frequency of the oscillation generated by a magnetron, is mainly determined by • A. The flux density of the external magnet • B. The ratio of the dc cathode voltage to the magnetic flux density • C. The number of the cavity resonators • D. The dimension of each cavity resonator 23. If the instantaneous RF potentials on the two sides of a magnetron cavity are of opposite polarity, the operation is in the • A. π mode • B. π/2 mode • C. 2π mode • D. π/4 mode 24. The Gunn diode oscillator • A. Is capable of generating continuous microwave power of the order of kilowatt • B. Generates frequencies which are below 100 MHz • C. Operates over a positive resistance characteristic • D. Depends on the formation of charge domain 25. What ferrite device can be used instead of duplexer of isolate microwave transmitter and receiver when both are connected to the same antenna? • A. Isolator • B. Magnetron • C. Simplex • D. Circulator 26. To achieve good bearing resolution when using a pulsed-radar set, an important requirement is • A. A narrow, antenna-beam width in the vertical plane • B. A narrow, antenna-beam width in the horizontal plane • C. A low repetition rate • D. A high duty cycle 27. When used in conjunction with a radar set, the purpose of an echo box is to provide an artificial target. • A. Which may be used to tune the radar synchronizer • B. Which may be used to tune the radar receiver • C. To the tone of the pulse repetition • D. Tune the magnetron to the correct frequency 28. In a radar-set receiver, the usual mixer stage is • A. And FET • B. A tunnel diode • C. A silicon crystal • D. A Rochelle salts crystal 29. Klystron oscillators are most often used in the frequency range of • A. 300 to 3000 MHz • B. 3000 to 30000 MHz • C. 30 to 30000 MHz • D. 10 to 10000 MHz 30. Oscillators of a klystron tube are maintained • A. By bunches of electrons passing the cavity grids • B. By plate-to-cathode feedback • C. By feedback between the accelerating grid and the repeller • D. By circulating bunches of electrons within the cavities. 31. What allow microwave to pass in only one direction? • A. RF emitter • B. Capacitor • C. Varactor-triac • D. Ferrite emitter 32. In an SHF pulsed radar set, a reflex klystron can be used as a • A. Single mixer stage • B. Local oscillator • C. Transmitter oscillator • D. Duplexer stage 33. A Class-S Emergency Position-Indicating Radio Beacon (E.P.I.R.B) • A. Must be capable of floating or being secured to a survival • B. Must have its battery replaced after emergency use • C. May be tested during the first five minutes of any hour • D. All of these 34. A PPI cathode-ray tube as used on a radar set • A. Is used to check the percentage of modulation • B. Indicates both the range and azimuth of a target • C. Indicates only the range of a target • D. Is used for receiver alignment 35. The resonant frequency of a cavity resonator depends upon • A. The mode of operation • B. Its electrical dimensions • C. Its physical dimensions • D. The capacitor which tunes it 36. The maximum usable range of the usual radar set (on any particular range setting) is determined by • A. The width of the transmitted pulses • B. The interval between transmitted pulses • C. The bandwidth of the receiver IF stages • D. The duty cycle 37. A reflex klystron is oscillating at the frequency of its resonant cavity. If the reflector voltage is made slightly less negative, the • A. Oscillation will cease • B. Output power would increase • C. The frequency will decrease • D. Bunching would occur earlier in time 38. The coarse frequency adjustment of a reflex klystron is accomplished by • A. The AFC system • B. Adjusting the flexible wall of the resonant cavity • C. An adjustment in the synchronizer • D. Varying the repeller voltage 39. In a pulsed radar set, the STC circuit is used to • A. Improve the target bearing resolution • B. Increases receiver sensitivity for echoes from targets • C. Vary the pulse frequency in order to control the maximum target • D. Reduce interference from the effects of sea return 40. In a pulsed radar set, the function of the duplexer is to • A. Aid in calibrating the display unit • B. Prevent frequency drift in the klystron • C. Allow the transmitter and the receiver to operate from a common antenna • D. All of these 41. A magnetron is operated at a duty cycle of 0.001. It has a peak power output of 100 kilowatts. Its average power is • A. 10,000 watts • B. 100 watts • C. 1,000 watts • D. 1,000,000 watts 42. The aquadag coating on the inside of PPI tube is used • A. To focus the beam of primary electrons • B. To shield the electron beam from unidirectional magnetic • C. As a second anode and to prevent the build-up of secondary field • D. All of these 43. If the duration of the radar transmitted pulse, on a particular range of operation, is increased, the required bandwidth of the receiver’s IF amplifiers • A. Must remain as before • B. Must be increased • C. May be decreased • D. Must be doubled 44. The main frequency determining element of a klystron is • A. The repeller voltage • B. The accelerating voltage • C. Its resonant cavity • D. Its mode of operation 45. A thin layer of dirt and grime coverts the reflecting surface of the parabolic dish of a radar set. The particular effect on the performance of the radar will be • A. A decrease in range • B. A reduction in horizontal resolution • C. No noticeable effect • D. A decrease in gain 46. Which of the following permits a microwave signal to travel in one direction with virtually no loss, but severely attenuates any signal attempting to travel in the reverse direction? • A. Isolator • B. Wave trap • C. Tunnel diode • D. Circulator 47. It is possible to increase the maximum range of a radar equipment by • A. Lowering the pulse frequency • B. Raising the peak power of the transmitter • C. Narrowing the beam width and increasing the pulse duration • D. All of these 48. When it is desired that short-range targets be clearly seen on a pulsed-radar set, it is important that the receiver and display system have • A. A long time constant • B. Low-pass filters • C. The shortest possible time • D. The restricted high-frequency response 49. Which of the following is used as a high power microwave oscillator? • A. Thyratron • B. Magnetron • C. Klystron • D. Reflex-klystron 50. Which of the following operating frequencies is used for the modern loran navigational system? • A. Loran C: 100 kHz • B. Loran D: 10.2 kHz • C. Loran A: 1950 kHz • D. Loran B: 900 kHz ANSWERS:- 1. Attenuation 2. 8493 km 3. towards the earth 4. S = 3λR/L 5. 10 GHz 6. Sixth 7. Slow fading 8. Slow fading 9. Large reflector 10. Delayed spreading 11. SONAR 12. Is equivalent to an LC resonant circuit 13. ± 2000 Hz 14. All of the above 15. magnetron 16. The absorption of energy by the signal from an electron stream 17. To keep the electrons from spreading out 18. Both B and C 19. 1 to 100 GHz 20. Degree of emission from the cathode 21. Velocity modulation at the input cavity creates density modulation at the output cavity 22. The dimension of each cavity resonator 23. π mode 24. Depends on the formation of charge domain 25. Circulator 26. A narrow, antenna-beam width in the horizontal plane 27. Which may be used to tune the radar receiver 28. A silicon crystal 29. 3000 to 30000 MHz 30. By bunches of electrons passing the cavity grids 31. Ferrite emitter 32. Local oscillator 33. All of these 34. Indicates both the range and azimuth of a target 35. Its physical dimensions 36. The interval between transmitted pulses 37. The frequency will decrease 38. Adjusting the flexible wall of the resonant cavity 39. Reduce interference from the effects of sea return 40. Allow the transmitter and the receiver to operate from a common antenna 41. 100 watts 42. As a second anode and to prevent the build-up of secondary field 43. May be decreased 44. Its resonant cavity 45. No noticeable effect 46. Isolator 47. All of these 48. The shortest possible time 49. Magnetron 50. Loran C: 100 kHz FREE SPACE LOSS CALCULATION The free space attenuation between two microwave antennas 40 km apart operating at 8GHz is • A. 146.7 dB • B. 142.55 dB • C. 82.5 dB • D. 86.7 dB • • The free space attenuation between two microwave antennas 40 km apart operating at 8GHz is SOLUTION:- 92.4 + 20 LOG 10 8+ 20 LOG 10 40 = 92.4+ 20 LOG 10320 = 92.4 + 20 [ 2.501] = 92.4 + 50.02 = 142.4 dB 92.40 50.02 142. 42 nearly 142.55 dB Multiple Choice Questions 1- MICROWAVE COMMUNICATION Solution at the bottom 1. The Wavelength correspond to Microwave frequency range is a. 30 to 300GHz b. 3 to 30 GHz c. 0.3 to 3 Ghz d. 300 to 3oooGHz 2.The main advantage of microwave is that- a. Highly Directive. b.Moves at the speed of light. c.S/N ratio grater. d. High penetration power. 3.Reflex Klystron is a - a.Ampilfier. b.Oscillator. c.Attenuator. d.Filter. 4.Klystron operates on the principle of- a. Amplitude Modulation. b.Frequency Modulation. c.Pulse Modulation. d.Velocity modulation. 5.In multicavity Klystron additional cavities are inserted between buncher and catcher cavities to achieve- a.Higher Gain b.Higher Efficiency c.Higher Frequency d.Higher Bandwidth 6.The modes in the reflex Klystron - a. give same frequency but different transit time. b.are caused by spurious frequency modulation. c.are just for theoretical consideration. d.result from excessive transit time across resonator gap. 7.A reflex Klystron function as a. Microwave Oscillator. b.Amplifier c.Phase shifter d.Both amplifier and phase shifter 8.A space between two cavities in two cavity klystron is a.Drift space b.Free space c.Running apce d.Normal space 9. Magnetron is an a. Amplifier b.Oscillator c. Phase shifter d.Both phase shifter and amplifier 10.TWT is a.Oscillator b. Tuned Amplifier c. Wide band Amplifier. d.Both amplifier and Oscillator Solution 1.b, 2.a, 3.b, 4.d, 5.a, 6.a, 7.a, 8.a, 9.b, 10.c REFLECTION COEFFICIENT CALCULATION A line has Z0 = 300 ∠ 0° Ω. If ZL = 150 ∠ 0° Ω, reflection coefficient is A. 0.5 B. 0.3333 C. -0.3333 D. -0.5 Answer & Explanation Answer: Option C Explanation: Reflection coefficient A line has a phase constant of 29.8 rad/m. At 1000 MHz the wavelength is A. 29.8 m B. 2.98 m C. 2.1 m D. 0.21 m Answer & Explanation Answer: Option D Explanation: . A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is A. 4000 Ω B. 400 Ω C. 40 Ω D. 4 Ω Answer & Explanation Answer: Option B Explanation: and is independent of line length. A waveguide section in a microwave circuit acts as A. LP filter B. Bandpass filter C. HP filter D. Band stop filter Answer & Explanation Answer: Option C Explanation: It allows high frequencies. A line has an attenuation of 0.054 Np/m. The attenuation in decibels is A. 4.7 dB/m B. 0.47 dB/m C. 0.54 dB/m D. 5.4 dB/m Answer & Explanation Answer: Option B Explanation: 0.054 x 8.68 = 0.47 dB/m. Free space path loss formula The free space path loss formula or free space path loss equation is quite simple to use. Not only is the path loss proportional to the square of the distance between the transmitter and receiver, but the signal level is also proportional to the square of the frequency in use for other reasons explained in a section below. Where: FSPL is the Free space path loss d is the distance of the receiver from the transmitter (metres) λ is the signal wavelength (metres) f is the signal frequency (Hertz) c is the speed of light in a vacuum (metres per second) The speed of light is 2.99792458 x 10^8 metres per second, although for most practical purposes, this is taken to be 3 x 10^8 metres per second. The free space path loss formula is applicable to situations where only the electromagnetic wave is present, i.e. for far field situations. It does not hold true for near field situations. Decibel version of free space path loss equation Most RF comparisons and measurements are performed in decibels. This gives an easy and consistent method to compare the signal levels present at various points. Accordingly it is very convenient to express the free space path loss formula, FSPL, in terms of decibels. It is easy to take the basic free space path loss equation and manipulate into a form that can be expressed in a logarithmic format. Where: d is the distance of the receiver from the transmitter (km) f is the signal frequency (MHz) 101. The frequency range over which a rectangular waveguide is excited in the dominant mode is limited to • a. the difference between the frequency for which the reflection angle is 90o and the frequency for which angle is zero • b. the difference between the frequency for which the free-space wavelength is equal to the cutoff value and the frequency for which the free-space wavelength is equal to the guide wavelength • c. the difference between the frequency at which the cutoff wavelength is twice the narrow dimension • d. none of these 102. If a rectangular waveguide is to be excited in the dominant mode, the E-probe should be inserted • a. at the sealed end • b. at a distance of one quarter –wavelength from the sealed end • c. at a distance of one-half wavelength from the sealed end • d. at a distance of three-quarters of a wavelength from the sealed end 103. A quarter-wave line is connected to an RF generator and is shorted out at the far end. What is the input impedance to the line generator? • a. A low value of resistance • b. A high value of resistance • c. A capacitive resistance which is equal in the value to the line’s surge impedance • d. An inductive resistance which is equal to the value to the line’s surge impedance 104. If the SWR on a transmission line has a high value, the reason could be • a. an impedance mismatch between the line and the load • b. that the line is non-resonant • c. a reflection coefficient of zero at the load • d. that the load is matched to the line 105. If a quarter-wave transmission line is shorted at one end • a. there is minimum current at the shorted end • b. the line behaves as a parallel-tuned circuit in relation to the generator • c. the line behaves as a series-tuned circuit in relation to the generator • d. there is a minimum voltage at the shorted end 106. A 50-ohm transmission line is feeding an antenna which represents a 50 ohm resistive load. To shorten the line, the length must be • a. any convenient value • b. an odd multiple of three quarters of a wavelength • c. an odd multiple of half a wavelength • d. an even multiple of a quarter of a wavelength 107. The outer conductor of the coaxial cable is usually grounded • a. at the beginning and at the end of the cable • b. only at the beginning of the cable and only at the end of the cable • c. only at the end of the cable • d. at the middle of the cable 108. A feature of an infinite transmission line is that • a. its input impedance at the generator is equal to the line’s surge impedance • b. its phase velocity is greater than the velocity of light • c. no RF current will be drawn from the generator • d. the impedance varies at different positions on the line 109. When the surge impedance of a line is matched to a load, the line will • a. transfer maximum current to the load • b. transfer maximum voltage to the load • c. transfer maximum power to the load • d. have a VSWR equal to zero 110. A lossless line is terminated by a resistive load which is not equal to the surge impedance. If the value of the reflection coefficient is 0.5, the VSWR is • a. 2 • b. 3 • c. 4 • d. 15 111. Ratio of the mismatch between the antenna and the transmitter power. • a. Standing wave pattern • b. Reflection coefficient • c. SWR • d. Index of refraction 112. Emission designation for a facsimile. • a. H3E and A4E • b. R3E and A4E • c. F4E and J3E • d. F3C and A3E 113. Commonly used telephone wire. • a. AWG #19 • b. AWG #18 • c. AWG #30 • d. AWG #33 114. What is the distance traveled by a wave in the time of one cycle? • a. Frequency • b. Hop • c. Wavelength • d. Crest 115. The velocity factor is inversely proportional with respect to the _______. • a. square of the dielectric constant • b. square root of the dielectric constant • c. dielectric current • d. square root of refractive index 116. ________ is a hollow structure that has no center conductor but allows waves to propagate down its length. • a. Waveguide • b. Hybrid • c. Pipe • d. Directional coupler 117. To connect a coaxial line to a parallel wire line, _______ is used. • a. hybrid circuit • b. balun • c. directional coupler • d. quarter-wave transformer matching circuit 118. What length for which the input power has been halved for a transmission line with an attenuation of 6 dB/km? • a. 1.5 km • b. 0.5 km • c. 63 km • d. 2 km 119. Ina waveguide, _______ is a specific configuration of electric and magnetic fields that allows a wave to propagate. • a. set-up • b. coupler • c. channel • d. mode 120. A rectangular waveguide has dimensions of 3 cm x 5 cm. What is the dominant mode cut-off frequency? • a. 2 GHz • b. 3 GHz • c. 2.5 GHz • d. 3.5 GHZ 121. ________ are transmission lines which can convey electromagnetic waves only in higher order modes? • a. Coaxial cables • b. Twisted pairs of telephone wire • c. Power cables • d. Waveguides 122. The amount of uncertainty in a system of symbols is also called • a. bandwidth • b. loss • c. entropy • d. quantum 123. The twists in twisted wire pairs • a. reduced electromagnetic interference • b. occur at a 30-degree angle • c. eliminate loading • d. were removed due to cost 124. An example of a bounded medium is • a. coaxial cable • b. waveguide • c. fiber-optic cable • d. all of the above 125. Loading means the addition of • a. resistor • b. capacitor • c. bullet • d. inductance 126. What is the most commonly used transmission line for high frequency application? • a. Two-wire balance line • b. Single wire • c. Three-wire line • d. Coaxial 127. The characteristic impedance of a transmission line does not depend upon its • a. length • b. conductor diameter • c. conductor spacing • d. dielectric material 128. One of the following is not a common transmission line impedance. • a. 50 ohms • b. 75 ohms • c. 120 ohms • d. 300 ohms 129. For maximum absorption of power at the antenna, the relationship between the characteristic impedance of the line Zoand the load impedance ZL should be • a. Zo = ZL • b. Zo > ZL • c. Zo < ZL • d. Zo = 0 130. The mismatch between antenna and transmission line impedance cannot be corrected for by • a. using LC matcging network • b. adjusting antenna length • c. using a balun • d. adjusting the length of transmission line 131. ________ is a pattern of voltage and current variations along a transmission line not terminated in its characteristic impedance. • a. An electric field • b. Radio waves • c. Standing waves • d. A magnetic field 132. Which is the desirable SWR on a transmission line? • a. 0 • b. 1 • c. 2 • d. Infinity 133. A 50ohm coax is connected to a 73-ohm antenna. What is the SWR? • a. 0.685 • b. 1 • c. 1.46 • d. 2.92 134. What is the most desirable reflection coefficient? • a. 0 • b. 0.5 • c. 1 • d. Infinity 135. What is the ratio expressing the percentage of incident voltage reflected on a transmission line? • a. Velocity factor • b. Standing-wave ratio • c. Reflection coefficient • d. Line efficiency 136. The minimum voltage along a transmission line is 260 V, while the maximum is 390 V, the SWR is • a. 0.67 • b. 1.0 • c. 1.2 • d. 1.5 137. One meter is one wavelength at a frequency of • a. 150 MHz • b. 164 MHz • c. 300 MHz • d. 328 MHz 138. At very high frequencies, transmission lines act as • a. Tuned circuits • b. Antennas • c. Insulators • d. Resistors 139. A shorted quarter-wave line at the operating frequency acts like a/an • a. Capacitor • b. Inductor • c. Series resonant circuit • d. Parallel resonant circuit 140. A shorted half-wave line at the operating frequency acts like a/an • a. Capacitor • b. Inductor • c. Series resonant circuit • d. Parallel resonant circuit 141. A medium least susceptible to noise? • a. Shielded pair • b. Twisted pair • c. Fiber-optic • d. Coaxial 142. A medium most widely used in LANs? • a. Parallel-wire line • b. Twisted pair • c. Fiber-optic cable • d. Coaxial 143. The most commonly used transmission line in television system. • a. Parallel-wire line • b. Coaxial cable • c. Waveguide • d. Open-wire ceramic supports 144. The impedance of a TV transmission line depends on several factors. Which is not one of those factors? • a. Diameter • b. Length of the wire • c. Dielectric material • d. Separation between conductors 145. DC blocks are used in coaxial transmission line for the purpose of • a. passing DC while blocking AC • b. passing AC voltage but prevent DC • c. preventing AC voltage from reaching the pre-amplifier • d. preventing AC power supply voltage from being shorted by a balun or band splitter 146. _______ is a type of interference caused by off-air TV channels 2 and 4, plus a satellite dish operating on channel 3. • a. Adjacent channel interference • b. Ghost • c. Co-channel interference • d. Crosstalk 147. Dithering (in TVRO communication) is a process of • a. Reducing the effect of noise on the TVRO video signal • b. Centering the video fine tuning on TVRO channels • c. Moving the feedhorn rotor to the precise angle • d. Moving the actuator exactly onto the desired satellite beam 148. A network that has an input of 75dB and an output of 35dB. The loss of the network is • a. -40db • b. 40db • c. 40dBm • d. -4dBm 149. Important useful quantities describing waveforms. • a. Time and frequency • b. Voltage and current • c. Frequency and voltage • d. Power and frequency 150. Halving the power means • a. 6-dB gain • b. 3-dB loss • c. 3-dB gain • d. 6-dB loss ANSWERS • 101. the difference between the frequency at which the cutoff wavelength is twice the narrow dimension • 102. at a distance of one quarter –wavelength from the sealed end • 103. A high value of resistance • 104. an impedance mismatch between the line and the load • 105. the line behaves as a parallel-tuned circuit in relation to the generator • 106. any convenient value • 107. at the beginning and at the end of the cable • 108. its input impedance at the generator is equal to the line’s surge impedance • 109. transfer maximum power to the load • 110. 3 • 111. SWR • 112. F3C and A3E • 113. AWG #19 • 114. Wavelength • 115. square root of the dielectric constant • 116. Waveguide • 117. balun • 118. 0.5 km • 119. mode • 120. 3 GHz • 121. Waveguides • 122. entropy • 123. reduced electromagnetic interference • 124. all of the above • 125. inductance • 126. Coaxial • 127. length • 128. 120 ohms • 129. Zo = ZL • 130. adjusting the length of transmission line • 131. Standing waves • 132. 1 • 133. 1.46 • 134. 0 • 135. Reflection coefficient • 136. 1.5 • 137. 300 MHz • 138. Antennas • 139. Parallel resonant circuit • 140. Series resonant circuit • 141. Coaxial • 142. Twisted pair • 143. Coaxial cable • 144. Length of the wire • 145. preventing AC power supply voltage from being shorted by a balun or band splitter • 146. Adjacent channel interference • 147. Reducing the effect of noise on the TVRO video signal • 148. 40db • 149. Frequency and voltage • 150. 3-dB loss • Read more: pinoybix/2014/10/answers-in-transmission-fundamentals-part3.html#ixzz3OijZN881
Posted on: Sat, 17 Jan 2015 00:21:32 +0000
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