1. ReThe first stage of a two-stage amplifier has a voltage gain of 10, a 600-ohm input resistor, a 1600-ohm equivalent noise resistance and a 27-kiloohm output resistor. For the second stage, these values are 25, 81 kiloohms, and 1 megaohm respectively. Calculate the equivalent input-noise resistance of this two-stage amplifier.A. 2200 ohmsC. 2356 ohmsB. 2518 ohms *D. 2135 ohms

2. A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. Calculate the receivers noise figure in decibels and its equivalent noise temperature.A. 2.04 dB, 154 KC. 2.04 dB, 174 K *B. 2.04 dB, 164 KD. 2.04 dB, 184 K

3. The tuned circuit of the oscillated in a simple AM transmitter employs a 50-microhenry (50-uH) and a 1-nanofarad (1-nF) capacitor. If the oscillator output is modulated by audio frequencies up to 10 kHz, what is the frequency range occupied by the sidebands?A. 722 to 702 kHz *C. 712 to 710 kHzB. 712 to 702 kHzD. 722 to 702 kHz

4. A certain transmitter radiates 9 kW with the carrier unmodulated, and 10.125 kW when the carrier is sinusoidally modulated. Calculate the modulation index, percent of modulation. If another sine wave, corresponding to 40 percent modulation, is transmitted simultaneously, determine the total radiated power.A. 0.25, 10.84 kWC. 0.5, 10.84 kW *B. 0.5, 8.64 kWD. 0.25, 9.84 kW

5. The antenna current of an AM broadcast transmitter, modulated to a depth of 40 percent by an audio sine wave, is 11 A. It increases to 12 A as a result of simultaneous modulation by another audio sine wave. What is the modulation index due to this second wave?A. 0.567C. 0.757B. 0.643 *D. 0.812

6. Calculate the percentage power saving when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 50 percent?A. 65.5 %C. 83.3%B. 76.6 %D. 94.4% *

7. In an FM system, when the audio frequency (AF) is 500 Hz and the AF voltage is 2.4 V, the deviation is 4.8 kHz. If the AF is now increased to 7.2 V, what is the new deviation? A. 14.4 kHz *C. 16.6 kHzB. 15.5 kHzD. 17.7 kHz

For Problems 8 to 10:FM wave represented by the voltage equation:v = 12 sin( 6x108t + 5 sin 1250t).

8. Find the carrier and modulating frequencies?A. 95.5 MHz, 199 Hz *C. 92.6 MHz, 169 HzB. 199 Hz, 95.5 mHzD. 169 Hz, 92.6 mHz

9. What is the modulation index?A. 4C. 6B. 5 *D. 7

10. What power will this FM wave dissipate in a 10-ohm resistor?A. 1.2 WC. 5.2 WB. 4.2 WD. 7.2 W *

11. In a broadcast superheterodyne receiver having no RF amplifier, the loaded Q of the antenna coupling circuit (at the input to the mixer) is 100. If the intermediate frequency is 455 kHz. Calculate the image frequency and its rejection ratio at 1000 kHz.A. 1910 kHz, 138.6 *C. 1910 kHz, 168.3B. 1810 kHz, 128.6D. 1810 kHz, 128.6

12. What is the minimum value that the characteristic impedance of an air-dielectric parallel-wire line could have?A. 50 ohmsC. 83 ohms *B. 75 ohmsD. 300 ohms

13. A coaxial cable, having an inner diameter of 0.025 mm and using an insulator with a dielectric constant of 2.56, is to have a characteristic impedance of 2000 ohms. What must be the outer conductor diameter?A. 209 light yearsC. 409 light years *B. 309 light yearsD. 509 light years

14. It is required to match a 200-ohm load to a 300-ohm transmission line, to reduce the SWR along the line to 1. What must be the characteristic impedance of the quarter-wave transformer used for this purpose, if it is connected to the load?A. 145 ohmsC. 285 ohmsB. 245 ohms *D. 290 ohms

15. A (200 + j75)-ohm load is to be matched a 300-ohm line to give SWR = 1. Calculate the reactance of the stub and the characteristic impedance of the quarter-wave transformer, both connected directly to the load.A. -610, 262C. -650, 262B. -650, 272D. -610, 282

16. A half-wave dipole antenna is capable of radiating 1-kW and has a 2.15-dB gain over an isotropic antenna. How much power must be delivered to the isotropic (omnidirectional) antenna, to match the field-strength directional antenna?A. 1350 WC. 1520 WB. 1480 WD. 1640 W *

17. If an antenna has a field gain (expressed in voltage) of 2, and the transmitter has an overall efficiency of 50 percent (the circuit and transmission line losses) then, if a 1-kW signal is fed to the finals, this will result in 500 W being fed to the antenna. What is the erp?A. 1000 WC. 3000 WB. 2000 W *D. 4000 W

18. Calculate the beamwidth between nulls of a 2-m paraboloid reflector used at 6 GHz. A. 1.75 degreesC. 0.875 degreeB. 3.5 degrees *D. 7 degrees

19. A parabolic antenna has a 0.5 beamwidth at 18 GHz. Calculate its gain in dB.A. 26.5C. 65.4B. 50.7 *D. 80.7

20. It is desired to build a /2 dipole to receive a 100-MHz broadcast. Determine the optimum length of the dipole.A. 3 mC. 1.43 m *B. 5.85 mD. 1.5 m21. Two /2 dipoles are separated by 50 km. They are aligned for optimum reception. The transmitter feeds its antenna with 10 W at 144 MHz. Calculate the power received.A. 2.96 x 10-10 W *C. 4.96 x 10-10 WB. 3.96 x 10-10 WD. 5.96 x 10-10 W22. Compute the power received at a satellite if the power gain of the transmitting parabolic dish antenna is 30000; the transmitter drives 2kW of power into the antenna at a carrier frequency of 6.21 GHz; the satellite receiving antenna has a power gain of 30; and the transmission path is 45000 km.A. 10.9 uWC. 10.9 pWB. 12.9 uWD. 12.9 pW *23. Calculate the ghost width for a 17-in wide TV screen when a reflected wave results from an object 3/8 mi behind a receiver.A. 3.21 inC. 2.35 inB. 4.27 in D. 1.28 in *24. Determine the characteristic impedance of RG-8A/U coaxial cable with D = 0.285 in and d = 0.08 in. It uses a polyethylene dielectric.A. 160 ohmsC. 150 ohmsB. 50 ohms *D. 80 ohms

25. A digital transmission has an error probability of 10-4 and is 109 bits long. Calculate the expected number of error bits and the BER.A. 105 , 104 *C. 106, 105B. 104 , 105D. 105, 10626. Determine the number of bits required for a binary code to represent 110 different possibilities.A. 6C. 8B. 7 *D. 9

27. A receiver has a 20-dB noise figure (NF), a 1-MHz bandwidth, a +5dBm third-order intercept point, and a 0-dB S/N. Determine its sensitivity.A. -74 dBmC. -84 dBmB. -94 dBm * D. -104 dBm

28. Determine the worst-case output S/N for a broadcast FM program that has a maximum intelligence frequency of 5 kHz. The input S/N is 2.A. 10C. 30 *B. 20D. 40

29. An FM signal has a center frequency of 100 MHz but is swinging between 100.001 MHz and 99.999 MHz at a rate of 100 times per second. Determine the intelligence frequency.A. 100 Hz *C. 1000 HzB. 2000 HzD. 500 Hz

30. A 2.5 MHz carrier is modulated by a music signal that has a frequency components ranging from 100 Hz to 5 kHz. What is the range of frequencies generated for the upper sideband?A. 2.5 MHz to 2.505 MHzB. 2.495 MHz ro 2.505 MHzC. 2.5001 MHz to 2.505 MHz *D. 2.495 MHz to 2.499 MHz

31. An AM broadcast station operates at its maximum allowed output power of 80W at a percent modulation of 60%. What is the upper sideband power?A. 6.1 watts *C. 9.23 wattsB. 18.47 wattsD. 12.2 watts

32. Determine the side frequency voltage if the modulation index is 70% and the carrier amplitude is 50V.A. 25C. 75B. 17.5 *D. 50

33. Determine the phase-shift represented by a 75 ns delay of a 4 MHz signal to a 75-ft cable with a dielectric constant of 2.3A. 108 degrees * C. 52 degreesB. 4.8 degrees D. 250 degrees34. By how much should two antennas be separated for space diversity in the 11 GHz band?A. 5.5 m * C. 9.5mB. 7.5m D. 11.5m35. The refractive indices of core and cladding materials of a step index fiber are 1.48 and 1.45, respectively. Calculate the fractional indices change.A. 0.0002C. 0.02 *B. 0.002D 0.236. How long does it take to dial the number 784-3745 using pulse dialing with .5s inter digit time?A. 6.5s C. 6.8s *B. 7.2s D. 12.5s37. Compute the bit rate for a 2000 baud 16-QAM signal.A. 8000 bps * C. 2000 bpsB. 4000 bps D. 500 bps38. Given a bandwidth of 6000 Hz for an ASK signal, what is the baud rate?A. 3000 Hz C. 12000 HzB. 2000 Hz D. 6000 Hz *39. A radiolink receiver has a noise figure of 8dB and an IF bandwidth of 12 MHz. What is the FM improvement threshold in dBW?A. -115.21 dBW *C. -123.21 dBWB. -125.21 dBWD. -199.21 dBW40. A LOS microwave radiolink requires an antenna with a 32-dB gain. The link operates at 6 GHz. What diameter of parabolic dish is required? Assume an aperture efficiency of 55%.A. 1.8 ftC. 2.8 ft *B. 2.0 ftD. 3.4 ft41. A transmission line operating at 125 MHz has Z0 = 40, = 0.02 (Np/m), and = 0.75 rad/m. Find the line parameter L.A. 38.2 nH/m *C. 38.2 uH/mB. 42.5 nH/mD. 42.5 uH/m42. A Satellite receiving system includes a dish antenna ( Teq = 35 K) connected via a coupling network (Teq= 40 K) to a microwave receiver (Teq=52 K referred to its input). What is the noise power to the receivers input over a 1-MHz frequency range?A. 1.75 x 10-15W * C. 1.15 x 10-15WB. 1.75 x 10-12W D. 1.15 x 10-12W

43. For a total capacity of 36 Mbps and 64-QAM of digital modulation, what is the ideal RF bandwidth? A. 4MHzC. 6 MHz*B. 5 MHzD. 7MHz44. Find the velocity of a satellite in a circular orbit 500 km above the earths surfaceA. 76 km/s C. 7.6 km/s *B. 76 m/s D. 7.6 km/s245. Calculate the length of the path to a geostationary satellite from an earth station where the angle of elevation is 30.A. 36,000 km C. 39,000 km *B. 36,000 mi D. 39,000 mi46. A dipole antenna has a radiation resistance of 67 ohms and a loss resistance of 5 ohms, measured at the feedpoint. Calculate the efficiencyA. 90% C. 92% B. 91%D. 93% *47. What is the phase velocity of a rectangular waveguide with a wall separation of 3 cm and a desired frequency of operation of 6 GHz?A. 3.45 x 108 m/s C. 4.53 x 108 m/sB. 4.35 x 108 m/s D. 5.43 x 108 m/s *

48. A fiber is rated as having a bandwidth-distance product of 500MHz-km. Find its dispersion in ns/km. A. 1 ns/km *C. 3 ns/kmB. 2 ns/kmD. 4 ns/km

49. A CDMA mobile measures the signal strength from the base as -100dBm. What should the mobile transmitter power be set to as a first approximation.A. 450 mWC. 250 mW *B. 350 mWD. 150 mW

50. In ionosphere incidence angle is 60. The maximum usable frequency fm is equal toA. 2fc *B. fcC. 0.5 fcD. sqrt. 3 x fc