Reference no: EM13275499
1. A group of antennas or antenna elements arranged to provide the desired directional characteristics is called:
A) a lumped element.
B) a vertical antenna.
C) a marconi antenna.
D) an antenna array.
2. Which of the following is a baseband type of signal?
A) PCM
B) PAM
C) RZ
D) PWM
3. Which of the following is not an advantage of FETs over BJTs in RF amplifier usage?
A) Their input impedance does not load down the Q of the circuit preceding the FET stage.
B) The availability of dual gate FETs provides an isolated injection point for the AGC.
C) Their input/output square-law relationship allows for lower distortion levels.
D) They have improved image frequency rejection.
4. A transmission line terminated with a load resistance that is equal to the transmission line's characteristic impedance has a reflection coefficient at the load of:
A) -1.
B) 0.
C) +1.
D) infinity.
5. A stage that produces a specific dc output voltage level based on the exact frequency of the input signal is known as:
A) a discriminator.
B) a direct FM modulator.
C) an indirect FM modulator.
D) a frequency multiplier.
6. The transmitter scheme in the figure is set up for:
A) high-level modulation.
B) low-level modulation.
C) medium-level modulation.
D) none of the above.
7. In this modulator, FM is created by having the intelligence signal cause a change in the transconductance of a JFET, which causes a change in the JFET amplifier's input capacitance, which shifts the resonant frequency of a tank circuit.
A) Varactor diode modulator
B) Reactance modulator
C) VCO modulator
D) PLL modulator
8. The model of the dipole antenna used in the Electronics Workbench Multisim simulation used an inductance of 1 H and series capacitor of 2.5pF. The resonant frequency of this antenna model is approximately:
A) 100 MHz.
B) 90 MHz.
C) 110 MHz.
D) 103.9 MHz.
9. A point in space that radiates equally in all directions is:
A) parabolic reflector.
B) isotropic Point source.
C) electromagnetic wave.
D) an antenna.
E) none of the above.
10. A transistor amplifier has a measured S/N power of 25 at its input and 8 at its output. Its noise figure in decibels is:
A) 118
B) 17
C) 9.10
D) 4.95
11. An advantage of PPM over PWM is:
A) its simplicity in design.
B) its frequency response of the intelligence signal.
C) its greater resistance to any error produced by noise.
D) its limited bandwidth.
12. FSK is a form of:
A) AM.
B) FM.
C) PM.
D) None of the above.
13. Input into the PLL is at the:
A) VCO.
B) low-pass filter
C) phase detector.
D) comparator circuit.
14. The FM detector design that does not require intricate coil adjustments to be tuned is the:
A) slope detector.
B) Foster-Seely detector.
C) ratio detector.
D) quadrature detector.
E) PLL detector.
15. The Ku band frequency range is approximately:
A) 1-2 GHz.
B) 2-4 GHz.
C) 4-8 GHz.
D) 8-12 GHz.
E) 12-18 GHz.
16. The parallel resonant circuit of the figure has a resonant frequency of approximately:
A) 259 kHz
B) 10.7 GHz
C) 41.3 kHz
D) 82.6 kHz
17. Which of the following is not produced when two sine waves are combined through a nonlinear device?
A) Components of each of the two original frequencies
B) Components at the sum and difference frequencies
C) Harmonics of the two original frequencies
D) ac level
18. Which of the following can be used to generate PWM?
A) PCM
B) PPM
C) PAM
D) PTM
19. Which of the following is a definition of characteristic impedance?
A) Coaxial line impedance
B) Impedance at any point
C) Impedance of infinite line
D) Impedance at front end
20. Why is the carrier signal needed in an SSB receiver?
A) It is needed for the receiver to maintain its sensitivity and selectivity
B) It is needed for the demodulator to be able to recreate the intelligence
C) The carrier actually contains the intelligence signal
D) Without a carrier, the signal strength of the received station is zero