MULTIPLE CHOICE
1. The microwave frequency range is considered to start at:
a. 100 MHz c. 10 GHz
b. 1 GHz d. 100 GHz
ANS: B
2. The UHF range is:
a. below the microwave range c. above the microwave range b. inside the microwave range d. same as the microwave range ANS: A
3. The dominant mode of a waveguide depends on:
a. the shape of the waveguide c. the point of signal injection b. the power level of the signal d. none of the above
ANS: A
4. The dominant mode of a rectangular waveguide is:
a. TE 01 c. TE 10
7. The characteristic impedance of a waveguide:
a. is fixed
b. depends on the frequency it carries
c. depends on the longer dimension of its cross section d. both b and c
ANS: D
8. Power can be coupled into or out of a waveguide:
a. with a magnetic field probe c. through a hole in the waveguide b. with an electric field probe d. all of the above
ANS: D
9. Directional couplers for waveguides are characterized by:
a. their insertion loss c. their directivity b. their coupling specification d. all of the above ANS: D
10. Striplines and microstrips are used to:
a. couple sections of waveguide c. couple components on a circuit board b. couple waveguides to antennas d. none of the above
ANS: C
11. A resonant cavity is a type of:
a. tuned circuit c. antenna
b. defect in a waveguide d. none of the above ANS: A
12. A TEE connector used with waveguides is:
a. an H-plane TEE c. a "magic" TEE
b. an E-plane TEE d. all of the above
ANS: D 13. TWT stands for:
a. Transverse Wave Transmission c. Traveling-Wave Tube
b. Transverse-Wave Tube d. Traveling-Wave Transmission ANS: C
14. An "isolator" is a device that:
a. isolates frequencies in a waveguide
b. allows a signal to pass in one direction only c. separates signals among various ports
d. prevents microwaves from leaking out of a waveguide ANS: B
15. A "circulator" is a device that:
a. rotates signal polarity in a waveguide b. allows a signal to pass in one direction only c. separates signals among various ports
d. prevents microwaves from being "trapped" in a waveguide ANS: C
16. GaAs stands for:
a. gallium arsenide c. gallium astenite
b. gallium assembly d. none of the above
ANS: A
17. IMPATT stands for:
a. impact avalanche and transit time c. implied power at transmission terminal b. induced mobility at transmission time d. none of the above
ANS: A 18. YIG stands for:
a. Yttrium-Iron-Gallium c. Yttrium-Iron-Garnet b. Yttrium-Iron-Germanium d. none of the above ANS: C
19. A YIG can be tuned by applying:
a. an electric field c. mechanical pressure b. a magnetic field d. an "exciter" signal ANS: B
20. The device commonly used in microwave ovens is the:
a. TWT c. magnetron
b. klystron d. YIG
ANS: C
21. The device commonly used in satellite communications is the:
a. TWT c. magnetron
b. klystron d. YIG
ANS: A
22. The device commonly used in UHF transmitters is the:
a. TWT c. magnetron
b. klystron d. YIG
ANS: B
23. A microwave phased array is often made using:
a. slots c. Fresnel lenses
b. Yagis d. all of the above
ANS: A
24. RADAR stands for:
a. radio ranging c. radio detection and ranging b. radio depth and ranging d. remote detection and ranging ANS: C
25. RADAR uses:
a. pulsed transmission c. the Doppler effect b. continuous transmission d. all of the above ANS: D
26. The maximum effective range for pulsed radar:
a. increases with increasing repetition rate c. decreases with increasing pulse period b. decreases with increasing repetition rate d. none of the above
ANS: B
27. The minimum effective range for pulsed radar:
a. increases with increasing pulse duration c. is always a tenth of the maximum range b. decreases with increasing pulse duration d. none of the above
ANS: A
COMPLETION
1. ____________________ is the effect of a pulse "spreading out" as it travels through a waveguide.
ANS: Dispersion
2. The electric field is ____________________ along the walls of a rectangular waveguide.
ANS: zero
3. The waveguide mode with the lowest cutoff frequency is the ____________________ mode.
ANS: dominant
4. In TE10 mode, the ____________________ field peaks in the middle of the waveguide cross section.
ANS: electric
5. In TE20 mode, the electric field has ____________________ peaks in the waveguide cross section.
ANS: two
6. In a circular waveguide, ____________________ mode is used because of its circular symmetry.
ANS: TM01
7. A waveguide acts as a ____________________-pass filter.
ANS: high
8. In a waveguide, group velocity is always ____________________ than the speed of light.
ANS: slower
9. In a waveguide, phase velocity is always ____________________ than the speed of light.
ANS: faster
10. In a waveguide, impedance ____________________ as frequency increases.
ANS: decreases
11. A ____________________ TEE is a combination of E-plane and H-plane TEES.
ANS: hybrid
12. The Q of a resonant cavity is very ____________________ compared to lumped LC circuits.
ANS: high
13. A wavemeter is a resonant ____________________ with an adjustable plunger.
ANS: cavity
14. A Gunn device oscillates because of its negative ____________________.
ANS: resistance
15. Both magnetrons and TWTs are slow ____________________ tubes.
ANS: wave
16. Both klystrons and TWTs are ____________________-beam tubes.
ANS: linear
17. A ____________________ antenna is just a waveguide with a hole in it.
ANS: slot
18. A ____________________ antenna is a flat piece of copper on an insulating substrate with a ground plane on the other side.
ANS: patch
19. The radar cross section of a target is typically ____________________ than its actual size.
ANS: smaller
20. The frequency of the returned signal will be ____________________ than the transmitted signal if the target is moving toward the radar antenna.
ANS: higher
SHORT ANSWER
1. Calculate the TE10 cutoff frequency for a rectangular waveguide if the longer dimension of its cross section is 5 cm.
ANS:
3 GHz
2. Calculate the group velocity in a waveguide carrying a signal that is twice its cutoff frequency.
ANS:
260 × 106 meters per second
3. Calculate the phase velocity in a waveguide carrying a signal that is twice its cutoff frequency.
ANS:
346 × 106 meters per second
4. Calculate the wavelength of a 2-GHz signal in a waveguide with a 1-GHz cutoff frequency.
ANS:
173 millimeters
5. Find the gain in dBi of a 10-GHz horn antenna with dE = dH= 60 mm.
ANS:
14.8
6. Find the maximum unambiguous range for a pulsed radar sending 10k pulses per second.
ANS:
15 km
7. Find the minimum unambiguous range for a pulsed radar sending 2-µsec duration pulses.
ANS:
300 meters