blake: antennas, microwave

a

The real part of an antenna's input impedance is due to:

a. the radiated signal

b. the reflected signal

c. the SWR

d. all of the above

b

A half-wave dipole is sometimes called:

a. a Marconi antenna

b. a Hertz antenna

c. a Yagi antenna

d. none of the above

d

The end-to-end length of a half-wave dipole antenna is actually:

a. one wavelength

b. one half-wavelength

c. slightly longer than a half-wavelength

d. slightly shorter than a half-wavelength

c

he radiation of energy from an antenna can be seen in the:

a. standing wave pattern around the antenna

b. SWR along the feed cable

c. radiation resistance of the antenna

d. I2R loss of the antenna

b

Measured on the ground, the field strength of a horizontally polarized half-wave dipole antenna is

strongest:

a. in one direction

b. in two directions

c. in all directions

d. depends on the number of elements

a

The ability of an antenna to radiate more energy in one direction than in other directions is called:

a. directivity

b. selectivity

c. active antenna

d. resonance

a

The front-to-back ratio of a half-wave dipole antenna is:

a. 0 dB

b. 3 dB

c. 10 dB

d. infinite

c

An antenna's beamwidth is measured:

a. from +90° to -90°

b. from front to back

c. between half-power points

d. between the minor side-lobes

d

ERP stands for:

a. Equivalent Radiation Pattern

b. Effective Radiation Pattern

c. Equivalent Radiated Power

d. Effective Radiated Power

a

"Ground Effects" refers to the effects on an antenna's radiation pattern caused by:

a. radio signals reflecting off the ground

b. buildings and other structures on the ground

c. fading

d. faulty connection of the feed cable ground

a

A 1-MHz monopole antenna must be:

a. mounted vertically

b. mounted horizontally

c. at least one half-wavelength long

d. at least one wavelength long

c

The typical antenna in an AM radio is a:

a. dipole

b. folded dipole

c. ferrite "loop-stick"

d. none of the above

b

The polarization of plane waves received from a satellite is changed by:

a. gamma rays

b. Faraday Rotation

c. helical rotation

d. the distance traveled

c

A nonresonant antenna:

a. will not transmit

b. will not receive

c. will cause SWR on the feed cable

d. all of the above

a

At resonance, the input impedance to a lossless antenna should be:

a. resistive

b. inductive

c. capacitive

d. infinite

d

An antenna can be matched to a feed line using:

a. a shorted stub

b. a loading coil

c. an LC network

d. all of the above

a

As the length of a "long-wire" antenna is increased:

a. the number of lobes increases

b. the number of nodes decreases

c. efficiency decreases

d. none of the above

d

Arrays can be:

a. phased

b. driven

c. parasitic

d. all of the above

b

An array with one driven element, a reflector, and one or more directors is called a:

a. Marconi

b. Yagi

c. Log-Periodic Dipole

d. stacked array

c

LPDA stands for:

a. Low-Power Dipole Array

b. Low-Power Directed Array

c. Log-Periodic Dipole Array

d. Log Power Dipole Array

a

The radiated beam from a parabolic "dish" transmitting antenna is:

a. collimated

b. phased

c. dispersed

d. none of the above

c

The energy picked up by a parabolic antenna is concentrated at the:

a. center

b. edges

c. focus

d. horn

b

Antennas are often tested in:

a. an echo chamber

b. an anechoic chamber

c. a vacuum chamber

d. an RF reflective chamber

d

Field strength at a distance from an antenna is measured with:

a. a slotted line

b. a dipole

c. an EIRP meter

d. a field-strength meter

b

The microwave frequency range is considered to start at:

a. 100 MHz

b. 1 GHz

c. 10 GHz

d. 100 GHz

a

The UHF range is:

a. below the microwave range

b. inside the microwave range

c. above the microwave range

d. same as the microwave range

a

The dominant mode of a waveguide depends on:

a. the shape of the waveguide

b. the power level of the signal

c. the point of signal injection

d. none of the above

c

The dominant mode of a rectangular waveguide is:

a. TE 01

b. TM 01

c. TE 10

d. TM 10

c

The dominant mode of a circular waveguide is:

a. TE01

b. TM01

c. TE11

d. TM11

b

Circular waveguides use TM01 mode because:

a. it is dominant

b. of its circular symmetry

c. it is the only mode possible

d. it is more efficient

d

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

d

Power can be coupled into or out of a waveguide:

a. with a magnetic field probe

b. with an electric field probe

c. through a hole in the waveguide

d. all of the above

d

Directional couplers for waveguides are characterized by:

a. their insertion loss

b. their coupling specification

c. their directivity

d. all of the above

c

Striplines and microstrips are used to:

a. couple sections of waveguide

b. couple waveguides to antennas

c. couple components on a circuit board

d. none of the above

a

A resonant cavity is a type of:

a. tuned circuit

b. defect in a waveguide

c. antenna

d. none of the above

d

A TEE connector used with waveguides is:

a. an H-plane TEE

b. an E-plane TEE

c. a "magic" TEE

d. all of the above

c

TWT stands for:

a. Transverse Wave Transmission

b. Transverse-Wave Tube

c. Traveling-Wave Tube

d. Traveling-Wave Transmission

b

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

c

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

a

GaAs stands for:

a. gallium arsenide

b. gallium assembly

c. gallium astenite

d. none of the above

a

IMPATT stands for:

a. impact avalanche and transit time

b. induced mobility at transmission time

c. implied power at transmission terminal

d. none of the above

c

YIG stands for:

a. Yttrium-Iron-Gallium

b. Yttrium-Iron-Germanium

c. Yttrium-Iron-Garnet

d. none of the above

b

A YIG can be tuned by applying:

a. an electric field

b. a magnetic field

c. mechanical pressure

d. an "exciter" signal

c

The device commonly used in microwave ovens is the:

a. TWT

b. klystron

c. magnetron

d. YIG

a

The device commonly used in satellite communications is the:

a. TWT

b. klystron

c. magnetron

d. YIG

b

The device commonly used in UHF transmitters is the:

a. TWT

b. klystron

c. magnetron

d. YIG

a

A microwave phased array is often made using:

a. slots

b. Yagis

c. Fresnel lenses

d. all of the above

c

RADAR stands for:

a. radio ranging

b. radio depth and ranging

c. radio detection and ranging

d. remote detection and ranging

d

RADAR uses:

a. pulsed transmission

b. continuous transmission

c. the Doppler effect

d. all of the above

b

The maximum effective range for pulsed radar:

a. increases with increasing repetition rate

b. decreases with increasing repetition rate

c. decreases with increasing pulse period

d. none of the above

a

he minimum effective range for pulsed radar:

a. increases with increasing pulse duration

b. decreases with increasing pulse duration

c. is always a tenth of the maximum range

d. none of the above