Microwave comms combined

C

is the most versatile microwave RF power amplifier and it has an extremely wide bandwidth of operation

The microwave tube, TWT __________.

A. uses cavity resonators to produce velocity modulation of the electron beam and produce amplification

B.uses only one cavity resonator and it is gradually replaced by Gunn Diode

C. is the most versatile microwave RF power amplifier and it has an extremely wide bandwidth of operation

D. it is a combination of a simple diode vacuum tube with built-in cavity resonator and an extremely powerful permanent magnet

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

B

Which of the following characteristics of a waveguide causes the lower-frequency limitation?

A. 12R loss

B. physical size

C. wall thickness

D. dielectric loss

C

Which of the following describes the IMPATT diode?

A. it does not have PN junction

B. they are more efficient than their TRAPATT counterparts but are noisier

C. it is designed to operate with a high reverse bias that causes them to avalanche or breakdown

D. produces an extremely high intensity reverse current pulse

A

IRL __________.

A. the RF signal level impinging on the far end receiver antenna as if it were an isotropic antenna

B. it is simply the level of signal at the receiving end of the transmission

C.it is defined by the radiated power by an antenna in its favored direction, taking into account as referenced to the isotropic radiator

D. it is simply the ratio of the received power and noise power

B

A helical antenna is made up of a coil and a __________.

A. director

B. reflector

C. dipole

D. horn

C

A probe __________.

A. is a flat conductor sandwiched between two ground planes

B. a flat conductor separated from a large conducting ground plane

C. is placed at a point of maximum electric field intensity

D. is placed at a point of maximum magnetic field intensity

C

A climatic factor of 0.25 is used for __________.

A.hot, humid areas

B.convert annual availability to worst month basis

C.average inland areas

D. very dry, mountainous areas

C

H lines have which of the following distinctive characteristics?

A. they are continuous straight lines

B. they are generated by voltage

C. they form closed loops

D. they form only in the wave-guide

C

Which of the following describes the tunnel diode?

A.ideal for low-signal applications

В.extremely small and has a tiny junction capacitance

C.it produces a narrow range of negative resistance when forward biased

D. the main application is frequency multiplication

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

B

The group velocity of a wavefront in a waveguide may be increased by which of the following actions?

A.decreasing the frequency of the input energy

B.increasing the frequency of the input energy

C.increasing the power of the input energy

D. decreasing the power of the input energy

A

The ability of a radar to determine the bearing to a target depends upon the __________.

A. antenna directivity

B. speed of the target

C.frequency of the signal

D. speed of light

B

The microwave tube, reflex klystron __________.

A.uses cavity resonators to produce velocity modulation of the electron beam and produce amplification

B. uses only one cavity resonator and it is radually replaced by Gunn Diode

C. sune most versatile microwave peratina mplifer and it has an extremely wide bandwidth of operation

D.an ex combination of a simple doy powerful permewith builtin cast resonator and an extremely powerful permanent magnet

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

B

A roughness factor of 1 is used __________.

A.over water or a very smooth terrain

B.over average terrain

C. over very rough, mountainous terrain

D. hot, humid areas

A

With a mode description of TE10, what maximum number of half-wave patterns exist across the "a" dimension of a waveguide?

A. One

B. Two

C. Three

D. Four

D

The Doppler Effect allows which characteristic of a target to be measured?

A. distance

B. azimuth

C.altitude

D.speed

B

Which of the following describes the TRAPATT diode?

A. it does not have PN junction

B. they are more efficient than their IMPATT counterparts but are noisier

C. it is designed to operate with a high reverse bias that causes them to avalanche or breakdown

D. produces an extremely high intensity reverse current pulse

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

B

RSL __________.

A. the RF signal level impinging on the far end receiver antenna as if it were an isotropic antenna

B. it is simply the level of signal at the receiving end of the transmission

C.it is defined by the radiated power by an antenna in its favored direction, taking into account as referenced to the isotropic radiator

D. it is simply the ratio of the received power and noise power

A

With the mode description, TE11, what maximum number of half-wave patterns exist across the diameter of a circular waveguide?

A. One

B. Two

C. Three

D. Four

C

The Doppler Effect is a change in what signal characteristic produced by relative motion between the radar set and a target?

A.amplitude

B. phase

C.frequency

D. duty cycle

D

A loop __________.

A. is a flat conductor sandwiched between two ground planes

В.is a flat conductor separated from a large conducting ground plane

C.is placed at a point of maximum electric field intensity

D.is placed at a point of maximum magnetic field intensity

D

Directional couplers for waveguides are characterized by __________.

A. their insertion loss

B. their coupling specification

C.their directivity

D. all of the above

D

To inject or remove energy from a waveguide, which of the following devices could you use?

A.slot

B. loop

C. probe

D. each of the above

B

What is a circulator?

A.a short segment of waveguide that acts as a high Q parallel resonant circuit

B.a microwave coupling device having a number of terminals so arranged that energy entering one terminal is transmitted to the next adjacent terminal in a particular direction

C.a junction consisting of two waveguides coupled together in such a manner that a traveling wave in either guide will induced a traveling wave in the same direction in the other guide

D. a microwave device which allows RF energy to pass through in one direction with very little loss but absorbs RF power in the other direction

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

D

Loop coupling is most efficient when the loop is placed at what point in which of the following fields?

A. at the point of maximum electric field

B. at the point of minimum electric field

C.at the point of minimum magnetic field

D. at the point of maximum magnetic field

B

Which of the following describes the hot-carrier diode?

A. ideal for low-signal applications

B. extremely small and has a tiny junction capacitance

C.it produces a narrow range of negative resistance when forward biased

D. the main application is frequency multiplication

A

A resonant cavity is a type of __________.

A. tuned circuit

B. defect in a waveguide

C. antenna

D. none of the above

C

Increasing the size of the loop wire increases which of the following loop capabilities?

A.efficiency

B. bandwidth coverage

C. power-handling capability

D. each of the above

C

Most radar antennas use a __________.

A. dipole

B. broadside array

C. horn and parabolic reflector

D. collinear array

A

Which description below describes a helical antenna?

A.this is a broadband VHF or UHF antenna that is ideally suited for applications for which radiating circular rather than horizontal

B.or vertical polarized electromagnetic waves are required a large dish-shaped structure made of metal or screen mesh

C. this provides extremely high gain and directivity and are very popular for microwave radio and satellite communication link

D. a flared waveguide

B

A waveguide iris that covers part of both the electric and magnetic planes acts as what type of equivalent circuit at the resonant frequency?

A. as a shunt inductive reactance

B. as a shunt resistance

C.as a shunt capacitive reactance

D. each of the above

D

A waveguide twist __________.

A. is a device that reduces the signal strength as the microwave

В.signals enter the waveguide

used when it is required to separate or combine two or more signals or for simpler interconnections

C.used when changes in direction is required

D. used if change in polarization is needed

B

In waveguides, the phase velocity __________.

A. is the actual speed at which signals travels down the guide

B.is the rate at which the wave appears to move along the wall of the guide based on the way the phase angle varies along the walls

C.is always less than the speed of light

D.all of these

C

The receiver threshold is dependent on __________.

A. the wideband noise power present at the input of the transmitter

B.the noise introduced within the transmitter

C.the noise sensitivity of the baseband detector

D. all of the above

D

A resistive device with the sole purpose of absorbing all the enegy in a waveguide without causing reflections is a/an __________.

A. Iris

B. horn

C. antenna

D. dummy load

A

What is the primary purpose of a directional coupler?

A. to sample the energy in a waveguide

B. to change the phase of the energy in the waveguide

C. to change the direction of energy travel in the waveguide

D. to allow energy in the waveguide to travel in one direction only

D

Radar is based upon __________.

A. microwaves

B.a water medium

C.the directional nature of radio signals

D. reflected radio signals

it does not have a PN junction

Which of the following describes the Gunn diode?

22 GHz

Which of the following is a microwave frequency?

produces an extremely high intensity reverse current pulse

Which of the following describes the step-recovery diode?

the transmitter uses two different frequencies and the receiver is tuned in either of the two frequencies

In frequency diversity, __________.

because electromagnetic fields are completely confined in coaxial lines

Coaxial lines are more efficient than two-wire lines at microwave frequencies for which of the following reasons?

mobile radio

Which of the following is not a common microwave application?

is a flat conductor separated from a large conducting ground plane

A microstrip __________.

ducts

Temperature inversions and/or moisture lapses in the atmosphere may extend or reduce the range of a radar by creating __________.

extend the range of a radio communications system

A "repeater" is used to __________.

large surface area

Copper or I²R losses are reduced by what physical property of waveguides?

high loss

Coaxial cable is not widely used for long microwave transmission lines because of its __________.

the main application is frequency multiplication

Which of the following describes the varactor diode?

duplexer

Which of the following radar components allows the use of one antenna for both transmitting the receiving radar energy?

the microwave beam is bent away from Earth

In k-factor conditions, what is sub-standard condition?

skin effect

In a coaxial line, the current-carrying area of the inner conductor is restricted to a small surface layer because of which of the following properties?

13 GHz

If a certain waveguide was designed to have a cut-off frequency of 17 GHz, which of the following signals will not pass thru the waveguide?

it is defined by the radiated power by an antenna in its favored direction, taking into account as referenced to the isotropic radiator

EIRP __________.

is a low pass filter

The following describes a waveguide, except:

cassegrain feed

Using a small reflector to beam waves to the larger parabolic reflector is known as __________.

accumulation of noise is reduced

An advantage of digital techniques over analog in a microwave system is __________.

A and B:

A. decreased beam width

B. increased gain

Increasing the diameter of a parabolic reflector causes which of the following?

consists of standard frequency diversity path where the two transmitter/receiver pairs at one end of the path are separated from each other and connected to antennas that are vertically separated as in space diversity

The hybrid diversity __________.

Ku

13 GHz is under which band?

troposphere

In a line-of-sight communications system, propagation is affected by which of the following layers of the atmosphere?

high gain, narrow beam width

Horn-driven paraboloid antennas have which of the following characteristics?

period of time from the beginning of one transmitter pulse to the beginning of the next

Pulse-repetition time is described as the __________.

tunnel

Which type of diode does not ordinarily operate with reverse bias?

provides the most reliable transmission

The quad diversity __________.

true north

The relative bearing of a radar echo is measured with respect to which of the following reference points?

FSL & FM

In terrestrial microwave communications, the signal is affected by __________.

oscillator

A two-cavity klystron that has a feedback path from the catcher cavity to the buncher cavity will operate as what type of circuit?

cavity resonators

The operating frequency of klystrons and magnetrons is set by the __________.

is used when it is required to separate or combine two or more signals or for simpler interconnections

A waveguide tee __________.

decreases with increasing repetition rate

The maximum effective range for pulsed radar __________.

low-noise and wide-bandwidth

Which of the following TWT characteristics makes it ideal for use as an RF amplifier?

oscillator

A magnetron is used only as an __________.

all of the above:

A. be enclosed by conducting walls;

B. possess resonant properties;

C. contain oscillating electromagnetic fields

For a device to be considered a resonant cavity, it must fulfill which of the following requirements?

more spectrum space

The main benefit of using microwaves is __________.

size and shape

What factors determine the primary frequency of a resonant cavity?

a microwave device which allows RF energy to pass through in one direction with very little loss but absorbs RF power in the other direction

What is an isolator?

a magnetic field

A YIG (Yttrium Iron Garnet) can be tuned by applying __________.

E-type tee junction

A waveguide junction in which the arm area extends from the main waveguide in the same direction as the electric field is an example of what type of junction?

higher-cost equipment

Which of the following is not a disadvantage of microwaves?

used when changes in direction is required

A waveguide bend __________.

magnetron

The device commonly used in microwave ovens is the __________.

high resistance to current flow

Ferrite devices are useful in electronic and microwave applications because they possess magnetic properties and offer which of the following other properties?

a short segment of waveguide that acts as a high Q parallel resonant circuit

What is a cavity resonator?

TWT

The device commonly used in satellite communications is the __________.

heat

The energy in a ferrite attenuator that is attenuated is dissipated as which of the following energy forms?

buncher cavity

In a klystron amplifier, velocity modulation of the electron beam is produced by the __________.

is also known as rat-race tee

In microwave communications, hybrid plane tee __________.

klystron

The device commonly used in UHF transmitters is the __________.

velocity modulation

The alternate speeding up and slowing down of electrons in a beam that produces electron bunches is known as which of the following modulation terms?

uses cavity resonators to produce velocity modulation of the electron beam and produce amplification

The microwave tube, klystron __________.

slots

A microwave phased array is often made using __________.

increases with increasing pulse duration

The minimum effective range for pulsed radar __________.

to decrease the forward velocity of the input

In a TWT, what is the primary purpose of the helix?

15 GHz

A waveguide has a cutoff frequency of 17 GHz. Which of the signals will not be passed by the waveguide?

is greater than in free space

The wavelength of a wave in a waveguide __________.