Deck 15: Waveguides and Radar

Question 1

When did the first practical use of waveguides occur?
A.Development of microwaves
B.Development of Doppler radar for traffic control
C.Development of radar during World War II
D.Development of radar for space rendezvous

Answer 1

Development of radar during World War II

Question 2

Doppler radar is a continuous-wave form of radar. Which of the following is it used to determine?
A.Speed of moving objects
B.Velocity of energy propagation
C.Peak power of a radar pulse
D.Transmission of microwave energy

Answer 2

Speed of moving objects

Question 3

For a wave to exist in a waveguide,it must satisfy __________ equations throughout the waveguide.
A.Doppler's
B.Smith's
C.Maxwell's
D.Ohm's

Answer 3

Maxwell's

Question 4

Which of the following is one of the original and still most widely used applications for waveguide?
A.FM broadcasting
B.Radar installations
C.Transmission lines
D.AM broadcasting

Question 5

Which of the following would be a use of a variable attenuator at microwave frequencies?
A.To prevent reflections
B.To change the physical direction of propagation
C.To measure signal levels
D.To change the plane of polarization of the wave

Question 6

In a radar system,which of the following are frequently detected when there is a large target close by?
A.Double range echoes
B.Second return echoes
C.Multiple-time around echoes
D.Duty cycles

Question 7

In what form does energy propagate down a waveguide?
A.Radio signal
B.Magnetic field
C.Radar pulse
D.Doppler radar

Question 8

Cavity resonators are metal-walled chambers fitted with devices for admitting and extracting what type of energy?
A.RF
B.Electromagnetic
C.Magnetic field
D.Microwave

Question 9

Why is a waveguide often pressurized with nitrogen?
A.To prevent contamination
B.To change the plane of polarization of the wave
C.To attach or weld a metal plate at the end of the waveguide
D.To prevent reflections

Question 10

Waveguides exhibit extremely low loss and are capable of handling very high __________.
A.radiation
B.powers
C.frequencies
D.circuits

Question 11

As with waveguides and transmission lines,the characteristic impedances of stripline and microstrip are determined by the type of dielectric and by the ____________.
A.cycle of operation
B.resonant frequency
C.duration of the transmitted pulse
D.physical dimensions

Question 12

What one unique advantage do ridged waveguides provide?
A.It consists of a main run with a rectangular waveguide and a circular rotating joint.
B.It is less expensive to manufacture than a standard rectangular waveguide.
C.It allows operation at lower frequencies for a given set of outside dimensions.
D.It has a value greater than the speed of light.

Question 13

Like coaxial lines,waveguides are perfectly shielded,which allows for no _____________.
A.radiation loss
B.power loss
C.energy loss
D.noise

Question 14

It is often necessary to change the physical direction of propagation or the wave's polarization in waveguides. What is the purpose of a twist section?
A.To produce shunting reactance across the guide
B.To change the plane of polarization of the wave
C.To change the physical direction of propagation
D.So low received power does no damage to the powerful transmitter output

Question 15

Any surface separating two media of distinctly different conductivities or permittivities has a guiding effect on _________________.
A.fiber-optic transmissions
B.propagation direction
C.frequency ranges
D.electromagnetic waves

Question 16

Which of the following is the most dominant mode of operation because it is the most "natural" one for operation?
A.RG-52/U
B.TE₁₀
C.GHz
D.TM

Question 17

How many feet is the nautical mile,which is the accepted unit of distance in radar?
A.6076 ft.
B.6000 ft.
C.5280 ft.
D.2000 ft.

Question 18

Transmission lines,antennas,and fiber optics are the commonly known means of _______________.
A.information-carrying capacity
B.high-frequency transmission
C.low-frequency transmission
D.electromagnetic waves

Question 19

What is the most popular shape of a waveguide?
A.Octagonal
B.Circular
C.Rectangular
D.Square

Question 20

The resonant frequency of a cavity may be varied by changing any of three parameters: cavity inductance,cavity capacitance,and cavity__________.
A.range
B.shape
C.mode
D.volume

Question 21

There are three methods of coupling energy into or out of a waveguide: probe,loop,and __________.
A.aperture
B.transverse electric
C.dominant mode
D.flexible

Question 22

The series tee is often used for _____________.
A.a single antenna to be used for both transmission and reception
B.adjusting signal levels
C.physically reversing a directional coupler
D.impedance matching

Question 23

What is necessary for radar to provide an accurate directional picture?
A.Highly directive antenna
B.Cavity capacitance
C.Electromagnetic energy
D.Maximum usable range

Question 24

___________ transfers energy from a primary to an adjacent secondary waveguide for energy traveling in the main guide in one direction only.
A.Microstrip
B.Pulse repetition frequency
C.Directional coupler
D.Stripline

Question 25

The process of locating objects via radar requires the measurement of three coordinates: range,angle of azimuth,and angle of _____________.
A.antenna curve
B.energy transmission
C.elevation
D.echo signal