NAVEDTRA 14183A, NEETS Mod. 11, Ch. 1

Question 1

The microwave region is that portion of the electromagnetic spectrum which falls between 1000 megahertz and what?

Answer 1

100,000 megahertz

Question 2

What is microwave theory based on?

Answer 2

Electromagnetic fields

Question 3

Which transmission media is more efficient than two-wire lines for transferring electromagnetic energy because the fields are completely confined by the conductors?

Answer 3

Coaxial lines

Question 4

What is the most efficient way to transfer electromagnetic energy?

Answer 4

Waveguides

Question 5

What is the primary lower-frequency limitation of waveguides?

Answer 5

Physical size

Question 6

A waveguide may be considered as having upper and lower quarter-wave sections and a central section which is a solid conductor that is called what?

Answer 6

Bus bar

Question 7

In practical applications, the wide dimension of a waveguide is usually what wavelength at the operating frequency?

Answer 7

0.7

Question 8

Two conditions, known as what, must be satisfied for energy to travel through a waveguide?

Answer 8

Boundary conditions

Question 9

When a quarter-wavelength probe is inserted into a waveguide and supplied with microwave energy, it will act as what type of antenna?

Answer 9

Quarter-wave vertical

Question 10

Which type of frequency in a waveguide would cause angles of incidence and reflection to be zero degrees?

Answer 10

Cutoff frequency

Question 11

What is the forward-progress velocity of the wavefront in a waveguide called that is somewhat slower than the speed of light?

Answer 11

Group velocity

Question 12

The cutoff wavelength of a circular guide is how many times the diameter of the waveguide?

Answer 12

1.71

Question 13

What are the three devices used to inject or remove energy from waveguides?

Answer 13

Probes, loops, and slots

Question 14

Power losses are greater in what type of waveguide because the inner surfaces are not perfectly smooth?

Answer 14

Flexible

Question 15

Permanent, semi-permanent, along with what else are the three basic types of waveguide joints?

Answer 15

Rotating

Question 16

What provides good electromagnetic continuity between sections of waveguide with very little power loss?

Answer 16

Choke joint

Question 17

Which electrical action takes place that causes very rapid corrosion of the metals when two dissimilar metals, such as copper and steel, are in direct contact?

Answer 17

Electrolysis

Question 18

Which type of device provides a method of sampling energy from within a waveguide for measurement or use in another circuit?

Answer 18

Directional coupler

Question 19

What is the upper frequency limit for a conventional resonant circuit?

Answer 19

2000-3000 MHz

Question 20

What is any space completely enclosed by conducting walls that can contain oscillating electromagnetic fields and possess resonant properties?

Answer 20

Resonant cavity

Question 21

Which two variables determine the primary frequency of any resonant cavity?

Answer 21

Physical size and shape

Question 22

The resonant frequency of a cavity can be varied by changing any of three parameters: cavity volume, cavity capacitance, or what else?

Answer 22

Cavity inductance

Question 23

What is it known as when you change the frequencies of a cavity?

Answer 23

Tuning

Question 24

What are used to determine the frequency of the energy traveling in a waveguide?

Answer 24

Cavities

Question 25

What is the most simple of the commonly used waveguide junctions?

Answer 25

T-Junction

Question 26

Which two basic types are T junctions divided into?

Answer 26

E and H Type

Question 27

What are the two most commonly used hybrid junctions?

Answer 27

Magic-T and Hybrid ring

Question 28

What permits a system to use the same antenna for both transmitting and receiving?

Answer 28

Duplexer

Question 29

Which type of device is composed of material that causes it to have useful magnetic properties and, at the same time, high resistance to current flow? 


Answer 29

Ferrite

Question 30

Which two basic types of motion do electrons have?

Answer 30

Orbital and Electron spin

Question 31

Which type of ferrite device can be constructed so that it allows microwave energy to pass in one direction but blocks energy in the other direction in a waveguide? 


Answer 31

Isolator