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

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Flashcards in NAVEDTRA 14183A, NEETS Mod. 11, Ch. 1 Deck (31):
1

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

100,000 megahertz

2

What is microwave theory based on?

Electromagnetic fields

3

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

Coaxial lines

4

What is the most efficient way to transfer electromagnetic energy?

Waveguides

5

What is the primary lower-frequency limitation of waveguides?

Physical size

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?

Bus bar

7

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

0.7

8

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

Boundary conditions

9

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

Quarter-wave vertical

10

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

Cutoff frequency

11

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

Group velocity

12

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

1.71

13

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

Probes, loops, and slots

14

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

Flexible

15

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

Rotating

16

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

Choke joint

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?

Electrolysis

18

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

Directional coupler

19

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

2000-3000 MHz

20

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

Resonant cavity

21

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

Physical size and shape

22

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

Cavity inductance

23

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

Tuning

24

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

Cavities

25

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

T-Junction

26

Which two basic types are T junctions divided into?

E and H Type

27

What are the two most commonly used hybrid junctions?

Magic-T and Hybrid ring

28

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

Duplexer

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? 


Ferrite

30

Which two basic types of motion do electrons have?

Orbital and Electron spin

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? 


Isolator