NAVEDTRA 14183A, NEETS Mod. 11, Ch. 1 Flashcards
(31 cards)
The microwave region is that portion of the electromagnetic spectrum which falls between 1000 megahertz and what?
100,000 megahertz
What is microwave theory based on?
Electromagnetic fields
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
What is the most efficient way to transfer electromagnetic energy?
Waveguides
What is the primary lower-frequency limitation of waveguides?
Physical size
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
In practical applications, the wide dimension of a waveguide is usually what wavelength at the operating frequency?
0.7
Two conditions, known as what, must be satisfied for energy to travel through a waveguide?
Boundary conditions
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
Which type of frequency in a waveguide would cause angles of incidence and reflection to be zero degrees?
Cutoff frequency
What is the forward-progress velocity of the wavefront in a waveguide called that is somewhat slower than the speed of light?
Group velocity
The cutoff wavelength of a circular guide is how many times the diameter of the waveguide?
1.71
What are the three devices used to inject or remove energy from waveguides?
Probes, loops, and slots
Power losses are greater in what type of waveguide because the inner surfaces are not perfectly smooth?
Flexible
Permanent, semi-permanent, along with what else are the three basic types of waveguide joints?
Rotating
What provides good electromagnetic continuity between sections of waveguide with very little power loss?
Choke joint
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
Which type of device provides a method of sampling energy from within a waveguide for measurement or use in another circuit?
Directional coupler
What is the upper frequency limit for a conventional resonant circuit?
2000-3000 MHz
What is any space completely enclosed by conducting walls that can contain oscillating electromagnetic fields and possess resonant properties?
Resonant cavity
Which two variables determine the primary frequency of any resonant cavity?
Physical size and shape
The resonant frequency of a cavity can be varied by changing any of three parameters: cavity volume, cavity capacitance, or what else?
Cavity inductance
What is it known as when you change the frequencies of a cavity?
Tuning
What are used to determine the frequency of the energy traveling in a waveguide?
Cavities
