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NAVEDTRA 14183A

MICROWAVE PRINCIPLES CH 1,2 ET2 BIBS 2017

QuestionAnswer
The microwave region is that portion of the electromagnetic spectrum which falls between 1000MHz and what? 100,000MHz
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 primary lower frequency limitation of waveguides? physical size
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
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 any space completely enclosed by conducting walls that can contain oscillating electromagnetic fields and posses 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
What is the most simple of the commonly used waveguide junctions? T-junction
Which two basic types are T-junction divided into? E and H type
What are the two most commonly used hybrid junctions? magic-t and hybrid junctions
What permits a system to use the same antenna for both transmitting and receiving? duplexer
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
Which two basic types of motion do electrons have? orbital and electron spin
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
Which theory do tubes that are efficient in the microwave range usually operate on? velocity modulation
What is the time required called for electrons to travel from the cathode to the plate? transit time
What can an electron be accelerated or decelerated by? electrostatic field
What is defined as that variation in the velocity of a beam of electrons caused by the alternate speeding up and slowing down of the electrons in the beam? velocity modulation
What are velocity-modulated tubes used in radar and communications equipment as oscillators and amplifiers? klystrons
What absorbs energy from the electron beam? catcher grids
What are used to reduce a signal to a smaller level for use or measurement? attenuators
Typically, what will a radar receiver be approximately rates at? -107dBm
Traveling-wave tubes have been designed for frequencies as low as 300MHz ad as high as what? 50GHz
What is a self-contained microwave oscillator that operates differently from the linear-beam tubes, such as the twt and the klystron? magnetron
The force exerted on an electron in a magnetic field is at what type of angles to both the field and the path of the electron? right
Which two classes are magnetron oscillators divided into? negative-resistance and electron-resonance
Oscillators are sustained in a magnetron because as electrons pass through the AC and DC fields, they gain energy from the DC field and give up energy to the AC field. What are the electrons that give up energy to the AC field called? working electrons
By what means can energy (rf) be removed from a magnetron? coupling loop
Which type of broadband microwave amplifier can also be used as an oscillator? platinotron
The bandwidth of CFA, at any given instant, is approximately plus or minus what percent of the rated center frequency? +-5
What is a PN junction with a very high concentration of impurities in both the P and N regions? tunnel-diode
Tunnel-diode oscillators can be mechanically or electrically tuned over frequency ranges of about one octave and have what approximate top-end frequency limit? 10GHz
What is the most common type of microwave tunnel-diode amplifiers? reflection-type circulator-coupled
What is a variable-capacitance, PN junction diode that makes good use of the voltage dependency of the depletion area capacitance of the diode? varactor
Which type of waveguide device allows energy to travel in only one direction? circulator
What is the primary limitation on receiver sensitivity and is the name given to very small randomly fluctuating voltages that are always present in electronic circuits? electronic noise
What is the typical gain of a parametric amplifier? 20dB
Which source of microwave energy uses the bulk-effect, gallium-arsenide semiconductor? Gunn oscillator
Point contact diodes, commonly called what, are the oldest microwave semiconductor devices? crystals
What year was the chip of N-type gallium-arsenide crystal made by J.B. Gunn? 1963
Created by: nng7294
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