Communications Chapter 11

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Communications Chapter 11

Homework From Chapter 11

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Which range of frequencies to Microwaves cover?
 
Microwaves cover 1 GHz to 300 GHz range of frequencies.
What precautions must be observed when working with microwaves? Why?
 
Watch out for the heat, radiation, and high voltage when working with microwaves. One would want to be cautious because these things could result in death.
State the primary mode of microwave propagation.
 
The primary mode of microwave propagation is line of sight.
Define mircrowave repeater and explain its purpose and operation.
 
A microwave repeater receives a frequency, converts it to another frequency, amplifies that frequency, and retransmits that new frequency. Its purpose is it works like a satellite.
What is a cavity resonator?
 
A cavity resonator is a precisely dimensioned enclosure thatís resonant to a specific frequency used to amplify and filter microwave energy.
How does a cavity behave near resonance?
 
Near resonance, a cavity behaves like a tank circuit.
Define waveguide and explain its structure.
 
A waveguide is precisely dimensioned hollow tubing used as a transmission line.
What does LASER stand for?
 
LASER Ė Light amplification by stimulated emission of radiation
What does MASER stand for?
 
MASER Ė Microwave amplification by stimulated emission of radiation
List five examples of electron beam tubes.
 
Five examples of electron beam tubes: 1.CRT 2.Multi-cavity Klystron 3.Magnetron 4.Beam power tube (triodes and pentodes) 5.Photo-multiplier (light detector)
Describe the klystron tube and list the most widely used types.
 
The klystron tube is a high energy device that RF is injected into. It increases the amount of energy. The most widely used types are multi-cavity klystron tubes and reflex klystron tubes.
What is the function of the TWT magnetic field?
 
The function of the TWT magnetic field is that it forces the scattering of electrons which allows other electrons to be in phase with those fields.
What is the function of the TWT electric field?
 
The function of the TWT electric field is used to focus and accelerate the electrons.
What is the function of the TWT collector?
 
The function of the TWT collector is the high voltage potential terminal used to attract the electron energy. Also called the plate.
State the function of the TWT grid.
 
The function of the TWT grid is that it turns the beam on and off. It controls the density of electrons. It also modulates the beam.
How can the TWT be coupled to a waveguide?
 
The TWT can be coupled to a waveguide by coaxial cables at low frequencies, at high frequencies, it can be directly coupled to a waveguide.
What precautions must be observed when handling a permanent magnet TWT?
 
When handling a permanent magnet TWT, the following precautions must be observed. Donít drop it. Use non-magnetized tools.