Microwave Devices Waveguides And AE Flashcards
Describe loop couplings
90• to H feilds at cavity wall
Describe probe coupling with the E fields
Parallel to E feilds at the cavities centre
Describe slot couplings
On the cavity wall with the wall currents across radiating slots
Characteristics of a magnetron
Noisy
High gain
Narrow bandwidth
Func a magnetron
High power oscillator in a radar Tx
Func or a TWT
Amplifier in Transmitter and receivers
Characteristics of TWT
High gain
Wide bandwidth
Low noise
Physical size
Func of a Gunn diode
Local oscillator in Rx
Characteristics of a Gunn diode
Electronically tuneable
Narrow bandwidth Low noise
How is energy loss reduced in wave guides
Coat with silver
Pressure with nitrogen
Purpose of the dummy load
To absorb microwave energy during servicing
Describe choke flange
Creates an rf short circuit 1/2 wavelength from the end of the joint to prevent leaks
Describe pencil beam
Narrow az & narrow elevation
Airborne interception
Describe fan beam
Narrow in az & broad in elevation
Long range search
Describe Cosec^2
Narrow az and broad el
Ground mapping
types of radar AE
Parabolic reflectors
Slotted arrays
Active arrays
Describe slotted planner array AE
Electronic beam mechanical steering
Describe slotted phased array AE
Electronic beam electronic steering
Describe active array
Lots of miniature txs and rxs fitted to the AE
Purpose of T/R switch
Protects the receiver when transmitting prevents low power returns passing to the transmitter
