Klystron amplifiers are commonly used in radar transmitters to generate high-power radio frequency (RF) pulses. Klystrons are vacuum tubes that use an electron beam and resonant cavities to amplify RF signals. Radar systems use klystrons as high power amplifiers because they can generate the mean and peak RF power required for radar pulses while offering stability, bandwidth, and cost effectiveness needed to meet modulation and signal processing requirements. The document provides an example of a radar using two klystrons that together provide 1 megawatt of output power at 2380 megahertz.

1. USES OF KLYSTRON AMPLIFIERS IN RADAR
 The radar transmitter produces the short duration high-power RF pulses of energy
that are radiated into space by the antenna.
 The radar transmitter is required to have the following characteristics:
Must have the ability to generate the required mean RF power and the required peak power.
Must have a suitable RF bandwidth.
Must have a high RF stability to meet signal processing requirements.
Must be easily modulated to meet waveform design requirements.
Must be cost effective.

2. Power Amplification Process
Amplification Occurs in Multiple Stages
 Driver Amplifier
 High Power Amplifier
o Vacuum Tube Amplifiers – Klystron, TWT
o Solid State Power Amplifier – Solid State Power Transistor
Requirement for power amplifier
 Low noise
 Minimum distortion to input signal
 The Radar uses two
klystrons that offer a
total o/p power of 1
MW at 2380 Mega
Hertz.

3.  Klystron amplifiers are high power microwave vacuum tubes.
 Klystrons make use of the transit-time effect by varying the velocity of an electron beam. A
klystron uses one or more special cavities, which modulate the electric field around the axis the
tube.
 Due to the number of the resonant cavities klystrons are divided up into:
 Multicavity Power Klystron
 Repeller Klystron

4. Klystron Tubes (Vacuum Devices)
MIT/LL Millstone Hill Radar