Noise measurements in a Ka-band gyroklystron amplifier

Gyroklystron amplifiers are attractive for use in millimeter wave radar transmitters, by virtue of their high peak and average power capability. However, the noise performance of the transmitter is also of great importance in modern coherent radars, since noise interferes with the advanced signal processing used to distinguish multiple targets, improve range resolution, and create images of targets in the presence of clutter. Therefore, as an early step in a detailed study of the noise properties of gyroklystrons, direct phase noise measurements in a 35 GHz, LC-cavity gyroklystron producing 50 /spl mu/s pulses of 175-210 kW power with 50-53 dB saturated gain have been performed. These initial measurements were made at a 10.7 MHz frequency offset from the carrier, where extrinsic noise from the modulator is limited.