A high performance transmitter for the NEXRAD radar system

An S-band radar transmitter developed for the Next Generation Weather Radar (NEXRAD) operates at dual RF pulsewidths of 1.5 and 5.0 μs and variable PRF (pulse repetition frequency) ranging between 300 and 1300 p.p.s. The transmitter has demonstrated a phase stability of better than 57 dB. The performance is achieved with a klystron amplifier cathode pulsed by an all-solid-state line-type modulator. Special attention is given to modulator pulse regulation, output regulation and inverter timing in the filament supply, and spectral conditioning in the solid-state RF driver. The peak modulator power level of 1.5 MW is capable of producing a peak RF output in excess of 750 kW. The authors describe the transmitter in terms of architecture, design details, and performance planned and achieved. Particular attention is given to the techniques used to ensure stability in the face of variation in pulsewidth and PRF