Frequency Diversity Wideband Waveforms for Dual-Polarization Weather Radars

The transition from traditional high powered transmitter to solid-state transmitter is essential to realize a network of low cost electronically steered X-band radars. However, solid-state transmitters have low peak powers which degrades the sensitivity of the radar. Sensitivity requirements with low peak power transmitters necessitates the use of pulse compression waveforms. Pulse compression radars transmit long wideband pulses to achieve adequate sensitivity and range resolution. Although pulse compression waveforms provide adequate sensitivity they have two main drawbacks. First, they suffer from blind zone that occur because the receiver does not receive any signal while the long pulse is being transmitted. Second, the presence of range sidelobes introduces contamination from neighbouring ranges.

In this paper a frequency diversity wideband waveform is proposed to mitigate low sensitivity of solid-state transmitters and also mitigate the blind zone problem associated with pulse compression. The proposed waveform is designed and implemented for a dual-polarization X-band radar operating in Simultaneous Transmit & Receive (STAR) mode. The impact of hardware performance such a phase noise and phase non-linearities on the performance of the waveform is analyzed. An analysis of the performance of pulse compression using mismatched compression filters is reported for dual-polarization weather radars. The impact of range sidelobe on the spectral moments and polarimetric variables are presented based on a simulations done at X-band.