Shortening the update time of a phased array weather radar

The update time of a phased array radar (PAR) can be reduced by applying adaptive scanning, decorrealting estimates via range oversampling, and transmitting few pulses into different directions and simultaneously receiving the returns. The latter approach is considered in this presentation. To separate signals transmitted to and received from different directions, frequency shifting (hoping) or phase coding of every transmit pulse could be employed. At S band, the frequency constraint is so tight that agile frequency technique has little chance to be allowed . The pulse to pulse phase coding is already in use in the WSR-88Ds for resolving range ambiguities and ground clutter cancelling. Most likely phase coding for these purposes will migrate to a future PAR and therefore would not be suitable to multiplex radar beams.

A new multiple beam technique (MBT) for a PAR that transmits few radar pulses into different directions and simultaneously receives returns is described. To separate out returns from different directions, some features of a realistic antenna pattern is used. The MBT is described in terms of the theoretical and measured antenna patterns of the WSR-88D, which is the benchmark for a weather PAR. It is shown that the technique is capable of separating returned voltages from different directions with relative signal powers of 93 dB, which is sufficient for all weather applications. For a weather PAR, the technique allows reducing the update time by a factor of three or four depending on the duty circle of transmitting modules.