Rejection-band improvement for gain- and phase-constrained high-pass filters

A technique was developed for the design of digital FIR filters that are constrained in transfer gain and phase. One application of this technique is to produce a filter that selectively cancels low frequency return, such as surface clutter from a ground-based radar, and to provide a desired transfer delay that is uniform for all unattenuated frequency components (i.e., a specific linear phase in the passband). This has application, at least, to Doppler-weather radar processing with a short-burst waveform in the presence of ground clutter. In practice, the design technique requires a compromise between the control of the gain response and the minimization of distortions in the delay response. The technique can be modified, however, to provide improved gain and delay responses simultaneously. This paper describes the existing technique and the suggested improvement