Error analysis of electronic roll stabilization for electronically scanned antennas

It is demonstrated that for non-gimballed electronically scanned antennas (ESAs), an approximate true elevation return can be generated using an RF resolver. Also presented is an error analysis of this method. How the resolver coefficients are chosen and how the resolved elevation discriminant slope is derived are described. It is shown how to linearly combine, via an RF resolver, the two monopulse returns from a four-quadrant (radar) ESA to create an elevation discriminant which is only approximately independent of target azimuth angle. The amount of target azimuth angle dependence is derived. The functional form of the discriminant is shown to be difficult to invert; therefore, to obtain accurate results, involved processing must be used. Several calibration schemes are shown to suffer from these approximations