Gain of pyramidal horn given the quadratic phase error factors S in the E- and H-planes and accounting for the 0.91 dB ATL of the cosine distribution in the H-plane over the range of reasonable values of S in the two planes.
RHOPTG (Linux version) - Pyramidal horn designed to gain
REBWDN (Linux version) – Pyramidal horn designed for given beamwidths
HORNPY (Linux version) – Pyramidal horn parameters from dimensions