An improvement of horn-gain formula

A new formula was derived for the far field and gain of the pyramidal horn, open-ended rectangular waveguide (0EG) and E-plane sectoral horn. In this new formula the concept of phase base marker plane for horn antennas was firstly proposed; the edge effect of the apertures was taken into account at the same time, the approximation of the path length was avoided by direct numerical integration for the gain and far field. The result shows that for the medium and small aperture pyramidal horn and E-plane as well as the 0EG horn, the improvement of the accuracy for the new formula is distinct, and the results of FDTD method and an experiment verified the the correctness of the new formula.