Quad-ridge horn utilizing resistive films to reduce sidelobes

This paper shows how the use of resistive films inside of a quad-ridge horn can be utilized to reduce the sidelobes and help equalize the E-plane and H-plane beamwidths. This extends the upper frequency limit, thereby enabling the antenna range to use fewer feed horns. The resistive films also tend to reduce the gain, however, in an antenna test range, the reduced gain is an acceptable trade-off for achieving reduced sidelobes and increased bandwidth.