Higher dynamic measurement of antenna passive intermodulation products, using ray optics

Passive intermodulation products may occur when two or more carriers are transmitted through a passive device such as a filter, a transmission line or an antenna or if they are reflected from one object. These products are generally due to distributed non-linearity along the transmission path or the reflector of the antenna. We show that ray optics can be used to determine easily the directions in which these products are in phase and reinforced. This is particularly significant for multi-horn fed reflector antennas, for multiple antennas systems and for higher dynamic in measurement of passive intermodulation.