Antenna designer´s notebook

The polarization requirements of EW and other systems often dictate that the antenna be capable of multiple polarizations, for example vertical, horizontal, and both senses of circular, i.e. V, H, RHCP, and LHCP. In some instances a fixed linear polarization such as +45° tilted linear can be used, but its response to the other polarizations involves polarization mismatch losses as shown in Table 1. Note that most combinations have a 3dB loss, and that +45° is "blind" to a co-polarized source. In cases where the 3dB loss is not tolerable, the antenna must generate the desired polarizations in a simple and cost effective manner.