Crosspolarisation characteristics of linear comb-line microstrip antennas

An experimental study of the cross-polarization characteristics of comb-line antennas is described, and criteria for cross-polarization suppression are obtained for particular board characteristics at 4.3 GHz. The use of a single comb-line in low sidelobe applications is limited by the cross-polarization level produced unless a low radiation efficiency (narrow maximum stubwidth) can be tolerated. It is shown that the two main sources of cross-polarized radiation in comb-line antennas are the transitions and the wide stubs.