A rectangular-cavity-backed cloverleaf slot antenna for circular polarization

Characteristics of a rectangular-cavity-backed cloverleaf slot antenna are investigated numerically and experimentally. The method of moments is used to calculate the antenna characteristics where the effects of the cavity are taken into account. The minimum axial ratio of 1.11 dB and the maximum gain of 10.6 dBi are obtained at 2.19 GHz. The frequency bandwidth for the axial ratio (AR) (< 3 dB) and VSWR (< 2) is 2.7%. The symmetrical radiation pattern is obtained with respect to the vertical. The calculated results on AR, VSWR, and radiation patterns are agree well with measured data