Rigorous analysis of probe-fed printed annular ring antennas

This paper presents calculated and measured results for the input impedance and radiation performance of probe-fed printed annular ring antennas. Geom etries featuring stacked rings as well as shorting posts are considered. A numerical model is presented that is based on a full-wave spectral-domain m oment-method solution. In this solution, a specialized attachment mode-expa nsion function is used to model the connection between the probe feed and t he printed ring. Measured results are presented and compare well with the t heory. Annular rings are found to have certain advantages over circular and rectangular microstrip antennas.