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. Geometries featuring stacked rings as well as shorting posts are considered. A numerical model is presented that is based on a full-wave spectral-domain moment-method solution. In this solution, a specialized attachment mode-expansion function is used to model the connection between the probe feed and the printed ring. Measured results are presented and compare well with the theory. Annular rings are found to have certain advantages over circular and rectangular microstrip antennas.