Design and Modeling of Dual-Band Dual-Mode Coupled Shorted Patch Antennas

This article presents the coupled shorted patch antennas (CSPAs), which exhibit dual-band operation of both broadside and conical radiation patterns and successfully overcome the major disadvantage of the large H-plane cross-polarization radiation of conventional shorted patch antennas (SPAs). The basic concept behind this breakthrough innovation is to create and explore the coupled TM
_0,1/2
modes. It will be shown that the CSPAs provide the horizontally polarized broadside radiation under the odd coupled TM
_0,1/2
mode for the low band and vertically polarized conical radiation patterns under the even coupled TM
_0,1/2
mode for the high band, respectively. The CSPAs have smaller resonant sizes when compared with those of the conventional SPAs for broadside radiation. The sum of the two resonant frequencies for the CSPAs is twice of that for the corresponding conventional SPAs based on a single microstrip. The ratio of two resonant frequencies depends on the odd and even mode impedances of the coupled microstrips. The calculated results are validated with the simulated and measured ones.