Dual-band patch antenna for mobile satellite systems

The launch of new mobile satellite communication links fur telephone and data applications demands development of small, low-profile, low-cost antennas. A single-layer, multi-band microstrip patch antenna is described, which operates over the frequency ranges of the Iridium and Globalstar satellite communication systems, 1.6 and 2.5GHz. The attenna excites: the TM10 and TM30 resonant modes which can operate with either dual linear polarisation or either hand of circular polarisation. The unwanted TM20 mode is suppressed using a combination of slots cut into the patch and by shaping the corners of the patch. Frequency band separations can be varied significantly from 1.3 to 2.5 x the lower frequency. Data for designing the patch dimensions is presented. The return loss, impedance characteristics and radiation patterns are presented for a practical design.