A dual-band stacked microstrip antenna array for mobile satellite applications

In mobile satellite communications, it is desirable to transmit and receive signals at a constant level despite the variations in the elevation angle and the attitude of the mobile station; consequently, wide angle circular polarization characteristics are required for the antenna element. Microstrip antennas are well-suited for such applications because of their light weight, small size, and low production cost. Though a conventional patch antenna can provide a circularly polarized radiation pattern with a single feed, the gain of the antenna decreases by about 10-15 dB as we move from the zenith towards the horizon, and the gain reduction is accompanied by a deterioration in the axial ratio as well. To overcome these limitations, a stacked patch-array design satisfying the gain and polarization specifications for mobile satellite applications has been proposed in Yang et al. (1994). The present authors explore the possibility of employing two such stacked array antennas operating over the INMARSAT frequency band for transmitting uplink frequencies of 1626-1660 MHz and receiving signals at down link frequencies of 1530-1560 MHz. Preliminary experimental results of the performance of the antenna array are presented.