Three miniature microstrip patch antennas are presented for use with dual band GPS systems. The designs are stacked patch structures that allow for simultaneous operation at both the LI (1575MHz) and L2 (1227MHz) bands used in GPS systems. Miniaturization is achieved via the use of Rogers TMM10 dielectric (€_r = 9.2), slots cut into the patch layers, and backing cavities. The antennas are fed using "L" shaped feed probes that proximity couple to the patches, which enhances the impedance match at both bands. AH of the designs achieved a 2:1 VSWR bandwidth greater than 5MHz at each band. A slot loaded antenna achieves gain bandwidths of 15MHz and 28MHz at L2 and LI respectively, with a total size of 36×36×6.5mm, and a cavity backed antenna achieves gain bandwidths of 11MHz and 23MHz at L2 and L1 respectively, while occupying a volume of 34×34×7mm, and is recessed in a ground plane.
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