A uniplanar corner-fed patch antenna is presented with single-point microstrip feed and single layer substrate. Two orthogonal polarized dominant modes TM010 and TM001 are excited at two different frequencies. By utilizing a corner-fed structure, impedance matching for two bands can be adjusted much independently and the small ratio between two operating frequencies is easy to achieve. In addition, this simple and compact structure makes the patch antenna very convenient to form an array. A patch antenna operating at 12.5 GHz and 14.25 GHz with two linear orthogonal polarizations has been designed. The frequency ratio is only 1.14. The return loss, current distribution and radiation patterns of the patch element are investigated in detail. An 8 by 8 array has been developed, of which gains more than 23.4 dBi have been obtained at dual frequencies. Measured results agree well with simulated ones, which validate the proposed structure.
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