Broadband gap-coupled microstrip antenna arrays

In order to increase the bandwidth of microstrip antennas, an antenna array using gap-coupled patches as the elements is proposed. The input impedance characteristics of gap-coupled patches are analyzed by the dyadic Green's function for a grounded dielectric slab and the moment method. The input impedance of gap-coupled patch arrays is by combination with the antenna elements and the feed network that consists of divider tees, bends and feed line. In addition, considering the surface currents solved from the integral equation, the far field patterns of gap-coupled patch arrays are calculated. Comparison with the ordinary rectangular patch arrays is made. It turns out that the impedance bandwidth for a voltage standing wave ratio of less than 2 of the two-element gap-coupled patch array is much wider than that of the ordinary patch antenna array. All microstrip antennas have been designed and fabricated on substrate with in /sub r/=2.86, h=1.5 mm.<
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