Miniature shorted dual-patch antenna

Two designs are constructed based on a two-layer dual-patch antenna with co axial feed. One of the shorter edges of the upper patch is connected to the lower patch and the other shorter edge is connected directly to the ground by another vertical wall without touching the lower patch. Tn the first de sign the upper patch is rectangular and the shorting wall to the ground is narrower than the width of the whole patch. In this case the resonant frequ ency of the patch can reduce by 72% when compared with the conventional hal fwave patch. It has a bandwidth of 8.8% and a gain of -1,7dBi in the broads ide direction. The pattern has a maximum gain 0.5dBi occurring at theta = - 40 degrees. In the second design, the upper patch is modified into a trapez oidal shape. The resonant frequency of this patch can reduce by 72% when co mpared with the conventional halfwave patch. It has a bandwidth 8.3% and a gain of -1.7dBi in the broadside direction, The pattern has a maximum gain 1,5 dBi at the direction of -35 degrees direction. Compared with the first design, a 1dBi gain improvement is obtained.