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Wideband U-shaped cross section antenna with a strip on a U-shaped ground plane

By placing a U-shaped cross section antenna on a U-shaped ground plane, a U-shaped cross section antenna for wideband application is presented. The bottom of the U-shaped cross section antenna is etched to form a strip at the center and four arms. It can be extended the number of degree of freedom to match the impedance. Simulated results show that the impedance matching for the proposed antenna depends on the width of the center strip, the width of four arms and the height of the vertical sides of the U-shaped cross section antenna, and the impedance bandwidth is mainly determined by the width of the U-shaped ground plane. Simulated results of return loss and radiation patterns are also compared with the measured results after the antenna is fabricated. Both are in good agreement. The antenna has a measured impedance bandwidth of 29.17% (2:1 VSWR) of the frequency range 2.06-2.76 GHz and average gain level of 9.0/spl plusmn/0.5 dBi. Good radiation characteristics have been obtained that is, the front-to-back ratio is more than 15 dB across the bandwidth and the maximum cross polarization level is low at the high frequency.