Array of a U-Shaped Element on A U-Shaped Ground Plane Wideband Antenna

A single element and a 1times4 array prototype antenna of a U-shaped cross-sectional on a U-shaped ground plane are proposed. By placing a U-shaped cross-sectional element on a U-shaped ground plane, a wide bandwidth is achieved. The radiating element bottom is etched to form a microstrip and four connected-strips for increasing the number of degree of freedom to match the impedance. The impedance consists of two mode matching, they are from the antenna element and the U-shaped ground plane. A single element is easy to compose for constructing an array antenna. The separation between element can be closed for decrease the side-lobe level by slightly changing of mutual coupling. The simulated results of the return loss and the radiation pattern are also compared with the measured results after the antenna are fabricated. Both are in good agreement. The antenna have a measured impedance bandwidth of 29.2%, 23.3% (2:1 VSWR) and gain of 8.5, 14 dBi at 2.45 GHz for a single and an 1times4 array structure, respectively. The front-to-back ratio is more than 15 dB