A Circularly Polarized Table-Like Air Patch Antenna With Four Grounded Metal Legs

A novel circularly polarized table-like air patch (CP-TAP) antenna is proposed in this letter. With four inherently built-in grounded legs at four corners of the patch, the new antenna can be easily self-supported on the ground plane without any dielectric supporting structure. Two feeding structures of the CP-TAP antenna are proposed. A single-probe-fed prototype operating at 2.45 GHz demonstrates a bandwidth of 7% for return loss of 10 dB and a bandwidth of 1.6% for 3-dB axial ratio. With a new n-shaped proximity coupling probe configuration, the impedance bandwidth of the proposed CP-TAP antenna can be as wide as 25%. In all cases, the peak gain of the proposed CP-TAP antenna is more than 1 dB higher than that of a conventional air patch antenna with comparable feeding structures. It can be expected that with the attractive features of low profile, high gain, and self-supporting, the new antenna configuration can find many practical applications.