A compact multi-folded patch antenna for UWB application at the UHF band

Patch antennas usually involve a ground plane much larger than the radiating element. To make a patch antenna compact, it is significant to reduce the size of the large ground plane. In this paper, a compact multi-folded patch antenna with a substantially small ground plane for UWB (ultra wideband) application at the UHF (ultrahigh frequency) band is presented. The proposed antenna is derived from an ordinary L-shaped monopole antenna, and with the dimension of only 0.22λL× 0.092λL× 0.091λL (λL is the longest wavelength in the operating bandwidth) after folding the L-shaped radiating patch over the small ground plane. The characteristics such as impedance bandwidth, gain and pattern stability are analyzed and measured. According to the measured results, the antenna has an impedance bandwidth up to 61.5% for VSWR≤2, ranging from 450 MHz to 850 MHz, covering the band of DVB-T (Digital Video Broadcasting-Terrestrial) (470 MHz-862 MHz) and DTV (Digital TV) (470 MHz-806 MHz). Details of the fabricated antenna are described, and a prototype of the design example is constructed and studied.