Study of small wideband folded-patch-feed antennas

Abstract

A small wideband patch antenna which exhibits an impedance bandwidth (Voltage Standing Wave Ratio (VSWR) ≤ 2) of more than 70% with an antenna size of 0.314λo×0.314λo×0.146λo (where λo is the guided wavelength of the centre operating frequency) is presented. Bandwidth broadening is achieved by an E-shaped patch fed by a folded-patch feed, whereas the size reduction is realised through the use of a shorting wall. As the antenna can be made from a single piece of copper plate, it is easier to fabricate than the wideband U-shaped-slot and L-shaped-slit folded-patch-feed antennas previously reported. Parametric studies of the proposed antenna are performed numerically to review its radiation mechanism. These include the purposes of having a shorting wall and two arms attaching on the upper patch forming the E-shaped pattern and the analysis of the input impedance of the antenna. Approximate equations for designing the proposed antenna are also presented. To verify the working principle, the proposed antennas are fabricated and tested for three different frequency bands. Stable radiation patterns are obtained across the band.