Low-profile inverted-F antenna with parasitic elements on an infinite ground plane

An inverted-F antenna (IFA) whose height is approximately one-tenth of the wavelength is analysed in the presence of a single parasitic element. The resonance phenomena of the parasitic element and IFA are investigated. Based on this investigation, an IFA with a pair of parasitic elements is fabricated and analysed. It is found that the lower and higher resonance frequencies are independently determined by the parasitic element length and the IFA inner length, respectively. The independent resonance phenomena lead to the enhancement of the VSWR frequency bandwidth. A 26% VSWR frequency bandwidth, which is more than three times as wide as that of a conventional inverted-F antenna without parasitic elements, is realised. The radiation pattern and gain are also presented and discussed