A small 1.1-cm3 one-turn loop patch antenna located 2.5 mm above an 18 × 25 mm ground plane separated by a dielectric substrate with relative permittivity of 9.8 is presented. By varying the length of a thin quarter-wavelength matching line, it is possible to change the resonant frequency. An RLC circuit model is used to determine the minimum quality factor Q. It is shown that the proposed loop yields a bandwidth performance close to the theoretical limit. The antenna has a 14.5% bandwidth at the resonant frequency of 2.04 GHz.
Microwave and Optical Technology Letters, 2005, Vol 45, Issue 2, p. 126-128