A small antenna consisting of short‐ended parallel stubs and capacitors

Abstract

A small antenna for mobile communication is proposed in which the ends of the shorted parallel plates are folded inward to generate a capacitive load between the gap. The balanced feed happens at an appropriate position on the parallel plates. When dual parallel plates are used, the antenna can be used at dual frequencies. This antenna is considered to ba a kind of small loop antenna and can be used at the electric field null (or the peak of the magnetic field) generated near the metallic furniture, a column with internal conductors and walls. In this paper, the far-field radiation pattern and the input impedance of this antenna are computed and the results are compared with the measured results. This comparison demonstrates that the method cannot quantitatively evaluate the antenna characteristics but can be useful for finding the tendency of these characteristics. Next, the design guideline of the antenna is presented according to the analysis method. Miniaturization limitations of the present antenna are discussed. The antenna proposed in this paper has a measured gain of G = −0.3 dBi and a bandwidth of 5.6 percent for a return loss of less than −10 dB with a maximum dimension of one-half wavelength. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (4): 83–95, 1996