Research Article

Balanced gain for a square metaloop antenna

Science and Engineering, Hosei University, Koganei, Tokyo, Japan

^* e-mail: hymat@hosei.ac.jp

Received: 29 August 2018
Accepted: 3 December 2018
Published online: 18 January 2019

Abstract

A square loop antenna implemented using a metamaterial line, referred to as a metaloop, is discussed. The metaloop radiates a counter circularly polarized (CP) broadside beam when the loop circumference equals one guided wavelength. The frequency response of the gain shows two different maximum values: gain G _Lmax for a left-handed CP wave at frequency f_GLmax and gain G_Rmax for a right-handed CP wave at frequency f_GRmax, where G_Lmax is smaller than G_Rmax. In order to increase G_Lmax, while not affecting the original G_Rmax as much as possible (i.e. balance the gain), a parasitic natural conducting loop (paraloop), whose circumference is one free-space wavelength at f_GLmax, is placed at height H_para above the metaloop. It is found that the difference in the gains can be reduced by choosing an appropriate H_para. The radiation pattern at f_GLmax is narrowed by the paraloop, while the VSWR is not remarkably affected.