Metamaterial Circularly Polarized Antennas: Integrating an epsilon negative transmission line and single split ring-type resonator

Abstract

This article discusses the future possibilities and analysis of metamaterial (MTM)-based compact circularly polarized (CP) antennas for wireless applications. Here an effective method is introduced for designing a simple and efficient MTM CP antennas by integrating with an epsilon negative (ENG) transmission line (TL) and single split ring (SSR)-type resonator. For improving the radiation characteristics, a compact size artificial magnetic conductor metasurface (AMC-MS) without via is loaded with the intended ENG TL-based radiator antenna as a ground plane. The novelty of this kind of ENG TL-based CP antenna with AMC-MS is discussed for the first time in the literature and further image theory concept is applied for finding the driving point impedance. This kind of design is suitable for all frequencies by proper optimization and scaling. The radiating element of the intended antenna acquires a smaller area due to its zeroth-order resonance (ZOR) property with dimension of 0.26 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz with an overall dimension with AMC-MS are 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.51 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.5 GHz. The measured results of the antenna show an impedance bandwidth of 16.36% and a CP bandwidth of 11.93%. The antenna shows a gain of 5.62 dBic and average radiation efficiency of 72.1% along the frequency band.