Epsilon Negative Zeroth- and First-Order Resonant Antennas With Extended Bandwidth and High Efficiency

This paper presents a new method to extend the bandwidth of metamaterial (MTM) antennas using an epsilon negative transmission line (ENG-TL). The bandwidth characteristics of zeroth-order resonance (ZOR) and first-order resonance (FOR) are analyzed and described using circuit parameters based on the ENG-TL theory. An equivalent circuit model for the FOR is derived to understand its working principle. The asymmetric coplanar waveguide (ACPW) adopted as the host TL not only offers high freedom to implement the circuit elements, but also overcomes the design constraint of the traditional CPW. Based on the proposed bandwidth extension technique, dual-band and wideband MTM antennas are designed. They provide size reduction, extended bandwidth and high efficiency, which are good candidates for modern wireless communication systems (GSM, UMTS, LTE, WLAN, WiMAX).