Design of a CRLH-TL metamaterial-based small antenna with bandwidth enhancement

Abstract

Metamaterial-based antennas are class of antenna implemented based on several unique properties from metamaterials. Due to their unusual characteristics, metamaterial received substantial interests and have been applied in some microwave circuit and antenna design. One of new applications is the CRLH-TL metamaterial-based small antenna. With extraordinary properties such as anti-parallel phase and group velocities and infinite wavelength of the guided wave, the antenna can be fabricated independent of the antenna’s size. In addition, the proposed coplanar structure is easy to implement and provides more design freedoms. Small size, low profile, low cost, and multi-bands are features of the CRLH-TL metamaterial-based antenna. This report focuses on CRLH-TL metamaterial and the application of this material on small antenna design. The coplanar waveguide technologies was chosen to improve narrow bandwidth problem form general metamaterial-based antennas. The analysis on CRLH-TL metamaterials and performances of antennas was carried in ANSYS HFSS microwave simulator. The size reduction was achieved and the antenna was fabricated for two frequency bands. The measured results showed that the resonant frequency at the zeroth order mode is at 2.1 GHz with the omnidirectional peak gain of -0.2 dBi and for the higher order mode, the resonant frequency is at 5.48 GHz with the gain of 2.94 dBi. The measured results presented the 10-dB fractional bandwidth of 3.5% and 15% for the zeroth order mode and the higher mode respectively. Because the proposed antenna has omnidirectional radiation, multi-bands, a compact size, acceptable realized gain, and possibility of covering the operational frequency ranges of Wi-Fi and mobile WiMAX, the CRLH-TL metamaterial antenna can be used in portable devices for wireless communication.