Dual Band Electrically Small Complementary Double Negative Structure Loaded Metamaterial Inspired Circular Microstrip Patch Antenna for WLAN Applications

Abstract

In this article, a compact dual band metamaterial inspired circular microstrip patch antenna for WLAN applications is presented. The antenna consists of a circular patch loaded with a complementary double negative metamaterial structure which produces a percentage miniaturisation of 60.7%. The circular microstrip patch antenna used for developing the proposed antenna has a resonant frequency of 6.2 GHz with an impedance bandwidth of 3.5% before the metamaterial structure is applied upon it. The loading of the proposed metamaterial structure inspires the antenna to lower its resonant frequency with enhanced bandwidth and generate one additional resonance. The designed antenna can be tuned throughout the C-band by simply altering the size of the metamaterial structure loaded upon it. However, the prototype of the antenna is designed for the most commonly used wireless communication bands at 2.4 GHz and 5.2 GHz. The 10 dB impedance bandwidth of 1.63% at 2.4 GHz and 13.15% at 5.2 GHz are achieved by this design. The electrical parameters of the proposed antenna are ka = 0.72 and QChu = 4.07 rendering it electrically small. This electrical compactness and bandwidth enhancement are caused by the loading of metamaterial structure. The proposed antenna is fabricated on low cost FR4 substrate and has an overall compact electrical size of 0.164 λ0 × 0.164 λ0 × 0.013 λ0 and physical dimensions 20 × 20 × 1.6 mm3, with peak gain 3.8 dBi and 2.9 dBi at 2.4 GHz and 5.2 GHz respectively.