Wide-b-and circularly polarised slot antenna by using artificial transmission line

A novel single-feed wide band planar single layer circularly polarised (CP) slot antenna is presented. This low cost slot antenna consists of an L-shaped feeding stub with metamaterial inspired complementary split ring resonator (MICSRR) and a wide 45 degrees rotated symmetric square aperture. Broadband impedance and CP radiation bandwidth (BW) is achieved by using a novel artificial exciting stub with defecting CSRRs on it. By controlling the excitation phase of L-shaped stub, a desirable circular polarisation can be generated and both impedance and CP BWs are considerably increased by up to 89%. The operating frequency ranges in S/C band about 1.5 octaves from 2.4-6.22GHz that covers most of the commercial wireless communication systems, such as WLAN (IEEE 802.11 (2.4/3.6/4.9/5/5.9GHz)), LTE and WiMAX (2.5/3.5/5.8GHz). The measured BWs of 3-dB axial ratio and voltage standing wave ratio <2 are around 91% (2.4-6.4GHz) and 89% (2.4-6.22GHz), respectively. The measured boresight gain is less than 6dBic over the CP BW.