Compact octagonal microstrip patch antenna for multiband applications

Abstract

Compact and multiband antennas are in great demand to meet the ever-expanding wireless/mobile communications requirement. A novel design for compact multiband uni-octagonal and bi-octagonal ring slot antennas are proposed to work at fourteen frequencies spread over six designated RF bands, these are C, X, Ku, K, Ka and V bands. The Roger RT/Duroid 5880 reinforced glass microfiber PTFE composite is used as substrate material for the two antennas with dielectric constant εr=2.2 with thickness of substrate h=1mm. The antenna parameters like return loss, VSWR, gain, radiation pattern and electric field distribution were thoroughly studied in evaluating the performance. The study revealed a uni-octagonal ring slot antenna has produced satisfactory performance at six resonant frequencies distributed over five designated RF bands. The bi-octagonal ring slot antenna is, in principle, an improvement made over the uni-octagonal ring slot antenna by adding an additional ring. The proposed antenna can operate at nine frequencies in five designated RF bands. The antenna can achieve the uni-octagonal ring slot reflected power of -12.2 dB, -14.0 dB, - 17.4 dB, -17.8 dB, -20.5 dB and - 10.9 dB at 7.6 GHz, 12 GHz, 24.6 GHz, 37.7 GHz, 43.2 GHz and 48 GHz respectively and the bi-octagonal ring slot reflected power of -20.9dB, -15.1dB, -22.8 dB, -17.0 dB, -25.4 dB, -37.4 dB, -15.0 dB, - 16.1 dB and -10.1 dB at 8.2 GHz, 11.4 GHz, 14.9 GHz, 21.1 GHz, 24.9 GHz, 28.9 GHz, 37.7 GHz,40.9 GHz and 45.8 GHz respectively. The bi-octagonal ring slot antenna gave improved return loss. The simulated and measured return losses are less than -10 dB at all the resonant frequencies. The achieved bandwidth is qualitatively of superior voltage standing wave ratio VSWR<2 for both uni-octagonal and bi-octagonal ring slot antennas. These antennas are found to be suitable for multiband wireless communication systems.