Miniaturised artificial magnetic conductor and its application in unidirectional circularly polarised slot antenna design

• Published in: IET microwaves, antennas & propagation Vol. 12; no. 12; pp. 1885 - 1889
• Main Authors: Li, Jianxing, Huo, Huimin, Chen, Juan, Zhu, Shitao, Shi, Hongyu, Zhang, Anxue
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 03.10.2018
• Subjects: air gap layer; air gaps; AMC reflector; antenna feeds; antenna system; axial ratio bandwidth; capacitors; circular polarisation radiation; circularly polarised square slot antenna; conductors (electric); coplanar waveguide; coplanar waveguides; CPSSA; diagonal corners; directive antennas; electromagnetic wave polarisation; frequency 2.71 GHz; interdigital capacitors; loss 10 dB; L‐shaped strips; miniaturised polarisation independent artificial magnetic conductor; reflector antenna feeds; Research Article; return loss impedance bandwidth; slot antennas; UHF antennas; unidirectional circularly polarised slot antenna design; unidirectional radiation; miniaturised polarisation independent artificial magnetic conductor; unidirectional radiation; conductors (electric); CPSSA; reflector antenna feeds; AMC reflector; interdigital capacitors; frequency 2.71 GHz; air gaps; unidirectional circularly polarised slot antenna design; coplanar waveguide; directive antennas; coplanar waveguides; antenna system; UHF antennas; diagonal corners; antenna feeds; loss 10 dB; circular polarisation radiation; circularly polarised square slot antenna; electromagnetic wave polarisation; air gap layer; return loss impedance bandwidth; slot antennas; capacitors; L-shaped strips; axial ratio bandwidth
• ISSN: 1751-8725; 1751-8733; 1751-8733
• DOI: 10.1049/iet-map.2018.0108

A polarisation independent artificial magnetic conductor (AMC) miniaturised using interdigital capacitors is investigated. Its performance is analysed and compared with two other previously reported AMCs. Then, a circularly polarised square slot antenna (CPSSA) utilising the proposed AMC as a reflector is implemented, which achieves unidirectional radiation and low profile simultaneously. The CPSSA is fed by a coplanar waveguide and loaded by two L-shaped strips placed around two diagonal corners, providing the required perturbation for circular polarisation radiation. In between the slot antenna and the AMC reflector is an air gap layer. The performance comparison of the whole antenna system employing different reflectors (three AMCs and one perfect electric conductor (PEC)) proves the advantage of the proposed AMC. As for the fabricated antenna prototype, the measured 10 dB return loss impedance bandwidth and 3 dB axial ratio bandwidth are 15.9 and 4.1%, respectively, corresponding to the centre frequency of 2.71 GHz. In addition, an almost constant gain of around 5.5 dBic has been obtained across the circular polarisation bandwidth within an overall antenna volume of 0.54λ0 × 0.54λ0 × 0.08λ0.