Design and Development of Mathematical Equivalent Circuit Model of Broadband Circularly Polarized Semi-Annular Ring-Shaped Monopole Antenna

This article presents a broadband circularly polarized (CP) semi-annular ring-shaped printed monopole antenna for wireless applications. A semi-annular monopole with symmetric partial ground plane is designed to achieve the impedance bandwidth with a behaviour of linearly polarized (LP) radiation wave. To achieve the CP behaviour with broadband axial ratio (AR) bandwidth, an asymmetric stair-shaped partial ground plane is incorporated in the semi-annular ring-shaped monopole structure. Different analysis of CP radiation is presented by analysing the surface current distribution, electric field distribution, and also its mathematical modelling using CST-MWS solver. Moreover, an equivalent circuit model of the proposed monopole antenna is developed using Foster canonical forms. The measured −10 dB impedance bandwidth and 3-dB AR bandwidth are 8.78 GHz [3.22–12.0 GHz] and 2.21 GHz [7.58–9.79 GHz], respectively. The peak realized gain and antenna efficiency are 4.32 dB at 7.61 GHz and 82% at 4.83 GHz, respectively. The proposed antenna can be suitable for C-band (4–8 GHz) and X-band (8–12 GHz) applications. © 2023, Electromagnetics Academy. All rights reserved.