Compact broadband circularly polarized printed antenna with a shifted monopole and modified ground plane

This paper presents a new and compact printed monopole antenna with broadband circular polarization (CP). The wide axial ratio bandwidth is achieved by placing and feeding a monopole on the side of an FR4 dielectric. In addition, a conventional horizontal ground plane is modified by shortening its width and adding a vertical extension. Experimental results show an |S₁₁| and axial ratio (AR) of 123.5% fractional bandwidth (2.6-11 GHz) and 70% fractional bandwidth (3-6.2 GHz), respectively. The presented antenna is compact with an area of 36 mm × 19.5 mm, simple to design and fabricate, and can achieve broadband AR without using: parasitic elements, and perturbations in terms of creating multiple slots and stubs.