A Broadband Circularly Polarized Antenna with Low-Profile and Wide Axial Ratio Beamwidth

In this work, the design and the characterization of a broadband circular polarized monopole having low-profile and wide axial ratio beamwidth were presented. The antenna was designed on readily available, inexpensive glass-reinforced epoxy substrate having an overall size of 0.56λ0×0.50λ0×0.029λ0 (at center frequency 5.5 GHz). The proposed antenna was a modification of a square-shaped monopole antenna, which incorporates a pair of peripheral slits and an off-center slot for a elliptical polarized radiation. A v-shaped notch below the feed line was introduced and extended as antenna ground to generate broadband circular polarization characteristics. The −10 dB reflection coefficient bandwidth and 3-dB axial-ratio bandwidth of the proposed antenna were measured to be of 47.6 and 27 %, respectively. The 3-dB axial ratio beamwidth of the antenna was 93.5°. The antenna proposed in this work covers multiple application frequency bands including HiperLAN/2 IEEE 802.11a (5.15 - 5.35 GHz / 5.47 - 5.725 GHz) band, WLAN frequency band (5.1 - 5.9 GHz), C-band uplink (5.925 - 6.325 GHz) and part of military application band (4.75 - 4.99 GHz). HIGHLIGHTS Design and characterization of a broadband circular polarized monopole having low-profile and wide axial ratio beamwidth Proposed antenna covers multiple application frequency bands including HiperLAN/2 IEEE 802.11a, WLAN, C-band uplink and part of military application bands Proposed antenna is compact, low-profile and exhibits good polarization purity GRAPHICAL ABSTRACT