A Compact Broadband and Wide Beam Circularly Polarized Antenna With Shorted Vertical Plates

Abstract

In this paper, a compact broadband and wide beam circularly polarized (CP) antenna are with novel vertical plate structure is proposed. The antenna is composed of two pairs of crossed dipoles, a slotted ground plane with four vertical right-angle plates and four shorted vertical plates. The shorted vertical plates are introduced to balance the current between the dipoles and the slotted ground. With this structure, the performance of bandwidth and beamwidth is improved significantly, and a good match is achieved. Also, a simple coaxial feed is applied without other feed networks. A prototype is fabricated and measured. The results show that the proposed antenna has a -10 dB impedance bandwidth of 92.6% and a 3 dB axial ratio (AR) of 71.8%. Simultaneously, a half-power beamwidth (HPBW) more than 120° and a 3-dB axial ratio beamwidth (ARBW) more than 100° are achieved within a passband of 62.8%. The antenna patterns are identical and symmetrical within the 120° beam range over the operating frequency. Moreover, the antenna has a compact size of 0.4λ0 × 0.4λ0 × 0.15λ0.