A Low Profile and Wideband Quadrifilar Helix Antenna with Wide Beamwidth

In this paper, we designed a broadband and wide-beam quadrifilar helix antenna (QHA). By loading a ceramic dielectric ring around the QHA, the beamwidth is significantly broadened. Specifically, the antenna achieves a wide beamwidth of 146° (with gain greater than 0 dBic) and a 3 dB axial-ratio beamwidth (ARBW) exceeding 125°. Additionally, a low profile of 0.085 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_0$</tex> is achieved due to the dielectric loading. The antenna operates in a broadside radiation mode with a maximum gain of 5.1 dBic. The proposed QHA exhibits a relative bandwidth of 46.8% and an axial-ratio bandwidth of 41%, covering the China Tiantong satellite frequency bands of 1980 MHz - 2010 MHz and 2170 MHz - 2200 MHz. Therefore, the proposed antenna, with its low profile and wide beamwidth, is highly suitable for vehicular antenna applications.