Design of a Low-Profile Single-Feed Circularly Polarized GNSS Antenna

This paper presents the design and analysis of a single-band patch antenna operating at the L5 frequency band (1.176 GHz) for Global Navigation Satellite System (GNSS) applications. The antenna utilizes a single coaxial feed and is implemented on an FR-4 substrate, known for its cost-effectiveness and ease of fabrication. Circular polarization is achieved through strategic truncations and slots on both the patch and ground plane without the use of any external phase shift and power divider network. The simulation results show a -10 dB reflection coefficient bandwidth of 70 MHz (1.140 GHz to 1.210 GHz) with an S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>value of-17.29 dB at the L5 frequency band and the 3 dB axial ratio bandwidth of approximately 20 MHz (1.166 GHz to1.186 GHz) with an axial ratio of 1.75 dB at the L5 frequency band. Additionally, a nine-element antenna array, measuring 260 mm x 270 mm, is developed using the same antenna element. The array provides a good impedance matchingwith an S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>value of -20.02 dB at the centre frequency and S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>of below - 10 dB within the operating bandwidth of GPS L5 frequency band and an axial ratio of 2.24 at the centre frequency and below 3 dB level over a narrow frequency range. The suitability of the antenna and its array for GNSS applications is validated through simulated results, which are thoroughly discussed in this paper. Furthermore, the beam-switching simulation results of the antenna array have also been carried out,allowing for dynamic adjustment of the antenna's radiation pattern to enhance signal reception and mitigate interference.