L-Band Dual-Band Dual-Circularly Polarized Active Antenna Design

This article describes a GPS that works on GPS L1L5 Design and implementation of dual-frequency dualcircularly polarized active antennas in frequency bands. The antenna structure is designed with a double-layer air microstrip antenna, which realizes the circularly polarized radiation of the two frequency bands of L1 and L5, and achieves a high gain of more than 8dBic, which is significantly improved compared with other satellite navigation antennas. In addition, the low-noise amplification circuit is used to realize the circular polarization of left-handed and right-handed two-way, and the right-handed circular polarization can be used to directly receive the signal transmitted by GPS satellites. The design of left-handed circular polarization is used to suppress the right-handed reflected signal, reduce the signal distortion caused by the multipath effect, and in the indoor occlusion area, the satellite direct signal may be blocked, and the reflected signal may become the main signal source, and the left-handed circular polarization antenna can preferentially receive the reflected signal. In addition, the use of low-noise amplification circuitry can greatly improve the gain of the whole system. Using the electromagnetic simulation software HFSS for simulation, the antenna can work in two frequency bands: L1 $1575.42 \mathrm{MHz} \pm 1.023 \mathrm{MHz}$, L5 $1176.45 \pm 10.23 \mathrm{MHz}$. The antenna gain can reach more than 8 dBic, the axial ratio is less than 2 dB, and the low-noise link gain can reach about 36 dB. The measured results are in good agreement with the simulation results, which verifies the correctness of the design.