Design and implementation of low cost active integraded microstrip circular polarized antenna for GPS application

In this paper, an active integrated circular polarized microstrip antenna (AICPMSA) for satellite receiver applications operating at GPS LI band is introduced. The active part is a low noise amplifier (LNA) designed using ATF-21170 high performance gallium arsenide Schottky barrier-gate field effect transistor (FET) housed in a hermetic. For the LNA design, a good trade-off between low noise figure, forward gain and stability has been achieved. Optimized LNA has −15.17 dB input return loss (Su), high gain (S2i) of 12.35 dB, and noise figure (NF) of 0.625 dB at 3 V biasing voltage. The LNA offers circuit stability parameter K=2.13. A circularly polarized (CP) antenna was designed for operation at GPS LI band. The antenna is a patch loaded with four V shaped slit and four circular slits for each quarter to reduce the patch size. The antenna designed as two layers with proximity coupled feed to increase the bandwidth. Also, the CP antenna was designed on low-cost lossy FR-4 substrate with comparison between simulated and measured results. The output gain for integrated system includes the proposed LNA and proposed antenna was more than 10 dB and NF less than 0.7dB.