Design of a Circularly Polarized High-Gain Patch Antenna Using a Higher-Order Mode With a Heterogeneous Substrate Layer for GPS Applications

This paper proposes a circularly polarized (CP) high-gain low-profile patch antenna using a higher-order mode with a heterogeneous layer for global positioning system (GPS) applications. To obtain theoretical insights, we analyze a CP patch using the cavity model, which has two feeding points. Radiated electric fields (E-fields) are derived from the sum of the
$\textrm {TM}_{030}^{x}$
and
$\textrm {TM}_{003}^{x}$
modes with a 90° phase difference at each port using a hybrid chip coupler. To verify the performance of the proposed antenna, it is fabricated and measured in a full anechoic chamber to obtain the antenna characteristics. The measured and simulated reflection coefficients of the proposed antenna are −33.1 dB and −28.3 dB at 1.575 GHz, respectively. The measured and simulated maximum gains are 9.1 dBic and 9.4 dBic at 1.575 GHz, respectively.