Design of subminiature microstrip antenna for GPS using perturbation effect.

Subminiature GPS L1 band (center frequency: 1575 MHz, wavelength [λ ${\rm{\lambda }}$]: 190 mm) microstrip antenna suitable for mounting in small electronic devices is proposed in this paper. The newly proposed antenna was transformed from the basic λ/2 microstrip patch antenna to a λ/4 microstrip antenna. To apply the perturbation theory, the width of the radiating element on the feeding point with strong magnetic field energy was narrowed. In addition, the open end of the radiating element with strong electric field energy was folded down in a "王" shape to reduce the antenna size. The size of the designed subminiature microstrip antenna is 10 mm (0.05λ ${\rm{\lambda }}$) × 9.5 mm (0.05λ ${\rm{\lambda }}$) × 8.5 mm (0.04λ ${\rm{\lambda }}$). For impedance matching, the position of the feeding point and the gap between the feeding line and the short stub were adjusted. The fabricated antenna obtained S11 ${S}_{11}$ of −17 dB at the center frequency of 1575 MHz. While the size of the ground plane was 48 mm (0.25λ) × 50 mm (0.26λ), the omnidirectional radiation characteristics for both Eθ ${E}_{{\rm{\theta }}}$ in the xz‐plane and xy‐plane with average gain of −0.3 and −1.7 dBi, respectively. A size reduction ratio of 98.9% was secured from the results compared to the basic λ/2 microstrip patch antenna. [ABSTRACT FROM AUTHOR]