Miniaturized Dual-Band Circularly Polarized Quadruple Inverted-F Antenna for GPS Applications
A miniaturized dual-band quadruple inverted-F antenna with size of  ${\text{0.1}}\lambda _{0}\times {\text{0.1}}\lambda _{0}\times {\text{0.04}}\lambda _{0}$ is presented in this letter. The proposed structure consists of an array of four sequentially rotated inverted-F elements with quadrature excitations for circular polarization. Two methods are utilized to reduce the antenna size, including folding the radiating elements into spiral and meander shapes and introducing the coupling between adjacent elements. This antenna operates in the global positioning system (GPS) L1 and L2 bands, and the maximum gain performances in the two bands can be adjusted separately. The experimental results confirm that the obtained 10 dB impedance, 3 dB axial-ratio, and 3 dB realized gain bandwidths can fully cover the GPS L1/L2 bands. The good performances demonstrate that the proposed antenna is suitable for portable GPS devices.