LTCC multilayer based CP patch antenna surrounded by a soft-and-hard surface for GPS applications

Abstract

A circularly polarized (CP) patch antenna is designed for GPS applications. The soft-and-hard surface (SHS) is utilized for reducing the backside radiation. LTCC multilayer technology is employed to realize the SHS structure by surrounding the patch antenna with a number of rings of metal vias that can be easily fabricated in this process. It is found that the backlobe level can be reduced by more than 14 dB (front-to-back ratio > 20 dB) by using six rings of vias. The SHS-surrounded CP patch antenna has a broad coverage (directivity >0 dBi over /spl theta/=0-75/spl deg/), a low cross-polarized level (axial ratio <2 dB over the upper hemisphere), and a good input impedance match (return loss <-10 dB).