Phase and group delays for circularly-polarized microstrip antennas

Applications such as high-precision GPS require an accurate characterization of the phase and group delays in the received signal. The purpose of this investigation is to explore and characterize both the phase and group delays for circularly-polarized (CP) microstrip antennas, which are common in GPS systems. Two types of CP patches are examined. The first is a square patch that is fed with a dual feed employing a 90/spl deg/ phase shifter. The second is a nearly-square patch that is fed along the diagonal. The L1 GPS frequency 1.575 GHz is used in both cases.