Seven-Element Circularly Polarized Patch Antenna

A seven-element microstrip patch antenna is designed to operate with circular polarization and high gain at a frequency of 2.2875 GHz. The antenna was developed in the early 1990s as a potential replacement for a helical antenna aboard the Advanced Tracking and Data Relay Satellite. Recently, the Federal Communications Commission allocated frequencies around 2.4 GHz for commercial communication systems. The present antenna is well suited for these systems, not only because it provides high gain in the desired frequency range, but also because like other patch antennas, it is lightweight, can be fabricated easily, can be mounted with a low profile, and is inexpensive. In addition, its circular polarization is especially advantageous in cellular-telephone and mobile communications, in that circular polarization can mitigate multipath fading, which is severe in urban environments.