This article explores the basic concepts of patch antennas. We use a simple rectangular, half wave long, probe-fed patch operating in its fundamental mode as an example. Topics include principles of operation, impedance matching, radiation pattern, circular polarization, bandwidth, efficiency, alternative feed types, stacked patches and higher mode behavior.

This article was originally published in September 2005. After it was published, we received substantial feedback from those who read it. The article has been revised based upon the feedback we received and this updated version was published in the RF Globalnet Newsletter of September 2009.