Bandwidth Limits of Multilayer Array of Patches Excited With Single and Dual Probes and With a Shorting Post

Maximum achievable bandwidth of a multilayer patch array is investigated. It is found that while the bandwidth increases significantly from one layer to two layers, but does not increase any further with additional layers. Furthermore, the bandwidth of a dual probe-fed patch with a series stub increases significantly from that of a single probe-fed patch array. A simple circuit model is presented to explain such bandwidth characteristics. A comparison of the electrical performances of single, dual probe-fed patches and a patch with a shorting post are presented. The circular polarization performance of a four probe-fed patch array is also shown.