Single-layer capacitive feed for wideband probe-fed microstrip antenna elements

In this paper, it is shown how a single-layer capacitive feeding mechanism, consisting of a small rectangular probe-fed patch, which is capacitively coupled to the radiating element, can be used to obtain wideband operation for probe-fed microstrip antennas on thick substrates. The main advantages of this feeding mechanism are that all the elements reside on a single layer and that it is very easy to fine-tune the input impedance. Calculated as well as measured results for rectangular, circular and annular-ring geometries are included.