Frequency estimation for compact microstrip antennas

A simple method is presented for estimating the resonant frequency of compact slotted microstrip antennas, based on their current distribution. The method has been first tested in two basic and symmetric geometries; afterwards, through the combination of these geometries, a multi-slotted structure has been analysed. Prototypes have also been manufactured in RT/Duroid 6002 and FR4 substrates, and good agreement has been obtained between estimations, simulations and measurements. A maximum estimation error of 10% has been achieved with this method, providing a useful tool for the design of compact slotted microstrip antennas.