Theory of miniaturized shorting-post microstrip antennas

An analytical theory for the eigenfrequencies and eigenmodes of shorting-post microstrip antennas (MPA´s) is presented. These antennas are seen as promising candidates for miniaturized mobile telecommunication handsets. In particular, it is shown that the zero mode of the unloaded MPA plays a central role for reducing the lowest operation frequency of the loaded MPA. The theory allows a complete calculation of all relevant antenna parameters and can easily be extended to the case of multiple shorting posts. Applications to the examples of rectangular and circular shorting post MPA´s are illustrated