On the influence of capacitive and inductive loading on different types of small patch/PIFA structures for use on mobile phones

Various kinds of patch or planar inverted-F antennas (PIFA) are extensively used for internal antennas in mobile phones. Some analytical design principles of such antennas are discussed resulting in a simplified way of estimating their performance. One result is a coupling factor which is defined and usable to estimate the bandwidth available for phones of different geometry. To optimize this coupling factor various impedances are shown to be very useful.