Bandwidth and radiation properties of internal handset antennas

This investigation focuses on the interaction between the internal antenna and the PCB of a mobile phone. It can be shown, that the impedance bandwidth of planar inverted-F antennas mounted on a PCB is different from that of the antennas mounted on an infinite ground plane. The reason is the special functioning of the PCB as a finite ground plane on one hand and as an active counterpole of the antenna on the other hand. The results show that the electrical functioning of the PCB depends strongly on the antenna orientation, and that the location of the antenna on the PCB is very important for the resulting bandwidth and for the radiation properties. The measurements and simulation results of this investigation give some basic ideas how the bandwidth and the radiation properties of an internal antenna in a mobile phone can be optimized.