PIFA Bandwidth Enhancement by Changing the Widths of Feed and Shorting Plates

The ultrawideband (UWB) systems require antennas having a very broad bandwidth. The planar inverted-F antenna (PIFA) is widely used in mobile systems due to its excellent performance. However, its bandwidth is very limited. This letter is aimed at addressing this problem by investigating the effects of changing the widths of the feed plate and shorting plate on the impedance bandwidth. It is shown that a PIFA with a much wider bandwidth (up to 65%) than previously reported can be achieved by optimizing the widths of the feed and shorting plates. Simulated and measured results are provided to verify the conclusion.