Two PIFA-related miniaturized dual-band antennas

There are two novel printed inverted-F antenna (PIFA) related dual-band antennas for 2.45 and 5.25 GHz; wireless local area network (WLAN) applications introduced in this paper. One is designed by spiraling the tail of the PIFA and the other is by modifying the feed structure of the PIFA into a coupling configuration. An equivalent transmission line model is proposed to explain the dual-band operation of the spiraling PIFA. The measurement results show that the former antenna has a 10 dB return loss with bandwidth 140 MHz in the 2.45 GHz frequency band and bandwidth 756 MHz at 5.25 GHz, whereas the latter one has the bandwidth 240 MHz at 2.45 GHz and bandwidth 672 MHz at 5.25 GHz. In addition, onmidirectional radiation patterns are achieved at those operating frequency bands with average antenna gains near 0 dBi. The proposed antenna possesses the properties of good performance, compact size (about 50% of a typical PIFA), low profile, and low cost; hence, it is suitable for practical applications in a combo WLAN system.