Miniature PIFA without empty space for 2.4 GHz ISM band applications

A novel miniature planar inverted-F antenna (PIFA) design without empty space is presented for 2.4 GHz ISM band applications. The antenna fabricated on an FR4 substrate has an overall size of only 10 (L) 3 (W) 3.5 (H) mm³ to be embedded inside the portable devices. By properly adding a shorting pin and etching a bent slot, the operating frequency of the antenna can be lowered more flexibly. Moreover, owing to no additional empty space, the circuit routing on the PCB is permitted underneath and around the antenna. The impedance bandwidth of the antenna is about 160 MHz from 2.39 to 2.55 GHz. Good omnidirectional radiation pattern with appreciable gain across the band can be obtained so that the proposed antenna is suitable for Bluetooth and WLAN applications.