Contents Introduction
PIFAs (Planar inverted-F antennas) have been widely used as internal antennas for mobile handsets, and many novel dual-frequency designs for achieving GSM (890–960 MHz) and DCS (1710–1880 MHz) operations have been reported [1]. In these designs, the radiating arm or the top patch of the PIFA is usually mounted above the ground plane, and a feed pin and a shorting pin, having a length the same as the distance between the radiating arm and the ground plane, are then connected at proper positions on the radiating arm. In this paper, we present an innovative PIFA design in which the feed pin, the shorting pin and the radiating arm of the PIFA are all printed on a flexible printed circuit board (FPCB), which is then bent by 90° and attached to and supported by a foam base. Without the need of soldering the feed pin and the shorting pin to the radiating arm, the proposed PIFA design is easier to construct. An example for the proposed PIFA applied to a folder-type mobile handset for GSM/DCS operation is demonstrated. In this case, the PIFA is positioned such that the distance between the user's head and the antenna is maximized, which can result in a much lower EM wave power absorption in the user's head, thereby reducing the risk of biological damage [2].
