Whip-PIFA combination in wireless handset application: a hybrid circuit model and full wave analysis

In this paper, a circuit model was developed in RF ADS to simulate the coupling effect of a retracted whip on a PIFA (Planar Inverted "F" antenna) in a wireless handset application. A PIFA was designed as the main antenna of a handset to cover the 800 MHz band (824 MHz ∼ 894 MHz) and 1900 MHz band (1850 MHz ∼ 1990 MHz). A parasitic dual band whip antenna was used to improve the performance of the PIFA especially when the handset is used against the head. In such a whip-PIFA combination environment, the retracted whip degrades the PIFA performance if it is not designed carefully. The purpose of this paper is to present an efficient method to optimize the PIFA performance when the whip is in retracted position.