Dual Band Diversity Antenna System for Mobile Phones

This paper presents a dual antenna system for diversity application in mobile phones. The system consists in two dual-band helical antennas closely spaced and arranged in two branches on top of a mobile phone. The antenna diversity system is analyzed using a transmission line matrix (TLM) method code. The return loss and the mutual power coupling between the antenna ports are simulated and measured; they both give a preliminary indication of the performance of the system. The complex radiation patterns of the antenna, at each port, are obtained from EM simulations. The received signals at the antenna ports, through a model of Rayleigh fading channel, are computed from the interaction of the radiation patterns and time variable random electromagnetic incident plane waves. The diversity antenna based on two commonly used mobile phone helical antennas is constructed. An experiment is conducted in a mode stirred reverberation chamber (MSRC) to measure the received signals in a multipath environment. The correlation coefficients of the signals and diversity gains for switch combining (SC) and maximum ratio combining (MRC) are evaluated