Analysis of a correlation coefficient of built-in diversity antennas for a portable telephone

The authors present a numerical analysis of correlation coefficient characteristics with antenna separation and incoming wave distribution for a built-in diversity antenna system comprising two planar inverted-F antennas (PIFAs) mounted on both sides of the radio case. It was found that even small antenna separation yields a sufficiently low correlation coefficient. Mutual couplings between the two antennas were found to play a major role in obtaining low correlation coefficients. It was also found that the built-in diversity antennas have good performance in terms of effective gain. The calculated results were in fairly good agreement with experimental results.<>