Handheld antenna diversity experiments at 450 MHz

Abstract

This paper presents one part of a set of experiments that were performed in the city of Liverpool to investigate the effectiveness of antenna diversity for handheld portable radio applications at 450 MHz. The work reported here concentrates on spatial antenna diversity. It is evident from the experimental findings that significantly low signal correlation can be produced by closely spaced antennas. Similar results, both experimental and theoretical, have been reported elsewhere. The authors are, however, unaware of any publication in which additional attention has been given to the effect of antenna radiation efficiency degradation produced by such small antenna separations. This work effectively combines the signal correlation and radiation efficiency into a single measure, namely the comparative antenna diversity gain. The results indicate that significant diversity gain is achievable from antennas whose separation is much less than that predicted by the established field autocorrelation models. Theoretical techniques developed by the authors show good agreement with the experimental results. Although the work was conducted at 450 MHz, the findings of the study are directly transferable to other (especially higher) frequencies.