Diversity techniques with parallel dipole antennas: Radiation pattern analysis

Two parallel dipoles are assessed for antenna diversity. The three-dimensional radiation pattern is considered for signals correlation coefficient. The pattern analysis reveals that, depending on dipole spacing, three types of diversity techniques are generated: space, amplitude-pattern and phase-pattern diversity. The weighting of each technique in signals correlation coefficient mitigation is investigated. The results show that for closely spaced dipoles, the generated phase-pattern diversity is the most dominant factor which greatly reduces the signals correlation coefficient. The diversity configuration is measured in a rich scattering environment. Results include signals correlation coefficient, diversity gain for selection combining and maximum ratio combining, effective diversity gain and antenna radiation efficiency can be demonstrated. We show that in rich multipath channel the minimum spatial distance, for effective diversity gain performance, is reduced from 0.5 lambda for uncoupled dipoles to 0.15 lambda for coupled dipoles.