Circular array of outward sloping monopoles for vehicular diversityantennas

A circular array of outward-sloping monopoles is analyzed as a diversity antenna for vehicle rooftop mounting. The monopoles are assumed to approximate minimum scattering antennas, have sinusoidal current distributions, and reside on an infinite, perfectly conducting ground plane. The envelopes of the received signals are considered Rayleigh distributed. The advantage of the array configuration is that the feedpoint spacing can be made almost arbitrarily small, even for a large number of branches. A three-element array with element lengths of 0.6 wavelengths and feedpoint spacing 0.1 wavelengths operating at 463 MHz was field-tested and the results are in good agreement with the analysis