Analysis of sparse trifilar array antenna

A sparse trifilar antenna can support two independent beams while, to reduce the interference between the beams, each array element supports only one beam. To minimize the grating lobe effects each beam is formed by three spiral arms resulting in a sparse random array arrangement. In this paper we investigate the impedance and radiation characteristics of such an array. We have shown that the active reflection coefficients are somewhat degraded in comparison to a fully populated array, however the directivity remains approximately the same, making the trifilar array a viable solution for multi-frequency, multi-beam communication applications.