A compact multi-polarised broadband antenna

An innovative concept to meet the multioctave polarization diverse challenge is described. Equal right- and left-hand polarization performance has been achieved from a single radiating aperture using an inherent symmetry. This concept employs an edge-fed, interleaved log-periodic antenna, referred to as the interLog antenna. The edge-fed geometry improves antenna reliability over that of the center-fed spiral due to mechanical and thermal stability. The antenna consists of four interleaved, curved dipole, log-periodic elements placed over an absorber-loaded cavity. Opposite elements are excited 180 degrees out of phase using a printed circuit infinite balun approach. Orthogonal circular polarizations are achieved by connecting the balun output to an integral stripline 90 degrees coupler. Analysis, measured pattern, VSWR (voltage standing wave ratio), and isolation data are given, demonstrating the effectiveness of the antenna approach.<>