Abstract: A direction finding antenna system includes a plurality of monopole elements disposed symmetrically around a center of a circular ground plane at the same radial distance from the center and a multimode combiner connected to the monopole elements to provide one or more mode outputs. A phase difference detector determines phase differences between selected ones of the mode outputs to provide azimuth bearing of a detected object. Typically, four or eight monopole elements are used. Placement of the inherently narrowband monopole elements in a bicone structure having a polarizer grid extends the useful bandwidth. Multiband coverage is achieved with a plurality of such antennas connected by a feed cable positioned on the polarizer grid to avoid interference.