Dual vertical beam properties of doubly curved reflectors

An investigation has been made of the vertical-plane dual-beam properties of a doubly curved shaped-beam reflector to provide design information relative to possible modifications for a large class of surveillance antennas (in particular, the cosecant-squared family) in order to improve their performance when working in the presence of serious ground clutter problems. Experimental results obtained with an -band model reflector utilizing various dual-feedhorn geometries are presented. Measured secondary patterns demonstrating several important performance characteristics are shown for a linearly polarized situation. Measured primary patterns for the feeds which generate these results are included, Two-way radar coverage diagrams for one set of dual-beam patterns are examined in detail. These plots make it clear that for many ground clutter minimizing applications it appears desirable to mix at RF the signals received by both feedhorns.