An adaptive nulling antenna system for space based radar with array element reuse

An adaptive nulling system has been designed for a space-based radar incorporating a phased array fed Cassegrain antenna. Auxiliaries are formed by reusing elements from the main antenna array feed together with an external horn antenna. Antenna patterns for the main antenna and for the auxiliaries are calculated using a physical optics-based reflector code. Nulling performance is calculated using an Applebaum array model, and results using array element reuse and external horn auxiliaries are compared. Using both types of auxiliaries together is considered. It is found that the array element reuse auxiliaries provide sufficient sidelobe coverage in most cases. Performance is found to degrade when jammers are at far-out sidelobe locations, and when multiple jammers are present. Optimal performance may be obtained with a combination of reuse and external horn auxiliaries.