Wide-band nulling performance versus number of pattern constraints for an array antenna

The problem of wide-band pattern nulling for an array antenna is addressed, in particular the relation between the number of constraints imposed and the sidelobe suppression achieved. The two constraint methods considered are multiple nulling over a narrow angular sector and nulling of the pattern and its derivatives at a single point. To first order the sidelobe cancellation is shown to be independent of the actual pattern type and is determined by only two parameters: the number of null constraints and the number of sidelobes to be cancelled. The latter parameter directly translates into a desired nulling bandwidth. A numerical solution to the problem is offered in the form of curves, from which the number of nulls required to suppress a jammer over a given bandwidth can be conveniently estimated. This number is indicative of how many degrees of freedom a conventional adaptive antenna system must allocate to attain a specific nulling performance.