1. A sidelobe cancelling system comprising: an antenna array with N elements; first means interconnected with said antenna array for generating a set of N subbeams from said array, each of the mainlobes of said subbeams being oriented at an azimuthal angle .theta..sub.k, k=1,. .. , N with the output signal of the subbeam oriented at .theta..sub.k being u.sub.k ; second means for selecting a nulling subset of nulling outputs (x.sub.2,. .. , x.sub.L), where L&lt;N, from the set of subbeam outputs (u.sub.2,. .. , u.sub.N), where x.sub.1 =u.sub.1 is the main antenna channel, and where x.sub.2,. .. , x.sub.L are u.sub.k 's necessary to null the effects of jammer signals in the main antenna channel sidelobes including means for selecting a first subbeam, different from the main channel, with a first jammer postioned in the mainlobe thereof and means for determining the number of output functions from subbeams adjacent to said first subbeam necessary to null the signal from said first jammer in the sidelobes of the main channel; and third means for processing said nulling outputs in said nulling set to null the effects of jammer signals in the main antenna channel sidelobes.