Adaptive cascade networks for deep nulling

Although the analogy between array antennas and tapped delay line filters is well established, there is nothing in antenna theory that is quite the same as the simple cascade connection of two or more filter sections. By applying adaptive techniques, however, it is possible to set up a cascade beam forming network having most of the advantages of the cascade filter connection. In particular, it is possible to provide deep nulls for the suppression of powerful jammers despite the presence of unavoidable errors in the parameter settings. Our calculations indicate that a subsidiary advantage is the fact that the cascade network will settle more rapidly than a conventional adaptive network when the eigenvalues are widely separated.