Abstract: An electronically or mechanically scanning monopulse radar has an antenna feeding incident microwave energy contaminated by jamming signal to a processor which has a sum channel and one or two difference channels generating a raw sum signal .SIGMA. along with a raw azimuthal difference signal .DELTA..sub..theta. and/or a raw elevational difference signal .DELTA..sub..phi.. Each channel includes an algebraic adder subtracting from its own raw output signal a contamination signal representing estimated disturbance which is derived with the aid of an adaptive cancellation loop from the raw output signal or signals of the other channel or channels, thereby producing a purged sum signal .SIGMA.' as well as one or two purged difference signals .DELTA.'.sub..theta., .DELTA.'.sub..phi.. The purged output signal of each channel is fed back to the corresponding cancellation loop for correlation with the raw output signal or signals from the other channel or channels.