  Multistatic radar system (MSRS) is considered an effective scheme to suppress
mainlobe jamming, since it has higher spatial resolution enabling jamming
cancellation from spatial domain. To develop electronic countermeasures against
MSRS, a random array subset selection (RASS)jamming method is proposed in this
paper. In the RASS jammer, elements of the array antenna are activated
randomly, leading to stable mainlobe and random sidelobes, different from the
traditional jammer that applies the complete antenna array enjoying constant
mainlobe and sidelobes. We study the covariance matrix of jamming signals
received by radars, and derive its rank, revealing that the covariance matrix
is of full rank. We also calculate the output jamming to signal and noise ratio
(JSNR) after the subspace-based jamming suppression methods used in MSRS under
the proposed jamming method, which demonstrates that the full rank property
invalidates such suppression methods. Numerical results verify our analytical
deduction and exhibit the improved countermeasure performance of our proposed
RASS jamming method compared to the traditional one.
