  Recently, several array radar structures combined with sub-Nyquist techniques
and corresponding algorithms have been extensively studied. Carrier frequency
and direction-of-arrival (DOA) estimations of multiple narrow-band signals
received by array radars at the sub-Nyquist rates are considered in this paper.
We propose a new sub-Nyquist array radar architecture (a binary array radar
separately connected to a multi-coset structure with M branches) and an
efficient joint estimation algorithm which can match frequencies up with
corresponding DOAs. We further come up with a delay pattern augmenting method,
by which the capability of the number of identifiable signals can increase from
M-1 to Q-1 (Q is extended degrees of freedom). We further conclude that the
minimum total sampling rate 2MB is sufficient to identify $ {K \leq Q-1}$
narrow-band signals of maximum bandwidth $B$ inside. The effectiveness and
performance of the estimation algorithm together with the augmenting method
have been verified by simulations.
