There is only one on the market that I know of that is close to what you need. It's the ETTUS X310 with a Twin-RX card ($$$$). Each card can receive 2 coherent channels. The X310 can accept 2 of these cards giving you 4 coherent channels, if you like. An example using it with GNU radio is at https://github.com/EttusResearch/gr-doa. Once calibrated, it works well.  

 

73,

Ray WA1CYB