simulating isolation between antenna using farfield of one antenna as source

Hi,

I have designed a very large antenna for radar application.
I need to check the isolation of two such antennas to confirm the least effect of transmission from one antenna into another antenna.
Its not possiible to simulate isolation with two antenna in CST. the whole dsign model is too big to simulate.

My quesstion - is it possible to get the isolation between antenna by using fafield of one antenna as source for second antenna in CST?
Please give some details.

Thanks

I would assume not, as coupling is largely dependant on near-field interaction as well (depending on separation distance).