Separate ground plane under FET connected to main ground plane?

Can we make separate ground plane under RF device? For example make rectangular area in ground plane separated from it by 0.2mm gap. This new ground plane connects to main ground plane in one or many points with resistors. It can be one resistor R Ohm or many resistors n*R Ohm, so final resistance would be n*R/n=R Ohm. If this rectangular ground plane is connected to common source FET, will it provide biasing (voltage drop across resistors in operating mode), so Vgs will become negative?

You're not actually asking if you can make it. That would only ask your skills to operate a layout tool and the answer is (hopefully) yes. I presume you mean "is it a reasonable idea"?

The answer would e.g. depend on the intended frequency range. Splitting a RF ground plane is generally a bad idea, but if it serves a purpose... Did you estimate the parasitic inductance involved with your design idea?

Yes, i worry about inductance. I was thinking what if that new ground plane is very huge, i think it will solve the problem...