rf pcb drawing

On drawing double layers PCB for RF, it is always necessary to place ground plane on both sides.
The problem is that, why is it necessary to avoid placing the ground plane around the RF filter and microstrip inductor ?
is it the paracistic cap. problem or others ?
thank you :)

well if your question is about placing grounds on either side of a transmission line on the PCB then ....
The basic aim of providing grounds on either side of traces carrying RF on the PCB is to ensure that there is no crosstalk or coupling between any two signals on closely spaced traces;:)
The reason why such grounds are not created around filters or inductors is that proximity to ground changes(to be precise increases) the impedance of the microstrip lines and since the realised impedances must be very near to the designed ones & in circuits like filters this may cause a considerable frequency shift if unaccounted for.