Hello everyone
Recently I have a question need to clarify on our RF PCB assembly. My RF PCB work at Ku band and the corresponding PCB substrate is FR4. The total RF system includes RF AMP, RF filter, RF detector and some passive conpoments on the RF PCB. Consider performance issue, do we need to insert additional metal plate under RF PCB to get more stable RF performance? Or could we get similar performance by multi-gould plane and multi-vias designing into PCB substrate? What is the corresponding principle for this issue?
Because I saw several design for RF EVB with additional metal plate under the RF PCB or RF PCB was enclosed by metal house at Ku band or higher band.

Thanks all in advance!