I am working on a design that requires 4 channels coming onto a PCB. The inputs are SMA connectors and are spaced 15mm apart from each other. These signals are routed with co-planar wave guides on the board to a SP4T RF switch. My operating frequency is 300Mhz - 900Mhz. The incoming signals have an amplitude range from -30dBm to 10dBm.
I am curious to know what kind of isolation can be expected in this situation. On my first experiment I was only able to obtain about 20dB of isolation between signals. From what I have read so far it seems that the best you can get is 40dB with a 2 layer board and a CPWG. Does anyone have any experience on how to improve this?
My next test board will involve all the connectors mounted so the signals are coming in at oblique angles to one another. However this does take up more space.