I am building a device that consists of an ordinary WiFi router (WDR4300) as shown here:
Which works as a client and scans for networks OK when alone. The problems appear when I add another board to the case, which also contains a Texas Instruments AM3517/AM3505. The final design is shown below. The antennas are on the opposite side now and there is also a plastic case (not in the picture). But then WiFi performance gets very bad, it scans fewer networks with bigger noises and they appear weaker.
What do you think may be the problem?