I have an 868MHz design incorporating a reference design for the transceiver. The aerial is connected to a PCB mounted SMA connector. The board sits in a metal box and the aerial passes partly through the box to attach to the board.
Range is acceptable if not great. The aerial manufacturer retuned the aerial for our box and said that unfortunately the most sensitive part of the aerial was inside the box thus we were losing range.
We tried removing the sma connector from the board and attaching a short 3-4 inches of coax with a bulk head mounting SMA connector to original mounting holes of the pcb mount connector. range was reduce to about 4 feet. We tried in and out of the box with no success. On looking at the IQ signals it appears that the Q signal is largely unaffected by the change, may be slighly higher amplitude but the I signal goes from good to collapsing over the 4 feet distance. The cable with connector is off the shelf and we hae tried several cables and several boards. Any clues what may be happening by adding the additional cable.
Thanks for any help
Paul