Bluetooth antenna tuning & measurement dilemma

Hello, I am having dilemma in measuring the bluetooth antenna performance. The problem I have is that there are unavoidable cables and flex nearby the monopole bluetooth antenna, typically the flex is < 1.5mm distance to the antenna while the cable is dangling around the antenna.

It has been a frustrating engineering work to tune the matching circuit while not getting the intended efficiency based on the good S11 that I achieved. I know this is due to the loading of the surroundings that just cause the reflection to be less as the line just sees it as a good 50ohm line.

I decided tune by to do a OTA RF power measurement. The more I did, I found the power too varies due to the dangling cables around the antenna. The cables location varies during assembly which I realized is causing my OTA power measurement to varies too.

Any useful ideas I should do in order to control my measurement and confirm the performance? Should I just remove the cable and flex and measure ? but I know the actual performance has to be in a complete set. There is little space to control the location of the flex and wire. What should I do to really quantify my measurement ? thanks....

Hello ,

You probably won't be able to cancel out the influences of surrounding cables nearby the antenna .
The efficiency of the antenna doesn't rely on the S11 parameters .

To check the performance i would mount your antenna in free space and measure the pattern/gain .
Once you know the values the place your antenna in the complete set and measuring it again .
This will show you the degradation and influences of the cables that surrounding the antenna .

thank you. If you were me, would you still be re-matching the matching circuit after you know the degradation
of the cable influences surrounding the antenna?