hello everyone, we're currently working with some nrf51822 beacons and throughout the project we recorded the antenna patterns of several of them. In the first batch we tested, there were quite large differences, while in second one the variance was very small (see attached .pdf files). We ordered the devices from mouser.com and noticed two different version labels on the packages. The first (worse) batch was labeled with 2014.32 and the second (better) one with 2014.27. I'm wondering if there were some production changes in between these two versions (matching networks, balun, etc.) which would explain such a large variance in the antenna patterns? Or are there any other possible reasons?
We tested in a RF measurement chamber, while each beacon was placed on a turn table individually. The pick-up antenna was 1.75m away from the beacon. The (roughly) 15° shift in the 2014.32 measurement came from a turn table offset.
Thank you very much for your help. Regards, mo
