TX power level vs antenna performance

[Valer_I]

Hi, At present time I perform many tests with power level and link stability. And noticed that if cover nRF base device with hand or put into pocket the disconnection with reconnection occure. The rssi level seem to be stable (about -65dbm) at exact test configuration but after some times device just disconnects.
The last sd_ble_gatts_hvx result before( or may be at) disconnection was: NRF_ERROR_INVALID_DATA. By this function I send RSSI value each second to peer cenral. Connection interval is about 500ms. After increasing TX power the problem aggravated. I think of decresing antenna performance by influence of reflected wave from screening material in near field region. The device is designed as wearable so this problem is very important for us. Any way out?

Device: nrf51422QFAAE0, SD110 v8.0.0.

[Dave_couling]

You need to tune your antenna to its average environment. This means tuning it when in close proximity to the human body. Human Body will likely downtune your center frequency and decrease your bandwidth. Therefore you must offset this, by up-tuning. Your best bet is to use a VNA to tune, and place the product on a human body while tuning.

-DC

[Valer_I]

Are the any antenna designs shared by Nordic? Or any recomendation documents?

[MartinBL]

Hi. We have some reference layouts here showing how we recommend to do the antenna layout. We also have a couple of antenna related white papers here. You can also create a MyPage account and submit a support ticket and ask for a confidential review of your design.