NRF8001 module connection problem

[tilitililili]

Hi to all!

I've developed a board with NRF8001 on it and it works fine. But I've noticed a strange behavior. I use a mobile phone with NRF master control panel to work with my device. If the distance between the board and the phone is 0-10 centimeters the board can be discovered by the application. If the distance is 10 - 100 centimeters it cannot be discovered. But if the distance is larger (up to 30 meters) the board can also be discovered.

So, I have an area around the mobile phone (10-100 cm), where the connection can't be established. What can be the reason of such a behavior?

Thank you in advance!

[tilitililili]

I've discovered a lot of interesting things =) I provided experiments with two boards - my own (let's call it board_1) and dev. board (board_2), which I've bought. 1.board_2 shows the same performance with shunt capacitor mounted or removed. The level is (-60 - -100 dbm) and the range is 0 - 200 cm. 2.board_1 shows the same characteristics as board_2 with antenna disconnected (!) - C12 removed. 3.With shunt capacitor removed (on board_1) I get a zone (10cm - 100cm), where board cannot be discovered by the application. But the level in 0cm-10cm zone is -20 dbm. 4.With C43 mounted board_1 works worse. 5.Seems like board_1 works better with shunt inductor instead of shunt capacitor. I haven't tested it fully yet. So, seems like the problem is not in my board - it's in board_2... Board_1 shows better range. The only problem is zone 10cm-100cm, I don't understand why the signal disappears.