There is a task given to me that I have to investigate a problematic RF remote controller against its weakness and make a suggestion report how it can be improved. This RF remote controller is used with two hands like PS console remotes. While it is functioning normally, in some cases, signal is not correctly or completely received by the receiver. Edit: The receiver is under the bed controlling motors.
Here are my findings, considerations and modifications;
1. Hands or human body on the remote controller are causing attenuation over the transmitted signals significantly at some directional orientation. (Observed with RF spectrum analyzer in dBm). At those moments, sometimes data is not properly received by the receiver but not always, unpredictable.
2. Antenna is on the 4-layers PCB. This anteanna is working OK when there is no obstacle. See image.
3. RF circuitry and micro-controller are all together and no shielding on the RF side. See image.
4. I have cut out on-board antenna and added a smd female RF connector. This way I experimented these steps; a. with teflon brown cable and connected a 17.3 cm wire. Antenna is inside the box: More or less same dBm measured as the on-board one. Data lost is not checked yet since it is not always the case. b. with teflon brown cable and connected a 433Mhz whip antenna. This is shorter, most likely it has a spiral version of 17.3 cm antenna inside. Antenna is outside the box: 30% more dBm measured than the on-board antenna does. And most importantly, hands and human body factors are quite less effective over the signals.
5. My point of view, the RF circuit part standalone is looking OK to me in terms of proper matching and harmonic suppression.
So, After those info and the image, what mistakes are you seeing (if there are)? How can this RF circuitry be made more effective by all the RF design technics considered?
I hope that I could explain what I am up to.