About this notes
This notes refers to GSM antenna side best practices in Raspberry PI u-GSM shield integration. itbrainpower.net u-GSM shield it is the worldwide first (and the only one) modular modem that supports ALL deployed GSM standards [LTE NB IoT / LTE CATM1 / LTE CAT4 / LTE CAT1 / UMTS-3G / GSM-2G] in one unified design!
What to prevent: RASPBERRY PI boards tends to be influenced by GSM radio waves in low bands as GSM 850 and GSM 900, especially in compact collocated electronic bundles.
Platforms: RASPBERRY PI any B+ type version [RPI3 B Plus / 3 / II / B+].
RPI gsm antenna guidelines, in a nut shell
In the image up-here, notice:
a. GSM pigtail / antenna cable goes to long side, not to the closest u-GSM PCB edge.
b. We recommend to use best quality pigtail / antenna cable.
Special hint regarding pigtail / antenna cable uFL connector. After some uFL connectors insertion / disconnection cycles [sometimes as little as 5-10 cycle, depending on pigtail uFL connector quality], most uFL connectors lose their electrical parameters and may cause additional interferences issues. Always use as new as posible pigtail [or, if you experience EM interferences or loose of performances, change first the pigtail cable].
In the image up-here, notice how the antenna pigtail cable is routed under the u-GSM shield.
- avoid RPI areas highligted with RED elipses. Those areas are quite sensible to RF interferences. Do not route the RF cables and do not place the GSM antenna or the pigtail connector in the proximity of those areas.
- ensure a generous enough bend radius for the antenna pigtails [do not bend it "corner" like!!!].
TUTORIAL PROVIDED WITHOUT ANY WARRANTY!!! USE IT AT YOUR OWN RISK!!!!