It is a little hard to see exactly what he has done
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There is a later version of the F-6988 BT module that has solder pads for a ufl connector on the reverse, which may affer some clues as to where the connections can be made. I would suggest that the central pin fo the connector is connected to the current antenna trace, with the outer annulus connected to the adjacent solder pad, shown as L1 in some images, such as this one:
https://www.aliexpress.com/item/32828745452.html
Looking at this site, it suggests that v2.3 of the board, as used on your module, also has the ufl solder pad on the reverse. :
https://www.blmworld.com/html_news/?12-BK3266-40PIN-audio-data-transmission-bluetooth-module-12.html
https://www.aliexpress.com/item/32828745452.html
Looking at this site, it suggests that v2.3 of the board, as used on your module, also has the ufl solder pad on the reverse. :
https://www.blmworld.com/html_news/?12-BK3266-40PIN-audio-data-transmission-bluetooth-module-12.html
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Good luck with this. Bluetooth works at 2.4GHz which does not survive any length of coax cable, especially thin cables. Likewise, connectors are going to be a signal degradation issue. Commercial "microwave" systems use waveguides, ie pipes. Microwave means wavelengths shorter than 30cm. Bluetooth is 12.5cm. Putting an antenna on a Bluetooth device is like putting car tires on a bicycle.
Why do they then use antenna on Wifi, also 2.4 gHz ? Do you then have any other ideas for extending the BT range (dB) ?
Usually the Tx/Rx is built onto the antenna, or a short run of large coax.
https://thejonspencerbluesexplosion.com/rg6-cable-vs-rg59/
Are these connectors waveguides/pipes ?
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Yes, otherwise you have effectively two antennas in parallel and the impedance will no longer be 50 Ohms.
Yes, ideally, but since most wifi router cases are plastic the connector is grounded via the coax shield to the pcb ground.
Its a connector, a waveguide is normally a hollow tube either circular or rectangular used at microwave frequencies for example 10GHz
This probably won't work so well. The best solution is to find an external 2.4GHz antenna with a coaxial cable so that you can solder the coax onto the pcb and mount the antenna externally on the case.
Something similar to this:
The pcb layout includes the use of a SMA connector in the design from the outset where the connector body is soldered to the ground plane and the pcb track from the RF output to the connector is 50 Ohms , in your bluetooth module in post #1 there's no ground plane at the edge of the pcb. There's only the microstrip antenna.
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In RF systems, the RF amplifier output, the pcb tracks, connectors and antennas are all designed to be 50 Ohms impedance, this ensures maximum power transfer and minimum losses. What looks like a squiggly pcb track is actually a microstrip antenna at 2.4GHz and has an impedance of 50 Ohms to match the output of the RF amplifier inside the bluetooth chip.