Electronics > Beginners

RT2571WF - External Antenna Hack

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Fraser:
Amnya,

Please do not take offence but you appear to be 'dabbling' in an area in which you lack experience. Neither I nor other members of this group can analyse what is going on with your Wi-Fi transceiver remotely. I have explained that you should draw out the schematic for the aerial/antenna section from where it leaves the transceiver. If we have that information we may be able to assist with some useful comment.

I have to ask why you believe your whip antenna will provide much increased performance ? If you were to take that type of antenna apart you would find a pretty poor design not much more efficient than a simple 2 element dipole at 2.4GHz. Have you tried the antenna on another Wi-Fi unit that is designed to feed an external antenna ? This would give you some idea of the performance that you can expect from the antenna when fitted to your USB stick.

P.S. that component that you described as 'Resistor' and were about to remove looks distinctly like a chip capacitor.

If you can't identify the components when drawing the schematic, at least draw small boxes and give them some form of identitiy so that we can tell you which ones are likely to be important to your modification. I can try to work out the circuit from your pictures but that takes time and I have little of that spare at the moment. If you get really stuck, I will have a go for you.

Fraser:
OK,

I took pity on your plight and drew the schematic on my notepad.

The RF path to/from the transceiver is clearly visible on your picture named 'Back.JPG'. It is in the lower left corner of the PCB ... a surface mount capacitor feeding a curved PCB track that in turn is connected to the RF test socket we have discussed. The output of the test socket connects to two capcitors, one is coupling to 0V and the other is the feed to the internal antenna. There is also a small black SMD resistor across the input to the internal antenna. Note. The RF test socket looks to contain an internal switch that disconnects the internal antenna when a probe is inserted into it.

The internal antenna should be removed from circuit by removing the capacitor that feeds it, and the capacitor to 0V. The transceiver input/output will then be connected only to the RF test socket. Connect you external antenna to the curved PCB trace (already mentioned) on the bottom of the PCB and connect the ground side of the antenna to the adjacent groundplane copper.

If this gives no significant improvement in performance, ensure you have your external antenna in the same polarisation as the antenna on the Wi-Fi access point. If there is no improvement, you either have a damaged external antenna or it is just cheap junk and should be replaced with something better.

Hope this helps.   

neoone:
thumbs up for your effort Aurora ;) That's basically what I meant with removing those elements.

Mechatrommer:
if me. i will cut the track as you shown above but not taking out any component, the track on the left will be connected to ground (already did) and just connect the sma connector to there. ie ground female to ground track, and center pin to the right side cutted track.

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