Electronics > RF, Microwave, Ham Radio

Moving RF wi-fi antenna jack/plug-in on other side of the PCB


Hi Guys,

Had some problems with my company laptop wifi integrated card, and seems something failed with the MB not with the card itself. Anyway since i'm the sys. admin in the company and I prefer to play instead getting new laptop or repairing this one with new motherboard (the book is out of warranty so I can do what i want with it). So I decided to integrate one USB wifi-card inside the nest of the CD-ROM, and place one HDD there too.
So for this purpose I will directly solder the usb wi-fi card to one of the usb, and wont use it anymore. Was thinking to place some usb hub there too, but prefer to have the full band of this usb dedicated for the wi-fi card.

I took the SATA/CD-rom converter from one caddy, placed the HDD then took apart the wi-fi card, placed it nice inside, but now the problem is I need to move that RF connector in the proper place, so i can place my antenna in the spot I want, and install some rails so the antenna can move in and out and look nice.
In the attached picture, i need to move the antenna over the red dot I placed. I know RF lines are really sensitive for any change like lenght, resitance, close to each other and so one. Ground is fine, the whole PCB is layed out with one big ground plate on that side, but the signal lane im worried.
I see one smd capacitor and right after it the signal line goes to the connector. I can soldier wire directly to the connector on the other side, clear some of the pcb and solder the ground but I think It would really make the antenna have worse parameters and loses since this tinny change of the signal line.

Any ideas if this is really going to rune the performance of the module? It will be like no more then 1cm wire (10mm) from different material, lenght, resistance, in the "air" not around the grounded plates and so on.

Thanks in advance guys :) 

At 2.4GHz a 1/4 wave is about 31mm long.  More than 10% of that (i.e.3 mm) is likely to cause a significant change in performance.

Thanks Ian!
31.25mm for 2.4Ghz & 60mm for 5Ghz range, so 15mm for it, if i'm not mistaking the Lambda=v/f
Anyway I did some ruffly measurements with some software tools under high load and found out the antenna boost only like 20% the signal (test was  based on distance from the AP (access point). So anyway will go without the antenna.


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