"John Popelish" wrote in message
. ..
amdx wrote:
"John Popelish" wrote in message
...
amdx wrote:
I'd like to install a higher gain antenna to this wifi adapter.
I'm looking for advice on the proper place to attach a 50 ohm
antenna ( or coax ).
I think you have come to a similar one that I would have come to, except
that I would scratch off the solder mask, around the large hole and
attach the shield at several points around it.

That sounds good to me. I'll give it a try when I get an antenna figured
out.
That part I suggested I would remove, I don't know what it is,
it measures 0 ohms in circuit.

It may just be a jumper to connect the antenna after board testing with
equipment connected to the large hole. Or it may be a capacitor or
inductor. The far side is shorted to ground through the antenna
structure, and the upstream side may also have an inductor or other low
resistance path to ground, in parallel with your resistance measurement.

I agree that you should remove it, but save it, in case your antenna
doesn't work well.

Well, I removed it, it's tiny maybe .05" x .03". I carefully opened
a small container, tipped my hand and the part disappeared somewhere on
the bench. Ok, so that just means the new antenna has to work :-).
I proceeded to connect this gigantic RG58 to the pcb. The late night
preliminary tests show dramatic improvement over the horn antenna
that was my first attempt. See comparision numbers below.
Horn antenna signal strength -72dbm to -74dbm
Biquad antenna signal strength -50dbm to -52dbm
That's a major improvement, a quick check of the neighboehood
signals showed higher levels and two new signals I haven't seen before.
I'll test it in it's final position today, but it sure looks good.

Notes; On the Horn antenna I cut a slot a 1/4 wavelength form the closed
end
and inserted the wifi adapter ( dongle). this was about an 8 db signal
improvement.
For the biquad I disconnected the internal antenna and connected a 6" coax
that went to the antenna. I built the antenna pretty much following this
site.
http://martybugs.net/wireless/biquad/
I used 1/4" copper tube, removed the jacket the length of the copper tube
and tinned the shield for a tight fit in the tube.
Mike