Phunky Monkey

As you might have guessed from the title, I'm looking for some help in modding my Netgear WG111 with an external antenna. I read this thread (18" dish + directional antenna + USB for only 30 bucks works great) but actually have a version of the adapter that is different. It has a uFL jack on it, and I have a pigtail and antenna for it, it doesn't seem to improve reception any.

So... I slapped the tiny board on my scanner, and took a couple of quick shots. The components are tiny, but I've dealt with smaller, so that's really no issue. My question is one of if/where I should solder a pigtail.

Caution: These pics are around 1mb each.
front
back

From what I can determine, the signal comes from the radio on the back, through the splitter/switch chip, one side to antenna 2, the other side to the uFL connector, then to antenna 1. My guess is that plugging in the uFL connector disables antenna 1. If that's the case, then perhaps my testing methodologies are faulty. For whatever reason, this thing gets incredible reception without an external antenna, but I'd really like to use it with several omni and directional antennas. It simply works so well with KisMac, and the 12" PowerBook has no PCMCIA slot.

Also... just so I don't get beat up too bad on my first post... I do also have a PC laptop, running NS, with an ornoco classic gold ;-).

Scruge

I've got a similar USB dongle. It uses a LTCC antenna, which is what I think yours has. (the green rectangle component) I haven't done much with mine yet. Been busy with other stuff. But I if I did I'd probably tack a tooth pick element to one of the ends of the LTCC to see the results. If that doesn't do much I'd probably next lift the LTCC off the board and replace it with a pig tail connected to a >5db antenna.
You might want to read up on LTCC (Low Temp Cofired Ceramic) antenna.
I started several months ago and got distracted by another project.

I'd be interested in your results so report back if you come up with anything.

BTW here's pictures of mine. At least it had a manufacturers name on the part of "WTC" Walsin tech Corp. no sure though.
WANTED (Your FCC ID #'s)
http://www.netstumbler.org/attachmen...achmentid=3037

a few links to examine
http://www.staratech.com/docs/hF/HFcatalogue01.pdf#search='walsin%20tech'
http://www.worldproducts.com/pdfs/WPSMLANT001A.pdf

wrzwaldo

Also note there are two antennas and diversity switching involved...

And does your WG111 have an FCC ID #?

Scruge

Could you replace one of the chips with a 50ohm dummy load so the card would use only one antenna?

wrzwaldo

You could just remove the switching. There is a thread here someplace (from not to long ago) where I posted a link to such an operation.

Found it.

help needed to make linksys wpc54g external antenna/pigtail

Phunky Monkey

FCC ID: PY3MA111

And yes, I did note the switching. It also appears that the uFL jack is stuck in the path of the line feeding antenna 2, so I'd assume that it would disable that antenna whenever I have the pigtail plugged in.

Now... a thought occured to me earlier on this: What if I put the whole contraption in a metal box (for shielding), with only the USB cord coming out one side, and an SMA header out the other. If it's using diversity switching, it should automatically choose the antenna with the best signal (which should work just as well as replacing the internal antennas with a dummy load). Unless that's a function of the driver... which could very well explain my problem.

In any case, I don't mind soldering this little beast, but I'd naturally prefer not to, as it is VERY small, and I no longer have access to a really nice set of tools. I actually used to work at an engineering firm that designed custom ICs... oh how I wish I could have an hour in the lab with a proper fab bench, spectrum analyzer, and stack of multimeters (sigh). My current idea is to try the metal box, and if that doesn't work, I'll just cut the antenna feed going in to the switching chip, and solder the coax straight to that.

Thoughts?

Scruge

I noticed in Wrzwaldo's link the guy cut the trace to the other antenna which seems easy enough. Is that an option for you?

Phunky Monkey

Yes, it is an option. Everything is an option. What I'm looking for is to accomplish my goal with a) the least irreversable damage to the card, b) least effort, and c) least cost. Unfortunately, I don't have access to a nice set of soldering tools, so making any kind of modification which requires soldering would also require me to buy/rent/borrow tools. Cutting traces doesn't require those tools, but permanently damages the card. I'm looking for the BEST solution here, as there are plenty that will work.

The really cool thing about this little USB dongle is that it is b/g, works with KisMac, and is indeed USB. My 12" PowerBook has no PCMCIA slot, and the internal wireless card lacks proper driver support for rfmon mode. furthermore, I can get several of these little dongles and set up an array of sector antennas for some REALLY powerful wardriving. Since it's USB, there is a much higher limit on the number of cards I can be using (instead of 1 or 2 PCMCIA slots), and I can move the rig much more easily from system to system. On top of all of that, USB cables can run for a good long distance without signal loss, where this is not the case with antenna cables.

wrzwaldo

I would cut the trace. Simple to do and simple to reverse. You can always bridge the cut trace (requires soldering).

Scruge

Well it sounds like you've got your answer. Drop your dongle into a tin can and seal it with foil and rubber band and test. If it doesn't work as expected you've got other options to try.

Phunky Monkey

Ok... results from my experiments:

Tested with dongle stuck in the side of my laptop... using this as the benchmark for normal reception.

Tested with dongle in metal radio shack project box... much reduced signal. It wasn't exactly an air tight seal, but I would have expected much, much lower signal levels.

Tested with dongle inside box, and uFL pigtail connected and the header side sticking out of the box... same results as previous.

Added a small, 3db omni to the header... same results as previous.

After that, I took everything out and retested the first condition (stuck in laptop, no box, no pigtail)... got normal signal level again.

At this point I decided that the diversity switching wasn't working (perhaps it's determined by the driver, and the hacked driver I'm using doesn't support it). So, to try and discover which antenna was the active one, I tried grounding each antenna to the shielding around the radio. No change in signal level. I then tried grounding the main antenna feed that comes out from under the shielding and feeds the switching chip... no change.

At this point, I'm reasonably frustrated. Either I read the circuit totally wrong (probably not the case), or my theory of grounding a signal line to the shielding doesn't apply in this case (more likely). So, I cut the main feed like between the capacitor and the switching chip. The signal dropped to 0. Then, I touched the switch side of the capacitor with the knife I was using, and it started picking up APs again.

So... long story short, this is an insane little contraption, and I'll have to solder in the pigtail to make it work the way I want. Fortunately, I think this will end up working better, as there was likely a decent amount of signal loss going through the circuitry for the switching.

I'll probably get an iron tomorrow (little 15W Radio Shack model should to the trick ... just need to dremel down the point a bit), and will update here when I make progress.

wrzwaldo

If you can also provide pictures please.

Phunky Monkey

Well, I finally found a chunk of free time (it only took 5 minutes... but I've been collecting the tools for a week now) to get this project done, and I believe I can declare it a success.

Originally, with no modifications, I could see 12 APs from my apartment. After attaching the pigtail, and hooking it to a 14dB patch antenna, I'm able to pick up 60. I'd say that's a tiny bit of an improvement . The cool part is that the pigtail and the antenna cable add up to no more than 18". Once I find some velcro, I'll affix the project box to the back of the antenna, for a truely slick sniffing solution.

I'll have pictures up asap. I'll also try and get the board itself on the scanner so you can all see my marvelous soldering skillz.

streaker69

If you have a digital camera set it to Macro mode, that way you can get a really fine detail shot of the board. That would probably work better than a scanner.

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Phunky Monkey

The pictures I included in my original post were taken by my scanner, and it's WAY more detailed than I could get with any camera I could find. Besides, I'd have to get one hell of a camera to even come close to making a single picture 3560 pixels wide. The only thing I'm worried about is that it's not going to lay too flat with the modification I made... but I'll do my best to get some kind of imagery up here for all to see.