USB mouse cable has an effect on signal strength

"me here" hath wroth:

Yes. The USB dongle has a very short antenna inside which belches RF in almost all directions including backwards towards the connector end of the dongle. The cable just reflects that signal towards the access point. It's not a great reflector, but does add a little gain. I would not count on it being a stable configuration because such arrangement are affected by literally everything in the room. If you want to experiment, punch a hole in the middle of a pie tin, pass the USB dongle through, and see if works better.

Yes. See:

some clues on building reflectors. You can pickup quite a bit of gain with a reflector.

Sheet mild steel is kinda marginal for RF reflectors. Aluminum, stainless steel, and copper flashing, work best.

Thanks Jeff.

So the USB cable (this is not a wireless mouse) is just acting as a reflector?

I suppose this could apply to any other cable in the near vicinity?

Cheers

Rob

Yes. Any metal in the general vicinity of the USB dongle will have an effect on the radiation pattern and gain. My rule of thumb is that metal has to be at least 6 wavelengths (or more) away from the RF source to not have a major effect. That's about 75cm at 2.4GHz. The tiny 2.4GHz antenna found in most USB dongles probably has a gain of about -3dBi. Put a pie plate refector behind the USB dongle and you'll perhaps get up to +8dBi gain. That's a huge improvement. I don't have a clue what tinkering with the USB cable will do, but it probably won't be any worse than the original -3dBi gain.

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

Jeff,

Why do you keep saying USB dongle ?

From the OP.....

'I just moved my old test PC (1ghz socket 370 M754 PCchips with Belkin

54g PCI card) to the back room of the house.'

'As the arial at the back of the PC was facing away from the signal'

Too much RF exposure, brain damage, too many windows open on the monitor, trying to do too much at the same time, talking on the phone with customers while typing, watching TV on the side, lack of sleep, irate at moderators playing censor, eating my own cooking for dinner, limited attention span, trying to remember what was posted days later instead of re-reading the entire thread, etc. Lots of reasons.

Ok, I missed it. I saw: "Is the USB mouse cable acting as an arial or primitive repeater in combination with the reflector panel?" and somehow turned it into a USB wireless dongle. Sorry.

Anyway, expept for the pie plate suggestion, my comments still apply. All the neaby metal wires, cables, and case parts have an affect on the antenna pattern. The exact effect is difficult to estimate. Moving the wires around randomly is not a great idea because even if a combination can be found that works, it will not be stable if anything moves. The best plan is to get the antenna out of the tangle of wires with an external antenna.

Like all bad ideas, there's always a way to make it worse: ftp://ftp10.dlink.com/images/products/DWA-547/DWA-547.jpg Sigh.

Sorry to say it, but I was a bit confused on the dongle thing also.

I didn't push the point - as Jeff has been extremely helpful in the past regarding setting up a 3Com888 for my dialup, and just appeared to have assumed the arial was a dongle type.

In the grand scheme of things it was a non-issue.

Moving right along, I suppose I have two options with this.

1) Continue to use a reflector panel of some sort to bounce the signal back towards the rear of the PC to the PCI arial.

or

2) see if I can get a remote arial with a cable connector to the 54g Belkin PCI card.

Would I have to use a Belkin one, or can I use aftermarket ones - are these connectors standard?

Directional or with a reflector?

If I continue to use a reflector attached to the wall behing the PC as I am now, would I be better off with a flat pannel (as is now) or would a curved panel be better?

Flat is easier to fit as it hides behind the curtain :-)

Cheers

Rob

Yech. Don't bother.

Yep.

Anything with a Reverse-SMA connector or adapter from something else.

You have quite a few options. Since this isn't going to be moving (as in a vehicle) I suggest a directional antenna. I don't think it has to have much gain. An 8dBi patch antenna will work. The only problem is that almost all of the aftermarket antennas have excessively small cables that are also excessively long. One omni antenna I found has a gain of 5dBi with a cable loss of 5dBi resulting in no net gain. Therefore look for something with decent directional gain, but a fairly short (1-2 meter) cable.

I usually build my own such antennas. I'm partial to a biquad but a coffee can antenna will also work. If these are aesthetically disgusting, then something smaller will work. I hate to recommend products I haven't tried, so beware of suprises here. Some typical products are:

|

| | | are probably more companies making similar antennas. I'm too lazy to search for vendors. Make sure it has a RP-SMA connector or that an adapter is available.

Flat plate is fine. I did a model comparison of the gains of a small Hawking "dish" antenna with the equivalent diameter flat plate reflector. Flat plate:

antenna: dish showed a gain of 7.8dBi, while the flat plate came in at

8.3dBi. Looks like the flat plat has 0.5dB more gain.

Thanks Jeff.

Much appreciated.

Cheers

Rob