2.4 Ghz SWR Meter
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Posted by amdx on June 24, 2008, 11:57 am
Please log in for more thread options antennas. The simplest device I see is shown here http://pe2er.nl/wifiswr/ It's an SWR meter that uses a uses a wifi signal to drive the antenna. Any thoughts or suggestions before I order parts? Mike | ||||||||||||||||||||||
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Posted by Jeff Liebermann on June 24, 2008, 4:16 pm
Please log in for more thread options I use a sweep generator HP8620a or Wiltron something, a directional coupler or reflection coefficient bridge, and a scope. Without a sweep generator or network analyzer, the VSWR bridge is kinda wasted. For antennas, you want to know the VSWR across the entire 2400-2583.5MHz band, and then some. > Any thoughts or suggestions before I order parts?
> Mike Nope. It works. I've built two. Adjusting the balance cap is a problem as it changes when I move the bridge, install the cover, and move things around. Build it solidly and inside a case so you won't lose the null. I didn't use a meter. The output went to a scope. If you can find scrap polysulfone PCB material, use it instead of G10/FR4. Less lossy. If using a Wi-Fi router for a signal source, you'll have problems seeing anything on the meter without the peak detector circuit. There's VSWR bridge in the middle of this page, somewhere, maybe: <http://yves.maguer.free.fr/WiFi/page_wifi_yves.html>
Also: <http://www.qsl.net/n9zia/wireless/appendixF.html>
The commercial Wiltron versions: <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120270695813>
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220162346759> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 | ||||||||||||||||||||||
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Posted by msg on June 24, 2008, 5:11 pm
Please log in for more thread options Jeff Liebermann wrote:
<snip>
> > If using a Wi-Fi router for a signal source, you'll have problems > seeing anything on the meter without the peak detector circuit. <snip>
Once again Jeff, are you ready to help the cause by acquiring (by hook or crook) the airsleuth stuff? They have code to do a sweep generator using the Proxim HomeRF stuff as well as their spectrum analyzer. Since there is more hardware out and about unmarried to their s/w, it would be nice to know what may be necessary to induce nuptials. Michael | ||||||||||||||||||||||
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Posted by Jeff Liebermann on June 24, 2008, 8:06 pm
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>Jeff Liebermann wrote:
> ><snip> >>
>> If using a Wi-Fi router for a signal source, you'll have problems >> seeing anything on the meter without the peak detector circuit. >
><snip> > >Once again Jeff, are you ready to help the cause by acquiring >(by hook or crook) the airsleuth stuff? They have code to >do a sweep generator using the Proxim HomeRF stuff as well >as their spectrum analyzer. Since there is more hardware >out and about unmarried to their s/w, it would be nice to >know what may be necessary to induce nuptials. Nope. Not interested, too busy, too lazy, it's summer, I got better things to do, no money in it, no fun, I hate grinding code, HomeRF is dead, etc. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 jeffl@comix.santa-cruz.ca.us # http://802.11junk.com jeffl@cruzio.com # http://www.LearnByDestroying.com AE6KS | ||||||||||||||||||||||
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Posted by amdx on June 24, 2008, 5:39 pm
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>
>> I'm thinking about building a device to measure the input impedance of
>> WiFi >>antennas. The simplest device I see is shown here http://pe2er.nl/wifiswr/ >>It's an SWR meter that uses a uses a wifi signal to drive the antenna. >
> I use a sweep generator HP8620a or Wiltron something, a directional > coupler or reflection coefficient bridge, and a scope. Without a > sweep generator or network analyzer, the VSWR bridge is kinda wasted. > For antennas, you want to know the VSWR across the entire > 2400-2583.5MHz band, and then some. Thanks for the input Jeff, I don't have any Ghz equipment so when I build an antenna I don't really know what I hav other than it works. I've compared signal strengths on the computers wireless utility so I know which is better, but not what makes an antenna match better. >> Any thoughts or suggestions before I order parts?
>> >> Mike >
When you mention balance cap, do you mean the cu foil that you trim or
> Nope. It works. I've built two. Adjusting the balance cap is a > problem as it changes when I move the bridge, install the cover, and > move things around. Build it solidly and inside a case so you won't > lose the null. > add. If so? I think you adjust this with a 50 ohm dummy load, to zero the output? I don't really see this? I think we're adjusting the 49.9 ohm resistors capacitance to ground. Tell me what you can, I'll have to study it more. Are you recommending a case on the head unit? PCB material ok? > I didn't use a meter. The output went to a scope.
You monitor the dc level with your scope? Never mind, I see that is a pulse coming out of the head unit. > If you can find scrap polysulfone PCB material, use it instead of
> G10/FR4. Less lossy. I have some Rogers Duroid .031", 5880 I think > If using a Wi-Fi router for a signal source, you'll have problems
> seeing anything on the meter without the peak detector circuit. Interesting, why do you think the author says it (the peak hold switch) is not needed? I think we're talking about the same thing! Did you use the BAT 62-03W diode? If not what did you use? Some one recommended the BAT 62-02W it's smaller so should be ok, and I can get it. Thanks again, Mike | ||||||||||||||||||||||
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>antennas. The simplest device I see is shown here http://pe2er.nl/wifiswr/
>It's an SWR meter that uses a uses a wifi signal to drive the antenna.