Looking for information on building a simple Spectrum Analyzer

[ChipG]

I am looking for to build a simple spectrum analyzer. I need to measure frequencies from 2GHz to 6GHz, or at least from 5GHz to 6GHz. I found a few designs that use UHF and VHF tuners, but they do not measure the frequencies I need. I will be using it for site surveys for WLAN applications in 2.4GHz, 5.3GHz, and 5.8GHz. This is my first RF project. Most of my experience is with the Biomedical and computer/netwroking fields.

Thanks

 

[60hzhmmm]

ChipG...... What you seek is one of the most expensive instruments there is. At these frequencies you are looking at 35 to 70 thousand bucks... I wish you luck. You will need it.

 

[ChipG]

That's why I am looking for information to build one. There are other ways I can accomplish what I want to do without it, but it will be easier if I can build one. I already have a PC card spectrum analyzer that will measure 2.4GHz to 2.5GHz. I picked it up for a little over $40 on ebay. There is no equivalent PC card for the 5GHz range though.

 

[zeitghost]

Have you thought of buying a second user HP spectrum analyzer? They tend to come in a bit cheaper than $70k.

I'm thinking of the scope plugins that cover 10MHz to 20GHz in an HP140 scope.

They are more difficult to use than the latest computer controlled wizardry, but still do the job (once you've figured out how they work!).

 

[IRstuff]

Don't waste your time trying to do it yourself; you'd need way too much in the way of software tools and other expertise.

TTFN

 

[Heydave]

You could look at using a local ocillator and mixer to form a front end for your current system and convert the high frequency spectrum to a lower one.

 

[ChipG]

Thanks, that's the kind of info I was looking for.

 

[zeitghost]

5.8GHz?

You might have a look in the Arrl Microwave books for mixers and oscillators that will work at that sort of frequency.

Bear in mind that electronics begins to resemble plumbing above about 2GHz.

I suspect that if this a work type project, after you've played with the home brew stuff, the 2nd hand HP141T and spectrum analyzer plugin are your best bet.

If it's for your own hobby interest, then have fun!

 

[ChipG]

It's a little of both. I did find an analyzer for 5.1GHz to 6.1GHZ for less than $4K. I imagine I'll end up with something like that eventually. Right now it's not critical. So, I'm treating it more like a personal project.

 

[zeitghost]

There are various microwave integrated circuits available that make design a good deal easier than using discrete components since input and output are 50ohms. Whether these will work up to 6GHz I don't know.

 

[nbucska]

If the sensitivity and speed is not a problem, you could
use a preamp/mixer the osc. frequency switched with the PC.

<nbucska@pcperipherals.com>