[time-nuts] VNA design

[Ed Palmer]

There's a DIY project to build a spectrum analyzer at 
http://scottyspectrumanalyzer.com .  Since it's modular, one version of 
the project is to add a couple of modules that change it into a network 
analyzer.

If you search ebay for directional couplers, I can almost guarantee that 
you will find what you want at a reasonable price.

Ed

On 6/2/2014 8:43 AM, Attila Kinali wrote:
> Hi,
>
> I know this is not exactly a time-nut question, but i guess this is
> the best place i know to ask about this stuff.
>
> I recently got introduced into the usefullness of a VNA. But these
> things are horribly expensive for home use, even if bought from ebay
> (before you say anything, remember i live in europe, where every
> boat anchor hast to travel a long way). But given that most of the
> designs that are on ebay are from the 80s and early 90s, i thought that
> with todays ICs it should be easy to come up with a design that does
> the same thing but can be build on a kitchen table.
>
> Well, my problem now is, that i don't know how to build a VNA.
> Yes, i understand the basic principle. I can come up with a design
> that should work. But i have no clue about any problems or difficulties
> in building these devices. Ie it's very likely that i fall into a dozen
> traps when i try to build one.
>
> I tried to get information on how to build a VNA, or what kind of trouble
> people had operating one, but beside the VNA book[1] Rick mentioned a couple
> of months ago and ko4bb's site (thanks man! your manual collection is a gold
> mine!), my searches came out blank. As i'm quite sure that there is
> information of that kind out there, i would like to ask whether someone
> could point me to some documents, webpages, books, papers, etc that would
> show me the detailed design of VNA, the problems people had with some
> designs or anything else that would be of interest in such an endavor.
>
>
> Also, any good resource on how to build a directional coupler that
> does 10-3000MHz without going to exotic materials would be much
> appreciated. All papers i found deal mostly with stuff above 5GHz.
> Seems like "low frequency" couplers are considered "a solved problem".
>
>
> 			Attila Kinali
>
> [1] Handbook of Microwave Component Measurements: with Advanced VNA Techniques
> by Dunsmore, 2012
>