cheap antenna analyzer

here are is one source that explains how to make them -

http://www.ad5x.com/images/Articles/PrecisionMismatches.pdf

I made mine with SMT resisters by the way, shrink wrap them and labled them.

here is where to but a set - which seems reasonable -

http://www.g3tjp.com/

AND QST has something in November 2015 with the review of the sark 110 in a side bar. It goes into detail of how to make them with Amp SMA caps (they make shorting cap and a 50 ohm cap but I think they make a lot more) and a BNC to SMA-f adapters - you get the caps from Mouser and the adapter from Techcables.com. The main article also goes into calibration techniques a bit.

 

Can someone please give a better understanding of what this is, or how it would benefit the user. I've read wiki's explanation, and sounds like it reads impedance (which I only half understand the concept).
I'd gladly pay $100 if I understood this better.

 

Do you mean, what an antenna analyzer is?

 

Yes, what an antenna analyzer is, and how it helps.

 

An Antenna Analyser is used to check a number of things, like resonance of the antenna, the reactance of the antenna (which takes some math the aa does it really in the software and reads out the results). There are other things that it can be used, like checking your coax/feedline for problems - put a known load on the end and check it. (sorry for the mis-spelled words in this post, my computer is not liking to work today.)

There is also something that is called Time Domain Reflectometer (TDR) which is used to find fault in coax and other cables - it can also tell you how much cable you have. A lot of AAs can do something like a TDR check in the software - I just like using a dedicated piece of equipment for that - pass on one for $30 a couple months ago but ended up buying a high end one off of Craigslist for ... $20 which needed power supply work. The real things run between $500 and $7000.

Now dude there is even a better thing called a Vector Network Analyser (VNA) which for the most part does a lot lot more. It is easy to understand how it works, unlike a AA, which sends one signal out the connector and reads what happens, the VNA sends two signals out which are close to each other and it measures a bunch more things like complex impedance. The problem is that it is more complex in how it is setup and used. It is one out connection but two imputs (that's what I have right now).

The one I have is simple home built version of the N2PK VNA, and I have a Raspberry Pi with a 4" display on it to run a ported software for linux. IT works but it needs some tweaking.

Hope that sort of answers your question.

I use thin film resistors, I found that there is a creep factor with carbon film ones. I got a bunch of SMT precision resistors in a supply kit from a military surplus sale a while go, it has in it a bunch of 5 ohm multiplied values (5, 10, 15, 20, 25, etc. ... ) up to 500 ohms. I want to try them out when I get back to making things like test loads.

 

This sounds way over my head... But I'm happy to hear raspberry Pi and Linux are getting some use. Those could be industry changers for the hobbyist!

 

I was kind of excited about this till the end of the vid. It was way off from his other two meters and he says it doesn't work. But thanks for getting me into watching these videos. Im not ready to spend a few hundred on an analyser but by watching learning what to look for I can at least tell if the shop I go to knows how to use theirs.