Putting A Poor Man’s Vector Analyzer Through Its Paces

If anything about electronics approaches the level of black magic, it’s antenna theory. Entire books dedicated to the subject often merely scratch the surface, and unless you’re a pro with all the expensive test gear needed to visualize what’s happening, the chances are pretty good that your antenna game is more practical than theoretical. Not that there’s anything wrong with that — hams and other RF enthusiasts have been getting by with antennas that work without really understanding why for generations.

But we’re living in the future, and the tools to properly analyze antenna designs are actually now within the means of almost everyone. [Andreas Spiess] recently reviewed one such instrument, the N1201SA vector impedance analyzer, available from the usual overseas sources for less than $150. [Andreas]’s review does not seem to be sponsored, so it seems like we’re getting his unvarnished opinion; spoiler alert, he loves it. And with good reason; while not a full vector network analyzer (VNA) that will blow a multi-thousand dollar hole in your wallet, this instrument looks like an incredible addition to your test suite. The tested unit works from 137 MHz to 2.4 GHz, so it covers the VHF and UHF ham bands as well as LoRa, WiFi, cell, ISM, and more. But of course, [Andreas] doesn’t just review the unit, he also gives us a healthy dose of theory in his approachable style.

[The guy with the Swiss accent] has been doing a lot of great work these days, covering everything from how not to forget your chores to reverse engineering an IoT Geiger counter. Check out his channel — almost everything he does is worth a watch.

Thanks to [Nita Vesa] for the tip.

20 thoughts on “Putting A Poor Man’s Vector Analyzer Through Its Paces

    1. Definitely. I quite like his accent and he has some excellent content on his channel. He apparently also seems to read most of the comments on his videos and reply readily to people, which is nice.

      As an aside, I’ve added this N1201SA on my shopping-list for when I have enough excess money to spend :)

    1. Look for the “poor hams scalar network analyser” to see how to DIY.
      Uses an Arduino & an eBay DDS module, goes from DC up to about 60MHz.

      Detector is a log amp, going to the Arduino ADC.

    1. Yeah, this isn’t “vector analyzer”. It’s Just an antenna/scalar analyzer. Products like the Minivna tiny and PocketVNA are true vector network analyzers but they cost just a bit more.

      That said, I *love* my PocketVNA. I used to make antennas and filter by guesswork and it was a real crapshoot. They’d work, but I’d have no real quantitative idea how well so I couldn’t iterate or compare. And I certainly didn’t feel confident enough to sell them on tindie or eBay.

      With the PocketVNA (and it’s linux support) I can see if that new antenna design I’m trying really is worth the complexity and tune filters. Since it’s a vector network analyzer I can even use it to check the properties of random ferrites I have sitting around and see it they’re appropriate for the use I want.

      Lately I’ve been working on a series of TEM horns and it’s been invaluable,

  1. That’s the first time I’ve heard S11 spoken as “S eleven”.

    (Hint: it’s an element of the S matrix at row = 1, column = 1. It’s not element eleven of anything.)

  2. This family of tools is very nice to have to explore a few aspects of an antenna. It can tell you the complex impedance, the sign of the reactive component, and how well it will match a feed line of a specific impedance. It will tell you that a high quality dummy load is the best antenna in the world.

    It’s can’t delve into radiation efficiency, antenna pattern, gain, polarization, multi-path susceptibility, etc. Antennas are an abyss. At MM wavelengths they mostly resemble optics. At HF, well, something entirely different. A loosely coupled primary in a transformer with the aether as the secondary. They’ll sing you a song if you’ll bother to listen.

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