From Leigh WA5ZNU via the Flying Pigs QRP Club mailing list:
I’ve been having lots of fun with my new vector network analyzer. It’s like an antenna analyzer, but it’s got two BNC connectors on it, So you can hook it to an antenna, or to a filter, or other stuff. It’s really small, though, about the size of a deck of cards. It covers 1-180Mhz.
I’ve often wanted the TimeWave AntennaSmith, but at $1300, I just can’t, even though it was developed by some local OMs. But I could afford this new thing, from Mini Radio Solutions. I’ve been following IW3HEV’s project for a year or so now, and they finally have something that seemed right for me. It’s a little over $200 (you have to order from Italy), and it requires a PC (works with Windows or Linux or Pocket PC).
At http://wa5znu.org/2006/07/analyzer/loop.jpg and http://wa5znu.org/2006/07/analyzer/loop4.jpg you can see a plot of the resistance and reactance and SWR of my big, low loop antenna through about 30 feet of 300-ohm window line and an Elecraft switchable balun at the 1:1 and 4:1 settings respectively. It has some nice resonances at 1.8Mhz, 3.5MHz, 5.2Mhz (60m), just below 7Mhz (though 1.3:1 at 7.035), but then after that something happens and things aren’t quite as good. This pretty much corresponds with the antenna behavior.
In the charts at the above URLs, the SWR is red and near the bottom (you want dips), the reactance is green and near the top (you want it to be 0, near the top of the screen), and the resistance is purple (you want it to be on the line labelled “50 ohms”).
It also will plot phase angles and return loss, and convert instantaneous reactance slope into inductance or capacitance at any frequency.
I’ve already used it to adjust my Hamsticks and know which ones to use with my step-up balun and which not to (though I did trim one of them a bit agressively and had to go buy another stinger). I also have some Bode plots (input vs output) of a switchable LPF I tested as well. It’s still uncalibrated and there’s probably some parasitics but it’s interesting to look at. See http://wa5znu.org/2006/06/bode
Minuses: doesn’t really know sign of reactance but tries to figure it out, no display (requires a laptop or computer), power output is a little low so it has some BCI rejection problems (I live 5 miles from a 50KW AM station, half of those miles over salt water), software still in development (but all open source), and calibration routines not yet developed.
This looks like a pretty neat little device to me…..Dan
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