It's all about the Software

Simon,
Would it be possible to produce a piece of software that plots the radiation pattern of a yagi antenna.

Some thing like output 0-360 degrees in say 5 degree steps to the rotator, Then read the signal strength from the SDR in db and plot it on a polar display.

Would make checking yagies a lot easier.

Thanks

David VK4ZF

As phrased the answer would be "Of course!" Now if you meant as part of SDRConsole while it might be interesting I'm not sure it's a winner. Thankfully I don't have to decide. That's for Simon to decide. And the data may suffer huge inaccuracies depending on objects near the antenna. The pattern with the antenna pointed North might only vaguely resemble the pattern pointed East if off to the East there was a nice chain link fence and off to the South there is an all metal barn 2 or three wavelengths away from the antenna. Of course, that means a nice pattern from a formal antenna range may not particularly resemble your site unless heights are identical and your site is relatively "clean" of collections of conductive stuff.

That's how I talked myself out of trying to do it when I had a nice beam up 70'....
{^_^}

VK4ZF wrote: ↑Wed Mar 24, 2021 7:36 am Simon,
Would it be possible to produce a piece of software that plots the radiation pattern of a yagi antenna.

Some thing like output 0-360 degrees in say 5 degree steps to the rotator, Then read the signal strength from the SDR in db and plot it on a polar display.

Would make checking yagies a lot easier.

Thanks

David VK4ZF

How would I read the rotator angle?

The software controlling my Sony tuner has this feature, it's simply plots relative signal strength on a chart. You just hit the start button and again to stop it along with controlling the rotator and the software assumes it's done 360°
I've found it useful to compare performance when I've changed Yagis.
I'd give a working example but no mast or antennas at the moment so here' s a grab of what it looks like.

A long time ago I used a piece of USA software to check a new Yagi.
In this process you had to calibrate the S meter in my Icom IC-910. (This was before the days of SDR radios)

This was done from a HP signal generator.
The rotator was then started from one of the stops and let rotate until it reached the other stop.
The software read the S meter at regular intervals and then plotted the result on a polar display.
This system assumed the rotator traveled in a linear time mode.

This worked fairly well as I found some pattern faults in the particular yagi.

What I was thinking about the new program could send a command to the rotator to go to, say 0 degrees then read the signal strength and store the reading.
Next the software tells the rotator to go to 0 + 5 degrees and again take a reading.
The rotator is then told to go to a further 5 degrees for another S reading and so until it has completer 360 degrees rotation.
Once the measurement is completer the computer plots the position and S meter value on a polar display.

I trust my explanation makes sense

David VK4ZF

Something I found some time ago:
https://github.com/kkonradpl/antpatt
https://github.com/kkonradpl/xdr-gtk

I haven't used this so I don't know how it works exactly, but the creator of the software showed that it can create pattern plots in this way.
https://forum.radiopolska.pl/index.php? ... t&p=432878
However it needs a modified XDR-F1HD radio.

Gentlemen,
I eventually found the program I used in the past.
http://www.seed-solutions.com/gregordy/ ... erLite.htm

Not as good as telling the rotators an exact direction but it will do until something comes along

David

"Late to the party again"
I was trying to do this myself a few weeks ago. I found that CSV Userlist browser has a signal plotter option that works with SDR console. It takes signal readings at a minimum of 0.5 second intervals. It doesn't produce a polar diagram just a time vs strength X-Y plot - but oh boy! it sure shows up the problems of pattern distortions mentioned by jdow. In my case yagi antennas about 7 m away from the yagi on the rotator as well reflections from nearby houses. One particular mid band station gives at best 7dB or so f/b ratio. Another station gives 30dB.