DJ3EI's blog

I provide a Python package antenna_simulation_driver. When you are here, I assume that you already knew that and have a notion what that is about. If you don’t, I recommend you head over to that project’s git repo and read its README.md.

hwg and short dipoles

This is about a Jupyter Notebook that showcases the use of the driver to run parameter studies.

The studies done here rely on nec2++’s impedance and efficiency values. (Nothing in here already uses the radiation pattern. I simply have no showcase for that yet.)

The notebook is available in a rendered version, which has fun graphs and a bit of antenna theory. Unfortunately, the Python code is formatted in a rather shitty way: This is simply Nikola’s out-of-the-box formatting, where Nikola is the static site generator I’m using for this web site / blog.

I want to improve on that formatting eventually with a helping of custom CSS sprinkling.

Workaround for bad Python code formatting

But some people are wanting to get their hands dirty and play themselves with my code. Of course, all such are warmly invited! So I decided to rather publish with shitty formatting now than let those wait.

Fortunately, for now, there is a workaround: Run jupyter notebook on your own computer.

Scroll down to the end of the above rendered version. There is an explanation which tells you how to install everything you need to run that notebook yourself. You can then download the same notebook as source, start jupyter notebook and in the browser window that opens, navigate to the file you just downloaded (assuming you were in the same directory where that file sits when starting jupyter notebook).

The installation steps hopefully enable you to rerun the entire notebook. But they’re quite a mouthful. For just nicer Python code formatting while reading, a simple pip install notebook followed by jupyter notebook should already do the trick.

Reproducing the ZS6BKW

The ZS6BKW is a well-known antenna invented by Brian Austin G0GSF, ex ZS6BKW. It consists of a center-fed dipole and a 400 Ω feedline. Feedline length and dipole length are carefully adjusted so this antenna shows low SWR on five different short-wave bands from 40 m through 10 m (not on 15 m and 30 m).

With a standard optimization algorithm, my interface to nec2++ and a bit of Python code to team those up, it is fairly straightforward to reconstruct the required dipole and feedline lengths from a list of frequencies on which to minimize SWR.

This is again demonstrated as a Jupyter Notebook. It is provided as a rendered version and source.