💾 Archived View for sdf.org › stug › phlog › 2021 › 20210916.txt captured on 2023-03-20 at 19:27:16.
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16 September 2021 The mind is a strange thing. Today feels better. Nothing has changed other than my having an idea during my best thinking time. I find the morning shower is obviously when that precious molecule of inspiration tends to hit. There is no active thought, no 'what am I doing later?' questioning, just doing. It enables me to listen to the background mind which has been processing matters and often those ideas are just what I need. Today it was about having a worksheet to define parameters as they get passed between electro-magnetic designers to mechanical designers. I expect push back as 'the information is already in the reports' but I keep hearing mixed responses to what is going on. One for next week. Hopefully the background mind will make sense of a particular antenna design I saw. I have been trying to work out a 20m dipole I could fit into a 10m wide loft. I ended up looking through a wonderful book on HF antennas for all locations by Les Moxon, G6XN. There was a bit of a section on small antennas which had 2 figures. One was a spiral loaded dipole and the other a planar loaded dipole. The planar loaded version involved significantly less wire than the spiral loaded version. Now, I understand the spiral one. The spiralled wire forms an inductor which allows for the reduced length dipole to be electrically representative of a half wave length. However, the planar version makes no sense. It consists of 3.3528m of wire arranged into 5 squares along a line. It is a bit weird. The planar part of the name is because the squares effectively are a plane but how is this loaded? Is it loaded in an inductive manner? I think so but keep questioning myself. G6XN sadly does not offer anything beyond a formula for the resonant resistance and the design for 20m. Searching the internet lead to little thanks to the planar part giving me a lot of information about PCB antenna design. I would love to work out how this design works and see if I can work out a 40m version as well. I might have to look ask the GQRP oracle for information. The other thing I have been questioning is whether I can use Octave for antenna simulation. I can certainly get graphical output from the instance on the MetaArray via X11 over SSH. Just need to investigate whether anyone has made a nice module which saves me doing lots of reading and understanding of the inherent maths. Mostly out of laziness. It is a good excuse to get used to Octave and Matlab after far too many years of not touching it. I sort of have an idea of using the MetaArray to run xFEMM for machine design to learn more about what my team do and be able to support them more.