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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.