I need to draw a 32 turn spiral pattern, for a "pancake" coil antenna,
that will be suitable for etching PCB's. IOW clean edges and uniform
widths for the tracks and spacing. Diameter is approx 150mm. Can
anyone please suggest how to do this accurately, preferably by
computer?
Charles Lind
You design a form on the computer that you can make in manufacturing.
The form is a cardboard (paperboard) helix that you print out, and roll
up onto a tube, so you can paste it onto a cardboard tube. The print job
prints the line of your antenna onto the paper. The finished tube has
lines on it now that you use a form for the positioning of the antenna
elements. Once everything is assembled, you remove the tube from within
the antenna, and all that is left is the antenna itself.
So the CAD design is for the printed helix before it gets rolled up onto
the tube form that is the diameter of your helix.
Done right, it will have your layout lines in all the right places so
that the antenna builders can build the antenna. Automated process can
be derived from similar fixtures and forms methods, but this antenna
style sounds difficult to automate too much.