December 2024
A while ago, I made a fiberglass copy of a small 80cm offset dish.
The procedure is simple. The dish was first covered by anti-stick wax , then a couple of fiberglass mat layers were carefully placed on the dish and soaked in polyester resin.
Safety comes first so throughout these experiments with polyester resin I wore a 3M 7502 with 6099 filters .
After drying to make the plastic dish reflect electromagnetic waves it had to get a reflective coating.
Covering it with aluminum tape worked very well, made the surface reflective and Ku band TV signals where on par with the 80cm alu dish.
See also:
https://twitter.com/SV1CAL/status/1551223828361142273
Next I removed the alu tape and briefly experimented with copper filled polyester resin basically adding copper powder to the resin to make it conductive.
That was somewhat promising, signals started to show up on my Satellite finder but the mix would need higher copper concentrations and much more refininemnt.
Then to move ahead , I just covered the dish with copper conductive paint (Tifoo) namely the one I use to copper plate my 3D printed feeds etc.
That made a huge difference . Even though conductivity is poor compared to pure copper, reflectivity of Ku band TV signals seems to be good.
Next step was to quickly copper plate the dish making a very thin copper layer.
The usual copper sulfate solution from Tifoo was employed, minus lead connected to the dish surface and then copper plating with a pen .
Finally reflectivity was compared to the solid dish and signals where on par.
These experiments explore alternatives to covering the homemade fiberglass with mesh wire or conductive tape.
Painting it with a conductive paint sounds an alternative, additionally plating it improves conductivity.
Since plating adds an extra processing step , avoiding it would simplify things. Probably increasing the copper concentration in the paint will make that possible.
Besides the 80cm dish , I am also working on a larger 2.5 m fiberglass dish.
For this a concrete paraboloid has been fabricated:
Michael Margaras SV1CAL - Amateur Radio and Electronics 