Really cool idea.. Have been reading about this for a few hours now.. One thing i came up on was that we also need to consider the Loss Tangent of the materials used.
So, what type of things are out there that have a low loss tangent at the needed frequencies and has a temperature-stable dielectric constant within the wanted range that's relatively cheap and is easy to obtain?
I'm thinking that a gas is probably the best and easiest since mixing 2 powders will most likely result in an uneven mixture in different areas of the globe, also we should see what types of different globes are out there since that will also affect the performance, but i suspect that the loss tangent is the most important for the globe since the sphere will be quite a low percentage of the whole system.
Maybe if someone is feeling up to he could create some graphs of the theoretical gain of different gasses with this?
Some interesting reading:
_http://books.google.se/books?id=P2cLPsLDHxcC&lpg=PA16&ots=yOjRArwY8X&dq=%22Loss%20Tangent%22%20%22dielectric%20constant%22&pg=PA22
Just a few crazy ideas for the contents:
- Fill the sphere with different types of balls with a low loss tangent but a bit higher dielectric constant. (Can we get the dc to the target range?)
- Pure CO2 has a DC of 1.6 but have not found any loss tangent for it.
- Any cheap noble gases with a low DC out there that we could use to mix a cheap high DC gas with? Probably need to keep the weight of the gases approximately the same.
- Can we maybe lower/raise the pressure in the sphere to lower raise the DC? Get a high DC gas and lower the pressure is probably the best way to go since that would reduce the loss tangent. But with this we would have to have a bit sturdier sphere.
Maybe the creator of the thread could create a table that we could fill up with information on DC/LT on the different materials?
Just some crazy ideas from a insomniac so don't take it word for word
U-zzz