Beamed Power

Some excellent points, good areas for research.

>

> > Sure, could it be even less than 1 mm thick ?
>
> Yes, but its limited by resistive heating I think.
>

We need to understand this. Resistive disspation will increase as
resistance falls, P = E^2 / R

The losses in the system should be quite small, the RF systems is
supposed to be efficient in the high 90's %.

Most of the heat loss should be in the solid state amplifiers.

> > thickness is unspecified,
> > looks like less than 0.1 mm
>
> It's not clear its upto the job though.
>

Need more specs and data.
Is there an antenna designer in the house ?

> Aerials have to conduct, you make it too thin it melts.
>

This might not follow. For AC fields most of the electricity is
carried
on the skin of the conductor, so the core could be non-conductive.

> > Does it need to be solid surface ? Would a mesh be OK ?
>
> Yes. But the amount of conductor stays the same, and the
> surface area goes down... less cooling. You're in a
> vacuum, only radiative cooling.
>

With a mesh it would reduce the amount of conductor per unit area.

Antennas need not be solid, mesh designs are fairly common. It depends
on frequcny. Mesh antennas are less common in the higher frequency
microwave regions.

>
> 1 Gigawatt/km^2 = 1kw/m^2. Sounds like it my be too much for
> aluminium foil. You'd need to do some more checking.
>

That is about the same as sunlight, 1 Kw / square metre.

And if the efficiency is 99%, then the waste heat to be dissipated would
be
10 Watts / square meter.

> For an example of what happens to aluminium foil when the
> power goes too high, stick an AOL CD in a microwave for a
> few seconds, next to a glass of water; label side up is
> best. (It WON'T wreck the microwave, provided you include the
> glass of water.)
>

Not sure of the mechanism here or how relevant that is.
Aluminum conducts and reflects the microwaves.
This can be quite spectacular, I did something like that once by
accident.
Our antenna would be tuned. Local heating could result if the antennas
went out of tune.

I am rather speculating here, not my area of expertise.

>
> Still, I'm wondering whether an electronically steerable
> diffraction grating could be constructed. Might be very much cheaper

Interesting idea, sounds patentable if it works.

We really need some research on antenna desings for high power microwave
beaming. The studies I have seen were rather superficial in that
area.
Can anybody post some links to something more specific ?

Cheers,

CR.