[TowerTalk] Fwd: Much Smaller Antennas Possible?

[Richard (Rick) Karlquist]

On 4/16/2015 3:49 PM, Erich wrote:
> My first thought on this is "there is no free lunch".  I have not yet
> read the paper, and do not understand what they call "symmetry
> breaking".  However, there are two things that limit the performance of
> physically small antennas.  First, power density is defined as power per
> unit area.  This means a small capture area will capture a small amount
> of power.  Second, physically small antennas usually mean small
> impedances.  That means high currents and high I^2*R losses.
> Superconducting antennas can get around some of these losses at the cost
> of high complexity.

You have a common misconception of "capture area".  It is NOT
the same as the physical area of the antenna.  If there were
no I^2R losses, all small antennas would have a gain of 1.5
along with the corresponding capture area, regardless of
physical size.

In any event, what really limits small antennas is the very high
Q that is necessary to get good efficiency.  Making the
antenna out of a superconductor doesn't fix this.  You still have
very narrow bandwidth and very limited power handling.
This is per K6OIK, who really knows this stuff.  See:

https://www.fars.k6ya.org/docs/k6oik#AntennaQ

Rick N6RK