[TowerTalk] URI magic antennas

[Jim Lux]

At 12:15 PM 6/8/2004 -0400, Dave Bernstein wrote:
>It is no longer necessary to use liquid helium to attain
>superconductivity. When last I checked, advances with ceramic materials
>had pushed superconductivity close to liquid nitrogen territory, and the
>goal of room-temperature superconductivity was still considered a
>possibility. See
>http://www.newscientist.com/news/news.jsp?id=ns99991618, for example...
>
>     73,
>
>         Dave, AA6YQ


Practically speaking, you don't need superconductivity to improve 
performance. Just cooling the metal will reduce the resistance, and hence 
the loss, somewhat.  I seem to recall that Cu has about 1/7th the 
resistance at LN2 (77K) temperatures compared to room temperature. It's 
roughly linear... Dry Ice (200K?) might get you half or a third of the way 
there.


Too bad, though, that you can't supercool the earth for some 20 wavelengths 
around, to reduce that source of loss.

Too bad, also, that reducing resistance isn't the only thing you have to do...