View Single Post
  #16   Report Post  
Old May 10th 04, 01:37 AM
Roy Lewallen
 
Posts: n/a
Default

JGBOYLES wrote:
The thread was "wire thickness versus bandwidth" As you know, to scale an
antenna from one frequency to another, you need to scale the wire diameter as
well. This will keep the bandwidth pretty much the same. . .


When you scale an antenna's dimensions, including the wire diameter, the
*fractional* bandwidth remains the same. So if you scale it for twice
the frequency, the bandwidth doubles.

This is assuming that loss is negligible. If loss is appreciable, it
becomes a factor in determining the bandwidth. And in order to preserve
the loss characteristics when scaling, you've also got to scale the
conductivity (as the square root of frequency). This is generally
impossible or at best highly impractical, so the bandwidth of a lossy
antenna won't scale like it will for a low-loss one.

Roy Lewallen, W7EL