Topband: wideband inv-L

Tom Rauch w8ji at
Wed Jan 5 20:24:25 EST 2005

> >... However, the slightest loss really extends the
bandwidth and I
> >suspect this is > what many find....

A 1/4 wl vertical from 18" face tower will cover the entire
160 meter band with under 2:1 SWR when over a perfect ground

Decreasing efficiency by exactly half from nearly 100% to
just under 50% just slightly less than doubles bandwidth.

> Yep, the universal bugger on 160. So much so that any sign
of new
> "bandwidth" generates a paranoid scurrying about to
discover what's
> gone wrong.
> Stated another way, particularly for 160, bandwidth
implies loss until
> loss has been carefully ruled out.

My highest efficiency mobile antennas have the widest
bandwidth by a significant margin.

A 1/4 wl tower with perfect ground has full band or nearly
full band coverage even with 100% efficiency.

Now if you see a half-wave wire dipole cover 200 kHz, you
need to be worried.

73 Tom

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