Topband: Another DXpedition 160 Vertical Idea

[Larry Higgins]

> At P40W I use a vertical dipole.  The big advantage - no ground system
> required.

It is often said that no radials are required for vertical dipoles.  If the
criterion is simply the ability to make QSOs, then the statement is correct.
However, it is also true that vertical dipoles do induce current in the
ground, and the energy transferred to ground comes from the transmitter.
The H field  won't induce any ground current, but the E field will.
Coupling is by electrostatic induction, rather than magnetic induction.

Because the radiation resistance of the dipole is higher than that of a
quarter wave vertical, the ground losses are lower for the dipole.  This is
so because the ratio of radiation resistance to loss resistance is higher.
But lower losses does not mean zero losses.  If you want to optimize the
system, a radial system is still required.  If you just want something that
will easily get on the air and is very portable, don't bother with radials.

> Tuning the antenna was easy - adjusting the length of the lower leg.  Try
to
> pull the top leg out as horizontally as possible, but it will still work
> even with a significant angle toward the ground.

If one leg is horizontal, how is this a vertical dipole?  Or is it a half
wave inverted L?

73
Larry, N9DX



-- 
Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.7.0 - Release Date: 1/17/2005