Topband: Quarter wave sloper on crank up tower ?

[Jim Brown]

On 5/11/2025 9:24 AM, jim.thom jim.thom at telus.net wrote:
> The concept behind the 1/4 wave sloper is...... the 50 ohm feed point is at
> the top of the tower...90' above ground.    And if it's less than 50 ohms,
> a simple helical hairpin  across the feedpoint is one solution.

That is ONE concept. The one I built is another.
> 
> To cover more of the band, it's a simple matter to use a loop at the top,
> then shunt it with a DPST  vac relay.   Then no matching network  required
> in the shack.
> 
> I have used 1/4 wave slopers on 75m  since 1977, on various
> height towers...up to 96'.
> Never tried a 1/4 wave sloper on 160m though.  That's why I was asking.
> 
> I have zero enthusiasm for installing radials below the existing lawn...
> but it is doable.

The functions of radials are (1) the SHIELD the antenna's field from the 
lossy earth and (2) to provide a low loss path for the antennas return 
current. The ONLY value in burying radials is to protect them from human 
or animal activity. Properly implemented, elevated radials can work 
quite well.

Radials connected to the base of a tower DO provide capacity coupling to 
the earth for lightning, which is quite helpful, because lightning is an 
impules, making primarily an RF event, NOT a DC event.

73, Jim K9YC