[TowerTalk] Gap Vertical, Verticals in general

[T. A. Russell]

On Wed, 6 Aug 1997 19:57:40 -0700 ftbrady@cosmoslink.net (Frank T. Brady)
writes:
>Tom,
>
>None of the responses to your thread described the vertical antenna
>characteristics in quite the same way as I have come to understand 
>them, so
>I thought I'd throw mine in after the dust settled.
>
>Regarding the effects of elevating the base of verticals:
>
>My understanding (mostly from from the Bill Orr W6SAI book) is that 
>the only
>thing that affects the takeoff angle for a single vertical radiating 
>element
>is the electrical length of that element. The angle is lowest for a 
>5/8 wave
>element.  Elevating the base of a vertical has no effect on the 
>takeoff angle.
>
>As the base of a vertical is elevated, the number of radials required 
>to
>minimize ground return losses drops rapidly from 120 (base at ground 
>level)
>to 3 or 4 (base 1/2 wavelength above ground). 


 The number of radials
>required continues to be reduced at greater than 1/2 wavelength 
>heights
>until it is approaches zero at 1 wavelength elevation.


>73,
> Frank T. Brady - W0ECS
>

ZERO  radials?  Really?!

Now THAT must present in interesting match
to a low impedance feedline!

BTW,  the ARRL antenna book shows a considerable lobe 
at high angles as the base is raised above ground, in addition
to the low angle lobe near the horizon.

de  Tom  N4KG

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