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-   -   Advantage in cancellation of radials? (https://www.radiobanter.com/antenna/122337-advantage-cancellation-radials.html)

David July 26th 07 08:14 PM

Advantage in cancellation of radials?
 
If the elevated radials on a quarterwave vertical antenna are horizontal,
the radials cancel out the most for the far field. The impedance will
probably be away from 50 ohms and therefore need matching.

If the radials are drooping, the antenna feedpoint impedance is close to 50
ohms.

Is there any advantage in having the radials horizontal to cancel out? Would
there be any advantage for field pattern or for the near field? Would there
be a dissipative effect? The field of the radials only cancels out in the
far field and not the near field, so the radials are still live with RF and
dangerous to touch.



Richard Clark July 26th 07 09:56 PM

Advantage in cancellation of radials?
 
On Thu, 26 Jul 2007 20:14:10 +0100, "David" nospam@nospam wrote:

Is there any advantage in having the radials horizontal to cancel out? Would
there be any advantage for field pattern or for the near field?


Hi David,

Radials are a choice for matching more than radiation. Advantages to
radiating or not radiating are largely won or lost by accident. The
sloping radials do tend to improve match and provide more signal -
however, neither is earthshaking as an advantage.

Would there be a dissipative effect?


Would it heat the air for any particular configuration? No. Drooping
radials being closer to the ground may lend to higher losses there;
but the "advantage" would be wider bandwidth.

73's
Richard Clark, KB7QHC


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