[600MRG] For discussion: Re: Top loading a vertical on LF/MF

[Pat Hamel]

For antenna planning, please look at:
http://www.500kc.com/downloads/Martin-Carter%20(RCA)%20LF%20Antennas.pdf
for information that might help.
Actually before spending money, you might look at all the "technical
downloads" in the downloads tab of www.500kc.com
The umbrella antenna (sloping top loading) has a lower effective height
because of the cancellation idea. The wire around the outside supposedly
helps efficiency a lot.
The only way I could get full top loading was to go with the inverted - L
idea with eleven 120 foot wires on copper pipe spreaders. 
When we dropped to 475KC, I added a (40 microhenry max) roller coil at the
bottom.
Happy Thanksgiving
Pat /6


-----Original Message-----
From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of Neil Klagge
Sent: Wednesday, November 27, 2013 5:18 PM
To: 600mrg at w7ekb.com
Subject: [600MRG] For discussion: Re: Top loading a vertical on LF/MF

 To the 600m gang:
The reason for initiating this discussion is that, for me and perhaps
others, it is not feasible or possible to add top loading wires to a 630m
vertical without sloping the load wires downward a considerable amount.

I know that when an antenna is "folded back on itself" there is
cancellation of some of the radiation from the antenna. This is certainly
the case for top loading wires that reach toward the ground down to less
than half of the height of the vertical section.

The question I find myself asking is this: "Is what I will gain in ERP
worth the effort it takes to add sloping top wires because of the
cancellation that will occur." I wonder if 1 or 2 dB gain is worth it at
the receiving end.

I would be interested in feedback from those who have any experience with
both situations: Namely, top loaded verticals and "topless" verticals  ;-)

73, Neil Klagge, WG2XSV, W0YSE


-- 
*"I use the original form of social networking, Amateur Radio." *
              *(my ham radio site is at 'w0yse.webs.com
<http://w0yse.webs.com/>' )*
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