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

[jrusgrove at comcast.net]

Neil

http://www.strobbe.eu/on7yd/136ant/

Scroll about 1/8 of the way down the page. Equations and graphs for tophat slope / length vs. Rr 
improvement. For 137 kHz but also applies to 500 kHz.

The whole piece is a good read if interested in short verticals.

Jay W1VD  WD2XNS  WE2XGR/2  WG2XRS/2


----- Original Message ----- 
From: "Neil Klagge" <w0yse.7 at gmail.com>
To: <600mrg at w7ekb.com>
Sent: Wednesday, November 27, 2013 6:18 PM
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


-- 
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