[600MRG] For discussion: Re: Top loading a vertical on LF/MF
Edward R Cole
kl7uw at acsalaska.net
Thu Nov 28 11:07:06 CST 2013
I built a 43-foot high by 122-foot long inverted-L. I parallel three
lines separated by 1-foot on the vertical section and two lines
separated 2-foot on the horizontal (to broad-band it a bit). I used
3/4-inch copper tube spreaders at the ends to short the leads together.
EzNec models the antenna to be Z = 0.81 - j681.5. I built a large
base loading coil to add enough inductance to resonate the
antenna. I tap the coil 2-1/2 turns from the ground end to match
50-ohms to coax.
Ground radials are inadequate but all I can do with limited
property. At resonance the antenna measures Z = 18 ohms so ground
loss is high. I calculate my ERP as 4.15w with 100w output from the amplifier.
Its all described on my 600m webpage:
http://www.kl7uw.com/600m.htm
73, Ed - KL7UW
At 07:20 AM 11/28/2013, sbjohnston at aol.com wrote:
>Some AM broadcast antennas have top loading... it has been shown to
>work best when the loading wires are closer to horizontal. I
>recall experiments with drooping the loading wires to try and
>control the vertical radiation pattern and reduce the signal at
>certain skywave takeoff angles, so that supports the idea mentioned
>that lowering the wires could cause cancellation for at least some angles.
>
>I'll try and find some references...
>
>
>
>
>Steve WD8DAS
>
>sbjohnston at aol.com
>http://www.wd8das.net/
>--------------------------------------------------------------------
>Radio is your best entertainment value.
>--------------------------------------------------------------------
>
>
>
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>
>
>-----Original Message-----
>From: 600mrg-request <600mrg-request at w7ekb.com>
>To: 600mrg <600mrg at w7ekb.com>
>Sent: Wed, Nov 27, 2013 10:16 pm
>Subject: 600MRG Digest, Vol 31, Issue 41
>
>
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>Today's Topics:
>
> 1. Re: For discussion: Re: Top loading a vertical on LF/MF
> (Eric NO3M)
> 2. Re: For discussion: Re: Top loading a vertical on LF/MF
> (jrusgrove at comcast.net)
> 3. Re: For discussion: Re: Top loading a vertical on LF/MF
> (Pat Hamel)
> 4. Neil - Vertical top loading (Ken Roberson)
> 5. /20 (Rudy Severns)
> 6. Re: /20 (Ralph Hartwell)
> 7. Re: /20 (Mike-WE0H)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Wed, 27 Nov 2013 19:02:17 -0500
>From: Eric NO3M <no3m at no3m.net>
>To: 600mrg at w7ekb.com
>Subject: Re: [600MRG] For discussion: Re: Top loading a vertical on
> LF/MF
>Message-ID: <52968809.5060804 at no3m.net>
>Content-Type: text/plain; charset=windows-1252; format=flowed
>
>Err, increase gain in a certain direction.....
>
>On 11/27/2013 06:58 PM, Eric NO3M wrote:
> > increase ERP concentrated in a certain direction
>
>
>
>
>------------------------------
>
>Message: 2
>Date: Wed, 27 Nov 2013 19:22:52 -0500
>From: <jrusgrove at comcast.net>
>To: <600mrg at w7ekb.com>
>Subject: Re: [600MRG] For discussion: Re: Top loading a vertical on
> LF/MF
>Message-ID: <006801ceebcf$fa9528c0$6401a8c0 at JAYDELL>
>Content-Type: text/plain; format=flowed; charset="Windows-1252";
> reply-type=original
>
>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
>
>
>--
>*"I use the original form of social networking, Amateur Radio." *
> *(my ham radio site is at 'w0yse.webs.com
><http://w0yse.webs.com/>' )*
>_______________________________________________
>600MRG mailing list
>600MRG at w7ekb.com
>http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>
>
>
>
>------------------------------
>
>Message: 3
>Date: Wed, 27 Nov 2013 19:02:32 -0600
>From: "Pat Hamel" <pehamel at cableone.net>
>To: "'Neil Klagge'" <w0yse.7 at gmail.com>, <600mrg at w7ekb.com>
>Subject: Re: [600MRG] For discussion: Re: Top loading a vertical on
> LF/MF
>Message-ID: <E01DB79813A84C62BA14C8770EDE0FD1 at MrSamPC>
>Content-Type: text/plain; charset="us-ascii"
>
>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/>' )*
>_______________________________________________
>600MRG mailing list
>600MRG at w7ekb.com
>http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>
>
>
>
>------------------------------
>
>Message: 4
>Date: Wed, 27 Nov 2013 19:17:35 -0800 (PST)
>From: Ken Roberson <kwroberson at yahoo.com>
>To: "600MRG at w7ekb.com" <600MRG at w7ekb.com>
>Subject: [600MRG] Neil - Vertical top loading
>Message-ID:
> <1385608655.86704.YahooMailNeo at web142701.mail.bf1.yahoo.com>
>Content-Type: text/plain; charset=us-ascii
>
>Neil,
>
>I installed 3 sloping wires on my 60 ft vertical, Each wire is
>45 ft . The ends are 35 ft above the ground, It seems to me
>That indeed it helped and I was able to remove 20 turns
>from my base loading coil, That had to help.
>Photo on QRZ.
>73 Ken K5DNL
>
>
>------------------------------
>
>Message: 5
>Date: Wed, 27 Nov 2013 19:58:50 -0800
>From: "Rudy Severns" <n6lf at arrl.net>
>To: "600MRG" <600mrg at w7ekb.com>
>Subject: [600MRG] /20
>Message-ID: <5E00FE77B51946F7A8A6035D29B65BBD at Rudy>
>Content-Type: text/plain; format=flowed; charset="Windows-1252";
> reply-type=original
>
>Another strange evening! I can see and hear XJM's WSPR signal. He's
>decoding at -6 dB which is very strong. This is the first time I've seen an
>actual trace for a WSPR signal. However, all the other signals are very
>light. I can see a trace for /12 but not hear him. No sign of Ralph, /7,
>yet. Why is XJM exceptional and everyone else is weak???
>
>Will continue to monitor.
>
>73, Rudy
>
>
>
>
>
>------------------------------
>
>Message: 6
>Date: Wed, 27 Nov 2013 22:12:10 -0600
>From: "Ralph Hartwell" <w5jgv at w5jgv.com>
>To: "'600MRG'" <600mrg at w7ekb.com>
>Subject: Re: [600MRG] /20
>Message-ID: <00f301ceebf0$0b46c9b0$21d45d10$@w5jgv.com>
>Content-Type: text/plain; charset="us-ascii"
>
> >No sign of Ralph, /7, yet. Why is
> > XJM exceptional and everyone else is weak???
>
>
>Dunno', but I'm doing my part to fill the power company's coffers what with
>the 4-400A amplifier throwing amps at the antenna. But I need the heat in
>the shack tonight - it's getting close to 20 degrees here overnight, which
>is downright cold for us.
>
>Best DX & 73,
>
>Ralph W5JGV - WD2XSH/7
>
>
>
>
>
>
>
>------------------------------
>
>Message: 7
>Date: Wed, 27 Nov 2013 22:16:05 -0600
>From: Mike-WE0H <we0h at yahoo.com>
>To: 600mrg at w7ekb.com
>Subject: Re: [600MRG] /20
>Message-ID: <5296C385.6040904 at yahoo.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>20F ??? It's warmer up here :-) 25F and clear skies. No snow :-)
>
>Mike
>WE0H
>/16
>
>
>
>Ralph wrote:
>
>
>...- it's getting close to 20 degrees here overnight, which
>is downright cold for us.
>
>Best DX & 73,
>
>Ralph W5JGV - WD2XSH/7
>
>
>
>------------------------------
>
>Subject: Digest Footer
>
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>------------------------------
>
>End of 600MRG Digest, Vol 31, Issue 41
>**************************************
>
>
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73, Ed - KL7UW
http://www.kl7uw.com
dubususa at gmail.com
"Kits made by KL7UW"
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