Fw: Fw: Re: [Antennas] 450 Ohm Ladder Line

2002年12月12日 12:27:18 -0700

Excuse me! I forgot! How many db's does it take to equal one S unit? 
In the far field?
How much less is the guy on the other end apt to hear me when I am
running my linear at 600 Watts v/s barefoot at 100 Watts?
73's de Jerry, K�EJF
On 2002年12月12日 13:25:37 -0500 "Joe Giacobello, K2XX" <[email protected]>
writes:
> I happened to save a copy of some test measurements that Tom, W8JI, 
> made 
> with 450 ohm ladder line back a few years ago. The experimental 
> data 
> show that there is substantial loss when burying the line in PVC 
> pipe. 
> His report is pasted below.
>> 73, Joe
>> You will be amazed at the attenuation caused by the soil, 
> especially if you allow the ladderline to get near the wall of the 
> buried pipe.
>> Balanced lines have a strong field extending at least a few 
> conductor spacings outside the line in a plane in-line with the flat 
>> part of the line, and to a lesser extent broadside to that plane 
> REGARDLESS of the fact they might have little far-field radiation.
>> My original post was:
>> Since no one knows what happens when open wire line is buried, I 
> measured some today. The line was heavy duty one inch spaced 
> twinline, with 14 gauge stranded conductors. The measured dry 
> impedance of a 50 foot dry sample was 328 ohms, although the 
> line is advertised as 450 ohm line.
>> Digital photographs are available if anyone wants to put this on a 
> Web Site. 
>> 50 foot 15 MHz loss measured with Wiltron Network Analyzer 
> (matched line conditions in every case):
>> Dry line suspended in air= .12 dB
>> Dry line laid on 3 inch tall dry grass, held up off the dirt unknown 
>> amount by the fairly thick grass= .83 dB
>> Dry line pulled in 2" PVC white plumbing pipe laying on grass = 
> 1.55 dB
>> Dry line buried 3-6 inches deep in PVC pipe in fairly dry dirt = 
> 4.12 
> dB
>> Same dry line in same pipe with dirt soaked with hose = 6.81 dB
>> Same dry line back in air = .15 dB
>> Line being wet down with heavy mist = .63 dB
>> Line slightly wet but not being misted for several minutes = .28 dB
>> Line was rematched to eliminate mismatch loss as impedance 
> changed, and matching network loss zeroed-out with analyzer.
>>> 73, Tom W8JI
> [email protected]
>>>> Dan Richardson wrote:
>> > At 12:35 PM 12/11/2002 -0600, you wrote:
> >
> >> On the other hand...........
> >>
> >> * Ladder line tests were performed at 50MHz to 150Mhz 
> (instrumentation
> >> limitation) where losses are greater .....not at HF, 160m - 
> 10m
> >
> >
> > Knowing those values it is easy to calculate the losses at lower 
> > frequencies. The formula is given in the article.
> >
> >> * Many of the tests were performed with Wireman Type 554 
> ....should
> >> also use the larger AWG.
> >
> >
> > Not so. He measured Wireman's numbers 551, 552, 553 & 554 the 
> results 
> > are shown in Table 1.
> >
> >> * The premise is that you are trying to load random length 
> dipoles 
> >> due to
> >> space limitations .....the antennas I feed are "tuned 
> dipoles".
> >
> >
> > I believe he was cautioning that substantial losses can and will 
> take 
> > place feeding short (less 3/8-wavelength) dipoles with window 
> line.
> >
> >> * Wet measurements are made by wetting the line, including an 
> open wire
> >> "reference line" which had NO change (indicates that a high 
> moisture
> >> "mist" dielectric was not considered) .....this also implies 
> that the
> >> change
> >> in impedance and attenuation shown is due to a wet ladder web 
> only.
> >> Making the web smaller should help this.
> >
> >
> > Mist? Really? And how are you going to qualify that one and make 
> it 
> > repeatable?
> >
> > Both wet and dry measurement are shown. (Again Table 1)
> >
> >
> >> I'd also like to know, for a HF antenna system, do you get more 
> power
> >> radiated by the resonant antenna if 1) you have an impedance 
> mismatch
> >> of 9:1 (with it's resultant SWR) between 200ft of 450ohm 
> transmission
> >> line and the 50ohm antenna .....or 2) if you use a toroidial 9:1
> >> transformer
> >> (with it's loss) between the balanced transmission line and the 
> balanced
> >> antenna ?
> >>
> >
> > The article addresses the window line losses only. For comparisons 
>> > with other systems you're going to have to dig deeper elsewhere.
> >
> > Danny
> >
> >
> >> Fun stuff.
> >>
> >> 73 Kees K5BCQ
> >>
> >> --------- Forwarded message ----------
> >> From: Sandy and Kees Talen <[email protected]>
> >> To: [email protected]
> >> Date: 2002年12月11日 11:06:33 -0600
> >> Subject: Fw: Re: [Antennas] 450 Ohm Ladder Line
> >>
> >> Great article, thanks Dan. It's always good to see real data, 
> determined
> >> using a controlled experiment, and excellent test equipment.
> >>
> >> 73 Kees K5BCQ
> >>
> >>
> >> ------- Forwarded message ----------
> >> From: Dan Richardson <[email protected]>
> >> To: [email protected]
> >> Date: 2002年12月11日 08:24:01 -0800
> >> Subject: Re: [Antennas] 450 Ohm Ladder Line
> >> Message-ID: 
> <[email protected]>
> >>
> >> For those interested here is URL which provides a very through 
> analysis
> >> on
> >> this subject.
> >>
> >> http://users.triconet.org/wesandlinda/ladder_line.pdf
> >>
> >> Danny, K6MHE
> >>
> >>
> >> No trees were destroyed in the sending of this message.
> >> However, a large number of electrons were terribly 
> inconvenienced.
> >>
> >> - - -
> >>
> >> Your moderator for this list is:
> >> Larry Wilson KE1HZ [email protected]
> >> _______________________________________________
> >> Antennas mailing list
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> >> - - -
> >>
> >> Your moderator for this list is:
> >> Larry Wilson KE1HZ [email protected]
> >> _______________________________________________
> >> Antennas mailing list
> >> [email protected]
> >> http://mailman.qth.net/mailman/listinfo/antennas
> >
> >
> > Danny
> > K6MHE
> >
> > No trees were destroyed in the sending of this message.
> > However, a large number of electrons were terribly 
> inconvenienced.
> >
> > - - -
> > Your moderator for this list is:
> > Larry Wilson KE1HZ [email protected]
> > _______________________________________________
> > Antennas mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/antennas
> >
> >
>>> - - - 
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
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>>
E. Jerold (Jerry) Forwood