Yes that was what I figured. A single 12 inch diameter plastic pipe with the
ladder line suspended in the middle or else convert from ladder line to coax
for the pipe run and then back again at the other side using transformers.
As you say a metal pipe would be interesting.
Mark N1UK
----- Original Message -----
From: "Martin Ewing" <martin.s.ewing@gmail.com>
To: "Barry Merrill" <barry@mxg.com>
Cc: <towertalk@contesting.com>
Sent: Friday, 21 November, 2008 9:26 AM
Subject: Re: [TowerTalk] Ladder Line Underground
> Quick answer is no. The electric and magnetic fields on ladder line
> extend
> out to several times the wire spacing. (Out to infinity, actually, but
> maybe 3 - 8 X for practical work.) Anything inside that radius will
> affect
> the impedance and/or loss of the line. So, if you're willing to put it
> centered in an 8 - 12" pipe (all by itself), it might work. (Actually, it
> becomes a kind of twinax if the pipe is conductive.)
>
> You can use transformers (baluns) to convert from balanced line to coax
> and
> back, but they want to work close to 1:1 SWR, and they have losses.
>
> 73 Martin AA6E
>
> On Fri, Nov 21, 2008 at 5:58 AM, Barry Merrill <barry@mxg.com> wrote:
>
>> A question from my Best Man, F/K9ORP:
>>
>> Can Ladder Line be run thru underground conduit under a road
>> to feed antennas on a tower across the road, with no impact?
>> By itself?
>> Would a mix of coax and ladder line also work?
>>
>> Barry, W5GN
>>
>> _______________________________________________
>>
>>
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>
>
>
> --
> Martin Ewing, AA6E
> Branford, CT
> _______________________________________________
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