Towertalk
[Top] [All Lists]

Re: [TowerTalk] Ladder Line Question?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Ladder Line Question?
From: jimlux <jimlux@earthlink.net>
Date: Sat, 13 Apr 2019 09:05:04 -0700
List-post: <mailto:towertalk@contesting.com>
On 4/13/19 8:44 AM, John Pieszcynski wrote:
See "A Novel Approach to Using Window Line" by W6NBC, QST August 2018.

The article is on his website @
http://www.w6nbc.com/articles/2018-08QSTladderline.pdf

73,
John W2FV


Fascinating data..

I would have liked to see one more test run, with the window line loss without any foam around it.

The lower loss on the metal roof may be a measurement artifact - I'd not be trusting 0.01 dB kinds of measurements. The metal roof is "mostly" farther away than the thickness of the foam, except where the roof ribs stick up.

'NBC didn't give the length of his line, but if we work from the 19.8 MHz half wave, that's about 7 meters (25 feet?), so he's taking the measurement and multiplying by 4 to get the "per 100 ft" - so 0.01 dB on the graph is really 0.0025 dB in the measurement. (the picture over the chairs is consistent with 25 feet)

I'd say that metal and free air are "the same within experiment uncertainty"


One cool thing here is that measurement tools like the VNA are common enough now that we can actually *measure* the losses, rather than speculating or using dialectic (aka arguing on forums, letters to the editor, and email lists).

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>