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

[Sandy and Kees Talen]

Hi Dan, thanks for the response.

>Knowing those values it is easy to calculate the losses at lower 
>frequencies. The formula is given in the article.

.....sure, but the statement was made that ladder line losses were not
insignificant followed by an analysis at 50-150Mhz ....my point 
being that the losses are lower at the lower frequencies (still not 
"insignificant" but pretty low)

>Not so. He measured Wireman's numbers 551, 552, 553 & 554 the 
>results are shown in Table 1.

....for some of the tests. I was referring to the plot where he shows 
554 only.

>I believe he was cautioning that substantial losses can and will take 
>place feeding short (less 3/8-wavelength) dipoles with window line.

..... Yes, I agree

>Mist? Really? And how are you going to qualify that one and make it 
>repeatable?

......Humidity chamber. I agree that it would be very difficult to
control 
but more representative of the rain and the air conditions during it. A 
moisture laden air dielectric has to provide a substantial influence 
making the dry/wet difference worse than shown in his data table. He 
also used artificial wetting agents to insure uniform wetting of the 
wires and the web which may be more representative of old, weathered, 
sun bleached ladder line like many of us have. Point being that if you 
take only his dry/wet data table (especially in light of the statement 
that the open wire reference line had "no change"), it would lead you 
to the conclusion that reducing the web size, or eliminating every other 
one, or  ? would be the proper course of action, since it is the only 
contributor causing change. I would have followed that scenario for 
another experiment. Open wire line not being effected by moisture,
("no change") thereby implying it's not affected by rain, is suspect. 

>The article addresses the window line losses only. For comparisons 
>with other systems you're going to have to dig deeper elsewhere.

....I wanted to see if anyone had some ideas. Many of these answers 
you can't get from a textbook due to the number of variables which 
must be considered and someone may have done some controlled 
testing.

73  Kees K5BCQ