[UK-CONTEST] Fishing line as support

[G3RAU at aol.com]

In a message dated 29/09/2011 00:39:12 GMT Daylight Time,  
g4lmw at btconnect.com writes:

My  question is - what breaking strain would be advisable? 


 
You could work out the total broadside cross sectional area of the antenna, 
 estimate your greatest wind gust speed (not average) at the height of the  
antenna, do the maths and you have the first part of the answer.
Secondly the tighter you pull the ant the greater the stress; the Arrl ant  
book looks at sag tensions in horizontal wires. 
Thirdly is there a balun or anything that could introduce a bouncing up and 
 down effect in high wind? More complicated to evaluate because you need to 
know  the stretch characteristics of the support line.
The practical answers which  have been suggested, although  empirical, 
sound very sensible to me, and save hours in the text books!
There is an old Indian trick (remember the  Lone Ranger?) of making a  loop 
at the end and dangling it in a U shape say 24 inches long.   Across the 
top of the loop you tie a short piece of you support material but  half cut 
through.  That way when the snow/ice arrives, and weighs down the  ant, the 
weak link snaps, the ant drops a foot suddenly and all the snow  falls off. 
The ant is still up there but a foot lower.
Have fun 
73 Derek G3RAU