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From: ralph@arising.com.au
Date: 26 Apr 2002
Time: 06:41:51
Remote Name: 203.37.110.244
I know of a person that wound a spiral top-hat that fitted inside a pie container for the top of his hf whip. This is what lead me to the idea of simulating a square shaped spiral coil for end loading of short verticals. I coined the phrase SLA and its was published in antennex. Since that time a few people have written to me to inform me of their sucess in getting the "square-loading" to work in their condos!
The trouble with adding such a structure to a mobile whip is the wind-resistance and relative weight and moments it introduces on the whip and the whip base. I thought of placing mine 1.3 way down from the top and using insulated guys to stop it bending.
As far as the shape goes it doesn't matter, square was easier for me to model than an actual spiral.