[Lowfer] A Tophat Question

Andy - KU4XR ku4xr at yahoo.com
Sun Oct 12 21:14:28 EDT 2008


Greetings all:

I am currently using a straight 40 foot " T " style tophat for my LOWfer beacon.I would like to try another style, but it needs to be as short as possible, and as lightweight as possible, so I can lift it into the air 
by myself, so PVC pipe will be the material. I have calculated the lengths of different formations, and the one that will fit on a 10 foot stick of PVC is the " BOWTIE " style such as the Butternut, Butterfly beam. 
By taking the 20 foot leg ( each side ), and shaping it into an " M " pattern with each section 5 feet long, it will take up about 7 feet of 
pipe. That will leave 3 feet to use as a mounting pipe. My thoughts were to make 2 bowties on the same pipe in an " X " pattern. This will be like turning the bowtie on its end ( 2 triangles standing tip to tip ). After saying all of this, my question now is; does the same rule apply for a physically shortened tophat in reference to its overall capacitance, as to the overall efficiency of a physically shortened antenna ?? I also keep reading statements that say the tophat dosen't actually radiate any RF, it just electrically pulls the RF current to the top of the antenna, so would the tophats heigth above ground affect antenna radiation ??
By the way; not to get into a debate with anyone, but I'm not so sure as to the electrical accuracy of the " dosen't radiate any " RF " statement in regards to the tophat. Suffice it to say however, that at such low frequencies, and short lengths; It May Not ! just something that raises my eyebrow when I read it. Thanks for any comments; 

73,  Andy  " XR "


      


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