[Lowfer] 600MRG> Using a Whip above the Top-Hat QUESTION ??

[Edward Cole]

At 11:14 AM 9/5/2009, Andy - KU4XR wrote:
>Hello all:
>
>I need to call upon your experiences again, this time on using
>a vertical " whip " above the Top-Hat on a lowFER ant. I have
>been searching the net for some info, but everything is pretty
>vague, and mostly dealing with mobile ant. But I'm sure the same
>principle applies to Base Vertical ant. as well. I notice that
>there is not much mention of LOWfers using whips above their
>Top-Hats, Is there no benefit to doing so ?? The summation of
>what I have been able to understand on the subject is that there
>is a relation to the length of the whip section, and the mast,
>as well as the whip, and the Top-Hat length. The Mast/Whip is
>primarily dealing with center loaded verticals with no Top-Hat.
>" XR " is Base loaded ( Variometer ) with a 20' long Top-Hat.
>The info I have read indicates that a whip above a Top-Hat
>should not exceed 1/2 the Top-Hat length. Too long on the whip,
>and it will begin to shorten the Effective Height of the ant.
>by Top-Hat shielding of the whip section. There is no formula
>that I have been able to find, to calculate this issue.
>
>With the above thought; I can add a 10' wire to the top of my
>vertical, and the total vertical length will be 40' long.
>Will the extra 10' above the Top-Hat provide any benefit ??
>
>Sidebar ::: The 10' at the top can easily be supported by a
>1/2" PVC pipe. I can't add it to the vertical section
>below the Top-Hat ( better I know ) because of where I have
>to place the ant.
>
>What are your thoughts ?? Thanks for your replies, 73 for now.
>
>
>Andy - KU4XR - EM75xr - Friendsville, TN.
>LOWfer Beacon " XR " @ 184.322 KHz ( QRSS-60 )
>Coordinates:  N:  35* 43' 54" - W:  84* 3' 16"
>http://www.myspace.com/beaconxr

Funny you ask about adding an extension beyond your "top-hat", 
because I had to add five feet above the corner of my inverted-L 
antenna to ahve it perform well (in the modeling sw - not built as yet).

Ed - KL7UW
/45

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73, Ed - KL7UW - WD2XSH/45 (500-KHz)   BP40iq
SDR-IQ using 900-foot Bev on Ground
100w CW Tx - surplus NDB, antenna TBD
http://www.kl7uw.com/600m.htm
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