[Antennas] Next dumb question

Sat Nov 24 16:55:54 EST 2012

No...that's not how a capacity hat works.
My 80M vertical has a capacity hat but NO "loading coil" to interact 
with. That would be a stretch anyway as the capacity hat is ~50 ft from 
the base of the antenna where the "loading coil" would be if I had one.
A capacity hat works by adding capacitive loading to the antenna. 
Ideally you want this as close to the end of the antenna as possible.
Read the ARRL Antenna Book or better yet ON4UN's "Low Band DXing" for a 
good explanation of capacity hats and how they work.
On 11/23/2012 9:28 PM, fred forbush wrote:
> Concerning the cap. hat the way I understand it is that the electrostatic
> field surrounding the hat interacts with the electromagnetic field of the
> loanding coil beneath it. I've found that using a cap. hat reduces the
> amount of coil needed when tuning to a frequency.
> 73, Fred
> k6kub
>>> On Fri, Nov 23, 2012 at 11:08 AM, Michael Josefsson <mj at isy.liu.se> wrote:
>>> On 23 Nov 2012, at 18:39, Jim Miller wrote:
>>>>> Is a capacity hat electrically connected (metal to metal) to the antenna
>>> itself or is it just sitting there insulated but "capacitively coupled"?
>>>>> It is electrically connected.
>>>>> The coil I bought was supposed to be for 15 to 80 meters. Well.. It only
>>> tunes down (no coil) to about 4.1 and SWR is too high to use even at
>> 3.963
>>> MHz (and it won't go into the 15 meter band either, 20 is tops). OK,
>>> shorter whip for 15.
>>>>>> But, for 80 meters, thinking about stationary operation and adding a
>>> temporary top hat to bring me into the top end of the band.
>>>>>> Better yet, also thinking about adding a few turns of extra coil at the
>> base
>>> to bring the whole thing down a bit. How much would it take me to move
>> from
>>> 4.1 down to 3.9 or so using existing coil for adjustment and my 102 in
>> whip?
>>> Say #12 THHN close wound on a 2 inch form (6,8,?)
>>>>> Everything depends on everything else... Trial and horror is your path :/
>>>> Cheers anyway:)
>>>> /Micke
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-- 
73,
Gary K9GS
Greater Milwaukee DX Association: http://www.gmdxa.org
Society of Midwest Contesters: http://www.w9smc.com
CW Ops #1032 http://www.cwops.org
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