[time-nuts] Choke Ring Antenna - Patch Placement?

[Don Latham]

A "choke ring" or "feed choke ring" search will give you a lot of info.
For cylindrical feeds, the phase origin can be taken as at the opening.
So the patch height should be taken as the same placement as the opening
of a cylindrical feed, at least for starters. Heck, start out by using
what you find to determine the best size for a single ring. Sizes of
things scale with frequency or wavelength linearly, so the best size of
the pans you have can be calculated. The patch then goes just a little
below the edge of the pan. You may want to cut the rim down or not,
again scale a successful ring.
Don



Bob Stewart
> Hi Bob,
>
> Thanks Bob.  It's hard to say whether or not it attenuates at the lower
> elevations, but it does add gain to the higher ones.  Well, at least I
> have some idea what I'm shooting for.
>
> Bob
>
>
>
>
>
>>________________________________
>> From: Bob Camp <lists at rtty.us>
>>To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>>Sent: Thursday, October 10, 2013 4:41 PM
>>Subject: Re: [time-nuts] Choke Ring Antenna - Patch Placement?
>>
>>
>>Hi
>>
>>You are looking for total rejection of any signal below the horizon,
>> and near total rejection of any signal within 10 degrees of the
>> horizon. Obviously total and near total could have db numbers
>> associated with them, but the numbers you get are what ever you get….
>>
>>Bob
>>
>>On Oct 10, 2013, at 2:15 PM, Bob Stewart <bob at evoria.net> wrote:
>>
>>> I bought a set of Wilton "tuned" pie pans yesterday to experiment
>>> with a choke ring antenna.  The "kit" consists of 4 pans of
>>> diameters 12", 10", 8", and 6".  The height of the sides is more or
>>> less 51mm.  I've been experimenting with placement of the patch in
>>> the pit, but I don't know what I'm looking for, so a little help
>>> would be appreciated.  Am I looking for best overall signal level
>>> from horizon to azimuth, or something else?  I'm not sure I would
>>> know how to measure multi-path levels.  There seems to be a definite
>>> difference depending on whether the patch is at the bottom, somewhere
>>> in the middle, level with the rim of the pans, or even perched on a
>>> DVD disk which is level with the rim.  I don't have any sort of
>>> metal container to use as a support for the patch at this point.
>>>
>>> Bob - AE6RV
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-- 
“The power of accurate observation is commonly called cynicism by those
who have not got it.”
-George Bernard Shaw



Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
POB 134
Huson, MT, 59846
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Skype: buffler2
www.lightningforensics.com
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