George, Some designs have been able to reduce the over all height of
the Franklin by folding out or back the high voltage top and bottom
portions. The phasing coupler is placed at the center with the
transmission line inside the insulated bottom section. The center feed
portion with a correct phase reversal is supposed to be crucial to
proper operation. WHO KSTP used Franklin antennas because they were by
assignment omni directional 50KW stations that wanted a bit more ERP
and a multi tower directional was not an option.
For hams this could easily be done with a "Z" type configuration with a
top wire and a bottom wire bringing the whole antenna to a two half
waves in phase array, assuming the center coupler thus exceeding the
gain at low angles well over a single bottom fed half wave radiator. A
folded Franklin might be easy to model to determine the point of
diminishing return on the folded portion.
Herb, KV4FZ
On 9/23/2011 5:22 PM, GeorgeWallner wrote:
> Herb,
>
> I have just looked it up. Interesting. For 160 the height would be tad
> excessive.
>
> TKS,
>
> George, AA7JV
>
>
> On Fri, 23 Sep 2011 01:21:39 -0400
> Herb Schoenbohm <herbs@vitelcom.net> wrote:
>> George, Are you familiar with the Franklyn antenna design?
>> Some broadcasters swear by them and claim a 3 db increase over a 1/4
>> vertical radiator.
>>
>>
>> Herb, KV4FZ
>>
>>
>>
>>
>>
>> On 9/22/2011 9:08 PM, GeorgeWallner wrote:
>>> On Tue, 20 Sep 2011 17:17:58 -0400
>>> Guy Olinger K2AV<olinger@bellsouth.net> wrote:
>>>> I share the frustration over the very minimal amount of
>>>> data out there.
>>>>
>>>> However...
>>>> Erection of a 260 foot vertical in a testing
>>>> environment...
>>> G'Day Topbanders,
>>>
>>> I am not sure how general a conclusions could be drawn
>>> from my experience, but I have a set up that is somewhat
>>> relevant to this thread, and have done some on the air
>>> testing with it.
>>>
>>> I have two verticals, about 2 meters apart. One is 21
>>> meters tall and the other one is 28 meters tall with a
>>> high Q center loading inductor to make it resonate at 1900
>>> kHz (this is my 160 m antenna). This antenna is fed via a
>>> low loss antenna coupler. The two antennas share a common
>>> ground system, which is salt-water to the east and a
>>> buried field of 40 radials of varying length between 30
>>> and 120 feet long to the west. On 80 meters the shorter
>>> antenna is a 1/4 wave vertical, while the longer one could
>>> be considered to be a half-wave vertical.
>>>
>>> I have done extensive tests on 80 meters, comparing the
>>> two antennas towards the east. I have used the reverse
>>> beacon network, and a couple of friends' SDR-s in Europe
>>> for these comparisons. In tests from my Florida QTH,
>>> towards the east (towards Europe) and the side where the
>>> salt water is, the taller antenna has almost always been
>>> better by 2 to 3 dB. Towards the west (and the land side)
>>> I have not done enough testing to draw conclusive results,
>>> but I feel that the 1/2 wave vertical is better in that
>>> direction too.
>>>
>>> I understand the 80 meters is not 160 meters, but...
>>>
>>> I would be happy to set up a test sched with anyone to my
>>> west or north-west, who is interested in carrying these
>>> studies further.
>>>
>>> 73,
>>>
>>> George, AA7JV
>>>
>>> PS: BTW, I almost always use the 1/4 vertical on 80
>>> meters, even towards the east, as going through the
>>> coupler is a PITA (as Guy has pointed out).
>>> _______________________________________________
>>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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