Patrick,
Back in the day, a company called Kirk made a series of what they called
"helicoidal" beams. The elements were tapered fiberglass with approx 1/4"
wide, thin copper strap wrapped around in a spiral, and the whole thing was
covered with something like spar varnish. Ring any bells?
73,
geo - n4ua
On Thu, Apr 28, 2016 at 8:44 AM, Patrick Greenlee <patrick_g@windstream.net>
wrote:
> Once upon a time a long time ago in San Diego many members of the tuna
> fleet were equipped with 4 band HF antennas called cat's whiskers (due to
> appearance.) They were 4 sets of horizontal dipoles driven with a single
> coax feed to a common midpoint. The dipoles came close together at their
> midpoint(s) but were "splayed" out several degrees so that farther out from
> the center point they were farther and farther apart in 3 dimensions, not
> 2. The elements were copper wire wrapped helical fashion on stout
> fiberglass poles. The wire was secured by a top coat of resin. I'm not
> sure if it was epoxy or polyester resin but it was UV resistant and lasted
> well in the harsh marine environment.
>
> There was, of course, some interaction between bands when trimming to tune
> for initial setup. Most installations did not use antenna tuners but some
> skippers and some navigators were hams and some of these used tuners to
> broadband the antennas for ham as well as marine HF bands.
>
> This sort of antenna is fairly easy to DIY. Being balanced
> aerodynamically they put a light torque load on the rotor/rotator due to
> wind. They are relatively light weight and don't require a super HD
> rotor/rotator.
>
> Some of the users in the tuna fleet did not employ a rotor/rotator and
> instead turned the boat to aim the antenna, an option of which many
> residences can't avail themselves. There were some cat's whiskers
> installed at residences of hams in the family of tuna fishing hams and
> seemed to work satisfactorily. I regret not being able to quote chapter
> and verse as to source, mfg, etc but this was some decades back so I'm
> claiming "Senior Privileged" employing selective memory.
>
>
> Patrick NJ5G
>
>
>
>
> On 4/28/2016 6:46 AM, kr2q@optimum.net wrote:
>
>> I googled your QTH and the QST article antenna probably won't work in
>> your situation since your
>> roof tower is way too short and the "dangling wires" will hit your house.
>>
>> Since you are a real ham (IE, cost is a factor), check this out and maybe
>> you can get some ideas for
>> a modified approach for a shorter version.
>>
>> http://www.pa1m.nl/pa1m/a-shortened-40-meter-rotary-dipole/
>>
>> GL
>>
>> de Doug KR2Q
>> _______________________________________________
>>
>>
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