[TowerTalk] Custom antenna design

[Michael Tope]

Matt,

Contrary to the caption which says "Monster on a 500 inch turning 
radius", it looks like the design you linked to uses an actual turning 
radius of 250" (20.8ft). This makes sense as fundamentally there is no 
reason why the linear dimension of this sort of antenna shouldn't scale 
with frequency (actually wavelength, they inverse scale with frequency) 
to first order. IMO, it wouldn't take much fixed loading or tip folding 
to tighten up the turning radius to 18ft. On the other hand, 4S7AB model 
predictions aren't terribly impressive. It doesn't look like it models 
out much better than a rotary dipole. Perhaps it is very frequency 
sensitive and works much better above or below that particular frequency.

73, Mike W4EF........

On 9/18/2013 9:38 AM, KM5VI wrote:
> Extrapolation of scaled dimensions is not a good assumption in this case...
> see link (and others)....  or model one.
>
> http://www.qsl.net/4s7ab/broadbandhexbeam40m4s7ab.htm
>
> KM5VI
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> Michael Tope
> Sent: Wednesday, September 18, 2013 9:37 AM
> To: Charlie Gallo
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Custom antenna design
>
> Charlie,
>
> I think the columns are shifted to the left by one because the 40 meter
> version is speculative (i.e. there is no actual model number assigned).
> Just by rough scaling, it wouldn't make sense for the 40 meter version to
> have a 40ft turning radius. A 40 meter version with a 19ft turning radius
> and weight of 40 lbs is a much more sensible extrapolation when you look at
> the 30 meter and 20 meter specs.
>
> 73, Mike W4EF..................
>
> On 9/18/2013 5:29 AM, Charlie Gallo wrote:
>> On 9/18/2013 Michael Tope wrote:
>>
>>> I think the 20 meter "Hex-Beam" has a 9.4 ft turning radius, so it
>>> stands to reason that a 40 meter version could (with a little
>>> tweaking) be made to fit inside an 18ft circle. In fact if you go to
>>> the "Traffie Technology" specs page you see what looks to be an
>>> incomplete entry for a 40 meter monoband version presumably with a
>>> 19ft turning radius and weighing 40 lbs:
>>> ttp://www.hexbeam.com/specs.shtml
>>> 73 Mike W4EF.................
>> Except they list the 40m as having a 40 ft turning radius...
>>
>>
>>