OK ... I see now that it is supposed to be parasitically directive.
Your original post said that the three loops would be in the shape of a
pyramid, which I took to mean that they would be arrayed symmetrically
around the mast in order to put their broadsides in three bilateral
directions. No way you will be able to put up such a structure without
guying the mast, though, and hoisting up three loops past the guys
sounds highly impractical to me.
The various comments you've received regarding PVC and ABS still hold,
of course.
73,
Dave AB7E
On 4/19/2012 2:18 PM, Alex Malyava wrote:
> The design I have in mind is here -
> http://dl2kq.de/mmana/lib/Loops/Switch/3el-slope_delta80.png
> It is 22 (or 24?) meter high non-conductive mast. Spacing between tops of
> the loops is about 6...7 feet.
> Horizontal parts of the loops are 10' above the ground... It has to be
> vertically polarized, of course...
>
> It looks so nice and promising so I started to think about it... If it does
> not work out due to technical difficulties - I would stick to 18m high
> SpiderBeam mast, top load it, lay down a bunch of radials and do low power
> single band from some NJ/PA campground.
>
>
> On Thu, Apr 19, 2012 at 5:10 PM, David Gilbert<xdavid@cis-broadband.com>wrote:
>
>>
>> Both PVC and ABS are totally unusable for such a tall mast. Neither
>> one is stiff enough in those lengths, and if you tried to guy them in
>> enough places to keep them up you wouldn't have room for any wires.
>> Picture trying to support a vertical wire by guying it and you would
>> come close to the same thing.
>>
>> I have to ask, though ... what's the appeal of having three delta
>> loops? It's not going to do any good to phase them if they are all
>> close enough to be suspended from the same support. If you feed them
>> with horizontal polarization they are going to perform very badly on
>> 80m, and if you feed them with vertical polarization they won't work any
>> better than a single omnidirectional vertical. And with a single
>> vertical you can top load it (make a portion of the upper guys
>> conductive to act as a top hat) and wouldn't need anything close to 80
>> feet in height.
>>
>> So what's with the delta loops? If you think the delta loops are going
>> to be lower noise I think you'd be surprised, and in any case you'd be
>> better off transmitting on the vertical and using a small loop to receive.
>>
>> 73,
>> Dave AB7E
>>
>>
>>
>> On 4/19/2012 12:56 PM, Alex Malyava wrote:
>>> Hi,
>>> I want to build an antenna for a Field Day or any other occasion, like
>>> going far away from my noisy house and enjoying low bands.
>>> The antenna I have in mind is 3 element delta loops for 80m band.
>>> Yes - 80 meters delta loops. Yes - three of them in a for of a pyramid.
>>> To hold all of that I need non-conductive mast about 80 feet high.
>>>
>>> What materials I better use?
>>> My original intent was to try 3" or 4" PVC/ABS pipes aka white and black
>>> plastic pipes used in plumbing.
>>> I can glue-in some inserts to connect pipes of the same diameter and put
>> a
>>> few levels of guy ropes.
>>> This noodle suppose to hold 750' of copper wire...
>>> Am I crazy and that thing gonna break? Should I telescope it like
>> starting
>>> with 6" at the bottom and and go all the way to 2" at the very top?
>>>
>>> Speaking of insulated: I thought I can use aluminum telescoped tubes, but
>>> how do I electrically break whole mast apart in a couple of places to be
>>> almost non-conductive?
>>> Another option is to use 4' military sections, but I am not sure how 20
>> of
>>> them gonna behave.
>>>
>>> Alex K2BB
>>> _______________________________________________
>>>
>>>
>>>
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