Perhaps a much more practical and objective evaluation would be to have someone
who has the proper equipment and knowledge of its use to spend the time to
determine the exact properties of any loading components involved (if any) and
then create accurate models. Use NEC 4 engine coupled with any number of
modeling programs, and I believe you would find that with proper segmentation
and NEC 4 the results are quite accurate. This would be a lot easier, less
expensive and more objective to compare antennas in this way than putting them
up one at a time and measuring gain and pattern from a signal source. As a
matter of fact the comparison every 50 kHz across the band would only take a
few minutes more. Stacks could be included as well.
Those who wanted to participate in such a test could be asked to provide the
model and then part of the analysis would be to verify the claim for the
loading component properties. For full sized, not loaded elements, this is all
pretty straight forward. Another objective analysis could be made for
survivability in both wind and ice.
73...Stan, K5GO
Sent from my iPad
On Oct 16, 2012, at 8:14 PM, Jim Lux <jimlux@earthlink.net> wrote:
> On 10/16/12 4:37 PM, EZ Rhino wrote:
>> No doubt about it! This is not a small undertaking. I'd consider
>> pre-ordering the book if it would help, and I bet a lot of others would pre
>> order too. What else can I do to help? If they were ready to test
>> tomorrow, I'd have my antenna of choice send to them to use for the test,
>> then they can ship it back to me when done so I can put it on the tower, but
>> I don't think they are quite ready yet. :-)
>>
>> If it were possible to get a hold of all antennas at the same time, I think
>> a good way to do this would be to do it the week of field day with one of
>> these bigger clubs that puts up several towers for their op. The test
>> antennas could be on portable towers in a big field, all pointed the same
>> way. Close range and further range testing could be done at the same time
>> (ie east coast or even EU). While we're dreaming here, maybe I can plan a
>> money tree....
>>
>> Chris
>> KF7P
>>
>>
>
> These kinds of tests are a big undertaking, and MUCH more than a day's or
> weekend's work.
>
> I think if I were doing it, I'd rent a crane or boom truck and fabricate some
> sort of pivoting mounting bracket on top, so I could lay the boom over, put
> the antenna on it, tilt the boom up, flatten the antenna, and then rotate it
> to get your pattern cuts.
>
> This is basically what you have on an antenna range (along with precision
> sources and equipment). It makes it pretty fast to put an antenna on, zip it
> up high, etc., and bring it back down.
>
> But then you have the work of assembling all those antennas on the ground
> (which could be done over a period of weeks if you have somewhere to store
> them).
>
> I can't recall what we charge to use the Mesa antenna range at JPL, but I
> think it's in the 500-1000/day ballpark. That gets you positioners, towers,
> sources on the other side of a valley a mile away, etc. I imagine it's
> competitive with other ranges. The reason I mention this is that by the time
> you rent a boom truck, etc, you're probably up in the price range where it
> might be worth it to find a real range to use.
>
> The way to get it cheaper is to find a professor to get a student to do the
> project as part of a senior project or master's thesis, and then you can
> apply for some grant money to fund it.
>
> I'd say you'd be doing well to do an average of an antenna a day (assemble,
> measure, disassemble). You might be able to overlap.
>
>
> So, if you're looking for kickstarter type funding... you will be paying the
> people working on it and for facilities, etc.
>
> Figure something like a work month for a senior engineer, a work month for a
> technician, and a couple week's range time. In round numbers, about $50k.
>
>
> Obviously, if you've got good scroungers, equipment to borrow, and people to
> help for free, you can do it for less. But the whole logistics thing means
> it takes careful planning.. Running multiple antennas up and down multiple
> times is pretty time consuming.
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