Hi Timon,
I'm not a big station builder, I've only helped a bit at the PI4DX station.
I was wondering why you want to have 3 multiband yagi's for multipliers?
Especially considering the fact that you want to have several monoband
yagi's on separate rotating towers.
As K3ZJ mentioned, it's probably best to keep your 15 meter yagi's and 40
meter yagi's far away from eachother. Furthermore, if you want to combine a
40 meter yagi with a higher band yagi (10 of 20 meter), keep in mind that
they have very different propagation paths.
At PI4DX we had no other option then to put our 10 meter yagi's, 20 meter
yagi and 40 meter yagi in the same tower. Because of the different
propagation paths we mounted our 40 meter yagi 180 degrees from our 10 and
20 meter yagi's.
Like Frank suggested, it's probably best to put you 40 meter yagi's in the
same tower.
I feel like our 40 meter yagi isn't performing as it's should be because of
it's close proximity to the other yagi's. Unfortunately, we can't put up
more tower so we have to work with what we got.
Good luck with you super station Timon, I will be following your progress
on your website with great interest.
73, Maarten PD2R
Op maandag 25 augustus 2014 heeft <donovanf@starpower.net> het volgende
geschreven:
> Hello Timon,
>
> Pete's email reminds me of K3NA's excellent eight part series in NCJ
> from 2003-2005 describing Yagi performance degradations caused by
> multiple Yagis installed on the same tower and on multiple towers.
> While many contesters are aware of performance degradations caused
> by close spaced Yagis on the same tower, we often forget about
> performance degradations caused by Yagis on nearby towers.
>
> Among other things, Eric made us aware of performance degradations
> when:
> - a Yagi points through a Yagi for the same band on a nearby tower ,
> - a 10 meter Yagi points through 15 meter Yagi on a nearby tower,
> - a 15 meter Yagi points through a full sized 40 meter Yagi
> on a nearby tower.
>
> Eric showed that performance degradations among Yagis installed on
> nearby towers is significant when the towers are spaced less than
> about five wavelengths apart (350 feet at 14 MHz). According to
> Eric's performance modelling, degradation doesn't become
> insignificant until tower spacings are greater than about ten
> wavelengths (700 feet at 14 MHz).
>
> Multi-band Yagis are much worse, because they cause performance
> degradations to Yagis on nearby towers on many bands. I usually
> discourage hams from installing them unless thay can be installed
> far away from higher performance monoband Yagis.
>
> Some of you have heard me say that a contester can never have too
> many antennas... unless (and this is important) they are too close to
> each other.
>
> Timon's towers are only one wavelength apart on 40 meters, two
> wavelengths apart at 14 MHz and four wavelengths apart on 10 meters.
> His Yagis on multiple towers will be much more closely spaced
> (especially on 40 and 20 meters) than 40 meters because of their
> boom lengths.
>
> My recommendation for his four towers is that he analyze all of the
> interactions when each Yagi points through another Yagi on another
> tower. His plan to install multi-band Yagis on three of his towers will
> surely cause significant degradation of the performance of his high
> performance stacked monoband Yagis and he should seriously
> reconsider that plan.
>
> The most serious degradation in his proposed antenna system will be
> caused by his two 40 meter Yagis that will be spaced much less than
> one wavelength apart when boom lengths are taken into consideration.
> A better plan is to stack his 40 meter Yagis on the same tower with
> each Yagi independently rotatable.
>
> My recommendation is that Timon start with each each of his four towers
> dedicated to a single band, this produces the least degradation among
> Yagis on multiple towers. After this initial installation is completed,
> additional antennas can be added and the resulting performance
> degradations can then be evaluated.
>
> 73
> Frank
> W3LPL
>
>
>
>
> ----- Original Message -----
>
> From: "Pete Smith N4ZR" <n4zr@contesting.com <javascript:;>>
> To: cq-contest@contesting.com <javascript:;>
> Sent: Monday, August 25, 2014 11:47:27 AM
> Subject: Re: [CQ-Contest] antenna setup question
>
> K3NA did some sophisticated studies a decade or so agoof the K4JA
> multi-tower station, for NCJ. You might be able to find those, Timon,
> or get in touch with him.
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network at
> http://reversebeacon.net,
> blog at reversebeacon.blogspot.com.
> For spots, please go to your favorite
> ARC V6 or VE7CC DX cluster node.
>
> On 8/24/2014 9:40 PM, David Siddall wrote:
> > Hi Timon,
> >
> > With multiple towers available, I would keep my 40 meter antennas off any
> > tower with 15 meter antennas -- whether monobander 15's or tribanders.
> Too
> > often 40's disrupt the pattern of the 15's. It seems to be very antenna-
> > and spacing- specific, and I am not 100% confidant in modeling for this
> > issue.
> >
> > GL es 73,
> >
> > Dave K3ZJ
> >
> >
> > On Sun, Aug 24, 2014 at 5:25 PM, Timon Kruijer <Pa1t@xs4all.nl
> <javascript:;>> wrote:
> >
> >> Hello fellow contesters.
> >>
> >>
> >>
> >> I have an antenna setup question.
> >>
> >>
> >>
> >> This year (and the next) I am building a new HF station. Next to the
> house
> >> I
> >> will have four rotary towers standing in a square which are 40 meters
> >> apart.
> >> The towers are rotatable and are 25m (83 feet) high from the ground.
> Every
> >> tower will also have a rotor in the top with a 2 meter mast so in total
> 27
> >> meters (90 feet). The towers have rings on 24 meters and on 11 meters
> (not
> >> fixed yet) as they are still lying on the ground.
> >>
> >> To rotate and calculate the directions for each tower and the top
> antenna I
> >> use Microham Station Master de Luxe.
> >>
> >> My goal is to have a competitive contest station for SO2R, Multi Singe
> and
> >> Multi-2 use.
> >>
> >> What would be a good suggestion for the antennas in the four towers?
> >>
> >> The terrain is flat.
> >>
> >>
> >>
> >> The antennas I have available at the moment are:
> >>
> >> - 2 el Force 12 40 meters
> >>
> >> - 4 el Steppir 10-15-20 meters
> >>
> >> - Optibeam 10 15 20 meters
> >>
> >> - Force 12 c31xr 10 15 20 meters
> >>
> >> My idea so far is to use these 4 antennas for multipliers etc.
> >>
> >> I would like to have additional 2 antenna stacks for 20, 15, and 10
> meters
> >> (which I have to build).
> >>
> >>
> >>
> >> A possible setup could be:
> >>
> >>
> >>
> >> Rotatable Tower 1
> >>
> >> top rotatable, Steppir
> >>
> >> bolted at the tower 20 meter yagi
> >>
> >> bolted at the tower 20 meter yagi
> >>
> >>
> >>
> >> Rotatable Tower 2
> >>
> >> top rotatable, c31xr
> >>
> >> bolted at the tower 15 meter yagi
> >>
> >> bolted at the tower 15 meter yagi
> >>
> >>
> >>
> >> Rotatable Tower 3
> >>
> >> top rotatable, 2el 40m
> >>
> >> bolted at the tower 10 meter yagi
> >>
> >> bolted at the tower 10 meter yagi
> >>
> >>
> >>
> >> Rotatable Tower 4
> >>
> >> top rotatable, 3 el 40m
> >>
> >> bolted at the tower optibeam 10 15 20M
> >>
> >> bolted at the tower 3 el 40m
> >>
> >>
> >>
> >> Or setup 1 multiplier tower and use the others for 10 to 40 meters.
> Which
> >> band to have a double set antennas when this would be a solution?
> >>
> >> For 40 and 80 meters I will have additional 4 squares behind these
> towers.
> >> Also possible would be to have wire 4 squares hanging on ropes between
> the
> >> towers (between the top rings on 24 meters).
> >>
> >> For 160 meters the towers can be a 4 square by itself (they are
> isolated).
> >> Also the ropes could be again for a 160 meter antenna.
> >>
> >>
> >>
> >> Suggestions and comments are very welcome. Please your ideas.
> >>
> >>
> >>
> >> '73 Timon
> >>
> >> PA1T
> >>
> >>
> >>
> >> Home page www.pa1t.com
> >>
> >> Tel 31 (0)598416308
> >>
> >> Cell phone 31 (0)657545506
> >>
> >>
> >>
> >> _______________________________________________
> >> CQ-Contest mailing list
> >> CQ-Contest@contesting.com <javascript:;>
> >> http://lists.contesting.com/mailman/listinfo/cq-contest
> >>
> > _______________________________________________
> > CQ-Contest mailing list
> > CQ-Contest@contesting.com <javascript:;>
> > http://lists.contesting.com/mailman/listinfo/cq-contest
> >
>
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--
73, Maarten PD2R
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