Bob,
SERIOUSLY!
I AM saying I am hearing this. This is not just the result of modeling, which
shows indeed that the highest angle will be favored (less often of course)...
this is a result of day to day operation ... why would I say otherwise?! Indeed
I’d say a good 10% of the time ... rough estimate, the BOP is favored over the
BIP! That is HERE, in South Carolina by the way – where I am of course – not
where you are or where anyone else is – but those higher angle/distance changes
would move to another part of the world if from a different location. Likewise
I’d surmise that propagation where you are far north from here would indeed be
different... I’m not saying what I’m seeing would be identical to every one
else. And I don’t doubt you see what you see...
Also when I had a 3 stack – and that was through the peak of the cycle but it
was from AZ (2005 – 2012) I never, not once, saw anything but all in phase be
the best on 20 ... last my first experience with being able to select was back
in 2008 when I was operating a contest from ILL ... I was operating 15 single
... I had a 5 element mono at 90’ .... and I had, just days before the contest,
received, assembled and installed a KLM 6 element 15 at 25’ on the tower (with
a fear of heights that was the best I could do by myself) ... over the whole
contest the lower antenna was essentially useless... until the last few hours
when all of a sudden EU was 10 – 15 db stronger on the lowest one ...
so I’m not sure what you’re protesting. This IS what I’ve seen ... as they say
YMMV. Obviously it does.
Oh and as a side note – in AZ I did not have the ability to go BOP. It is BOP
that primarily is the best selection here – NOT using just the bottom antenna
alone. My experience using the bottom alone mimics yours - although I have
maybe twice seen the bottom alone perform better – its only when I am BOP that
I see as much as 10 db difference (on a calibrated S meter by the way).
The reason why I brought it up is if considering a stack one might consider
going with a matching device that allows BOP ... I’m glad I did. Again: YMMV!
Gary
K9RX
From: Bob Shohet, KQ2M
Sent: Sunday, July 23, 2017 8:59 PM
To: StellarCAT
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Takeoff angle
Gary,
The lower the better? Rare when higher is better? Seriously?
Just for an example, I operated WPXSSB and WPXCW full-time (36 hours) with my
5/5/5 on 20, 5/5/5/5 on 15 and 5/5/5/5 on 10. At no time was my lowest 20
meter 5L Hygain @ 58’ even close to being the best antenna for EU. Even the
middle 5L @ 82’ was down almost the entire time both weekends to the 5L @ 130’.
Yes, geomagnetic cndx were extremely disturbed, but we had some sunspots. In
18 months they will be flatline and high angle high band signals from EU will
be almost non-existent for the vast majority of the bottom of the cycle. As it
has been for at least the past 4 sunspot cycles that I have operated in.
15 and 10 will be even worse.
My qth is in Western Connecticut about 10 miles from the W2 border so EU should
be even more high angle from here than for you in W9 or for Jeff in W0.
There will be occasional times when a DX station might be briefly louder on a
lower antenna than a higher one, but for the next 4 years that will be the
exception rather than the rule and my stacks on 10, 15 and 20 provide a great
testing ground for the signal arrival angles. This is even true for South
America which is the closest continent and one might think should have stronger
signal strengths with lower antennas. They don’t, at least from the East
Coast. Higher is still better.
As we progress into the new sunspot cycle and the spots return, lower antennas
will perform progressively better and near the peak of the cycle, you can watch
the the arrival angles of signals change rapidly – the top opens the band, then
shortly after it opens, the middle or second antenna down becomes loudest then
the lower one and then the lowest. This happens on all the high bands 10 – 20.
But now we are the opposite end of the cycle – where you want your antennas to
be higher rather than lower. Signal arrival angles change throughout the
opening, but the highest antennas predominate now and will continue to do so
for the next few years.
As valuable as books and computer plots can be, there is nothing like actively
operating contests to see how the propagation and arrival angles change
throughout the contest on each of the bands with stations from every part of
the globe. And being able to switch phasing combinations instantaneously
provides useful real-time data as to which antennas are actually (not
theoretically) “hearing best” at any time. Hearing is believing!
73
Bob KQ2M
From: StellarCAT
Sent: Sunday, July 23, 2017 7:33 PM
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Takeoff angle
If you are using the HFTA from the ARRL AB then you have all that info there
already! It’s the Elevation File. They have one for every state for EU, AFR,
AS etc etc ...
for the most part the lower the better... there are times, rare, when higher
is actually better. For example I can select top/bottom/BIP/BOP with 2
stacked 20 meter yagis using a RemoteQTH match ... the TOP is never the best
(for all practical purposes) so the choices are BIP, BOT, BOP in that order
... and indeed there are times, like in the afternoon going from here to
Africa where the BOP position can be as much as 10 db stronger than the BIP.
The differences are 8° and 19° for my terrain and location.
Be sure to put YOUR local terrain profile in. Either manually (not as bad as
some make it out to be) or using Stu, K6TU's site... unless its flat there
might well be some differences ... I literally used HFTA as one of the top
criteria (for me it was THE top) in selecting where we moved to when moving
back to SC! On some paths there can be 10's of db enhancement (or
degradation!)
Gary
K9RX
-----Original Message-----
From: Dave Clemons
Sent: Sunday, July 23, 2017 2:35 PM
To: 'Jeff Draughn'
Cc: towertalk@contesting.com ; Dave@egh.com
Subject: Re: [TowerTalk] Takeoff angle
A number of years ago Dean Straw gave some presentations on takeoff angles.
His presentation included a big binder of information (I think called "All
the Right Angles"). I don't remember who published it, perhaps K8CC or
possibly K3LR.
Dave K1VUT
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jeff
Draughn
Sent: Sunday, July 23, 2017 12:39 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Takeoff angle
I've been playing around with HFTA trying to figure out the best height/
configuration for my antennas and it dawned on me I wasn't sure what the
best take off angles are. I know low is better than high for DX, I'm
assuming it's a range that I'm looking for.
When looking at the plots what would be considered good take off angles for
DX contests from the midwest.
What is considered too high of an angle for DX?
Thanks
Jeff, N0OST
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