[Fourlanders] adjusting takeoff angle

[GORDON MACIE]

I was thinking the same thing. I think the "Golden
Rule" is YOU CAN NEVER HAVE TOO MANY ANTENNAS.
I was looking at W8JI's site last night and I think in
1 photo he mentioned having 50 something possibilities
for receive antennas.

Gordon N4LR


--- Sherman Banks <w4atl at earthlink.net> wrote:

> How about a simple dipole antenna?  Something that
> can take full power so we
> can switch the amp from the stacked beams to the
> high-radiation angle
> antenna easily?
> 
> -----Original Message-----
> From: fourlanders-bounces at contesting.com
> [mailto:fourlanders-bounces at contesting.com] On
> Behalf Of Rogers, Ron
> Sent: Wednesday, June 13, 2007 1:18 PM
> To: Paul Yeager, ABR(R), REALTOR(R); Fourlanders
> Subject: Re: [Fourlanders] adjusting takeoff angle
> 
> Hi guys,
> 
> For those that weren't on the mountain to hear our
> discussions about
> this 6 meter antenna experiment, here is some
> history.
> 
> This W4NH idea started between myself and NX9O a few
> weeks ago when I
> was discussing a 6 meter experiment that we tried at
> W9ICE in EN60 with
> our frustrations of not being able to score 6 meter
> contacts into
> eastern PA and NY where some key population
> densities were. Brian picked
> up on a fact real quickly and pointed out that the
> areas being targeted
> by W9ICE were the same areas targeted by W4NH and,
> in fact, were about
> the same distances.
> 
> A quick calculation of our W9ICE easterly take off
> angle and E-layer
> reflective result showed our first touch-down point
> to be out in the
> Atlantic ocean somewhere. So, one of the final W9ICE
> contests we simply
> put a Cushcraft 5 element beam on the ground and
> pointed it in the
> desired direction, then propped it up to about 45
> degrees and had a coax
> switch back at the station to switch between our 2
> antennas. The result
> was that we started harvesting more close in
> contacts (500 miles) using
> the antenna pointing upward. It appeared that the 45
> degree angle off
> the E-Layer (un-enhanced) shortened the first touch
> down point to about
> 500 miles out. 
> 
> Now, if you add up what we use on Soco Bald on 6
> meters (5500'
> elevation, stacked 5 element beams, and tight
> vertical plane take-off)
> theory says this is actually detrimental to our
> desire to put the 18,000
> Watts ERP into the high population areas (or even
> hear the 100 watt
> stations calling you) within 500 miles of our
> location. In fact, it
> would suggest that the incident angle to the E-Layer
> would be even
> further out, thus even a longer distance to first
> touch down point.
> 
> If you take a quick measurement of the shortened 500
> mile radius from
> W4NH desired by us, that would include New York,
> Philly, Cleveland,
> Chicago, St. Louis, Jacksonville, etc. 
> 
> If you could view the 6 meter log Sunday evening
> when there really
> wasn't any wild sporadic "E" openings taking place,
> the suggestion was
> made to point the 6 meter beams to the W-NW after
> they had been pointing
> to the N-NE, what did we see started happening ? 
> 
> We actually started scoring contacts in the DN & DM
> grid
> areas.......yep, about 1200 miles out. That's why
> some of us suspicion
> we may be overshooting the upper east coast
> population density using too
> high of gain antennas at such a high altitude.
> 
> 
> For the elevated antenna experiment we already have
> a beam lined
> up......a Cushcraft 5 element beam not being used
> right now. We don't
> need anything fancy, and certainly DON'T need a lot
> of gain and
> directivity for this experiment.
> 
> It's light enough for the Yaesu 5400 AZ-EL rotor and
> we already have the
> mounting figured out......IF we want to do it that
> way in Sept.
> 
> But, the initial plan in Sept. was to simply use the
> Cushcraft, set its
> ass on the ground, point it toward FN21/31 (or
> EN51-61), then point up
> toward 45 degrees, and held there by a inverted "V"
> wooden frame made
> from 2X2 lumber or even wooden step ladder. I have
> 100' of Beldon 8214
> coax and a 2 KW antenna switch to handle the power.
> 
> We just think it would make an interesting
> experiment for W4NH to try.
> Who knows. If the theory pans out and validates a
> few assumptions to us,
> it would make a nice case study to present at an
> upcoming VHF
> conference.   
> 
> Anyhow, enough rambling about theories for
> now..........
> 
> 
> Ron 
> WW8RR
> 
> 
> -----Original Message-----
> From: fourlanders-bounces at contesting.com
> [mailto:fourlanders-bounces at contesting.com] On
> Behalf Of Paul Yeager,
> ABR(R), REALTOR(R)
> Sent: Wednesday, June 13, 2007 1:28 AM
> To: Fourlanders
> Subject: [Fourlanders] adjusting takeoff angle
> 
> Ron WW8RR points out that our high-gain stacked
> beams are likely
> striking the ionosphere quite some distance away,
> due to their low
> takeoff angle.  Ron further suggests that this is
> causing us to miss
> closer in stations that we might be able to work, if
> could arrange a
> higher takeoff angle.  (Ron - please let me know if
> I have misstated
> something here)
>    
>   I see two obvious ways to change the takeoff
> angle.
>    
>   1) Mount anntenna(s) on an az-el rotator.  This
> seems pretty simple,
> but when one considers the details, it becomes a bit
> complex
> mechanically.  How does one mount a
> horizontally-polarized yagi on an
> az-el rotator?  The only way I can see is to mount
> it on a rather long
> "boom", rotated by the elevation rotator.  The boom
> needs to be rather
> long to avoid interaction between the antenna and
> the tower/rotator, and
> may need to be fiberglass or other non-conductive
> material to avoid
> degrading the performance of the antenna.   This
> will also place quite a
> side load on the rotator and tower, unless the boom
> is extended to the
> side opposite the rotator with a counterweight.
>    
>   Alternatively, we  might extend the antenna's
> boom, then add a right
> angle to the rotator.  This increases the load on
> the elevation rotator
> considerably, unless a counterweight is added.
>    
>   See what I mean about mechanical complexity?
>    
>   2) Using a similar antenna arrangement to the one
> we used for the
> contest, adjust takeoff angle by adjusting the phase
> between the two
> antennas.  Mechanically, this is no more complex
> than the current
> arrangement.  Electrically, it's quite more complex.
>  Not rocket
> science, but certainly more complex than a single
> feedline running to a
> splitter feeding both antennas.
>    
>   We could do something as simple as selecting
> upper/lower/both yagis,
> or get more complex and switch sections of feedline
> in and out to
> actually change the phase.  Two switchable sections
> of 
=== message truncated ===



 
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