Tower heights and height of antennas on the Tower are typically band
dependant. Antennas are like shoes. One size does not fit all.
Increasing your tower height from 50' to 70' might help your signal on
one band to some areas and at the same time decrease your signal on
another band to some of your favorite target areas. All this depends
upon the distance between you and the person with whom you are trying to
communicate.
For reference, I'll give a few examples of our experiences in Jamaica at
6Y1V
20 Meters - Stacked 6 over 6 at 59' and 100'
--------------------------------------------------
Toward USA and Japan
When working US station on 20 meters, signals are almost always stronger
on the bottom antenna. When working Japan, signals are always stronger
on the top antenna or stack of both antenna. Outside of contests, when I
can ask US stations to standby, I usually work Asia using both antennas.
This heps reduce fading on the signals. During contests, when the band
opens to Asia (4:30pm local time) I almost always switch to only the top
antenna. This typically reduces the US signal strengths by 5db and
increases the the Asian signals by 5db.
The effect is that now the strongest Asian signals are about as strong
as the average US station signals. During CQWW where US station count 2
points and Japanese count 3 points this becomes critical for us to
maximize points per contact. Without the stack this would be impossible.
We also have a 4 element SteppIR at 25' and often US station in the
southeast are 10db stronger on this antenna than either of the 6 element
stacks.
Toward Europe, Middle East and Long Path Pacific
-------------------------------------------------------
When working Europe on 20 meters, we typically find that western
European signals are strongest on the lower antenna at 59' and the most
eastern and middle eastern signals are strongest on the stack and
sometimes top antenna alone. Most Middle Eastern stations are strongest
on the stack, but when the band opens to Australia long path at 2pm in
the afternoon, VK6's are typically 30db over S9 on the top antenna
alone. It is actually quite amazing to hear these VK's pounding into the
Caribbean with such huge signals. This opening typically lasts for about
45 minutes to an hour.
We experience similar results with the 6 over 6 stacks on 15 meters at
32' and 65'.
40 Meters - Stacked 3 over 3 at 70' and 140'
--------------------------------------------------
The 40 meter stacks play a little differently, but in usually see
similar results. The 3 over 3 SteppIR 40 meter stacks are configured a
bit differently since they have ring rotors and can be rotated
individually. This works great during contests like ARRL where we can
point the top antenna at the west coast and the lower one toward the
east coast. The west coast signals are strongest on the top antenna and
the east coast stronger on the lower antenna.
When working Europe and other DX locations, signals are almost always
strongest using both antennas as a stack.
If I were to draw any conclusions from my 30+ years of experience with
antennas, working DX and contesting, I would advise people to give
serious consideration to their favorite activity first, then favorite
band before making any rash decisions on increasing the height of their
tower.
For example, if your favorite activity is working DX, a height increase
for your tribander may improve your signal on 20 meters while ruining
your signal on 10 meters. If your favorite contest is sweepstakes,
increasing the height of your tribander might improve your dx'ing
endeavors while decreasing your chance of winning sweepstakes.
Obviously, the best choice for erecting antennas is to have multiple
towers with multiple antennas at different heights. We all know this
isn't practical for the majority of amateurs, so take some time to think
about what it is you love most and optimize for that activity. IF you
have the ability to increase the height of your tower, I recommend you
do it and get your 20 meters and low band antennas as high as possible
(66' being great for 20 meters). If you have the means, you can throw in
an extra antenna at a lower height for 10 and 15 meters. For example, a
20 meter monobander on top of a 70' tower would be great with a 10/15
meter duobander at 45 feet might work really well.
I hope this information was helpful. I'd love to write more if I had the
time.
David ~ KY1V
I think that doubling you height thing is one old wives tale that some
of the guys on the reflector can speak to. Lots of guys out there now
that have the same antenna stacked at 160 ft 100 feet and 40feet that
can phase em all, or use any individual beam separately. I am sure they
will weigh in on this. Of course it depends on whether you are a
contester or a dx'er but The PVRC video tapes featuring W3LPL recommend
that if you can only have one tower, make it a 100 Footer. At any given
time on any given band you will find large differences between the high
and low beam and stacking 2 or 3 of em fills in most of the nulls in
between.
73
Chet
-----Original Message-----
From: cq-contest-bounces@contesting.com
[mailto:cq-contest-bounces@contesting.com] On Behalf Of Edward Swynar
Sent: Saturday, March 20, 2010 6:12 PM
To: Ralph Bellas; cq-contest@contesting.com
Subject: Re: [CQ-Contest] Going from 50 to 70 ft.
Hi Ralph,
This is totally unsubstantiated with any personal "...blood, sweat, &
tears"
on my part, but I recall reading somewhere years & years ago (the "NCJ",
maybe...?) that in order to experience any detectable/noticeable benefit
in making your tower taller, you have to at least double the existing
height...
Increments of one, or two, sections just doesn't cut it, apparently...
...But I defer to the real-world experts reading this who have
first-hand practical knowledge & experience in all this...!
~73~ de Eddy VE3CUI - VE3XZ
************************************
--- Original Message -----
From: "Ralph Bellas" <k9zo@hotmail.com>
To: <cq-contest@contesting.com>
Sent: Saturday, March 20, 2010 10:17 AM
Subject: [CQ-Contest] Going from 50 to 70 ft.
>
> Folks,
>
>
>
> I'm beginning to frame up an article for the July/August NCJ
> "Contesting
on a Budget" column. The topic will be to look at the benefits, costs,
and considerations associated with raising a tower from 50 feet to 70
feet.
Here are some of the thoughts I have:
>
>
>
> Benefits:
>
> You will hear and work dx which was previously unavailable. My
> estimate
is that you will add an S unit.
>
> Occasionally get to run dx, especially during non-contest times.
>
> Be able to raise your lowband antennas.
>
> Add the possibility of mounting a tribander in a fixed direction to
> add
contest flexibility.
>
> Possibly decrease RF in your shack and get rid of unresolved problems.
>
>
>
> Considerations:
>
> If you live in a hill, or have a good view, perhaps there will not be
> as
great a benefit.
>
> Now you always must use proper safety equipment when climbing.
>
> Perhaps this is the time to replace coax, or go to a bigger antenna.
>
> It becomes more noticable
>
> Is a permit required?
>
> You will need to locate a gin pole for the last few sections.
>
> Could your signal be worse to certain areas?
>
>
>
> Costs:
>
> Probably you will be moving away from the simple house bracketed tower
> and
will have to add real anchors and guy wires.
> You might have to relocate the tower and use two sets of guy wires.
>
> Two sections of tower, turnbuckles, clamps, rotor cable, coax, tape
>
>
>
>
>
> If you have been in the situation where you have raised your tower I'd
love to hear from you and learn what you came across. Thanks.
>
>
>
> Ralph
>
> K9ZO
>
> _________________________________________________________________
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