[TowerTalk] Sloper or Inverted V

Wed Apr 22 11:49:20 PDT 2009

Comments embedded..

 >-----Original Message-----
   >From: towertalk-bounces at contesting.com
   >[mailto:towertalk-bounces at contesting.com]On Behalf Of David Gilbert
   >Sent: Wednesday, April 22, 2009 01:41
   >To: TowerTalk
   >Subject: Re: [TowerTalk] Sloper or Inverted V
   >
   >
   >
   >That statement hasn't been accurate for about three decades.
   >Mechanical
   >engineers now understand and can model exactly how bumblebees and
   >hummingbirds fly.  The only reason the myth lives on is because people
   >are so fond of quoting it as a rationalization for believing as
   >they want.
   >

Dave,

I apologize if I stepped on your engineering toes. That was not my intent
with my candid remarks. As usual, conjecture can bring out the best or worse
of us.

   >Within known limitations (close-spaced wires, wires near ground, etc),
   >computer programs do a pretty good job of modeling antennas as well.

Agreed.

   >9 times out of 10, those antennas that are claimed
   >to defy the modeling programs don't.

I don't have any "evidence" to counter support for that one. Besides I did
not knock Modeling in my posts. I merely stated that I had not modeled any
of my antennas.

   >They might defy the careless modeler, but I
   >don't think
   >ham radio is advanced at all by non-quantifiable endorsements and
   >anecdotal experience, at least not when objective inspection and theory
   >would indicate otherwise.

He was not asking for "quantifiable endorsements". As far as your "anecdotal
experience" I have the logbook to prove the antennas in question work.
However this is not a brag forum. I saw no benefit to Cal to brag about my
accomplishments.

But for your criticism, I offer that In recent years I have worked Asia,
Europe, Russia and South America on 40M RTTY with 50 watts. I accomplished
this with a 1/4 wave Sloper off the West side of my tower. I also have
worked 38 states on 40M since moving to this QTH all with the same 40M
sloper.

I will not argue with your Modeling and the results it shows. However,
please consider that Theory has its place and so does operational reality.

I stand by my remarks about the sloper/inverted V antennas. Please re-read
the post which Cal placed and I answered. Here is a reminder:
---------------
> I'm working on plans for a 90' tower.
> Has anyone used the top set of guy wires, with johnnyball insulators at
the correct places of course to make an inverted V, or Sloper?
>
> OR..maybe using the guy wires connected at 60' for another sloper or
Inverted V?
---------------
I simply answered his question. I have seen responses to this kind of
question advocating both sides of the house. Hence my reasoning for
answering Cal's query with my own experience.

Is the sloper/inverted V a good antenna? Compared to What?

Simply stated "Inverted V & Slopers DO work". How well, depends on your
perspective. If you compare it to a dipole in free space, they are probably
not as good. However, they work extremely well compared to using Bed springs
for an antenna.

Please don't laugh at that comment.
I have personally loaded a double bed spring with an old ART-13 and made
many contacts on 40 & 80 meters.

When I first became a ham I was living in a very small house with no real
estate for antennas. So in these conditions you improvise. I had heard that
the ART-13 (my first transmitter) would load anything that had metal in it,
so I set out to prove it. It worked.

Perhaps you could practice modeling that one. I used a double bed open
spring installed in a wooden bed frame. Counting the house foundation, the
spring was perhaps 4 ft off the ground.

By the way that was when you were 6 years old. I'll let you model the math.

   >....was correct when he said that a
   >half-sloper (quarter wavelength of wire fed at the tower) is basically
   >an Inverted-V with a very sharp angle (lots of field cancellation) and
   >one leg grounded.

An accurate description. Does that make it good or bad? Again, conjecture
fits.

   >It doesn't sound very attractive in that
   >light, which
   >is probably why historically few hams with something to
   >directly compare
   >it against have ever been very impressed with it.

There has been some form of Sloper/Inverted V in the Antenna/ARRL handbooks
since I can remember. That should tell you something about its acceptance.

Based on your personal lack of acceptance, maybe you could convince all the
authors to quit including it in their antenna books. Perhaps you need to
take another approach toward convincing those of us that have successfully
used that type antenna for the past 55 years.

Dave, Amateur radio was built on experimentation along with trial and error.
Please provide a space in your mind for the practical side of the house and
enjoy this great hobby for what it was founded on. There is no argument,
theory has its place, but the bottom line is the satisfaction of making a
contact using something you built, regardless of how you got there.

Again, I apologize if I hit a nerve. I wish you the best of DX. in the mean
time, I will continue to use my slopers, "It works for me".

   * 73's Jim W5IFP *

   >
   >73,
   >Dave   AB7E
   >
   >
   >
   >Jim Hargrave wrote:
   >> Antennas are kind of like the Bumble bee. Aeronautical
   >engineers tell you it
   >> can't fly, but they failed to tell the Bumble Bee.
   >>
   >>
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