The program W6ELProp gives the take-off-angle needed for any path. Looking
at 80 meter paths (it does 801-0 meters) the angles for DX paths are in the
range of 3-15 degrees.
Dave WX7G
___
UR RST IS ... ... ..9 QSB QSB - hw? BK
What I am saying is that ground loss must increase the higher we go in
frequency, attenuating the surface wave more and more the higher and higher
we go.
But Rich is also talking about the radiation at zero degrees bouncing off
the ionosphere and returning to the earth at some distant point.
doubtful that radiation at 5* will do much
better unless its all over salt water.
Carl
KM1H
- Original Message -
From: Mike Waters
To: topband
Cc: ZR
Sent: Monday, May 07, 2012 10:22 PM
Subject: Re: Topband: Monopole Radiation Patterns, takeoff angles etc
I've never
Landskov n...@cox.net
To: Mike Waters mikew...@gmail.com; topband topband@contesting.com
Cc: ZR z...@jeremy.mv.com; Richard Fry r...@adams.net
Sent: Monday, May 07, 2012 11:02 PM
Subject: Re: Topband: Monopole Radiation Patterns, takeoff angles etc
- Original Message -
From: Mike Waters mikew
The NEC surface wave includes low-angle fields well above zero degrees
elevation that do not appear in a NEC far-field plot, and they are in fact
space waves (see link below).
And that's the piece that probably not been underscored in this discussion.
Some have probably concluded that the
Some USN subs used to be retrofitted here in the VI and I was called to
pick up some of the transmitters which required a fork lift to put the
transformers on the back of a truck. The RF deck used a pair of
4CX5000's and they appear to drive some sort of transducer for
underwater
Dave WX7G wrote:
The program W6ELProp gives the take-off-angle needed for any path. Looking
at 80 meter paths (it does 801-0 meters) the angles for DX paths are in the
range of 3-15 degrees.
Assuming those angles are true for DX paths, note that if the NEC far-field
elevation pattern for a
If the radiation at 3 degrees is -8.9 dB relative to the maximum amplitude
we can still work DX.
Dave WX7G
On May 8, 2012 9:18 AM, Richard Fry r...@adams.net wrote:
Dave WX7G wrote:
The program W6ELProp gives the take-off-angle needed for any path. Looking
at 80 meter paths (it does 801-0
One really needs to evaluate the usefulness of 5 degrees and under in a
case-by-case basis. Most people in populated areas have 5 degrees
completely obliterated by conductive and semi-conductive clutter...houses,
trees, overhead powerlines, buildings, yada yada. And probably 10 and 15
degrees are
Guy Olinger wrote:
BLE gave their study conductivity limits as between 20 and 100
milli-Siemens !!!
Those who believe so might want to review the conversion from the e.m.u.
units used for earth conductivity in the BLE publication to the mS/m units
more commonly used today.
-- The
A common use for correctly defined NEC models shows the electrical
characteristics of the radiator system itself. But NEC also will show the
field intensities that system will produce at a given distance for a given
applied power, frequency, and earth characteristics -- and do so quite
I'm pretty sure this surface wave at ~0 degrees elevation is useful on (and
below) the AM broadcast band (especially the lower portion) and 160 meters.
But what about at 3.5, 5, 7, 10, 14, 18, 21, 24, and 28 MHz? That's what
I've been trying to figure out: exactly how useful is this radiation at
And this seems like a good place and time to ask another question.
I get the experience that the usefulness of NVIS radiation peaks around 80
meters. It's not useful on the AM broadcast band, and it's not useful on 20
meters. How accurate is my assumption?
73, Mike
www.w0btu.com
: Monopole Radiation Patterns, takeoff angles etc
I'm pretty sure this surface wave at ~0 degrees elevation is useful on
(and
below) the AM broadcast band (especially the lower portion) and 160
meters.
But what about at 3.5, 5, 7, 10, 14, 18, 21, 24, and 28 MHz? That's what
I've been trying
I've never operated mobile, but it sounds like you're saying the daytime
local range on 160 and 10 is comparable.
But Rich is also talking about the radiation at zero degrees bouncing off
the ionosphere and returning to the earth at some distant point. That's
what I'm wondering about. Local is
Let me expand on what I said previously.
I always thought that ground wave propagation decreased with frequency. For
example, don't AM broadcast stations in the lower end of the AM broadcast
band have greater coverage than at the high end, all things being equal? I
have always thought that, and I
- Original Message -
From: Mike Waters mikew...@gmail.com
To: topband topband@contesting.com
Cc: ZR z...@jeremy.mv.com; Richard Fry r...@adams.net
Sent: Monday, May 07, 2012 7:35 PM
Subject: Re: Topband: Monopole Radiation Patterns, takeoff angles etc
Let me expand on what I said
Hi all..
This thread has been very interesting and educational...I guess we all
strive to make our installation as efficient as we possibly can...Much
of the radial theory has to go out the window for those who don't have
the room, (acres) to install a good radial field and have to compromise
All vertical monopoles of 5/8-wavelength __and less__ radiate (launch) their
maximum relative field (E/Emax) in the horizontal plane. This is true no
matter what the loss in the r-f ground connection they use.
A lossy ground connection will reduce the gain of the antenna system, but it
will not
Guy Olinger wrote:
It IS TECHNICALLY TRUE what you say, no argument, but of little use since
you don't get to keep it, UNLESS you can get it over salt water, or off a
mountain top. ... I can only spend take-home pay, and I can only make QSO's
with the take-home pattern. I don't see anything
And your point is ??
That is not the only place where substitute arithmetic will produce a
different figure. You can do the same with ground losses in the immediate
vicinity, where if you do anything except the Norton-Sommerfield
estimations you come up with a different figure. NOBODY has
On 05/06/2012 11:10 AM, Richard Fry wrote:
Unless that propagation path is obstructed by some physical object, nothing
prevents such low-angle waves from traveling on to the ionosphere, which
under the right conditions will result in their reflections returning to the
earth as skywave.
The
Rik van Riel wrote:
The problem is that radiation does not just have an amplitude,
it also has a phase angle.
At certain ground resistances, the ground wave and the low angle
sky wave will cancel each other out, which moves the angle of
radiation up.
If that were true, the low-angle radiation
In 2006 Tom Rauch, W8JI mentioned the disappointment with 3/8 wave
vertical antennas and Carl mention today abut how BCB stations migrated
from 5/8 wave and 1/2 wave antennas. I added to Tom's rejoinder that
several AM stations spent considerable amounts of money with the
Franklyn design
One has to be careful with 5/8 wavelength verticals. A radiator that is
physically 5/8 wavelength is already electrically too tall. That is why
a 300 foot BC tower would not work well at low angles on 160. There are
too things to considers one is that towers have velocity factor just
like
WHO-AM (1040 KHz) still uses the modified Franklin.
Their 50KW covers the entire state of Iowa + during the day and goes
international at night.
On 05/06/2012 11:31 AM, ZR wrote:
The BCB stations migrated from 1/2 and 5/8 wave antennas, diamond shaped
towers, and mountain tops by the early to
Patterns, takeoff angles etc
One has to be careful with 5/8 wavelength verticals. A radiator that is
physically 5/8 wavelength is already electrically too tall. That is why
a 300 foot BC tower would not work well at low angles on 160. There are
too things to considers one is that towers have
And your point is ?? That is not the only place where substitute
arithmetic will produce a
different figure.
I ran a 4Nec2 (with NEC/4.2 engine) surface wave plot for a 160m 1/4-wave
vertical radiator over a
field of 60 radials with average ground conductivity. Input power = 1.5KW.
4Nec2
I think Carl may have his time line backwards. In the 20s and early 30s
many stations used various forms of wire antennae including dipoles and
various cage designs. During the 30s Dr Brown and colleagues studied and
tested various vertical radiators and ground systems. The result of that
work
Radiation Patterns, takeoff angles etc
In 2006 Tom Rauch, W8JI mentioned the disappointment with 3/8 wave
vertical antennas and Carl mention today abut how BCB stations migrated
from 5/8 wave and 1/2 wave antennas. I added to Tom's rejoinder that
several AM stations spent considerable amounts
Carl has nothing backwards, best do your research the next time.
- Original Message -
From: W2XJ w...@nyc.rr.com
To: topband@contesting.com
Sent: Sunday, May 06, 2012 7:40 PM
Subject: Re: Topband: Monopole Radiation Patterns, takeoff angles etc
I think Carl may have his time line
-
From: W2XJw...@nyc.rr.com
To:topband@contesting.com
Sent: Sunday, May 06, 2012 7:40 PM
Subject: Re: Topband: Monopole Radiation Patterns, takeoff angles etc
I think Carl may have his time line backwards. In the 20s and early 30s
many stations used various forms of wire antennae including
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