"Roy Lewallen" wrote in message
...
This can easily be done with the free EZNEC demo program available from
http://eznec.com. Here's a step-by-step for the demo or any other EZNEC v.
4.0 program:

1. Open example file Vert1.EZ. (Click the Open button, enter Vert1, then
.........

.........Objects, then check the 2D Pattern box. This will superimpose a
correctly oriented 2D pattern on the drawing of the antenna.

I did the experiment using a 30 degree tilt, and found a difference of
1.31 dB at an indicated elevation angle of 30 degrees. That would be at
the horizon, taking into account the ground tilt. At an indicated
elevation angle of 40 degrees (10 degrees above the horizon when ground
tilt is considered), the difference is 1.77 dB. You can modify the ground
conductivity and permittivity and repeat the experiment to see how this
changes with different ground types.

Roy Lewallen, W7EL

Frank wrote:

Since NEC cannot model a sloping ground, just try modeling a leaning
vertical, and see how it effects the pattern. I seriously doubt there
would be much difference. Certainly nothing you would notice.

Frank

Thanks for the info, but I already have the EZNEC demo. It does seem to be
an excellent program, providing a low cost antenna modeling tool. I have
been using another version of NEC for quite a few years and, to be honest, I
prefer to work directly with the NEC cards. I feel lost if I cannot get in
and edit the lines of code. I must admit I often use some of the
additional program features to check if I have the correct card sequence,
and also for tag rotation. I can also use any card listed in the NEC User's
Guide.

Fact is I was not that interested in actually modeling a leaning vertical,
although the problem is trivial. Now that you have done it, I may give it a
try to see if I get the same results. Assume you used a slightly elevated
radial ground plane with the S/N ground model applied.

Regards,

Frank

In message , Richard Clark
writes
On 02 Dec 2004 11:51:12 EST, am (Gary V.
Deutschmann, Sr.) wrote:
What Gives?

Hi Gary,

Do they have the faith to build their walls that way too? Look at the
horizontals. Do they ridge run, or do they follow the down hill slope
too?

The better question is: How much better is theirs than their
neighbor's vertical (as opposed to their perpendicular)?

The best question is: How do they know?

Kinda reminds me of the Katherine Hepburn movie "Bringing Up Baby"
where she breaks one heel of her high heels and starts loping along:
"I feel like I was born on the side of a hill."

Did you know that the sheep in Wales have shorter legs on one side than
the other? To allow them to graze more easily on the hillsides.

Mike

Hello Gary,

Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.

Good luck.

Chuck

chuck wrote:

Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.


The advantages of which Moxon wrote are for *horizontal* polarization
only. If the antenna height above ground is correct, the ground
reflection can reinforce low-angle radiation in the downslope direction.

But Moxon also shows specifically that there are *no* such advantages
for vertical polarization. The ground-reflected ray is lost at a high
angle.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Hello, Ian.

Yes, I was a bit hasty in citing Moxon.

But thinking a little more about this I wonder. Intuitively, and looking
at Moxon's sketch, it would seem that the effect would be simply to
rotate the vertical pattern by the amount of the slope. Aiming the
pattern "down the slope" rather than "toward the horizon" does not seem
to be a necessarily worse situation as Moxon suggests. Wouldn't that
actually put more energy out toward the horizon?

Tilting a VHF ground plane antenna toward the horizon would be different
because the vertical pattern at zero degrees is not attenuated by ground
losses.

Chuck








Ian White, G3SEK wrote:
chuck wrote:


Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.


The advantages of which Moxon wrote are for *horizontal* polarization
only. If the antenna height above ground is correct, the ground
reflection can reinforce low-angle radiation in the downslope direction.

But Moxon also shows specifically that there are *no* such advantages
for vertical polarization. The ground-reflected ray is lost at a high
angle.

chuck wrote:
Intuitively, and looking at Moxon's sketch, it would seem that the
effect would be simply to rotate the vertical pattern by the amount of
the slope. Aiming the pattern "down the slope" rather than "toward the
horizon" does not seem to be a necessarily worse situation as Moxon
suggests. Wouldn't that actually put more energy out toward the horizon?

That is true in principle, but the problem with a ground-mounted
vertical antenna is that the angle of maximum radiation is fixed in
relation to the ground. That means the angle of the slope has to be just
right, and in general it also needs to be very steep.

With a horizontal antenna, you can vary the angle of maximum radiation
by adjusting the height above ground. That makes it easy to apply the
technique over a wide range of quite moderate slope angles, using quite
modest antenna heights.

Changing the subject slightly, hams have become over-conditioned into
wanting a "low" angle of radiation. It's true that we generally do need
more radiation at lower angles than we can easily achieve; but until
recently, we haven't had the information to understand what angles of
radiation we actually *do* need.

Modern HF propagation programs give us that information. Not
surprisingly, the optimum angle varies according to the path, the number
of hops involved, the heights of the respective layers and the
ionization levels... and hence the optimum angle also depends on the
time of day, the season, and the year in the sunspot cycle. Recent
editions of the ARRL Antenna Handbook analyse this problem in some
detail, and show that "lowest possible angle" is not always the best
objective if you're aiming to cover all possible cases.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

From decades of looking at optimum take-off-angles (TOA) at HF for long
paths, I have found that TOAs are rarely above 12 degrees and only
occasionally below 2 degrees. This leads to the conclusion that if cost
were not an issue and one could only put up one horizontally polarized gain
antenna (Yagi, LPDA, or such), the antenna should be 2 to 2.5 WL high. At
least one edition of the ARRL Antenna Book has the same conclusion.

A higher antenna starts to have nulls in the useful range of TOAs.

As usual, Ian has the right idea.

73 Mac N8TT


--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Ian White, G3SEK"

That is true in principle, but the problem with a ground-mounted
vertical antenna is that the angle of maximum radiation is fixed in
relation to the ground. That means the angle of the slope has to be just
right, and in general it also needs to be very steep.

With a horizontal antenna, you can vary the angle of maximum radiation
by adjusting the height above ground. That makes it easy to apply the
technique over a wide range of quite moderate slope angles, using quite
modest antenna heights.

Changing the subject slightly, hams have become over-conditioned into
wanting a "low" angle of radiation. It's true that we generally do need
more radiation at lower angles than we can easily achieve; but until
recently, we haven't had the information to understand what angles of
radiation we actually *do* need.

Modern HF propagation programs give us that information. Not
surprisingly, the optimum angle varies according to the path, the number
of hops involved, the heights of the respective layers and the
ionization levels... and hence the optimum angle also depends on the
time of day, the season, and the year in the sunspot cycle. Recent
editions of the ARRL Antenna Handbook analyse this problem in some
detail, and show that "lowest possible angle" is not always the best
objective if you're aiming to cover all possible cases.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.


The advantages of which Moxon wrote are for *horizontal* polarization
only. If the antenna height above ground is correct, the ground
reflection can reinforce low-angle radiation in the downslope direction.

But Moxon also shows specifically that there are *no* such advantages
for vertical polarization. The ground-reflected ray is lost at a high
angle.
--
73 from Ian G3SEK

==================================

Dear Ian, what has Moxon got to do with it?

Without personal experience how do you know you are not plagiarising and
further propagating old-wives' tales?

If you have personal experience do you need anybody else's support anyway?

Just state the facts on your own authority.

Or do authors all belong to the same masonic club which adds nothing to
veracity?

My only little axe is that I find it irritating when I read about quite
unnecessary references which add nothing but verbiage to the conversation.
Perhaps I'm funny or just impatient in that way.

But I'm sure you understand my non-technical interruption to this thread
with my appology. Reply not needed.

(PS: I have only vaguely heard of Moxon in these newsgroups. Never read him.
Not the slightest disrespect to him, or her, intended. But my own reference
bibles are restricted to Ohm, Ampere and Volta.)
----
I think I can still call you my Internet friend. ;o)
----
Yours, Reg, G4FGQ

Reg Edwards wrote:
Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.


The advantages of which Moxon wrote are for *horizontal* polarization
only. If the antenna height above ground is correct, the ground
reflection can reinforce low-angle radiation in the downslope direction.

But Moxon also shows specifically that there are *no* such advantages
for vertical polarization. The ground-reflected ray is lost at a high
angle.
--
73 from Ian G3SEK

==================================

Dear Ian, what has Moxon got to do with it?

He was the person who was being misquoted. In the first reply, I was
setting that record straight.

Without personal experience how do you know you are not plagiarising and
further propagating old-wives' tales?

Because, whatever else I read, I also do my own thinking.

If you have personal experience do you need anybody else's support anyway?

Just state the facts on your own authority.

Or do authors all belong to the same masonic club which adds nothing to
veracity?

Certainly not; most authors do value a cross-check on their own thinking
- and above all, a cross-check against reality.

I certainly do, because it's how I was trained.

The value of the major academic textbooks is that most of them have been
in the public domain for decades, and available for critique and
cross-checking and correction in later editions. If your own findings
don't agree with the pool of knowledge that's already out there, you'd
better have some strong reasons to hand.

In this respect, all amateur radio publications are in a lesser league.
They are still going through the process of critique and technical
clarification - marvellously accelerated by the Internet in recent years
- but they're not there yet.

(PS: I have only vaguely heard of Moxon in these newsgroups. Never read him.
Not the slightest disrespect to him, or her, intended.

Perhaps you should: Moxon was a lot like you in his methods and his ways
of thinking.

But my own reference
bibles are restricted to Ohm, Ampere and Volta.)

All three of whom are conveniently not available for comment.

----
I think I can still call you my Internet friend. ;o)
----

For about 15 hours out of 24, I reckon.

But anytime after your first glass of the evening, and before my first
cup of coffee the next day, don't push your luck :-)


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Hi Chuck

At least we have one sane person in the group eh!

I moved from St. Louis to Knoxville last year, as of yet I have not
installed my HF9V here, in St. Louis it was mounted vertical on flat
ground with about 3,500 feet of radials.

The only logical place for me to install my antenna is some 100 feet
below the top of our hill, because of the radial bed. The grade of
the hill is roughly a 30 inch average drop every 10 feet at the top of
the hill.

Unless I build an elevated counterpoise that would have one side of it
about 20 feet in the air, how would the underground radials affect the
operation of the antenna if it is vertical?

Of the hams I have spoken with, those that have theirs vertical say
there is no difference whether the antenna is vertical or not, and
they should be mounted vertically.
Of those that have theirs leaning perpendicular to the grade line,
they claim they could not communicate with certain stations when their
antenna was vertical, but can with it perpendicular.

Although Knoxville is considered to be in a Valley, my home is
situated on the north slope near the top of one of the foothills, but
my property does go to the top, unfortunately, a little too far away
from the house for the VHF/UHF, but it is roughly 30 feet above the
crest of the hill, 60 feet above ground level at the shack.

I guess I could install two separate mounts, one vertical and one
perpendicular and try both ways, but retuning those HF9V's especially
when you have the 160 coil is a real nightmare.

FWIW: I cleared a line through the woods to run some dipoles. My
first installation I mounted the dipoles horizontal with the grade
line. But after putting up the VHF/UHF tower I moved many of the
dipoles upward so they are closer to level. On the higher bands I did
notice some difference, but on the lower bands they seemed to work
about equally as well.

It seems all the 10 meter paper chasers have their ground mounted
antennas perpendicular to the ground, while serious hams have theirs
all mounted vertically.

Even those hams who live in the bottom of the valley have no trouble
with HF communications, but those on top of hills often use large
beams and yagi's to take advantage of their prime location.

I have no antenna restrictions at my new home here, Yeah, other than
what the FAA dictates regarding lighting if they are over a certain
height.

TTUL
Gary




chuck verbositized:

Hello Gary,

Don't know from personal experience, but Les Moxon, author of HF
Antennas for all Locations, seems to believe it creates an advantage.
You might want to read his thoughts on that.

Good luck.

Chuck