On 27 Mar, 09:55, (Richard Harrison) wrote:
Art wrote:

"---yet I am not finding any documented proof other than emperical
work."

As usual, Terman has answers. See page 882 of his 1955 opus: "Effect of
Ground on the Directional Pattern of Ungrounded Antennas - Image
Antennas."

It`s in the book; math, diagrams, tables, as needed to imagine what
happens.

Best regards, Richard Harrison, KB5WZI

Thank you for that I will get right on it. I presume it does give
direct relationships between electrical and magnetic vectors relative
to the conductor and ground !

Richard Harrison wrote:
Jim Pennino wrote:
"Have you ever heard of a helix?"

Most would likely enjoy Kraus` story of his invention of the axial-mode
helix in his 3rd edition of "Antennas".

' "No," he replied, "I've tried it and it doesn't work."'

On 27 mar, 19:47, "art" wrote:
On 27 Mar, 10:20, (Richard Harrison) wrote:

Jim Pennino wrote:

"Have you ever heard of a helix?"

Most would likely enjoy Kraus` story of his invention of the axial-mode
helix in his 3rd edition of "Antennas". This is a choice book!

Best regards, Richard Harrison, KB5WZI

I have his second edition and I find no mention of radiation from the
beginning where current is applied onwards. Have you found anything
that can
contribute other than empirical grounds? You have avoided the question
so far

Hello Art,

Radiation from accelerating charge is fully understood (from theory
and verified practically), hence antenna theory. When you take the
complete formula for fields (near and far) generated by a short wire
segment (hertzian dipole), you can calculate the far and near field
(magnitude, orientation, phase, etc) from every construction. The only
problem is that you have to know the current distribution in your
construction.

It is not of interest whether the charge is excited by just a voltage
source or EM radiation (like in reflection of waves on conductors and
dielectrics). This is done in many FEM programs.

Of course in many practical circumstances it is easier to use the
"laws" from other people (that are derived from basic theory). One of
the results are the Fresnel formulas for reflection.

When you know the properties of the soil at the operating frequency,
you can calculate the complex surface impedance and hence the complex
reflection coefficient.

Just mentioning words as "curl", "vector", "Gaussian" etc, doesn't
make sense without further information.

Best Regards,


Wim

On 27 Mar, 12:22, "Wimpie" wrote:
On 27 mar, 19:47, "art" wrote:





On 27 Mar, 10:20, (Richard Harrison) wrote:

Jim Pennino wrote:

"Have you ever heard of a helix?"

Most would likely enjoy Kraus` story of his invention of the axial-mode
helix in his 3rd edition of "Antennas". This is a choice book!

Best regards, Richard Harrison, KB5WZI

I have his second edition and I find no mention of radiation from the
beginning where current is applied onwards. Have you found anything
that can
contribute other than empirical grounds? You have avoided the question
so far

Hello Art,

Radiation from accelerating charge is fully understood (from theory
and verified practically), hence antenna theory. When you take the
complete formula for fields (near and far) generated by a short wire
segment (hertzian dipole), you can calculate the far and near field
(magnitude, orientation, phase, etc) from every construction. The only
problem is that you have to know the current distribution in your
construction.

It is not of interest whether the charge is excited by just a voltage
source or EM radiation (like in reflection of waves on conductors and
dielectrics). This is done in many FEM programs.

Of course in many practical circumstances it is easier to use the
"laws" from other people (that are derived from basic theory). One of
the results are the Fresnel formulas for reflection.

When you know the properties of the soil at the operating frequency,
you can calculate the complex surface impedance and hence the complex
reflection coefficient.

Just mentioning words as "curl", "vector", "Gaussian" etc, doesn't
make sense without further information.

Best Regards,

Wim- Hide quoted text -

- Show quoted text -
Wim
I accept all of what you write . I can get the angle from computor
programs based on Maxwell. but the computor program is not enough!
I would like to see a mathematical proof of the tip angle required of
a vertical to provide a wave front at 90 degrees to the tip angle. I
see graphs of tip angles for a long legged "v" in Terman but not for a
simple vertical or horizontal radiator. Can you point me to a paper
that burrows deeply into this question either over a perfect ground or
in free space?
Art

On 27 Mar 2007 10:51:27 -0700, "art" wrote:

I presume it does give
direct relationships between electrical and magnetic vectors relative
to the conductor and ground !

Hi Art,

As this is all very elementary stuff, of course Terman does.

73's
Richard Clark, KB7QHC

Art wrote:
"I have his (Kraus`) second edition (Antennas) and I find no mention of
radiation from the beginning where current is applied onward."

I think I have that edition too. If you review the chapter on "Point
Sources" you`ll find: power patterns, a power theorem and its
application to isotropic sources, rediation intensity, source with
hemispheric power pattern, unidirectional cosine power pattern, etc.,
etc..

The new, now available 3rd ed. of "Antennas" by Kraus, Marhefka, and a
host of others is greatly expanded and improved. It is worth the
investment.

Being uncertain of what Art really wants, doesn`t stop me from advising
him to start by having a look at the famous Sommerfeld formula on page
804 of Terman`s 1955 opus.
It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile
from a short vertical transmitting antenna given a certain ground
conductivity and other conditions.

Best regards, Richard Harrison, KB5WZI

On 27 Mar, 15:12, (Richard Harrison) wrote:
Art wrote:

"I have his (Kraus`) second edition (Antennas) and I find no mention of
radiation from the beginning where current is applied onward."

I think I have that edition too. If you review the chapter on "Point
Sources" you`ll find: power patterns, a power theorem and its
application to isotropic sources, rediation intensity, source with
hemispheric power pattern, unidirectional cosine power pattern, etc.,
etc..

The new, now available 3rd ed. of "Antennas" by Kraus, Marhefka, and a
host of others is greatly expanded and improved. It is worth the
investment.

Being uncertain of what Art really wants, doesn`t stop me from advising
him to start by having a look at the famous Sommerfeld formula on page
804 of Terman`s 1955 opus.
It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile
from a short vertical transmitting antenna given a certain ground
conductivity and other conditions.

Best regards, Richard Harrison, KB5WZI

Richard, I have lots of books but as yet have not found the answer
even tho many have posted none appear to really have an answer other
than to throw stones. You apparently have found the answer! Could you
quote from the books that you are refering to the angle of radiation
relative to the radiator, thats it ? If you can't understand that then
relay to me the angle of a radiation front relative to a radiator, I'm
sure some other people are interested in what you found. Even better,
let me know the TOA of a dipole in free space and how much it varies
to that of the same dipole over a perfect ground. Use a computor
program if you like, anything that sheds light on the matter . The
books say that a horizontal "v" antenna should be tipped for max gain,
doesn't that raise your interest about the reasoning and mathematics
behind this? Jimmie D asked me to state this angle but I have only a
expensive computor program that doesn't give the math with the answer.
Please read off the angle and the specifics so we all can move on, I
don't want a 160 thread postings some thrust upon Walt
Art

On Tue, 27 Mar 2007 17:12:47 -0500, (Richard
Harrison) wrote:

It predicts 1 kilowatt will produce 186 mv per m at a distance of 1 mile
from a short vertical transmitting antenna given a certain ground
conductivity and other conditions.

Hi Richard,

You've missed the point of Art's pining "why?"

Explain how the conductivity of ground forces some polarization issues
- you know, the basic stuff of propagation.

73's
Richard Clark, KB7QHC

Art wrote:
"Could you quote from the books that you are referring to the angle
relative to the radiator, that`s it?"

O.K.. but the angle is relative to the horizontal in the statement.
Termans 1955 opus on page 804 says the strength of radiation from a
short vertical antenna is proportional to the cosine of the elevation
angle. That`s right because at zero angle, radiation is maximumm as
cosine of zero degrees is 1, and cosine of 90 degrees is zero.

Best regards, Richard Harrison, KB5WZI

Richard Clark, W7QHC wrote:
"-you know, the basic stuff of propagation."

I may be able to respond to a question, but I don`t write books.

On the question of ground conductivity and polarization: Soil loss makes
vertically polarized waves tilt forward in the direction of their travel
as if dragging their feet. It`s not all bad as this tilt makes a
horizontal antenna, the Beverage, receive these vertically polarized
waves well.

Best regards, Richard Harrison, KB5WZI