It may be recalled I recently reported an error in program GRNDWAV3
which deals with groundwave propagation from a short vertical antenna
versus frequency and type of terrain.

Although the field strength at the receiving site was correctly
computed, the available receiver input power was exactly 6 dB greater
than it should be.

The error was due to a misunderstanding of vertical antenna gain
relative to an isotrope when mounted above a groundplane. It appears
some of the learned text books are unclear on this point.

My immediate problem was eventually sorted out by Roy and proved by
EZNEC-type programs which are not interested in man-made notions about
antenna gain and isotropes.

The faulty program has now been replaced by program GRNDWAV4 which
makes no use of antenna gains at either end of the path. Download it
and delete the older version.

I am grateful to Icelandic radio amateur, Villi, TF3DX for informing
me of the error. He went back to fundamental principles to prove me
wrong. I have no idea what aroused his suspicions and we are not in
contact with each other at present. He said he intended to write a
paper on the subject.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

"Reg Edwards" wrote in message
...
It may be recalled I recently reported an error in program GRNDWAV3
which deals with groundwave propagation from a short vertical antenna
versus frequency and type of terrain.

Although the field strength at the receiving site was correctly
computed, the available receiver input power was exactly 6 dB greater
than it should be.

The error was due to a misunderstanding of vertical antenna gain
relative to an isotrope when mounted above a groundplane. It appears
some of the learned text books are unclear on this point.

My immediate problem was eventually sorted out by Roy and proved by
EZNEC-type programs which are not interested in man-made notions about
antenna gain and isotropes.

The faulty program has now been replaced by program GRNDWAV4 which
makes no use of antenna gains at either end of the path. Download it
and delete the older version.

I am grateful to Icelandic radio amateur, Villi, TF3DX for informing
me of the error. He went back to fundamental principles to prove me
wrong. I have no idea what aroused his suspicions and we are not in
contact with each other at present. He said he intended to write a
paper on the subject.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp

Thanks Reg. My NEC2 agreed with your previous program, so do not know where
I went wrong. Will try and figure it out.

Regards,

Frank

Thanks Reg. My NEC2 agreed with your previous program, so do not
know where
I went wrong. Will try and figure it out.

Regards,

Frank
==========================================

Frank,

The situation changes by the hour so I suggest you don't spend a great
deal of time trying to sort things out. Either the program is in error
or you have entered incorrect data. Or (see below) both you and I have
the correct answer in the first place.

From the situation at present we have :-

It seems the numerous Bibles written by learned professors don't agree
on the subject.

Computer programs, whose results are falsely taken as being gospel
truths, don't agree on the subject.

The 'experts' who contribute to this newsgroup can't agree on the
subject. But, from the frequency of arguments which result. this is
perfectly normal.

I remain as an innocent, neutral bystander, in danger of being
unjustly accused of being a troll, whereas -

All I need is an answer to my simple but essentially fundamental and
practical question -

"What is the voltage measured between the bottom end of a 1 metre high
vertical antenna and ground, when the field strength is 1 volt per
metre?"

It goes without saying, a perfect ground is assumed, the antenna
height is less than 1/4-wavelength and the radio wave is vertically
polarised.

Is the measured voltage 1 volt or is it 0.5 volts?

There's a simple factor of 2 involved somewhere. Should I take a
statistical average of the replies if there are any?

What happens on an isolated dipole is irrevalant. It is just a
time-wasting diversion.

I don't have access to the 'learned Bibles' or to computer programs
(except my own). So there is no point in referring to them. But I
don't consider this to be any handicap. Short, logical, convincing
explanations in plain English and perhaps a little arithmetic would be
welcome of course.
----
Reg, G4FGQ.

As I said, I do not have access to the many ancient, learned volumes
about radio transmission and antennas. Or to the many computer
programs.

But I do recall mention of "Effective Height" of vertical antennas
which has NOT been mentioned in the numerous prolonged threads on this
newsgroup about the relationship between receiver input power and
field strength.

What "Effective Height" means may be vague. But some sort of a
definition may be a clue to solving my problem. Don't mention
Marconi, Terman, Kraus, Balani, et al.,
----
Reg, G4FGQ

On Fri, 16 Dec 2005 17:57:08 +0000 (UTC), "Reg Edwards"
wrote:

I remain as an innocent, neutral bystander, in danger of being
unjustly accused of being a troll, whereas -
....
There's a simple factor of 2 involved somewhere.

Hmm, I asked a simple question involving your arbitrary use of a
factor of two (2) and you dismissed it as my "anger," or somesuch
clumsy diversion.

Most of your correspondence has been tainted with trolling, what is
different in this case?

Sorry, that is now two (2) simple questions which, no doubt, you will
find undecipherable. Don't worry, we are all capable of observing
that given Richard H. directly responded to your question with a
straight answer - your lack of returning to him puts this troll
squarely at your doorstep.

As for your observation (if it quacks like a troll...):
Computer programs, whose results are falsely taken as being gospel
truths, don't agree on the subject.
it seems you are now the author of two (2) such programs that covers
both sides of the argument. I suppose the chance of being 50% right
outweighs the risk of being 100% wrong. ;-)

That, of course, presumes an insecure perspective (which is validated
by having two answers for any question - rather returns us to your
typical trolls, doesn't it?).

Lord Kelvinator is winding up another pitch to wing a chunk of
railroad chalk off your noggin'. Watching you duck throughout these
threads has become an amusing prospect.

Thanx for the entertainment,
Richard Clark, KB7QHC

Punchinello has no time to waste on drivel and says "phooey".

As I said, I do not have access to the many ancient, learned volumes
about radio transmission and antennas. Or to the many computer
programs.

But I do recall mention of "Effective Height" of vertical antennas
which has NOT been mentioned in the numerous prolonged threads on this
newsgroup about the relationship between receiver input power and
field strength.

What "Effective Height" means may be vague. But some sort of a
definition may be a clue to solving my problem. Don't mention
Marconi, Terman, Kraus, Balani, et al.,
----
Reg, G4FGQ

Repeating what was previously posted. The following model treats a 1 meter
(perfect conductor) monopole, of 0.814 mm diameter, connected to a perfectly
conducting ground. I have applied a vertically polarized incident E-field
of 1 V/m (peak). The base of the antenna is loaded with the antennas
complex conjugate of 1.747 + j823.796. NEC2 computes the current through
the load ast 0.2863 Amps (peak), which is 0.5001 V peak. This appears to
agree with Reg's program.

Possibly someone can point out if there are any errors in the following
code:

CM 1 Meter Vertical
CE
GW 1 50 0 0 1 0 0 0 0.000814
GS 0 0 1
GE 1
GN 1
EX 1 1 1 0 90 0 0 1 1 1
LD 4 1 50 50 1.747 823.796
FR 0 3 0 0 19.9 0.1
RP 0 181 1 1000 -90 90 1.00000 1.00000
EN

Regards,

Frank

Hopefully my recent posting on the "Antenna reception theory" thread
will clarify things a bit.

Roy Lewallen, W7EL

Reg Edwards wrote:

Frank,

The situation changes by the hour so I suggest you don't spend a great
deal of time trying to sort things out. Either the program is in error
or you have entered incorrect data. Or (see below) both you and I have
the correct answer in the first place.

From the situation at present we have :-

It seems the numerous Bibles written by learned professors don't agree
on the subject.

Computer programs, whose results are falsely taken as being gospel
truths, don't agree on the subject.

The 'experts' who contribute to this newsgroup can't agree on the
subject. But, from the frequency of arguments which result. this is
perfectly normal.

I remain as an innocent, neutral bystander, in danger of being
unjustly accused of being a troll, whereas -

All I need is an answer to my simple but essentially fundamental and
practical question -

"What is the voltage measured between the bottom end of a 1 metre high
vertical antenna and ground, when the field strength is 1 volt per
metre?"

It goes without saying, a perfect ground is assumed, the antenna
height is less than 1/4-wavelength and the radio wave is vertically
polarised.

Is the measured voltage 1 volt or is it 0.5 volts?

There's a simple factor of 2 involved somewhere. Should I take a
statistical average of the replies if there are any?

What happens on an isolated dipole is irrevalant. It is just a
time-wasting diversion.

I don't have access to the 'learned Bibles' or to computer programs
(except my own). So there is no point in referring to them. But I
don't consider this to be any handicap. Short, logical, convincing
explanations in plain English and perhaps a little arithmetic would be
welcome of course.
----
Reg, G4FGQ.

Frank wrote:

Repeating what was previously posted. The following model treats a 1 meter
(perfect conductor) monopole, of 0.814 mm diameter, connected to a perfectly
conducting ground. I have applied a vertically polarized incident E-field
of 1 V/m (peak). The base of the antenna is loaded with the antennas
complex conjugate of 1.747 + j823.796. NEC2 computes the current through
the load ast 0.2863 Amps (peak), which is 0.5001 V peak. This appears to
agree with Reg's program.
. . .

Possibly someone can point out if there are any errors in the following
code:

CM 1 Meter Vertical
CE
GW 1 50 0 0 1 0 0 0 0.000814
GS 0 0 1
GE 1
GN 1
EX 1 1 1 0 90 0 0 1 1 1
LD 4 1 50 50 1.747 823.796
FR 0 3 0 0 19.9 0.1
RP 0 181 1 1000 -90 90 1.00000 1.00000
EN

You've specified a plane wave of 1 V/m peak arriving in a horizontal
direction over a ground plane. This results in a field strength of 2 V/m
peak at the antenna. For more information about this, look at my
postings over the last couple of weeks on the thread "Antenna reception
theory".

Roy Lewallen, W7EL

I can no longer resist the urge....

As with most things: it depends.

The whole antenna world knows that a short, thin, uniform metal rod that is
normal to a conducting plane has an open circuit voltage at its base that is
equal to one half of the size of the incident vertically polarized E field
multiplied by the rod's length. Such an antenna has a "height" that is one
half of its physical length.

Note: open circuit voltage
Note: short - less than 0.1 WL
Note: the current distribution of the subject rod tapers linearly to
zero at the distant end of the rod
Note: the voltage or power delivered to something other than an open
circuit is not discussed
Note: many references that discuss short rods are assuming a constant
current along the rod's length - such rods have a "height" equal to their
physical length

I have dealt with approximations of the subject device. In each case,
an extremely high input impedance amplifying device is placed at the base of
the antenna that has a known voltage amplification and a 50 ohm output
impedance. Knowing that a close approximation of the open circuit voltage
is amplified by a known amount, a calibrated, tuned voltmeter (at 50 ohms)
is able to measure the size of vertically polarized E (with the usual
uncertainties). (and a bit of arithmetic)

73 Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
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