A short 160M antenna
 

I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.



--
Jim Pennino

A short 160M antenna
 

On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

--

Rick

A short 160M antenna
 

rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

The effective height of an antenna multiplied by the incident electric
field strength gives the terminal voltage at the antenna feed.

--
Jim Pennino

A short 160M antenna
 

On 11/5/2014 9:32 PM, wrote:
rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

How do you determine the "height of the antenna's center of radiation
above the ground"?

The effective height of an antenna multiplied by the incident electric
field strength gives the terminal voltage at the antenna feed.



--

Rick

A short 160M antenna
 

rickman wrote:
On 11/5/2014 9:32 PM, wrote:
rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

How do you determine the "height of the antenna's center of radiation
above the ground"?

http://personal.ee.surrey.ac.uk/Pers...nnaheight.html
http://en.wikipedia.org/wiki/Effective_height

In depth treatment:

http://tinyurl.com/lfee64g



--
Jim Pennino

A short 160M antenna
 

On 11/5/2014 10:37 PM, wrote:
rickman wrote:
On 11/5/2014 9:32 PM, wrote:
rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

How do you determine the "height of the antenna's center of radiation
above the ground"?

http://personal.ee.surrey.ac.uk/Pers...nnaheight.html
http://en.wikipedia.org/wiki/Effective_height

In depth treatment:

http://tinyurl.com/lfee64g

I didn't ask for links. I'm asking you for a specific reason.

Your first link relates the effective height to the "actual height"
without explaining just what that is.

Your second link simply states the same words that you used.

Your third reference seems to be referring to transmitting antenna and
does not relate this property to the antenna itself.

How do you determine the "height of the antenna's center of radiation
above the ground" given the physical parameters of an antenna?

The effective height is a parameter that indicates the effectiveness of
a receiving antenna. I dug into this for a loop antenna and it is a
function of the diameter, the number of turns and if any magnetic
material is used, the properties of that. I'm wondering what the nature
of the equations are for other antennas?

--

Rick

A short 160M antenna
 

On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

A short 160M antenna
 

On 11/5/2014 6:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

I'm looking forward to it, Jim. It should be enlightening.

John

A short 160M antenna
 

On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?

--

Rick

A short 160M antenna
 

On 11/6/2014 10:52 AM, rickman wrote:
On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I have not used an equation. I used EZNEC. You can get a free trial
version. It has limitations, but no time limit IIRC.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?


In receiving, it seems that size matters when it comes to small antennas
like we are discussing.

If you could increase the (receiver) input impedance you will get more
voltage. No matter what you do, you cannot increase the power received
except by refining your system. The (volts/meter)^2 is fixed. It is up
you to capture the available signal. And, I think it will take somewhat
heroic efforts at your frequency of interest.

BTW, have you seen the extremely tiny ferrite rod antennas used in the
so-called Atomic wris****ches?

A short 160M antenna
 

"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

A short 160M antenna
 

On 11/6/2014 12:11 PM, John S wrote:
On 11/6/2014 10:52 AM, rickman wrote:
On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that
correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I have not used an equation. I used EZNEC. You can get a free trial
version. It has limitations, but no time limit IIRC.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?


In receiving, it seems that size matters when it comes to small antennas
like we are discussing.

If you could increase the (receiver) input impedance you will get more
voltage. No matter what you do, you cannot increase the power received
except by refining your system. The (volts/meter)^2 is fixed. It is up
you to capture the available signal. And, I think it will take somewhat
heroic efforts at your frequency of interest.

The power "received" may be a given for the antenna, but the power (or
voltage) delivered to the receiver is not set in the same way.

BTW, have you seen the extremely tiny ferrite rod antennas used in the
so-called Atomic wris****ches?

Yes, but they are not optimal for my application where I need as large a
voltage as possible. If I end up using a preamp I may consider using a
ferrite antenna.

--

Rick

A short 160M antenna
 

rickman wrote:
On 11/5/2014 10:37 PM, wrote:
rickman wrote:
On 11/5/2014 9:32 PM, wrote:
rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

How do you determine the "height of the antenna's center of radiation
above the ground"?

http://personal.ee.surrey.ac.uk/Pers...nnaheight.html
http://en.wikipedia.org/wiki/Effective_height

In depth treatment:

http://tinyurl.com/lfee64g

I didn't ask for links. I'm asking you for a specific reason.

That is all well and good, but if you look at the last link you will
see the answer is not all that simple.

Your first link relates the effective height to the "actual height"
without explaining just what that is.

Your second link simply states the same words that you used.

They were both simplifications which is why there is the third link.

Your third reference seems to be referring to transmitting antenna and
does not relate this property to the antenna itself.

It is referring to antenas, which are reciprocal devices.

How do you determine the "height of the antenna's center of radiation
above the ground" given the physical parameters of an antenna?

You do all the math shown in the third link, or for simple antennas
you make some simplifying assumptions and get a reasonable approximation
as discussed in the second link.

The effective height is a parameter that indicates the effectiveness of
a receiving antenna. I dug into this for a loop antenna and it is a
function of the diameter, the number of turns and if any magnetic
material is used, the properties of that. I'm wondering what the nature
of the equations are for other antennas?

All the links apply to all antennas.


--
Jim Pennino

A short 160M antenna
 

rickman wrote:
On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?

All antennas are reciprocal.

One result of that is that if a given voltage at input produces a particular
field, the same field will produce the same voltage upon receiving and
the terminal voltage and field are related by the effective height as
discussed at length in the third link I gave you.

In the second link I gave you it says:

"For an antenna with a symmetrical current distribution, the center of
radiation is the center of the distribution."


--
Jim Pennino

A short 160M antenna
 

On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

I will answer your question if you can tell me the efficiency of an
isotropic radiator.

A short 160M antenna
 

rickman wrote:
On 11/6/2014 12:11 PM, John S wrote:
On 11/6/2014 10:52 AM, rickman wrote:
On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that
correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I have not used an equation. I used EZNEC. You can get a free trial
version. It has limitations, but no time limit IIRC.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?


In receiving, it seems that size matters when it comes to small antennas
like we are discussing.

If you could increase the (receiver) input impedance you will get more
voltage. No matter what you do, you cannot increase the power received
except by refining your system. The (volts/meter)^2 is fixed. It is up
you to capture the available signal. And, I think it will take somewhat
heroic efforts at your frequency of interest.

The power "received" may be a given for the antenna, but the power (or
voltage) delivered to the receiver is not set in the same way.

The voltage delivered to the receiver is determined by Ohms Law.

The antenna is a voltage source in series with the impedance of the
antenna.

If voltage = E, impedance = Ri, receiver impedance = Rl, then the
receiver voltage is (E * Rl)/(Ri + Rl).



--
Jim Pennino

A short 160M antenna
 

On 11/6/2014 11:33 AM, rickman wrote:
On 11/6/2014 12:11 PM, John S wrote:
On 11/6/2014 10:52 AM, rickman wrote:
On 11/6/2014 11:08 AM, John S wrote:
On 11/5/2014 7:16 PM, rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got
what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I
seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the
same
and does relate directly to the length of the antenna. Is that
correct?

I ran a simulation to confirm that the received signal is some function
of the length of a wire antenna. My model was a 6 foot zero-loss
wire 10
miles from the source with a load of 1000 ohms. The frequency is 1MHz.

Wire length Volts received
6' 0.001499
12' 0.005408

So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

Is this what you wanted to know?

That is a nice experimental verification. I guess I figured this is the
sort of thing that there would be an equation for. A loop antenna has a
simple equation defining its effective height (ability to convert the
field to a voltage). I expect there is a similar equation for each
antenna type.

I have not used an equation. I used EZNEC. You can get a free trial
version. It has limitations, but no time limit IIRC.

I guess the point is that for receiving it is important to match the
size of the antenna to the signal to receive the maximum power. Or is
there something equivalent to the matching network that would equalize
the power received? In your example you said you used a 1000 ohm load.
Is there a way to improve the signal from the shorter antenna?


In receiving, it seems that size matters when it comes to small antennas
like we are discussing.

If you could increase the (receiver) input impedance you will get more
voltage. No matter what you do, you cannot increase the power received
except by refining your system. The (volts/meter)^2 is fixed. It is up
you to capture the available signal. And, I think it will take somewhat
heroic efforts at your frequency of interest.

The power "received" may be a given for the antenna, but the power (or
voltage) delivered to the receiver is not set in the same way.

Yes. I mentioned that a larger impedance load (the receiver input
impedance) would result in a greater voltage. For example, the voltage
available at the receiver terminals in my previous post was 0.001499 V
for the 6' wire and 1000 ohms load. If I now increase the impedance to
1Meg + j0, the voltage is 0.01666 V, more than 10 times as much.

Is that what you mean?

BTW, have you seen the extremely tiny ferrite rod antennas used in the
so-called Atomic wris****ches?

Yes, but they are not optimal for my application where I need as large a
voltage as possible. If I end up using a preamp I may consider using a
ferrite antenna.

Very well, I understand.

John

A short 160M antenna
 

"John S" wrote in message
...
On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures
about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

I will answer your question if you can tell me the efficiency of an
isotropic radiator.

As for all religion, an isotropic radiator is make-believe, and like all
religions, you can make up whatever you choose to be your story.

A short 160M antenna
 

"gareth" wrote in message
...
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator.

So, can I expect an apology from all the Yanks who badmouthed me
in order to try to hide their own ignorance on the matter?

A short 160M antenna
 

On 7/11/2014 9:31 AM, gareth wrote:
"gareth" wrote in message
...
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator.

So, can I expect an apology from all the Yanks who badmouthed me
in order to try to hide their own ignorance on the matter?



doubtful
you are no matter other mistakes a foolish troll

A short 160M antenna
 

On 11/6/2014 1:19 PM, wrote:
rickman wrote:
On 11/5/2014 10:37 PM, wrote:
rickman wrote:
On 11/5/2014 9:32 PM, wrote:
rickman wrote:
On 11/5/2014 7:28 PM, wrote:
I started to do some modeling on a short antenna for 160M and got what
I think are interesting results.

I will post those as soon as I get a chance to write up all the data.

All this stuff for short antenna is in the context of transmissions,
right? For receiving a short antenna is at a disadvantage, no? I seem
to recall a parameter called "effective height". For loop antenna it
pertains to the signal collected irrespective of the actual dimensions
of the loop. For other types of antenna I assume this is not the same
and does relate directly to the length of the antenna. Is that correct?

All antennas made of linear material are reciprocal in all properties.

The only antennas I know of that include non-linear material are some
microwave antennas with ferrite components.

Generally effective height is the height of the antenna's center of
radiation above the ground.

How do you determine the "height of the antenna's center of radiation
above the ground"?

http://personal.ee.surrey.ac.uk/Pers...nnaheight.html
http://en.wikipedia.org/wiki/Effective_height

In depth treatment:

http://tinyurl.com/lfee64g

I didn't ask for links. I'm asking you for a specific reason.

That is all well and good, but if you look at the last link you will
see the answer is not all that simple.

Your first link relates the effective height to the "actual height"
without explaining just what that is.

Your second link simply states the same words that you used.

They were both simplifications which is why there is the third link.

Your third reference seems to be referring to transmitting antenna and
does not relate this property to the antenna itself.

It is referring to antenas, which are reciprocal devices.

How do you determine the "height of the antenna's center of radiation
above the ground" given the physical parameters of an antenna?

You do all the math shown in the third link, or for simple antennas
you make some simplifying assumptions and get a reasonable approximation
as discussed in the second link.

The effective height is a parameter that indicates the effectiveness of
a receiving antenna. I dug into this for a loop antenna and it is a
function of the diameter, the number of turns and if any magnetic
material is used, the properties of that. I'm wondering what the nature
of the equations are for other antennas?

All the links apply to all antennas.

Yes, I could also start with Maxwell's equations and solve it all
myself. I didn't ask for a complete analysis of an antenna, I asked for
the way that the effective height of a given antenna is determined.

I think the topic is moot now.

--

Rick

A short 160M antenna
 

On Fri, 07 Nov 2014 10:47:36 +1000, atec77 wrote:

On 7/11/2014 9:31 AM, gareth wrote:
"gareth" wrote in message
...
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures
about 3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna
is an inefficient radiator.

So, can I expect an apology from all the Yanks who badmouthed me in
order to try to hide their own ignorance on the matter?



doubtful
you are no matter other mistakes a foolish troll

He's a deeply unpleasant, deliberately disruptive, dunce.

A short 160M antenna
 

On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

No, not at all. If the kind of reciprocity to which you refer were true,
then the receiving antenna would capture ALL the power radiated. That
obviously cannot be, so I think your idea of reciprocity may be a bit
flawed.

A short 160M antenna
 

"John S" wrote in message
...
On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures
about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

No, not at all. If the kind of reciprocity to which you refer were true,
then the receiving antenna would capture ALL the power radiated.

Non-sequitur

A short 160M antenna
 

On 07/11/2014 12:03, John S wrote:
On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures
about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

No, not at all. If the kind of reciprocity to which you refer were true,
then the receiving antenna would capture ALL the power radiated. That
obviously cannot be, so I think your idea of reciprocity may be a bit
flawed.


His whole grasp of antenna theory is flawed.

He was trying to (indirectly) argue the other day via his his
interpretation of Maxwell's Equations you could generate an EM wave
by waving a magnet about. When corrected, he introduced another
variation.

A short 160M antenna
 

"Brian Reay" wrote in message
...

His whole grasp of antenna theory is flawed.
He was trying to (indirectly) argue the other day via his his
interpretation of Maxwell's Equations you could generate an EM wave
by waving a magnet about. When corrected, he introduced another
variation.

Well, Brian, M3OSN, Old Chum, as was pointed out to you, all of your
posts these days are personal attacks aimed at one or another.

Why do you behave like that?

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.

A short 160M antenna
 

rickman wrote:

snip

Yes, I could also start with Maxwell's equations and solve it all
myself. I didn't ask for a complete analysis of an antenna, I asked for
the way that the effective height of a given antenna is determined.

And I gave you several links that tell you exactly that.

I'm sorry it didn't boil down to a trivial equation.


--
Jim Pennino

A short 160M antenna
 

On 11/8/2014 1:20 AM, wrote:
rickman wrote:

snip

Yes, I could also start with Maxwell's equations and solve it all
myself. I didn't ask for a complete analysis of an antenna, I asked for
the way that the effective height of a given antenna is determined.

And I gave you several links that tell you exactly that.

I'm sorry it didn't boil down to a trivial equation.

I must have missed that. What I saw was a fundamental analysis of
antennas. Yes, I am looking for an equation similar to what I found for
the loop antenna. Every design of antenna has a similar simple
description.

--

Rick

A short 160M antenna
 

In rec.radio.amateur.antenna gareth wrote:
"Brian Reay" wrote in message
...

His whole grasp of antenna theory is flawed.
He was trying to (indirectly) argue the other day via his his
interpretation of Maxwell's Equations you could generate an EM wave
by waving a magnet about. When corrected, he introduced another
variation.

Well, Brian, M3OSN, Old Chum, as was pointed out to you, all of your
posts these days are personal attacks aimed at one or another.

Why do you behave like that?

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.

No, that point is utterly, completely, and absolutely false and goes
once again to show you have no clue as to the difference between an
electric field, a magnetic field, and an electromagnetic field.


--
Jim Pennino

A short 160M antenna
 

"gareth" wrote in message
...
"Brian Reay" wrote in message
...
His whole grasp of antenna theory is flawed.
He was trying to (indirectly) argue the other day via his his
interpretation of Maxwell's Equations you could generate an EM wave
by waving a magnet about. When corrected, he introduced another
variation.

Well, Brian, M3OSN, Old Chum, as was pointed out to you, all of your
posts these days are personal attacks aimed at one or another.

Why do you behave like that?

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.

I think your arms would start to ache quite quickly.
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk

A short 160M antenna
 

John S wrote in :

On 11/6/2014 11:33 AM, gareth wrote:
"John S" wrote in message
...
So, it appears that doubling the length of a short antenna captures about
3.6 times the signal.

And, therefore, by the reciprocity characteristic, the short antenna is
an inefficient radiator?

No, not at all. If the kind of reciprocity to which you refer were true,
then the receiving antenna would capture ALL the power radiated. That
obviously cannot be, so I think your idea of reciprocity may be a bit
flawed.


Jim said something the other day that made it clearest for me. He said (of
reciprocity, and not verbatim) that if some field arriving at an antenna
created some electrical signal at its feed point, then recreating that signal
would recreate that field at the antenna itself. My interpretation of that is
that while a receiving antenna, made bigger, captures more energy from a
diverging field from another source, this cannot be equated with transmission
where the whole energy source is transmitted from the antenna regardless of
size if impedance matching is good.

A short 160M antenna
 

"FranK Turner-Smith G3VKI" wrote in
:

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.

I think your arms would start to ache quite quickly.


:) Just a tad...

Why would waving a magnet, at ANY speed, do it? I never heard of such. Got to
be a stationary conductor involved too, somewhere very nearby. The speed
would have far less to do with anything than the matching of kinetic energy
into the conductor, and the matching of that to whatever part of that
conductor is an antenna.

A magnet moving on its own reminds me of the question 'what is the sound of
one hand clapping?'

A short 160M antenna
 

"gareth" wrote in message

Certainly, as I corrected myself, if you wave a magnet about fast enough,
say, 1000,000,000 times per second, you will certainly generate an EM wave
and no-one has corrected me on that point because that point is true.


If it were true, then you'd be able to make a steel teaspoon stick to a
transmitting antenna made of copper as if that copper were a magnet. I don't
think that will happen.

A short 160M antenna
 

Brian Reay wrote in
:

Why would waving a magnet, at ANY speed, do it? I never heard of such.
Got to be a stationary conductor involved too, somewhere very nearby.
The speed would have far less to do with anything than the matching of
kinetic energy into the conductor, and the matching of that to whatever
part of that conductor is an antenna.

Not a moving conductor, a changing electric field.


I mentioned stationary conductor, but my example was not rigorous..

He also seems to think that it is frequency which determines if it is an
EM wave, why else the
comment re fast enough. You can have a ELF radio wave, I know of
amateurs with NoVs to operate
around 9kHz.


Exactly so. That's what I was gettign at, that speed in itself means nothing,
it only becomes important when calculations need a frequency.


A magnet moving on its own reminds me of the question 'what is the
sound of one hand clapping?'

An apt comment.


:)

A short 160M antenna
 

Brian Reay wrote in news:835469977437141262.223254no.sp-
:

I think your arms would start to ache quite quickly.

I wonder what he would expect if he waved a battery about.


I'd expect muscle crapms, and if persistent, arthritis.

A short 160M antenna
 

On Sat, 08 Nov 2014 06:41:10 -0600, Lostgallifreyan wrote:

An apt comment.



And somewhat too deep for this conversation :-)



--
M0WYM

A short 160M antenna
 

"Brian Reay" wrote in message
...

He isn't the first fool to think he could generate an EM wave breaking
Maxwell's laws.

You continue to be the one who originates ths abuse that you seek to lay at
others'
door, and you continue to misunderstand Maxwell.

The changing magnetic field cause by rotating a magent at such a speed that
it would cease to be a short antennae will create a changing electric field,
as described by Maxwell

He also seems to think that it is frequency which determines if it is an
EM
wave, why else the
comment re fast enough.

Once again you misunderstand, and knowing you, it is a deliberate
misunderstanding
to give you the chance to be abusive. As to fast enough, see the comment
above re
no longer bing a short antenna.

A magnet moving on its own reminds me of the question 'what is the sound
of
one hand clapping?'
An apt comment.

Two ignoramuses do not make for a knowledgeable person.

A short 160M antenna
 

"Brian Reay" wrote in message
...

I wonder what he would expect if he waved a battery about.

I expect that you would use it as an excuse to heap abuse in my direction.

A short 160M antenna
 

On Sat, 08 Nov 2014 17:46:57 +0000, gareth wrote:


Two ignoramuses do not make for a knowledgeable person.

Neither does one really fat ignoramus, so it seems.

A short 160M antenna
 

In rec.radio.amateur.antenna gareth wrote:
"Brian Reay" wrote in message
...

He isn't the first fool to think he could generate an EM wave breaking
Maxwell's laws.

You continue to be the one who originates ths abuse that you seek to lay at
others'
door, and you continue to misunderstand Maxwell.

The changing magnetic field cause by rotating a magent at such a speed that
it would cease to be a short antennae will create a changing electric field,
as described by Maxwell

Babbling nonsense, gas bag, and if you actually understood Maxwell you
would know why.

He also seems to think that it is frequency which determines if it is an
EM
wave, why else the
comment re fast enough.

Once again you misunderstand, and knowing you, it is a deliberate
misunderstanding
to give you the chance to be abusive. As to fast enough, see the comment
above re
no longer bing a short antenna.

Yet more babbling nonsense, gas bag.

A permenant magnet is NOT an antenna of any sort.


--
Jim Pennino