On 1/22/2014 5:32 PM, Irv Finkleman wrote:
Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?


Definitely. Antenna efficiency works both ways - a less efficient
antenna will affect both transmit and received signals.

Just pondering on the matter. Because I have to operate with
restricted space antennas, usually with low efficiency, I wonder how
much of a relationship exists between Efficiency and Received Signal
Strength?


Just as much as between efficiency and transmitted signal strength.

This leads to more questions such as how much do radials contribute
to efficiency?


That depends on a lot of factors such as number of radials, length,
height above ground and ground conductivity, for start. Each situation
is different. But generally, for antennas such as 1/4 wave verticals,
radials will help.

IF that isn't enough, how much do radials contribute to the bandwidth?


See above.

And...

And...

I'm never to old to learn, but I am old enough that a lot of mathematical
mumbo jumbo and Smith Charts tend to confound me!


Unfortunately, the only way to predict how an antenna is going to work
in a specific situation with any accuracy is with math and Smith Charts.
So you can use the "tried and true" method - put it up and see what
happens

For starters, I will be operating using an MP-1 antenna and a Yaesu
FT-817ND. I also have an MFJ-931 Artificial Ground, but propose
attaching the radials to the feedpoint on the MP-1. I intend to cut four
radials for 20M and spread them around the base of the antenna in
my room, and once the weather warms up, I'll try the antenna out on
the balcony with the radials spread around whatever real estate it
provides.


Not an ideal situation, but you do what you can.

Thanks for any input on the matter....

Irv VE6BP

RADIATE OR DIE TRYING!









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I'm sorry Jerry, but you don't know what you are talking about.

Smith Charts do not have anything to do with antenna efficiency or resonance.
The only thing that Smith Charts does is explain what is happening inside of a piece of coax X inches long. Note I do not use feet - since that is too vague.

On 1/23/2014 3:30 PM, Channel Jumper wrote:

Jerry Stuckle;814478 Wrote:
On 1/22/2014 5:32 PM, Irv Finkleman wrote:-
Q. Is there a relationship between the efficiency of an antenna and
the
received signal strength?
-

That depends on a lot of factors such as number of radials, length,
height above ground and ground conductivity, for start. Each situation

is different. But generally, for antennas such as 1/4 wave verticals,
radials will help.

Unfortunately, the only way to predict how an antenna is going to work
in a specific situation with any accuracy is with math and Smith Charts.

So you can use the "tried and true" method - put it up and see what
happens

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

I'm sorry Jerry, but you don't know what you are talking about.

Smith Charts do not have anything to do with antenna efficiency or
resonance.
The only thing that Smith Charts does is explain what is happening
inside of a piece of coax X inches long. Note I do not use feet -
since that is too vague.


Again, wrong. Smith Charts explain a LOT about antennas. But then I
can see you've never used one - but you have to try to correct someone
who knows more than you, anyway. But you only show your ignorance.

And BTW - I was using Smith Charts before you were born.

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On 1/24/2014 2:38 AM, Jeff wrote:

I'm sorry Jerry, but you don't know what you are talking about.

Smith Charts do not have anything to do with antenna efficiency or
resonance.
The only thing that Smith Charts does is explain what is happening
inside of a piece of coax X inches long. Note I do not use feet -
since that is too vague.

Whilst I agree with your first point, Smiths Charts do not "explain what
is happening inside of a piece of coax X inches long". They are an easy
way to plot impedances, and show what happens if you *change* the length
of coax, but more importantly they give you an easy way of working out
how to match impedances (with or without any length of coax involved).
They can also display other valuable quantities such as Q.

jeff


They do if you know how to use them properly. For instance, they will
tell you when the reactive portion of the impedance is zero (neither
capacitive nor inductive), which indicates resonance. They will also
tell you the antenna's impedance at a specific frequency. Both can be
used to indirectly determine antenna efficiency.

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On 1/25/2014 6:18 AM, Jeff wrote:

Whilst I agree with your first point, Smiths Charts do not "explain what
is happening inside of a piece of coax X inches long". They are an easy
way to plot impedances, and show what happens if you *change* the length
of coax, but more importantly they give you an easy way of working out
how to match impedances (with or without any length of coax involved).
They can also display other valuable quantities such as Q.

jeff


They do if you know how to use them properly. For instance, they will
tell you when the reactive portion of the impedance is zero (neither
capacitive nor inductive), which indicates resonance. They will also
tell you the antenna's impedance at a specific frequency. Both can be
used to indirectly determine antenna efficiency.


Rubbish, they tell you nothing more than the impedance at the point
that you wish to plot it. They tell you nothing about how well an
antenna may, or may, not radiate. A 50 ohm resistor will be purely
resistive (parasitic elements neglected) but won't radiate well. Also an
antenna does not have to resonant to radiate well or have high efficiency.

Jeff

Keep thinking that, Jeff, while those who know how to use Smith Charts
continue to design antennas.

Your ignorance is underwhelming.

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On 1/26/2014 5:09 AM, Jeff wrote:

Rubbish, they tell you nothing more than the impedance at the point
that you wish to plot it. They tell you nothing about how well an
antenna may, or may, not radiate. A 50 ohm resistor will be purely
resistive (parasitic elements neglected) but won't radiate well. Also an
antenna does not have to resonant to radiate well or have high
efficiency.

Jeff

Keep thinking that, Jeff, while those who know how to use Smith Charts
continue to design antennas.

Your ignorance is underwhelming.


Well Jerry, please help me increase my knowledge. Please tell me now to
show what "goes on *inside* a bit of coax" on a Smith chart, or how to
show the efficiency of an antenna from a Smith chart.

Jeff

I'll tell you what, troll. You go to college. Get a EE degree. Learn
the math and the theory. Them maybe you can understand basics and we
can discuss the subject intelligently (although I doubt it).

Usenet is not the place to try to teach you four years of math, physics
and electronics.

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On 1/26/2014 11:12 AM, Jeff wrote:
On 26/01/2014 15:50, Jerry Stuckle wrote:
On 1/26/2014 5:09 AM, Jeff wrote:

Rubbish, they tell you nothing more than the impedance at the point
that you wish to plot it. They tell you nothing about how well an
antenna may, or may, not radiate. A 50 ohm resistor will be purely
resistive (parasitic elements neglected) but won't radiate well.
Also an
antenna does not have to resonant to radiate well or have high
efficiency.

Jeff

Keep thinking that, Jeff, while those who know how to use Smith Charts
continue to design antennas.

Your ignorance is underwhelming.


Well Jerry, please help me increase my knowledge. Please tell me now to
show what "goes on *inside* a bit of coax" on a Smith chart, or how to
show the efficiency of an antenna from a Smith chart.

Jeff

I'll tell you what, troll. You go to college. Get a EE degree. Learn
the math and the theory. Them maybe you can understand basics and we
can discuss the subject intelligently (although I doubt it).


Been there done that, and spend 30+ designing and specifying radio
equipment, and using Smith charts.


Yea, right.

I'll take it as a "no I can't" then. Which of course is true you can't
how what "goes on *inside* a bit of coax" on a Smith chart, or how to
show the efficiency of an antenna from a Smith chart.


Nope, I'm not even going to try to teach the pig to sing, especially in
a newsgroup. But trolls don't understand that.

Try reading Mr Smith's excellent book on his Smith Chart and you might
find out what it can and can't do!!!

Jeff

Try getting your EE degree along with the math, physics and electrical
theory. Then maybe we can discuss this intelligently.

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On 1/27/2014 2:40 AM, Jeff wrote:
Jeff

Try getting your EE degree along with the math, physics and electrical
theory. Then maybe we can discuss this intelligently.


I am offering to discuss this intelligently by asking you to explain and
enlighten me as to how a Smith chart shows what "goes on inside a bit of
coax" on a Smith chart, or how to show the efficiency of an antenna from
a Smith chart, but you are the one coming back with (incorrect) personal
insults!!

Jeff

When you get the sufficient background in electronics, math and physics,
we can discuss this intelligently. Until then, it's like teaching a pig
to sing.

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Jerry Stuckle

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

Jeff wrote:

I'm sorry Jerry, but you don't know what you are talking about.

Smith Charts do not have anything to do with antenna efficiency or
resonance.
The only thing that Smith Charts does is explain what is happening
inside of a piece of coax X inches long. Note I do not use feet -
since that is too vague.

Whilst I agree with your first point, Smiths Charts do not "explain what
is happening inside of a piece of coax X inches long". They are an easy
way to plot impedances, and show what happens if you *change* the length
of coax, but more importantly they give you an easy way of working out
how to match impedances (with or without any length of coax involved).
They can also display other valuable quantities such as Q.

jeff

A Smith chart is a plot of reactance and resistance versus frequency and
can be used for just about anything, if you know how to use one.

In the case of an antenna, the chart shows what you have to match at any
particular frequency and the resonant frequency of the antenna, i.e. the
point where the reactance is zero.


--
Jim Pennino

"Jerry Stuckle" wrote in message
...
On 1/22/2014 5:32 PM, Irv Finkleman wrote:
Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?


Definitely. Antenna efficiency works both ways - a less efficient antenna
will affect both transmit and received signals.

Just pondering on the matter. Because I have to operate with
restricted space antennas, usually with low efficiency, I wonder how
much of a relationship exists between Efficiency and Received Signal
Strength?


Just as much as between efficiency and transmitted signal strength.

This leads to more questions such as how much do radials contribute
to efficiency?


That depends on a lot of factors such as number of radials, length, height
above ground and ground conductivity, for start. Each situation is
different. But generally, for antennas such as 1/4 wave verticals,
radials will help.

IF that isn't enough, how much do radials contribute to the bandwidth?


See above.

And...

And...

I'm never to old to learn, but I am old enough that a lot of mathematical
mumbo jumbo and Smith Charts tend to confound me!

Unfortunately, the only way to predict how an antenna is going to work
in a specific situation with any accuracy is with math and Smith Charts.
So you can use the "tried and true" method - put it up and see what
happens


In this case the smith chart and antenna modling programs probably won't
work. In the small confins there are too many variables in the near field
of the antenna. Not that the program would not work, but it might take
years to measuer everything in the near field of the antenna.

Like you said , the tried and true method. Put something up and see how it
works.

Often people tend to overthink a simple problem or over think a problem
there is no easy solution for.

For now, it might be just as good and easy to tack a dipole up in the
cealing of the room even if it is bent at all kinds of angles.



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