Yagi efficiency
 

Art:

OK, so I've read all of your posts, and all of the replies, but somehow,
I still don't know where you're trying to work Europe from....

Maybe I'm dense, or can't comprehend the previous posts, but the best
I've been able to find is that you have a 4000 mile path. Still, that
could be quite a number of locations, given a 4000 mile circle around
europe, though it may not really make much difference...

What bands are you trying to use?
Where are you located?
Why are you so concerned about high angle radiation? The vagarities of
multi-hop propagation often provide some really interesing contacts from
high angle radiation...

Please provide actual information, instead of vagarities...

Thanks
--Rick AH7H



art wrote:
Hans, you are so full of it, like Andy Capp waving his hands around in
the air to
vent his fraustration. Go back to the initial posting and what it says.
All of your comments refer to side issues brought up that are not
relavent to the initial question
wthich also is not a guessing game to those skilled in the art
Ar





KØHB wrote:

"Denny" wrote in message
groups.com...

You are right... You are so far ahead of this group that we can not
even comprehend the question...


Denny,

This is all apparently intended as a guessing game, as art has given us just one
single parameter of the exercise --- he wants to communicate with the UK in the
winter.

From where?

At what time(s) of day?

On what QRG(s)?

What construction constraints? (budget, zoning, etc.)

73, de Hans, K0HB
--
Homepage:
http://www.home.earthlink.net/~k0hb
Member:
ARRL http://www.arrl.org
SOC http://www.qsl.net/soc
VWOA http://www.vwoa.org
A-1 Operator Club http://www.arrl.org/awards/a1-op/
TCDXA http://www.tcdxa.org
MWA http://www.w0aa.org
TCFMC http://www.tcfmc.org
FISTS http://www.fists.org
LVDXA http://www.upstel.net/borken/lvdxa.htm
NCI http://www.nocode.org

Yagi efficiency
 

Rick my call is KB9MZ My antenna which is not of the Yagi design has a
TOA of 10 degrees and hopefully will be up before the weather gets to
cold. I am restricted in height to 120 feet So as you can see I am
pretty well committed to what array I am using. But the initial
posting was not about antennas per se but about the efficiency of the
Yagi with respect to desired radiation. Some would have you believe
that radiation
which is not within the main lobe is miniscual so I suggest you imagine
two models one of which has all lobes removed except the main lobe Do
you feel that both models now need to be labelled to avoid confusion as
they look so much alike?. As for other side comments regarding TOA I
suggest one reads the post from Mac which I whole heartedly agree with
(Thanks Mac, tried to get in touch with you a few months ago but E mail
was rejected)
Art




Rick Frazier wrote:
Art:

OK, so I've read all of your posts, and all of the replies, but somehow,
I still don't know where you're trying to work Europe from....

Maybe I'm dense, or can't comprehend the previous posts, but the best
I've been able to find is that you have a 4000 mile path. Still, that
could be quite a number of locations, given a 4000 mile circle around
europe, though it may not really make much difference...

What bands are you trying to use?
Where are you located?
Why are you so concerned about high angle radiation? The vagarities of
multi-hop propagation often provide some really interesing contacts from
high angle radiation...

Please provide actual information, instead of vagarities...

Thanks
--Rick AH7H



art wrote:
Hans, you are so full of it, like Andy Capp waving his hands around in
the air to
vent his fraustration. Go back to the initial posting and what it says.
All of your comments refer to side issues brought up that are not
relavent to the initial question
wthich also is not a guessing game to those skilled in the art
Ar





KØHB wrote:

"Denny" wrote in message
groups.com...

You are right... You are so far ahead of this group that we can not
even comprehend the question...


Denny,

This is all apparently intended as a guessing game, as art has given us just one
single parameter of the exercise --- he wants to communicate with the UK in the
winter.

From where?

At what time(s) of day?

On what QRG(s)?

What construction constraints? (budget, zoning, etc.)

73, de Hans, K0HB
--
Homepage:
http://www.home.earthlink.net/~k0hb
Member:
ARRL http://www.arrl.org
SOC http://www.qsl.net/soc
VWOA http://www.vwoa.org
A-1 Operator Club http://www.arrl.org/awards/a1-op/
TCDXA http://www.tcdxa.org
MWA http://www.w0aa.org
TCFMC http://www.tcfmc.org
FISTS http://www.fists.org
LVDXA http://www.upstel.net/borken/lvdxa.htm
NCI http://www.nocode.org

Yagi efficiency
 

It is a long time since I completed the Oxford and Cambridge entrance
exam on written english so I probably have lost some of my style
because of my under pinninings of being a Cockney It took a while
working in America to obtain communication skills but not long ago
while in San Diego I came across the college for American spoken
english
which I was unaware of. However because of a broken brain which is the
result of a heart attack it is too late for corrective action.
Fortunately I have no difficulty in the
comprehension of the main style american language which allows for a
modicom of understanding

Art


Roy Lewallen wrote:
Owen Duffy wrote:
On Fri, 22 Sep 2006 13:21:47 -0700, Roy Lewallen
wrote:


Egad. There's no point in my wasting time by attempting to contribute
further to this. I'll leave you to your alternate reality.

Roy, it was obviously a troll, and many of us have been caught
(again).

Art's lead in "one can see that the yagi is very inefficient" should
have been recognised by us all as bait.

No, whatever art's problems are, I don't believe he's a troll. I'm
confident that he's sincere in his statements and questions. It's just
that he often makes no sense to me, and when he does, it's sometimes so
contrary to established physics that it's reminiscent of the new age
folks. His unconventional use of "efficiency" is typical, like the use
of "energy" by the paraphysical crowd. Once in a while I make an honest
try to contribute something rational, but usually end up just making him
mad and provoking even sillier statements -- as happened again this
time. So there's really no point in it.

Roy Lewallen, W7EL

Yagi efficiency
 

ORIGINAL MESSAGE:

On 21 Sep 2006 19:09:38 -0700, "art" wrote:


Well this is where I am comming from, I am presently building an
antenna for this winter where I will be communicating with the U.K.
Thus my major lobe needs to be robust between about 10 degtrees and 4
degrees to ensnare most of the communication.

------------ REPLY FOLLOWS ------------

A parabolic dish about 500 feet across will fit your needs just fine.

Once again, proving how a little knowledge is a dangerous thing. As if
more proof were needed. :-)

Bill, W6WRT

Yagi efficiency
 

Some would have you believe that radiation which is not within the main
lobe is miniscual so I suggest
you imagine two models one of which has all lobes removed except the main
lobe Do
you feel that both models now need to be labelled to avoid confusion as
they look so much alike?.

How do you suggest that the power that is not in the main lobe is removed?
You either have to somehow concentrate it into the main lobe or dissipate
as heat in a load.
If you concentrate it into the main lobe then the gain of the main lobe will
go up, if you dissipate it as heat then the gain will remain the same. If
either were possible they would not look like the original yagi.

You seem to miss the point that the gain in the main lobe is effectively the
power in the area illuminated by the main lobe divided by the power in all
other directions.

Reduce the power in the sidelobes then the gain must go up, (unless it is
dissipated as heat, which is not possible in a yagi).

73
Jeff

Yagi efficiency
 

*Sigh*. Guess I'll try one more time.

Suppose that the Yagi has a front/back ratio of only 6 dB, and that the
angular span ("height" and "width") of the rear lobe is the same as that
of the front lobe.

1. Figure out how much power is contained in the rear lobe compared to
the front lobe.

2. Express that ratio in dB.

That's the amount you'd gain by eliminating all the power in the rear
lobe, and moving it into the front lobe -- if you can do it without
increasing the angular span of the front lobe.

Repeat with a 10 dB front/back ratio or whatever you think your present
Yagi has.

Now, that wasn't so hard, was it?

Roy Lewallen, W7EL

Jeff wrote:
Some would have you believe that radiation which is not within the main
lobe is miniscual so I suggest
you imagine two models one of which has all lobes removed except the main
lobe Do
you feel that both models now need to be labelled to avoid confusion as
they look so much alike?.

How do you suggest that the power that is not in the main lobe is removed?
You either have to somehow concentrate it into the main lobe or dissipate
as heat in a load.
If you concentrate it into the main lobe then the gain of the main lobe will
go up, if you dissipate it as heat then the gain will remain the same. If
either were possible they would not look like the original yagi.

You seem to miss the point that the gain in the main lobe is effectively the
power in the area illuminated by the main lobe divided by the power in all
other directions.

Reduce the power in the sidelobes then the gain must go up, (unless it is
dissipated as heat, which is not possible in a yagi).

73
Jeff

Yagi efficiency
 

On Sun, 24 Sep 2006 09:48:24 +0100, "Jeff" wrote:


You seem to miss the point that the gain in the main lobe is effectively the
power in the area illuminated by the main lobe divided by the power in all
other directions.

An unconventional definition of the term "gain".

How can there be rational discussion of principles when some people
must invent their own meaning for terms that have well defined
conventional meaning?

Owen
--

Yagi efficiency
 

You seem to miss the point that the gain in the main lobe is effectively
the
power in the area illuminated by the main lobe divided by the power in all
other directions.

An unconventional definition of the term "gain".

How can there be rational discussion of principles when some people
must invent their own meaning for terms that have well defined
conventional meaning?

Owen
--

Yagi efficiency
 

I'm sorry, I didn't say what I intended to. What I meant for step 2 was:

2. Assume for a moment that all the power was in a single front lobe.
Calculate how much, in dB, that front lobe power would be reduced by
putting the fraction in the rear lobe which you calculated in step 1.

It's been a long, long time since I took an amateur exam. But I'd think
the ability to make these calculations would be within the reach of
anyone who passed the General class exam.

Roy Lewallen, W7EL

Roy Lewallen wrote:
*Sigh*. Guess I'll try one more time.

Suppose that the Yagi has a front/back ratio of only 6 dB, and that the
angular span ("height" and "width") of the rear lobe is the same as that
of the front lobe.

1. Figure out how much power is contained in the rear lobe compared to
the front lobe.

2. Express that ratio in dB.

That's the amount you'd gain by eliminating all the power in the rear
lobe, and moving it into the front lobe -- if you can do it without
increasing the angular span of the front lobe.

Repeat with a 10 dB front/back ratio or whatever you think your present
Yagi has.

Now, that wasn't so hard, was it?

Roy Lewallen, W7EL

Yagi efficiency
 

Owen Duffy wrote:
How can there be rational discussion of principles when some people
must invent their own meaning for terms that have well defined
conventional meaning?

How about "power", Owen. Some physicists say that a
Poynting vector contains no power until some work
is done - that if an EM wave in free space never
encounters anything to which to transfer its energy,
its ExH watts are not power.

My question is: If an EM wave's ExH watts are not
power, what are those watts called? i.e. the units
of power are watts, but if in some cases, watts are
not power, what are they?
--
73, Cecil http://www.w5dxp.com