On Saturday, November 15, 2014 7:01:13 PM UTC-6, FBMboomer wrote:
On 11/15/2014 6:23 PM, wrote:
On Saturday, November 15, 2014 5:25:01 PM UTC-6, FBMboomer wrote:

Yes, smaller is better. I strongly encourage you to use 1/4 inch
antennas. It is like homeopathy, less is more powerful. Getting your
antenna length down to microns is the answer.

Are you suggesting I use a 33 ft tall mobile antenna?
Or are you just being silly because you have no other alternatives?


If a short antenna is just as good as a full size dipole, than why not
use a 1/4 inch antenna. Or might there be something said for large full
size antennas? Or could it be, size actually matters.

Who ever said a short antenna is just as good as a full size version?
Certainly not I. I only corrected your confusion about the reason for
a lack of system efficiency with the usual garden variety G5RV.
And it's not the first time I've attempted to correct your false ideas
concerning that particular antenna.
It seems to enter into one side of your brain pan, and exit the other
side in an awful quick hurry, without bearing any fruit in the middle.

Trust me, the shortcomings in using a G5RV on 75m CAN be corrected if
one does away with the lousy method many use to feed them on that band.
The garden variety G5RV fed in the usual manner was never really intended
to be used on 75m in the first place. But you CAN change the feed method
so it can be quite efficient on that band. The slightly shorter length
of the radiator is not the reason for the usual lower *system efficiency*
with the typical "designed for 20m" G5RV being used on 75m, vs a full
size dipole.

You could use a 130 ft full size radiator, but if one feeds it in the
same perverted manner IE: coax to choke to ladder line, it will suffer
excess feeder losses also, same as the 102 ft G5RV radiator.

On 75m, I use full size dipoles or turnstiles fed with coax. An *antenna
system* so efficient it really can't be beat unless you used a tuned open
line feeder with no antenna tuner involved. The differences between the
two would likely be undetectable on the air on that band.
On VHF/UHF, you would notice more of a difference, with the tuned open
wire feeder being the most efficient system by a noticeable amount.

You can feed a full size loop in the same manner, with the same high
system efficiency on the band it's cut for. You might need to add a
short length of 75 ohm coax as a series transformer to better match the
slightly higher 75-100 ohm feed point if one has a picky transmitter,
but coax series transformers add very little loss in such a case.

The main reason I use full size dipoles is not some magical property
with that length radiator. It's because it allows me to use a highly
efficient method of feeding, with no tuner involved to add loss.
Which means that most of my power makes it to the radiator, instead
of turning into heat on the way to it, as with the usual improperly
fed G5RV many try to use on 75m.

In the past, you admitted you don't know too much antenna theory, but
like the one who shalt not be mentioned, you seem to have a problem
taking the the advice of people who do, and instead retort with pure
silliness.

On 11/15/2014 8:52 PM, wrote:
On Saturday, November 15, 2014 7:01:13 PM UTC-6, FBMboomer wrote:
On 11/15/2014 6:23 PM, wrote:
On Saturday, November 15, 2014 5:25:01 PM UTC-6, FBMboomer wrote:

Yes, smaller is better. I strongly encourage you to use 1/4 inch
antennas. It is like homeopathy, less is more powerful. Getting your
antenna length down to microns is the answer.

Are you suggesting I use a 33 ft tall mobile antenna?
Or are you just being silly because you have no other alternatives?


If a short antenna is just as good as a full size dipole, than why not
use a 1/4 inch antenna. Or might there be something said for large full
size antennas? Or could it be, size actually matters.

Who ever said a short antenna is just as good as a full size version?
Certainly not I. I only corrected your confusion about the reason for
a lack of system efficiency with the usual garden variety G5RV.
And it's not the first time I've attempted to correct your false ideas
concerning that particular antenna.
It seems to enter into one side of your brain pan, and exit the other
side in an awful quick hurry, without bearing any fruit in the middle.

Trust me, the shortcomings in using a G5RV on 75m CAN be corrected if
one does away with the lousy method many use to feed them on that band.
The garden variety G5RV fed in the usual manner was never really intended
to be used on 75m in the first place. But you CAN change the feed method
so it can be quite efficient on that band. The slightly shorter length
of the radiator is not the reason for the usual lower *system efficiency*
with the typical "designed for 20m" G5RV being used on 75m, vs a full
size dipole.

You could use a 130 ft full size radiator, but if one feeds it in the
same perverted manner IE: coax to choke to ladder line, it will suffer
excess feeder losses also, same as the 102 ft G5RV radiator.

On 75m, I use full size dipoles or turnstiles fed with coax. An *antenna
system* so efficient it really can't be beat unless you used a tuned open
line feeder with no antenna tuner involved. The differences between the
two would likely be undetectable on the air on that band.
On VHF/UHF, you would notice more of a difference, with the tuned open
wire feeder being the most efficient system by a noticeable amount.

You can feed a full size loop in the same manner, with the same high
system efficiency on the band it's cut for. You might need to add a
short length of 75 ohm coax as a series transformer to better match the
slightly higher 75-100 ohm feed point if one has a picky transmitter,
but coax series transformers add very little loss in such a case.

The main reason I use full size dipoles is not some magical property
with that length radiator. It's because it allows me to use a highly
efficient method of feeding, with no tuner involved to add loss.
Which means that most of my power makes it to the radiator, instead
of turning into heat on the way to it, as with the usual improperly
fed G5RV many try to use on 75m.

In the past, you admitted you don't know too much antenna theory, but
like the one who shalt not be mentioned, you seem to have a problem
taking the the advice of people who do, and instead retort with pure
silliness.


Very good reply. Well stated. However, I do not take the advice of those
who use what are supposed to be antenna modelling software that consider
all variables. They never do. I take the advice of hams who have spent a
lifetime experimenting with antennas and know which ones work and which
ones do not. 100 miles from me is a ham with 90 acres. He has many
different antennas up. He can switch between an inverted vee with the
apex at 200 feet or a double bazooka at 75 feet. He can switch to a
vertical loop with a reflector. He tried just about every thing
including a sterba curtain over the last 57 years. I live in the middle
of a small town. I have lots of QRN. He told me to put up a horizontal
loop. It worked wonders over my dipole for noise. I fed it with 450 ohm
window line. He told me to use home made 600 ohm line. I could not see
how that could make it better. I finally put up that 600 ohm feed line a
couple of years after putting up the loop. I kick myself now for not
doing what he said immediately. Somehow, the 600 ohm line works
significantly better than 450 ohm window line. He does not know theory
either. He just knows what works and what does not work. I will take
advice from empirical experiments any time over mathematical modelling.

When a new ham breaks into our round tables on 75 during the day, I
always ask him how much power he is running, where he is located, and
what he is using for an antenna. Empirical evidence so far, has G5RV's
as losers every single time. Putting up a G5RV is a very attractive
solution to a new ham. It gives him a lot of hf bands on one antenna. It
takes a while before he begins to take the advice of someone who has
experience and is radiating a nice signal. Now, if a G5RV can be made to
work as well as a 1/2 wave dipole, I am guessing that it is not easily
done. I have never heard a G5RV that was anything but lame. Perhaps
everyone puts up the G5RV using short cuts. I don't know.

I do know that the best antenna for someone like myself who lives in a
densely populated area 3 blocks from down town is a horizontal loop.
This nulls the radiation from the horizontal sources. It still allows
angular radiation and reception. At 35 feet (my tree sizes) it makes an
incredible NVIS antenna on 75. It works very well on the bands above 75.
Of course it does not work on 160. By dumb luck it needs no tuner on 20,
15, and 10. 75, 40, and 17 meters need a tuner. I have no experience
with vertical hf antennas except when installed on boats and ships. On
marine vessels I have decades of experience. But all that experience is
on one type of antenna, the random wire.

Again, you are right, I know little about antenna theory. But, I do take
the advice of those who know what works and what does not work.

FBMboomer wrote:

snip

Very good reply. Well stated. However, I do not take the advice of those
who use what are supposed to be antenna modelling software that consider
all variables. They never do. I take the advice of hams who have spent a
lifetime experimenting with antennas and know which ones work and which
ones do not. 100 miles from me is a ham with 90 acres. He has many
different antennas up. He can switch between an inverted vee with the
apex at 200 feet or a double bazooka at 75 feet. He can switch to a
vertical loop with a reflector. He tried just about every thing
including a sterba curtain over the last 57 years. I live in the middle
of a small town. I have lots of QRN. He told me to put up a horizontal
loop. It worked wonders over my dipole for noise. I fed it with 450 ohm
window line. He told me to use home made 600 ohm line. I could not see
how that could make it better. I finally put up that 600 ohm feed line a
couple of years after putting up the loop. I kick myself now for not
doing what he said immediately. Somehow, the 600 ohm line works
significantly better than 450 ohm window line. He does not know theory
either. He just knows what works and what does not work. I will take
advice from empirical experiments any time over mathematical modelling.

Yep, and it only took him 57 years to figure it out.

While modeling may not be perfect, it shows you in minutes what can
take days, weeks or even months with empirical experiments.

Every antenna I have modeled and built has performed as the model predicted
to the accuracy of the ham grade test equipment I have.

And I have avoided spending time trying to emperically get something
to work which modeling shows in minutes is a waste of time.

It is your life, spend what time you have doing what you want to do.


--
Jim Pennino

On Sunday, November 16, 2014 12:53:27 PM UTC-6, FBMboomer wrote:
I do not take the advice of those
who use what are supposed to be antenna modelling software that consider
all variables. They never do.

Antenna modeling is quite useful, and quite accurate as long as you
consider the possible faults, and quite useful as a learning tool.
I've modeled half a gazillion antennas, and most all were quite
accurate as long as you don't run into one of the few "gotcha's"
that can occur. That is normally not a problem with the vast majority
of antennas one would model.


Now, if a G5RV can be made to
work as well as a 1/2 wave dipole, I am guessing that it is not easily
done.

It's quite easy. Just ditch the designed for 20m feed system and
replace it with something more suitable for 75m.
The best would be to use a tuned ladder line, or a tuned open wire
line. Of course, you would need to change the lengths of the tuned
feeder if you change bands, but that can be done with knife switches,
etc..
The 2nd best would be to feed it with an untuned ladder or open wire
feeder, and use a tuner at the shack. The tuner loss won't be huge,
and it will perform better than the usual garden variety G5RV.

Myself, I would prefer to use a 130 ft dipole, and feed like this if
I were to use a tuned feeder.
http://www.w5dxp.com/notuner.HTM
But you can feed a 102 ft dipole the same way if you vary the feeder
length for a good match, with good results.

I have never heard a G5RV that was anything but lame. Perhaps
everyone puts up the G5RV using short cuts. I don't know.

No, they are just using the garden variety G5RV, which was designed
as a 20m antenna. And many use a tuner at the shack, which adds even
more loss.

Using an untuned ladder or open wire line with a tuner at the shack
should give quite an improvement over the usual 20m method most newby's
use. That's the easy way out for a decent improvement.

Now, feeding a half size dipole with the same method can lead to some
pretty serious losses if one uses a T match tuner, etc. You would want
to avoid that. I always prefer a 1/2 WL dipole for the lowest band
to be used to avoid that if feeding with ladder/open wire line and most
common tuners "IE: T match, etc" at the shack.

But I've always preferred coax fed dipoles and such. The coax fed turnstile
is one of the best NVIS antennas for the low bands I've tried so far.
Low feeder loss same as a 1/2 wave dipole, and also no tuner required.
And you can even steer the pattern a bit if you rig up a way to change
the phasing between the two crossed dipoles.

The horizontal loop is a good NVIS antenna, but I could see no real
advantage over the dipole or turnstile when considering the extra hassle
of installing one. But I wasn't worried about local noise even though
I'm in the city.
Evidently the pattern you are getting from yours has pretty low gain
at the low angles, which is likely why you are hearing less local noise.
Which is fine. But you have to consider that antennas are generally
reciprocal between transmit and receive, so if you are hearing less
noise at those lower angles on receive, you will also transmit less RF
at those same low angles. With a NVIS antenna, not really an issue though.
For DX, it would likely be inferior to the previous dipole you used.

And modeling should show you the difference between the two patterns
at those low angles quite accurately.

wrote in message
...
It's quite easy. Just ditch the designed for 20m feed system and
replace it with something more suitable for 75m.

But the 102 ft top together with the 34 ft ladder is designed for 3.5MHz!

On 11/16/2014 4:36 PM, wrote:
On Sunday, November 16, 2014 12:53:27 PM UTC-6, FBMboomer wrote:
I do not take the advice of those
who use what are supposed to be antenna modelling software that consider
all variables. They never do.

Antenna modeling is quite useful, and quite accurate as long as you
consider the possible faults, and quite useful as a learning tool.
I've modeled half a gazillion antennas, and most all were quite
accurate as long as you don't run into one of the few "gotcha's"
that can occur. That is normally not a problem with the vast majority
of antennas one would model.


Now, if a G5RV can be made to
work as well as a 1/2 wave dipole, I am guessing that it is not easily
done.

It's quite easy. Just ditch the designed for 20m feed system and
replace it with something more suitable for 75m.
The best would be to use a tuned ladder line, or a tuned open wire
line. Of course, you would need to change the lengths of the tuned
feeder if you change bands, but that can be done with knife switches,
etc..
The 2nd best would be to feed it with an untuned ladder or open wire
feeder, and use a tuner at the shack. The tuner loss won't be huge,
and it will perform better than the usual garden variety G5RV.

Myself, I would prefer to use a 130 ft dipole, and feed like this if
I were to use a tuned feeder.
http://www.w5dxp.com/notuner.HTM
But you can feed a 102 ft dipole the same way if you vary the feeder
length for a good match, with good results.

I have never heard a G5RV that was anything but lame. Perhaps
everyone puts up the G5RV using short cuts. I don't know.

No, they are just using the garden variety G5RV, which was designed
as a 20m antenna. And many use a tuner at the shack, which adds even
more loss.

Using an untuned ladder or open wire line with a tuner at the shack
should give quite an improvement over the usual 20m method most newby's
use. That's the easy way out for a decent improvement.

Now, feeding a half size dipole with the same method can lead to some
pretty serious losses if one uses a T match tuner, etc. You would want
to avoid that. I always prefer a 1/2 WL dipole for the lowest band
to be used to avoid that if feeding with ladder/open wire line and most
common tuners "IE: T match, etc" at the shack.

But I've always preferred coax fed dipoles and such. The coax fed turnstile
is one of the best NVIS antennas for the low bands I've tried so far.
Low feeder loss same as a 1/2 wave dipole, and also no tuner required.
And you can even steer the pattern a bit if you rig up a way to change
the phasing between the two crossed dipoles.

The horizontal loop is a good NVIS antenna, but I could see no real
advantage over the dipole or turnstile when considering the extra hassle
of installing one. But I wasn't worried about local noise even though
I'm in the city.
Evidently the pattern you are getting from yours has pretty low gain
at the low angles, which is likely why you are hearing less local noise.
Which is fine. But you have to consider that antennas are generally
reciprocal between transmit and receive, so if you are hearing less
noise at those lower angles on receive, you will also transmit less RF
at those same low angles. With a NVIS antenna, not really an issue though.
For DX, it would likely be inferior to the previous dipole you used.

And modeling should show you the difference between the two patterns
at those low angles quite accurately.


I have a Pixel magnetic loop with an A/B switch for receive using the
full size horizontal loop or the vertical Pixel loop. The full size loop
is almost invariably better on 75. On 40, the Pixel may or may not be
better. Mostly the full size antenna is better. On 20, 15, 17, and 10
the Pixel magnetic loop is better for me. Not always. But most of the
time. Having the A/B switch is really good for tracking QSB. For some
reason I do not understand, as the signal strength from the full size
loop decreases, the signal on the magnetic loop increases. This
phenomena is very consistent on the higher frequency bands. DX
performance of the full size loop is very good from 20 meters on up.
Perhaps the fact that the antenna is resonant with no tuner on 20, 15,
and 10 may have something to do with this. I have read that the angle of
radiation from this loop is lower on the higher frequencies.

My magnetic loop receiving antenna has a 30 db preamp. Even with this
preamp the noise floor is always lower than my full size loop. My S
meter invariably shows the noise floor at 0 on all bands.

And, yes, on 75 I do not expect and do not receive much DX. During the
day I seem to have only a 250 mile radius of effective use. And at 300
miles my signal is pretty well cut off. Of course this changes at night.
My friend with the inverted V at 200 feet is easily able to make day
contacts out to 800 miles. He has the room and 200 foot towers.

I spent 400 dollars on that Pixel antenna. It has been worth it for me.
For someone who lives in the country side with no QRN, it may not be
helpful. I have owned it for 6 months now. I did not discover the
reciprocal reception phenomena when used with my 75 meter loop until a
couple of months ago. I now take full advantage of this now on the high
frequency bands.

On Sunday, November 16, 2014 4:47:35 PM UTC-6, gareth wrote:
wrote in message
...
It's quite easy. Just ditch the designed for 20m feed system and
replace it with something more suitable for 75m.

But the 102 ft top together with the 34 ft ladder is designed for 3.5MHz!

Not exactly.. It's a bit long when used as the makeup section
on 75m. But I believe it's the use of the chokes which cause the
losses many people see. Many claim it can be fairly efficient on 80m
using the standard G5RV with the 34 ft ladder line. On paper I suppose
it can if all clicks in an orderly military manner..

If...

And the various types of chokes are not created equal for this type of use.

I just don't like the design myself. On bands that show a large reactance
on the load side of the choke, you can saturate the core of the choke, which
turns RF to heat. No bueno..
In those cases, I think it would be better to ditch the choke and live with
the feed line radiation unless it causes problems.

I think it's kind of a mickey mouse design for my uses, but I'm spoiled
on the highly efficient coax fed dipoles, and see no reason to compromise
with lesser designs. Life is too short for compromise antennas unless one
actually needs one to fit the space, or really wants to work all bands
with a single wire up. That's not me.. I don't work the high bands that
much, and I have a tower and tri-bander I can put up if I really wanted to.
I'm not worried about room for the dipoles.
I can fit a full size 80m dipole no problem here at home, and I have
room for anything I can think of at the dirt patch.

I think ladder line all the way is the best for all band G5RV use, and is
the only way I would run one, if I were to run one.

I've also seen quite a few examples of excess choke losses on many of
the various commercial windoms.

I've never used a G5RV or windom myself, and I doubt I ever will, being
I can run full size dipoles. I've tried a few portable, and was not
impressed at all with the ones I used. One particular G5RV I once used at
a field day was fairly pathetic on 80m, and had me pulling my hair out.

Wasn't mine, so not sure on the type of choke, etc.. But it was bad news
vs a coax fed dipole. Terrible I tell you.. yuk.. I refused to ever be
stuck on one again after that, and always took supplies to build my own
dipoles on later field days. The next year, they were using a windom on 40m.
I strung up a coax fed 40m dipole also, and used a switch to A/B the two.
The owner of the windom was fairly shocked at the difference between the
two. I've talking 2-3 S units worth of difference on the rig's meter.
All signals, noise floor, the whole ball of wax was way up on the dipole.
And again, I lay most of the blame on the choke that was used more than
anything, but I've also never really been a fan of OCF wires either.
I guess I don't have to tell which antenna I used.. :|

I'd rather run parallel fed coax fed dipoles for more than one band. And
also, I rarely have a need to work all bands being as I run the lower bands
most of the time.
I generally work 80 and 40 mostly, so the parallel 80 and 40 dipoles fed
with a single coax feed is a better choice for me and is a highly efficient
system. I usually run the dipoles at right angles if possible to reduce
interaction, which can sometimes cause tuning quirks for the higher band
dipole. I never run them closely stacked like some do unless no other choice.

And that will work some of the higher bands with a reasonable SWR on the
harmonics if I want to take a walk on the wild side and work a higher
frequency. I just slap a tuner inline as a line flattener and live with the
losses, which will vary to the quality of the coax and the band used.
Some parallel dipole setups I also add 160m legs, but if I don't, I just
tie the coax together at the shack and feed as a T vertical on 160m,
which often is just as good, or even better on longer paths.

On Sunday, November 16, 2014 7:39:53 PM UTC-6, FBMboomer wrote:

I have a Pixel magnetic loop with an A/B switch for receive using the
full size horizontal loop or the vertical Pixel loop. The full size loop
is almost invariably better on 75. On 40, the Pixel may or may not be
better. Mostly the full size antenna is better. On 20, 15, 17, and 10
the Pixel magnetic loop is better for me. Not always. But most of the
time. Having the A/B switch is really good for tracking QSB. For some
reason I do not understand, as the signal strength from the full size
loop decreases, the signal on the magnetic loop increases. This
phenomena is very consistent on the higher frequency bands.

The 80m horizontal loops I've modeled didn't seem too hot on the
upper bands. Pretty high angles for most all the upper HF bands.
So what you see sounds fairly normal. I just checked one model for
one at 30 feet, and none of the higher bands were doing all that great.
And the higher bands all had the max gain at fairly high angles.

DX
performance of the full size loop is very good from 20 meters on up.

Dunno. I don't think it's all that good, considering what you mentioned.
Usable I'm sure, but not great by any means.


Perhaps the fact that the antenna is resonant with no tuner on 20, 15,
and 10 may have something to do with this. I have read that the angle of
radiation from this loop is lower on the higher frequencies.

Lower than 80m, but not too low vs better antennas for those bands.


My magnetic loop receiving antenna has a 30 db preamp. Even with this
preamp the noise floor is always lower than my full size loop. My S
meter invariably shows the noise floor at 0 on all bands.

Normal for a small loop. Doesn't mean much. Only the s/n ratio really
matters. As long as you have enough signal to bring the background noise
up when connecting the antenna, should be good enough.

wrote in message
...
On Sunday, November 16, 2014 4:47:35 PM UTC-6, gareth wrote:
wrote in message
...
It's quite easy. Just ditch the designed for 20m feed system and
replace it with something more suitable for 75m.

But the 102 ft top together with the 34 ft ladder is designed for 3.5MHz!

Not exactly.. It's a bit long when used as the makeup section
on 75m. But I believe it's the use of the chokes which cause the
losses many people see.

The G5RV design has no chokes.

El 15-11-14 20:01, Jerry Stuckle escribió:
On 11/15/2014 1:58 PM, wrote:
On Saturday, November 15, 2014 12:40:29 PM UTC-6, Jerry Stuckle wrote:
On 11/15/2014 12:58 PM, wrote:
Jerry wrote:
On 11/14/2014 10:02 PM, wrote:
Jerry wrote:
On 11/14/2014 4:26 PM, wrote:
Jerry wrote:
On 11/14/2014 3:55 PM, wrote:
Jerry wrote:

snip

You ignore the fact this is an idealized environment. That is NEVER the
case in a real installation.

You ignore the fact this is modeled on an AVERAGE environment.


But you claim it is an absolute fact that an 80 meter antenna at less
than 100' is crap. This is solid proof.

I never made any such claim nor did I say "an 80 meter antenna at less
than 100' is crap".


That's true. You said is sucks. Let me quote you:

"Any dipole type antenna will suck on 75M if mounted less than about
100 feet, or about .4 wavelengths."

That was in response to the original poster who said his antenna sucked,
not me.


It is still your statement.

It was the posters statement and my response to that statement.

snip remaining puerile drivel



Wrong again, as the archives prove. And you can't lie your way out of it.

You can copy and paste. But you do not UNDERSTAND.


So much drama, so little time... :|


I just don't want people to think his crap is the truth. It's far from
it.

He makes all kinds of claims - which knowledgeable people know are
false. But others might get the wrong idea.


It is not just a matter of little drama.

There is a subject named "a short 160m antenna - loading and hats".
Simulation results were presented for a 0.029lambda long radiator over
REAL ground.

The only reason I gave a reaction was to avoid that other people might
get a wrong idea. The statements on the loading coil are very likely
valid, but the gain figures are far from reality considering the
conditions stated.

Other issue was radiation from a rotating permament magnet. Some
people act in a way that is far from constructive, misleading, or even
insulting. The misleading reactions may give less instructed readers a
wrong idea.


--
Wim
PA3DJS
Please remove abc first in case of PM