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FBMboomer[_2_] · November 16th 14, 06:53 PM posted to rec.radio.amateur.antenna

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.