RadioBanter - It is a truism

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It is a truism that short antennae are poor inefficient radiators, and no
amount of infantile bluster by Americanoramuses will change that.

The truth does not need the violence of abuse to force its way down
people's throats.

gareth wrote:
It is a truism that short antennae are poor inefficient radiators, and no

How short is a "short antenna"?

What is the metric for a "poor inefficient radiator"?

Without numbers all you have is arm waving.

--
Jim Pennino

On 11/12/2014 1:50 PM, gareth wrote:
It is a truism that short antennae are poor inefficient radiators, and no
amount of infantile bluster by Americanoramuses will change that.

The truth does not need the violence of abuse to force its way down
people's throats.

A perfect example is a G5RV on 75 meters. They suck. When someone joins
our group rag chew on 75, and they have a poor signal, The first thing I
ask is "Are you using a G5RV". We all have a chuckle when they answer
yes and then ask how we knew. :-)

Trying to prove with math that short antennae work as well as say a 1/2
wave dipole may give someone great sport. However, in the real world,
short antennae suck big time. I have been an American for most of my
life. Please do not paint us all with the same brush.

FBMboomer wrote:
On 11/12/2014 1:50 PM, gareth wrote:
It is a truism that short antennae are poor inefficient radiators, and no
amount of infantile bluster by Americanoramuses will change that.

The truth does not need the violence of abuse to force its way down
people's throats.

A perfect example is a G5RV on 75 meters. They suck. When someone joins
our group rag chew on 75, and they have a poor signal, The first thing I
ask is "Are you using a G5RV". We all have a chuckle when they answer
yes and then ask how we knew. :-)

Trying to prove with math that short antennae work as well as say a 1/2
wave dipole may give someone great sport. However, in the real world,
short antennae suck big time. I have been an American for most of my
life. Please do not paint us all with the same brush.

Any dipole type antenna will suck on 75M if mounted less than about
100 feet, or about .4 wavelengths. Below that you are warming clouds.

Height Gain @ Elevation
lambda

0.1 3.89 90
0.15 5.55 90
0.2 5.95 90
0.25 5.81 62
0.3 5.80 48
0.35 6.00 40
0.4 6.38 35
0.45 6.86 31
0.5 7.41 28
0.55 7.76 25
0.6 7.87 23
0.65 7.76 21

--
Jim Pennino

El 13-11-14 21:39, FBMboomer escribió:
On 11/12/2014 1:50 PM, gareth wrote:
It is a truism that short antennae are poor inefficient radiators,
and no
amount of infantile bluster by Americanoramuses will change that.

The truth does not need the violence of abuse to force its way down
people's throats.

A perfect example is a G5RV on 75 meters. They suck. When someone
joins our group rag chew on 75, and they have a poor signal, The first
thing I ask is "Are you using a G5RV". We all have a chuckle when they
answer yes and then ask how we knew. :-)

Trying to prove with math that short antennae work as well as say a
1/2 wave dipole may give someone great sport. However, in the real
world, short antennae suck big time. I have been an American for most
of my life. Please do not paint us all with the same brush.

I agree that in many practical circumstances electrically small
antennas do not perform well. I also know that having an antanna is
better than nothing.

The smaller the antenna, the more difficulties you will experience to
get radiation out of it (heat radiation doesn't count).

In free space you can make a rather efficient antenna with say maximum
size of 0.03lambda, as long as you are a good electron tamer. If not,
electrons escape from the structure showing a nice corona, or full
breakdown occurs. Examples are tuned loops and short dipoles with
capacitive end plates and series inductors to arrive at some nice
impedance.

Tuning in the shack with lots of cable and a bad ferrite balun between
tuner and antenne mostly results in good VSWR but low efficiency (as
many people know).

In real world even a very small very efficient antenna may not perform
as expected Close to the antenna (say within 0.1 lambda), reactive
fields are very strong and they increase rapidly when reducing the
distance. This is also valid for "magnetic loops" (that Jennings HV
vacuum capacitor or thick potato cutter/slicer is for a reason). When
you put such a nice small antenna close to lossy dielectric (building
materials, ground, etc), significant part of the RF power may be
dissipated in that lossy dielectric materials.

In case of short monopoles, lots of power is mostly dissipated in the
ground/counterpoise system (saline wetlands, sea and large metallic
surfaces excepted). Of course we can solve this with lots of burried
radials, or somewhat less elevated radials, but such solutions don't
qualify for an electrically small antenna anymore.

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

But most people do not have access to tower that can get their dipole antenna 100' off the ground for 75 meters!

The
G5RV was designed to work on 20 meters.
The ladder line is the matching network.
It does not perform well on 10 or 40 meters.

That usually has something to do with a cut dipole not working well on anything that is the first harmonic.

A portion of this planet is inhabited by morons that does not know that and that picks their antenna by price rather than by performance!

My inverted V - 80M off center fed dipole antenna is only 30' off the ground in the middle and maybe 20' off the ground on the ends.
It is fed with about 60' of LMR 400 and I can converse with anyone that I can hear.

Most of the people I hear are using 600 - 1200 watt amplifiers and some other type of dipole antenna, and although their signal is louder than mine, my audio is much cleaner then theirs!

To me - amplifiers are for CB'rs that are hard of hearing and thinks that you cannot carry on a conversation unless you are 20/9!

When I become a O&O - the first thing I am going to do is send each and every one of those people a pink slip and have them explain why they use more power than necessary.

I would keep on sending them pink slips until they either get the message - that the reason for the signal report is so you can adjust your power to the minimum amount necessary to carry on the conversation, or until the ARRL / FCC gets tired of it and sends them a greetings to come and see them and explain why they can't follow the rules!

As far as these people bragging about how they pick on those that are on a G5RV - I would gladly send them pink slips also - until they reduce their power or answer for their actions in front of a FCC examiner...

I would love to see how many of these people could still pass a General Class Examination and how many of them bought their license and will let it drop - if they are asked to retest...

On Thursday, November 13, 2014 2:38:40 PM UTC-6, FBMboomer wrote:
On 11/12/2014 1:50 PM, gareth wrote:
It is a truism that short antennae are poor inefficient radiators, and no
amount of infantile bluster by Americanoramuses will change that.

The truth does not need the violence of abuse to force its way down
people's throats.

A perfect example is a G5RV on 75 meters. They suck. When someone joins
our group rag chew on 75, and they have a poor signal, The first thing I
ask is "Are you using a G5RV". We all have a chuckle when they answer
yes and then ask how we knew. :-)

Trying to prove with math that short antennae work as well as say a 1/2
wave dipole may give someone great sport. However, in the real world,
short antennae suck big time. I have been an American for most of my
life. Please do not paint us all with the same brush.

But again, as everyone has pointed out, it's not the radiator, it's
the feed system that provides the losses.
The *usual* G5RV is generally lousy compared to a coax fed 1/2 dipole
because of the funky poorly designed feed system, not the radiator.
IE: coax to a choke balun to twin lead to the radiator. That's a joke..

The feed system is the culprit, not the slightly shortened radiator.
Which BTW, is not really all that short, as far as short antennas go.
It's more like a reduced size radiator, rather than actually short like
say a short mobile antenna, or a very small dipole.

If you can feed a 102 ft dipole with nothing but twin lead, the
antenna system is quite efficient. Say if you use Cecil Moore's
method of feeding a G5RV with ladder line.

You are blaming the wrong culprit, same as Gareth continues to do.
You have to consider the whole antenna *system*, not just the radiator.
Only the *very* short radiators suffer from ohmic losses. The 102 ft
dipole used with a G5RV does not qualify in that regard. Most all
the loss is in the feed system, not the radiator itself. And that can
be corrected to be pretty much a non issue.

On Thursday, November 13, 2014 10:13:02 PM UTC-6, Channel Jumper wrote:
But most people do not have access to tower that can get their dipole
antenna 100' off the ground for 75 meters!

I actually want my 80 meter antennas to shoot straight up. I'm
working NVIS paths 98 percent of the time. Only the DX'ers need
a high dipole. Or a good vertical, which generally is better.

When I become a O&O - the first thing I am going to do is send each and
every one of those people a pink slip and have them explain why they use
more power than necessary.

Knock yourself out. You will only succeed in looking like a jackass,
and the FCC could care less as long as they don't exceed the legal
limit or cause splatter due to an underloaded amp, etc.