I've been trying to understand the basics of HT radio antennas. The
first part that puzzles me is the "ground" side of an antenna. Or if I
can use a Dipole as an example one side of the dipole. Or if we use a
groundplane the radials. With an HT are we just "doing without"? Or is
this just my dumbness in action?

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

In my mind I would simply like an antenna that was effective but
flexable. Length is not "critical" as I plan to hang it up high on an
LB harness. The idea is a rough and tumble antenna that can work in the
woods on a Search and Rescue mission but will give me the very best
range out (not so much up/dn)

Has anyone done any serious work with HT antennas? Is there anyone
clued into how to match these properly? And has anyone looking into
using spring steel (Such as Measuring tape) for the antenna as the
Military uses in many of their radios?

Thanks for any thoughts on this de Jay W0VNE

On May 7, 11:31*am, James186282 wrote:
I've been trying to understand the basics of HT radio antennas. *The
first part that puzzles me is the "ground" side of an antenna. *Or if I
can use a Dipole as an example one side of the dipole. *Or if we use a
groundplane the radials. *With an HT are we just "doing without"? *Or is
this just my dumbness in action?

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

In my mind I would simply like an antenna that was effective but
flexable. *Length is not "critical" as I plan to hang it up high on an
LB harness. *The idea is a rough and tumble antenna that can work in the
woods on a Search and Rescue mission but will give me the very best
range out (not so much up/dn)

Has anyone done any serious work with HT antennas? *Is there anyone
clued into how to match these properly? *And has anyone looking into
using spring steel (Such as Measuring tape) for the antenna as the
Military uses in many of their radios?

Thanks for any thoughts on this de Jay W0VNE

With an HT, the radio and the person holding it are the lower half
of the antenna if using a 1/4 wave or 5/8 wave. And yes, a full
length antenna will trounce most rubber ducks.
A good antenna for HT's is the half wave. But I've seen the 5/8's
do pretty well even considering the problems.
A 1/4 wave is a good cheap antenna. IE: get an adapter that
converts the rubber duck connector to a SO-239. Then stick
a 1/4 wave whip in the center pin hole. Quicky 1/4 wave that will eat
most all rubber ducks. And using external ground planes, verticals
works well too.

On Fri, 07 May 2010 16:31:48 +0000, James186282
wrote:

The
first part that puzzles me is the "ground" side of an antenna. Or if I
can use a Dipole as an example one side of the dipole. Or if we use a
groundplane the radials. With an HT are we just "doing without"?

The case of the HT and your hand are acting as the counterpoise (other
half of the antenna). There have been some efforts to improve on the
HT antenna by adding a wire counterpoise:
http://www.hamuniverse.com/htantennamod.html
It goes under the trade name of "Tiger Tail". There are some boring
You Tube videos describing the construction.

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

If you start with a monopole, shortening the antenna in half with a
loading coil will result in half the gain or -3dB loss. 1/4th the
length is 1/4th the gain or -6dB loss. Etc. Shortening the antenna
doesn't change the pattern much. You still end up with roughly a
torus (donut) pattern. The torus is far from perfect and probably
resembles more of a sphere. Therefore, you don't have to worry much
about the loss of signal in the axial directions.

A 5/8 wave antenna is the longest length (and therefore highest gain)
antenna that can be built before the antenna pattern starts to
resemble a cloverleaf (with deep nulls). The gain is about 1.5dB more
than a dipole. That's a fabulous 19% increase, which is kinda
marginal considering the added length.

All this assumes that some effort has been made to match the proposed
antenna to 50 ohms.

In my mind I would simply like an antenna that was effective but
flexable.

Flexible as in like rubber? Or flexible as in versatile?

Length is not "critical" as I plan to hang it up high on an
LB harness. The idea is a rough and tumble antenna that can work in the
woods on a Search and Rescue mission but will give me the very best
range out (not so much up/dn)

Large antennas in the brush is a bad idea. It will tangle with the
brush and the brush always wins. Your requirements are probably the
same as any emergency responder. It has to be unobtrusive (not get in
the way) but still effective. Smashing through the brush with a 5/8
wave 2m antenna is not my idea of unobtrusive.

My suggestion is to have two antennas. One is the traditional 6"
rubber ducky antenna that comes with most HT's. It's not great, but
it's small enough not to get in the way. In your back pack, carry a
length of RG-58/u with the last 19" of braid pulled back over the
outer jacket. This forms a "coaxial antenna", where the exposed 19"
of center conductor is the driven element, and the folded back braid
is the counterpoise. The impedance is officially 70 ohms, but the
mismatch loss to 50 ohms is minimal. The trick is that this antenna
is attached with a long length of coax cable, that can be thrown into
the trees, or hoisted on a pole, to get added elevation.

If you have a harness, it might be possible to sew an antenna into the
webbing. While not the best for gain and non-directionality, it is
very convenient not to have an antenna sticking you in the armpit.

Has anyone done any serious work with HT antennas?

Ummm... the cell phone and public safety radio sector has done
considerable work on optimizing the antenna. The cell phone horde has
decided that non-projecting antennas are more important than
convenience. They've also decided that it's acceptable to place the
antenna at the BASE of the cell phone (as in the Motorola RAZR).
Convenience is more important than performance. The public safety and
land mobile sector has correctly decided to solve the problem at the
other end of the link. They're leaving the antennas at about 3-6" in
length, and concentrating on improving performance by adding sites,
better base antennas, voting systems, etc. Why mess with 1,000 HT's
when you can get better results by improving one mountaintop site?

There are also external speaker microphones for HT's that have
antennas in the microphone (thus insuring that your brain gets the
maximum RF exposure).
http://www.dhgate.com/kmc-26-microphone-speaker-mic-for-kenwood/p-ff808081220be3b101220d87650c1504.html

Is there anyone
clued into how to match these properly?

Sure. The 5/8 wave uses a transformer or tapped inductor to step up
the 50 ohms to about 1000 ohms. Shorter than 1/4 wave antennas use a
loading coil (series inductor). 70 ohm coax antennas and 35 ohm
monopoles are close enough to 50 ohms for VSWR not to be an issue. The
added bulk and RF losses of the matching system, has to be balanced
against the antenna mismatch loss. It's often better to tolerate the
mismatch loss.

And has anyone looking into
using spring steel (Such as Measuring tape) for the antenna as the
Military uses in many of their radios?

http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm
http://www.open-circuit.co.uk/tape.php
The problem is that spring steel (as found on a tape measure) is not
exactly a good RF conductor. The military HF dipole antennas I played
with were stainless steel, which has better surface conductivity.
http://www.qsl.net/n2ckh/HA4000.htm
The problem with tape measure antennas at VHF and UHF is accuracy. The
cut length of the antenna needs to be fairly accurate to work at UHF.
For example, the difference in length of a UHF 1/4 wave radiator is:
440 MHz = 170.5 mm
450 MHz = 166.7 mm
To get it somewhere in the band, you need to adjust the tape measure
to within plus or minus 1.9mm. That's not easy (or practical).
There's also no antenna tuner to compensate for errors. That's why
field adjustable antennas are not very popular at UHF frequencies.

Instead of floundering around with generalities, could you kindly
disclose what problem you're trying to solve and what equipment you
have to work with? Perhaps the answers will be more specific.

Thanks for any thoughts on this de Jay W0VNE

Hint: Making a better HT antenna is easy. Making one that is better
but also smaller, more efficient, and ergonomic, is not so easy.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On May 7, 11:31*am, James186282 wrote:
I've been trying to understand the basics of HT radio antennas.

http://adjunct.diodon349.com/Radio/h..._good_info.htm

http://www.pgh-net.com/ae3c/tiger-tail.html
--
73, Cecil, w5dxp.com

On 7 mayo, 18:31, James186282 wrote:
I've been trying to understand the basics of HT radio antennas. *The
first part that puzzles me is the "ground" side of an antenna. *Or if I
can use a Dipole as an example one side of the dipole. *Or if we use a
groundplane the radials. *With an HT are we just "doing without"? *Or is
this just my dumbness in action?

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

In my mind I would simply like an antenna that was effective but
flexable. *Length is not "critical" as I plan to hang it up high on an
LB harness. *The idea is a rough and tumble antenna that can work in the
woods on a Search and Rescue mission but will give me the very best
range out (not so much up/dn)

Has anyone done any serious work with HT antennas? *Is there anyone
clued into how to match these properly? *And has anyone looking into
using spring steel (Such as Measuring tape) for the antenna as the
Military uses in many of their radios?

Thanks for any thoughts on this de Jay W0VNE

Hello James,

As you know, every mA that goes into the antenna, has to come from the
shield from the coaxial cable, or the jack on your HT. From there, the
current is pulled out of your hand (assuming VHF). Your had acts as
the counterpoise.

The lower the radiation resistance, the more current goes into the
antenna given same power. To reduce the current, and losses, in your
hand, a half wave resonating antenna is my preferred option. The only
"problem" with the HW antenna is that you need a descent match because
of that high radiation resistance (several hundreds to kOhms depending
on length/thickness ratio).

As others said, the sleeve dipole is an attractive option when you can
erect it into a tree. Because of the plastic sheet that is between the
shield and the folded back shield, the length must be less then a
quarter wave to have good choking function. To get the antenna in
resonance, the "radiator" section has to be bit longer. Note that the
folded back braid does radiate as much as the upper part.

The 5/8 lambda antenna only has its gain advantage when the image
antenna is present. As there is no image (as you don't have an
infinite ground plane), the HW antenna will perform better then the
5/8 lambda antenna.

I support Jeff's strategy, have a small easy to handle one for normal
use, and the good very flexible one for when it is really necessary.

Best regards,

Wim
PA3DJS
www.tetech.nl
in case of PM, please remove abc first.

Jeff Liebermann wrote:
On Fri, 07 May 2010 16:31:48 +0000, James186282
wrote:

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

If you start with a monopole, shortening the antenna in half with a
loading coil will result in half the gain or -3dB loss. 1/4th the
length is 1/4th the gain or -6dB loss. Etc. Shortening the antenna
doesn't change the pattern much. You still end up with roughly a
torus (donut) pattern. The torus is far from perfect and probably
resembles more of a sphere. Therefore, you don't have to worry much
about the loss of signal in the axial directions.

This isn't at all true generally. Shortening an antenna doesn't by
itself reduce the gain significantly -- less than 1/2 dB going from a
half wavelength dipole to an infinitesimally short one, due to change in
current distribution. Shorter antennas are typically less efficient than
longer ones due to loss in the matching components, whether those
components are in the form of a loading coil or some external matching
network, and ground loss if significant current flows through the
ground. And the amount of loss varies a great deal depending on the
components and other factors. Because of this, no firm number can be
attached to the change in efficiency or field strength with length, and
even approximate numbers should be viewed with suspicion.

A 5/8 wave antenna is the longest length (and therefore highest gain)
antenna that can be built before the antenna pattern starts to
resemble a cloverleaf (with deep nulls). The gain is about 1.5dB more
than a dipole. That's a fabulous 19% increase, which is kinda
marginal considering the added length.

The gain of a 5/8 wavelength radiator over a quarter wavelength under
ideal conditions is about 2.8 dB, not 1.5. The pattern is already
beginning to resemble a cloverleaf at this length, with a high-angle
lobe. But the high lobes aren't yet quite big enough to significantly
reduce the power in the main lobe, resulting in the gain. But this is
under ideal conditions, with perfect ground reflection. In an HT
environment, all bets are off. I personally use a half wavelength whip
on an HT, because its high end impedance minimizes current to the HT and
my body, leaving the whip itself to do most of the radiating.

. . .

Roy Lewallen, W7EL

James186282 wrote:
I've been trying to understand the basics of HT radio antennas. The
first part that puzzles me is the "ground" side of an antenna. Or if I
can use a Dipole as an example one side of the dipole. Or if we use a
groundplane the radials. With an HT are we just "doing without"? Or is
this just my dumbness in action?

Antennas are a lot easier to understand if you forget about "ground"
unless you're talking about a direct connection to the earth. Calling
one side of an antenna "ground" doesn't impart special qualities;
current flowing on any conductor creates a field, and it doesn't matter
if it's on a "ground" side of an antenna or any other part of it. Some
structures like a "ground plane" elevated radial system are designed to
carry current yet radiate very little, so they're reasonably called
"counterpoises".

My second question is in asking how effective is the typical rubber duck
antenna versus say a truly resonant antenna or even a 5/8th wave which
tries (if I understand it) to squish the pattern down from a sphere to a
doughnut so its hears and talks better out then "up and down"

A rubber ducky has, for practical purposes, exactly the same pattern as
a quarter wavelength antenna. Longer antennas have different patterns.
But remember, your HT and body are just as much a part of the radiating
antenna system as the "antenna". If you put, say, a half wave whip onto
your HT, your body and HT are more effectively removed from the system
(although they'll still radiate some due to coupled current). That will
likely make more of a difference to the pattern than the difference
caused by whip length.

In my mind I would simply like an antenna that was effective but
flexable. Length is not "critical" as I plan to hang it up high on an
LB harness. The idea is a rough and tumble antenna that can work in the
woods on a Search and Rescue mission but will give me the very best
range out (not so much up/dn)

Has anyone done any serious work with HT antennas? Is there anyone
clued into how to match these properly? And has anyone looking into
using spring steel (Such as Measuring tape) for the antenna as the
Military uses in many of their radios?

I'd think military implementations deserve a good look, since they have
similar requirements to yours. Any solution will be a trade-off, so you
have to decide what you're willing to trade for what you'll get.

I recommend you get the _ARRL Antenna Compendium, Vol. 4_ and read "An
Investigation of 2-Meter HT Antenna Performance" by Ken Pierpoint KF0OW
and Ed Brummer W4RTZ. It's the only experimental work I know of on the
topic which has been published in the civilian press. The results aren't
totally unambiguous, but it's a good study.

Roy Lewallen, W7EL

There are others on the group who can get into the technical side of
things -- I just thought I'd tell you what I'd use in the bush, or anywhere
else for that matter. Make up a twin lead J-pole -- its flexible and you can
hang it from almost anything. If you Google J-pole you'll find a hundred
different designs, but electrically they are all the same thing. The
twin-lead version can be hung anywhere from a string, and then
rolls up and fits in your pocket when you're done. If you want you
can hang it on a stick or twig tied to your backpack! A very
easy to make, versatile, and effective antenna! It's the only
one you'll ever really need!

Irv VE6BP


"James186282" wrote in message
...
In my mind I would simply like an antenna that was effective but flexable.
Length is not "critical" as I plan to hang it up high on an LB harness.
The idea is a rough and tumble antenna that can work in the woods on a
Search and Rescue mission but will give me the very best range out (not so
much up/dn)

Irv Finkleman wrote:
There are others on the group who can get into the technical side of
things -- I just thought I'd tell you what I'd use in the bush, or anywhere
else for that matter. Make up a twin lead J-pole -- its flexible and you can
hang it from almost anything. If you Google J-pole you'll find a hundred
different designs, but electrically they are all the same thing. The
twin-lead version can be hung anywhere from a string, and then
rolls up and fits in your pocket when you're done. If you want you
can hang it on a stick or twig tied to your backpack! A very
easy to make, versatile, and effective antenna! It's the only
one you'll ever really need!

Irv VE6BP

I tried that a long time ago and came to a different conclusion. What I
found in the remote areas was a lot of multipath reception. Sorry about
the technical term -- the consequence of multipath is that the signal
strength changes dramatically as you move. It's the cause of the "picket
fencing" familiar to mobile operators. Changing antenna position even a
few inches can take a signal from unreadable to nearly full quieting.
With an HT mounted whip, I move the HT around until I hit a hot spot,
and hold it there while communicating. When I hung an antenna from a
tree, it was a crap shoot (how's that for keeping it non-technical?)
whether it would end up at a hot spot or a lousy spot.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Irv Finkleman wrote:
There are others on the group who can get into the technical side of
things -- I just thought I'd tell you what I'd use in the bush, or
anywhere
else for that matter. Make up a twin lead J-pole -- its flexible and
you can
hang it from almost anything. If you Google J-pole you'll find a hundred
different designs, but electrically they are all the same thing. The
twin-lead version can be hung anywhere from a string, and then
rolls up and fits in your pocket when you're done. If you want you
can hang it on a stick or twig tied to your backpack! A very
easy to make, versatile, and effective antenna! It's the only
one you'll ever really need!

Irv VE6BP

I tried that a long time ago and came to a different conclusion. . .

Sorry, I missed the suggestion of hanging the J-pole from your backpack.
That would allow moving around for the best reception in the multipath
environment. My comments were in response to the suggestion of hanging
it from a string, which I found not to be a good idea.

Like most vertical radiators isolated from earth ground, a J-pole can
couple quite a bit of current to the feedline, making the feedline, rig,
and your body part of the antenna system. So you might find some
feedline lengths and orientations to work better than others.

Roy Lewallen, W7EL