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Author Topic: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs  (Read 303 times)

N4SRN

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Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« on: December 21, 2022, 05:03:08 AM »

I see the topic has been touched on in several threads over the years but thought I’d start a specific thread on use of telescopic whip antennas for UHF/VHF antennas. Rubber duck and whip antennas are a compromise for dual band use and optimal RX/TX should come from properly tuned antennas. Adding adapters between a BNC/SMA mount on an HT and the antenna might vary the length significantly, so accounting for that factor may come into play. How to tune an antenna on an HT seems difficult, by other than calculated lengths. Tuning off the HT might have errors.

Is it feasible, for any given HT, to tune/mark telescopic antennas for optimal utility?

Counterpoise wires are said to enhance utility. Some information suggests that such a wire at the antenna base dangling past the radio body may do more harm than good. One person advocates a 10g wire at the antenna base protruding stiffly almost horizontal to the HT.

For portable use while moving about, high efficiency solutions suffer from fragility and inconvenience. For stationary use, there are better solutions other than an antenna mounted on the HT itself. Where I’m focused would be portable use when one might stop and extend a more fragile and inconvenient antenna for a timed checkin period - maybe 5min at 3hr intervals.

Thanks for your thoughts!

Bret/N4SRN
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Bret/N4SRN
Bedford, NH  USA

K5LXP

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #1 on: December 21, 2022, 06:51:17 AM »

Sleeve dipole on a stick.  Could be your walking stick as you move about.  Extend it in the air for optimum range.  Being a "full size" dipole, bandwidth is wide and tuning non critical.  Omni up high gives you better performance than gain down low.

Mark K5LXP
Albuquerque, NM
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N4SRN

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #2 on: December 21, 2022, 07:29:38 AM »

Sleeve dipole on a stick.  Could be your walking stick as you move about.  Extend it in the air for optimum range.  Being a "full size" dipole, bandwidth is wide and tuning non critical.  Omni up high gives you better performance than gain down low.

Mark K5LXP
Albuquerque, NM

Interesting idea! I often carry an Ed Fong DBJ-2 Rollup Dual Band antenna while hiking and just hang it from a tree branch when stopped for lunch. Putting it inside a walking stick might be possible but I’d have to source lightweight but strong non-conductive tubing that wouldn’t block RF.
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Bret/N4SRN
Bedford, NH  USA

WB6BYU

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #3 on: December 21, 2022, 08:45:23 AM »

Quote from: N4SRN

Is it feasible, for any given HT, to tune/mark telescopic antennas for optimal utility?



In practice, I haven't found that it makes much difference.

My first observation is that you don't want to be using a
telescoping whip in motion if you can help it.    When I
worked for the Forest Service in Alaska they gave me
a radio with a telescoping whip, and it took me about a
day to break walking through the bush.  Turns out the
standard procedure was to listen with the whip down
(where it was protected inside the case), then stop and
pull it up when someone called you.

As far as finding the optimum length, you can do that
by setting the radio in a fixed location and measuring
the relative field strength at a distance as the length of
the antenna is changed.  But I haven't found any significant
difference between, say, an 18" whip and a 20" whip for
operation on 2m.  A full quarter wave antenna has a
reasonable wide SWR bandwidth, and most HTs aren't
too fussy anyway, given the range of antennas that they
get used with.

If you try to mark it, you need to make sure that you
pull the sections out in the same sequence if it isn't
fully extended.  Probably something like "3 1/2 sections
extended" is close enough.  If you need more accuracy,
then attach a piece of string to the antenna jack and
mark that as a guide to the required length.  (If you use
a quarter wave radial, just pull out the antenna until it
is the same length as the radial.)

My best results so far have been with flexible quarter
wave whips, but I don't use 440 much while in the field.
For dual-band operation, one of the short 2m quarter
wave whips that works as 5/8 wave on 440 is probably
the best approach, although I'd also consider just using
my 2m antenna on 440 for simplicity if I didn't need
high gain.

Generally, you don't want to go longer than 1/2 wave
on an HT, not just due to stress on the antenna connector,
but because a 5/8 wave whip only gives the expected
gain when mounted directly over an infinite flat ground
plane, and that isn't the case with an HT.


For serious use while in motion, the best antenna I've
used is a 1/2 wave whip (the radiator from a CB mobile
antenna) mounted on the top of my packframe, with
the HT in a pocket of the pack and a speaker mic
clipped on my chest.  That maintained communications
in some pretty tough areas when I was out with Search
and Rescue (although knowing how to pick a good spot
to transmit from also helped a lot).  I'm now in the
process of trying to build a replacement, as I gave the
original one away years ago, and I need to design a
different mount for my current packframe.


On the other hand, over the last 25 years I've spent
more time carrying a 2m yagi with me when running
through the forest, but that is because I use it for DF.
They are generally built using tape measure for the
elements, so the elements snap back into place after
bashing through the bushes.



Quote

Counterpoise wires are said to enhance utility.



I'm a big believer in using a counterpoise on an HT.

I ran a study years ago where we measured the signal
strength with multiple antennas, both with and without
a counterpoise, and on average the counterpoise added
9 dB to the received signal strength for antennas up to
1/4 wavelength tall.  Not bad for a cheap little piece of
wire!

Now, there were some unexplained quirks in the data,
and other measurements haven't always given the same
results, but in my experience it makes a significant
improvement on 2m, especially as radios have gotten
smaller over the years.

Of course, you could make a homebrew version of
Radio Shack's "Exclusive Range-Boost Circuitry" that
they advertised for their CB handhelds, and just provide
a piece of metal where you grip the case to turn your
body into a radial.

No need for a weight on the end.  #22 or smaller
insulated hookup wire works quite well, and if it is
solid (like #30 wire-wrap wire) then it should be
stiff enough that you can shape it to hand down, but
I haven't had problems with stranded wire that had
a bit of a curl to it.  I just twist a loop in the end to
fit under the antenna connector and slip it over the
antenna jack before installing the antenna.

AI5BC

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #4 on: December 21, 2022, 10:15:31 AM »

I concur with WB6BYU, most antenna designs for portables are just mostly hype and ham foolery. Anythin other than a 1/4 wave stub or 1/2-wave whip is a waste of money looking for ham pigeons to pluck like the toroid and ferrite markets.

For example, you see all kinds of 5/8 wave antennas made for mobiles and portables in the snake oil market. If you knew anything about antennas, you would know all the claims made are complete BS. The only way a 5/8-wave vertical can work is ground mounted, on perfectly flat terrain for a minimum 2 wavelengths without any obstructions using a massive counterpoise made from radials. Great for commercial broadcast AM who can afford the land and to to build such and antenna. All but impossible for Sammy Hammy to build. Elevate the 5/8 vertical off the ground, and they do not have as much gain as a 1/4-wave whip.

As for a Rat or Tiger Tail counterpoise, there might be some benefits on the amateur 2M band portables, but not UHF. Amateur HT are poorly made with the cheapest materials possible. They all lack a metal frame, and those that do have any kind of metal chassis is so small it is not adequate to make a counter poise. They rely on the user to be the counter poise with tight grip on the radio. Wrap your hands around the radio when you TX. Commercial HT made for Public Safety, utilities, and industry are larger with full metal chassis frames to act as a counterpoise, or have a counterpoise built into them. So, you might be get some benefit using a Rat Tail on 150 MHz VHF band. Useless at UHF and higher. 
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K6CPO

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #5 on: December 21, 2022, 11:11:10 AM »

I see the topic has been touched on in several threads over the years but thought I’d start a specific thread on use of telescopic whip antennas for UHF/VHF antennas. Rubber duck and whip antennas are a compromise for dual band use and optimal RX/TX should come from properly tuned antennas. Adding adapters between a BNC/SMA mount on an HT and the antenna might vary the length significantly, so accounting for that factor may come into play. How to tune an antenna on an HT seems difficult, by other than calculated lengths. Tuning off the HT might have errors.

Is it feasible, for any given HT, to tune/mark telescopic antennas for optimal utility?

Counterpoise wires are said to enhance utility. Some information suggests that such a wire at the antenna base dangling past the radio body may do more harm than good. One person advocates a 10g wire at the antenna base protruding stiffly almost horizontal to the HT.

For portable use while moving about, high efficiency solutions suffer from fragility and inconvenience. For stationary use, there are better solutions other than an antenna mounted on the HT itself. Where I’m focused would be portable use when one might stop and extend a more fragile and inconvenient antenna for a timed checkin period - maybe 5min at 3hr intervals.

Thanks for your thoughts!

Bret/N4SRN

I think a lot of the so-called "enhancements" for handheld radios end up destroying the reason for a handheld in the first place; utility and ease of use in a field situation. Features such as a longer antenna or a counterpoise serve no useful purpose other than to get in the way. I think a lot of these changes stem from trying to improve the performance of the cheap imported radios that seem to be so popular. I discarded all my long antennas some time ago in favor of flexible antennas with an overall length of about 8 inches. Radios that don't have the flexible antennas have the OEM antennas on them, although I'm not a big fan of those either. They are characteristically too stiff and when they get bent, it's impossible to return them to their original shape. 

Surely some will say that the enhancements are needed when out in the boonies and not close to a repeater or a vehicle with a mobile radio. I have that covered with a couple of different portable go-kits, including one that is a completely self-contained radio station with a 50W mobile radio, battery, coax, antenna, and speaker all in a small backpack and weighing about 14 pounds.
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WB6BYU

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #6 on: December 21, 2022, 03:40:25 PM »

Quote from: K6CPO

I think a lot of the so-called "enhancements" for handheld radios end up destroying the reason for a handheld in the first place; utility and ease of use in a field situation. Features such as a longer antenna or a counterpoise serve no useful purpose other than to get in the way. I think a lot of these changes stem from trying to improve the performance of the cheap imported radios that seem to be so popular...



I would agree in general with many of your comments,
especially that many hams (especially newer ones) may
have unreasonable expectations of what they can do with
an HT.  In many cases, a mobile rig may be more
appropriate for their needs.

But this certainly predates the smaller radios - I went
through it with my Kenwood TR-2600 about 35 years ago.

Mostly I run my HTs on low power.  If that isn't enough,
then I add an external antenna.  But in most cases I'm
only using it for local chat - it isn't my primary radio.
(When it was, I had it plugged in to an external antenna.)

But in those cases when I do carry an HT in the field
for serious purposes, such as with the Forest Service or
Search and Rescue, then there are two important steps
that I take beforehand:


1.  Make sure I have whatever I need to get the most out
of the radio.  That might be a spare telescoping antenna,
or an external one (mounted on my backpack, or that I can
throw over a tree branch).  It may also include a radial
wire.  I'd also take spare batteries:  the SAR radios
that were notorious for bad NiCad batteries, and we could
be out in the field for many hours,so I carried a set of
Alkaline AAs (that I could also use in my flashlights, etc.)


2.  Know what to do when your radio doesn't work,
either because you are out of the primary coverage
area, or it got dropped into salt water, the antenna
broke, or whatever else might happen.  Don't be
totally dependent on a single comparatively fragile
piece of equipment.

I actually worked several years for the Forest Service
before we ever had radios, even in our trucks.  So
that part wasn't a problem.  But in Alaska where we
were more remote they were critical for ordering
supplies and scheduling aircraft pickups.

Still, you had to know what to do when it didn't work.
Sometimes that meant you had to hike a few miles
back to camp, or at least to a road where someone
might find you and bring you home. 

When my antenna broke, I used a clip lead as a
temporary replacement for a couple weeks until I
could get into town to the radio shop.  At one
point we were behind a ridge and couldn't hit the
local repeater, so I climbed 30' up into a spruce
tree with my radio.  Still couldn't hit the repeater,
but was able to hit the dispatcher's remote base
station on a mountain top nearly 100 miles away on
simplex.  That became my daily routine to call the
helicopter to pick us up at the end of the day.

At other times, I would find a high point to call
from, rather than standing on the trail at the bottom
of a canyon.  In one case with Search and Rescue,
we found the footprints we were looking for in
the process.

And, sometimes you simply can't make contact, for
whatever reason, so you plan for that in advance.

It's all part of understanding the role of the radio,
and how to use it most effectively for your
objectives.


It does all depend on the specific application and
circumstances, of course.  That includes how critical
the radio is to the reason you are out there in the
field in the first place, as well as the local repeater
coverage where you are.  Sometimes I might carry
a complete spare radio - or have someone else
carry it, in case I take a tumble in the creek.  Other
times it is a "nice to have", and I'll just shrug my
shoulders and put it back in my pack if it doesn't
work, and carry on with whatever else I'm doing.

N4SRN

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #7 on: December 21, 2022, 04:09:18 PM »

I’ll just keep it simple with the HTs. I’ve been a big fan of Signal Stick antennas so far - they can be curled into a circle to save space and survive well when moving about. I’ll try a Smiley Antenna Triband telescopic antenna but bring the Signal Stick along should I bend it.

Thanks for the comment!

Bret/N4SRN
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Bret/N4SRN
Bedford, NH  USA

KM3F

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #8 on: December 25, 2022, 09:02:04 PM »

I have done work in this area some time ago and found it not that difficult to improve HT distance with custom built L network matched antenna elements in the 30+" length. Nothing more than an End Fed Element in HF terms but matched for a single band.
Done on an Analyzer and transferred to the HT.
Doing the match network on an Analyzer, the Analyzer is metal and larger than the HT. No hand effect seen, hand on or off.
I have also mounted an SWR/Power meter on the HT and same antenna on the meter to see the match and Power has not changes but very little as would be expected.
Now today, I use an HT driving a 35 watt FM amp the same as any other radio for mobile use. Works for me.
I grant that conditions are different with an HT and may not even be at 50 ohm reference, but not insurmountable.
First, the HT is meant for reasonable close use to a Repeater such that the Antenna is really not a problem no matter as long as the Repeater can detect its signal.
The SWR is also not that critical.
The device usually operates on about 7 volts. The Device is not in any danger of being lost from high SWR at that voltage level.
Being hand held, the SWR match condition is all over with movement and position and still works.
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AI5BC

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #9 on: December 26, 2022, 09:27:10 AM »

custom built L network matched antenna elements in the 30+" length. Nothing more than an End Fed Element in HF terms but matched for a single band.
Well, that is handy. At least mine is hands free. Tells everyone who and what I am.

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WA3SKN

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Re: Tuned/Optimized Telescopic Antennas for UHF/VHF HTs
« Reply #10 on: January 12, 2023, 10:52:02 AM »

Telescopic antennas were not popular because they were ALWAYS getting bent or broken... a constant maintenance item.  Rubber Ducks became popular for convienence and THEY WERE CHEAP!

-Mike.
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