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AB7R

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another antenna question
« on: April 15, 2022, 03:41:00 PM »

So...I'm in this how situation and most operating will be portable in southwest Idaho.  I'm on the antenna phase.  I often won't have trees available.  I'm considering something like a packtenna 9:1 EF antenna and a Sotabeams 7000hds, or the chameleon MPAS 2.0 thinking I would use the vertical option most, or the wires when supports are available.
I know the latter is about $350 more but I would prefer to buy once.
Anyone have experience with both?

Tnx
Greg
AB7R
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WA3SKN

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Re: another antenna question
« Reply #1 on: April 15, 2022, 04:07:15 PM »

What bands, what modes, how portable???
Describe your intended operations a little better, please.

-Mike.
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AB7R

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Re: another antenna question
« Reply #2 on: April 15, 2022, 04:21:22 PM »

80-6m
Ic705 with 10AH battery
Hardrock 50 at times with tuner
CW, SSB, DIGI
Mostly from parks.

Tnx
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W6MK

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Re: another antenna question
« Reply #3 on: April 15, 2022, 05:00:37 PM »


I know the latter is about $350 more but I would prefer to buy once.


You can make something for much less money which can do as well as any commercial product, or better.

Telescoping fiberglass pole, some wire, a portable tuner. Your imagination.
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WB6BYU

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Re: another antenna question
« Reply #4 on: April 15, 2022, 06:43:57 PM »

Quote from: AB7R

So...I'm in this how situation and most operating will be portable in southwest Idaho.  I'm on the antenna phase.  I often won't have trees available.  I'm considering something like a packtenna 9:1 EF antenna and a Sotabeams 7000hds, or the chameleon MPAS 2.0 thinking I would use the vertical option most, or the wires when supports are available...




So the most critical aspect of choosing an antenna is figuring out what
you want to accomplish, rather than reading all the glossy advertising
and assuming that their criteria for "portable" operation are exactly
the same as  what you are planning to do.

Clue:  they often aren't.

And I'd be particularly wary of any equipment sold as "pseudo-military":
the military has some very specific requirements, especially for NVIS
operation, that generally don't apply in ham usage, and performance,
especially on 80m, can suffer accordingly.


So, first, let's understand your needs.

I'm going to start by making an assumption.  Yes, I know that is
dangerous, but let's make it explicit from the onset.  I am going
to assume that you are more interested in having an antenna
system with good performance than simply being able to brag
about how much it cost, how fancy it is, or the many other
aspects that some manufacturers would prefer to focus on
rather than glossing over how poor their product really works.

Why is this important?  Because for some manufacturers, being
able to get a low SWR with a wide-range tuner appears to
be their definition of an antenna "working" on a band, even if
you get 1 watt radiated with 100 watts applied to the antenna.
(Yes, by actual measurement.)


So let's look at the first item on your list:

Quote

80-6m



What this doesn't mention is, who do you want to work on
each of those bands?
  That makes a big difference in
selecting an antenna.

On 80m and 40m, if you want to work relatively local stations
(when the ionosphere permits), then you probably want to be
using horizontal polarization.  This involves NVIS propagation
out to 300 miles or so, which requires maximum radiation
straight up.  A vertical whip has a null overhead, right where
you want maximum signal for these paths.

Much of my portable operation has been on 40m, and a simple
dipole up 15 - 20 feet provides excellent performance, at a cost
much lower than most commercial offerings.  And, once adjusted,
it doesn't need an antenna tuner.  Combining a 40m dipole with
a dual-band dipole for 20m and 80m in about the same length
gives a very effective multiband installation, where the antenna
wires can be used as guys for your mast.

Or you can use one of the many link dipole designs that will
work all bands.  I happen to prefer being able to change bands
without needing to lower the antenna, especially in the middle
of a storm, but those are individual trade-offs that we each make
based on our own criteria.

In fact, I've been surprised how many SOTA operators have
mentioned that they have switched from verticals to dipoles
because they get much better results, even if the are a bit
more work to set up.

Over longer distances, typical of the higher bands where they
are rarely open for distances under 500 miles, then vertical
antennas become more practical, as long as you can provide
an effective ground system for them.  Note that some of the
commercial offerings are (intentionally?) vague on just what
is needed:  one cute little antenna suggested you could use
a single radial wire wadded up in your backpack.  (No, the
antenna won't even match in that condition.)  The truth is,
the radial wires are critical to proper operation of a vertical,
and it may be embarrassing for a manufacturer to admit that
they may radiate more RF than the fancy, expensive part
called the "antenna".

The late W4RNL described the "Revere Theory of Vacation
Antennas"
:  horizontal if by land, and vertical if by sea.
That's not to say that vertically polarized antennas can't work, but they
will also be dependent on your local soil conditions, which I suspect are
more like the volcanic soils of Oregon (some of which came from Idaho
and Eastern Washington years ago) rather than the higher conductivity
soils of the Great Plains, where vertical polarization works better.


Now, let's look at the other end of the spectrum:  6m.

It is rare that a single antenna will work well for 80m through 6m,
especially something lightweight for portable operation.  First, it
makes a big difference whether you are working FM repeaters, or
weak signal modes like SSB or CW, because the former would want
a vertical antenna and the latter probably horizontal.  A small beam
for 6m isn't out of the question in the latter case, especially if you
can set it up on a convenient hilltop, although that may require a
sturdier mast than the 7000HDS.

Fortunately it isn't difficult to set up a sectional mast, even by yourself.


If you can manage a somewhat taller mast, in a longer package,
then some of the 10m / 33' telescoping poles may give enough
performance improvement to be worth considering.  I have a
couple that I use with a drive-on mount that goes under one
tire on my van.

But western Oregon is well-blessed with Douglas Fir and other
tall trees, so I don't use my masts that often, except for Field Day.

There are lots of other considerations that go into choosing a
portable antenna that meets your needs, because there are
many variations of "portable operation" with different
requirements.

If you only have an hour or two to operate, then a quick
mediocre antenna may still make enough contacts.  In more
marginal conditions (and particularly when operating QRP),
taking some extra time to improve the antenna may often
result in more contacts, even with less operating time.


So there is no perfect answer.

The most important thing, however, is to remember that, just
because an advertising brochure says an antenna is "perfect for
portable operation", that might not be true, especially not for
your particular operating style, preferences, and circumstances.


My backpack dipole kit has traveled half way around the world
with me, weighs a couple pounds, fits in a belt pouch, and
probably can be duplicated for $20 or less with a bit of scrounging
at hamfests.  It's adaptable to a wide range of situations:  I've
hung it from trees, masts, rocks, fence posts, etc.  You probably
don't need it that small if you plan to operate from a vehicle, in
which case I have a larger one with longer coax.

That's not to say that it would be the right antenna for you, since
I don't know all your preferences.  But it probably out-performs many
of the fancy commercial kits.  Simplicity is often an important
criterion!

AE0Q

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Re: another antenna question
« Reply #5 on: April 15, 2022, 06:52:44 PM »

80-6m,   Ic705 with 10AH battery,   Hardrock 50 at times with tuner
CW, SSB, DIGI,   Mostly from parks.   
I use a 32 ft fiberglass mast from The Mast Company and a trailer hitch mount.  Lots of parks in the West don't have trees, and many places don't like you throwing wires in the ones they do have.

https://www.tmastco.com/main/page_products_telescopic_poles.html

The pole from TMC is almost twice as thick at the top as the Jackite pole of same height, it bends less.  The Sotabeams 7000hds mast is almost 10 ft shorter and on 20m and higher bands that will give your antennas a much higher angle pattern, not great for DX or working people farther out.

I have various wire antennas, FULL size, no loading coils.  A 32 ft 20m EFHW wire up the mast for quick setup and smaller footprint.  A 40-10m 65 ft EFHW supported in the middle like an Inverted-Vee where there is space to stretch out (same 49:1 xfmr as the 20m wire), and a 40m/20m linked dipole.

Many times a few hours on 20m is plenty of radio action for the day so the fast setup antenna is nice.  Almost any full-size wire antenna will give you a better signal than a base-loaded vertical near the ground.

de AE0Q
« Last Edit: April 15, 2022, 06:58:04 PM by AE0Q »
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W1VT

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Re: another antenna question
« Reply #6 on: April 15, 2022, 06:56:20 PM »

My HF portable operations have usually used single band dipoles supported by trees.

For 6M I have a TV tripod and 20 ft of TV masting.  I have a metal plate I can park my car over.
I can choose between a little 2 element Yagi or a 14 ft boom 4 element Yagi.  12V rotator.

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W4FID

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Re: another antenna question
« Reply #7 on: April 16, 2022, 03:22:46 AM »

I think ID is similar to where I am in FL as far as ground goes. End fed antennas need something to be the "other half of the antenna" -- the "ground". Nice soil that conducts can work fairly easily. Sand like I have doesn't. If you have dry or rocky you won't do well just pounding in a ground rod. You'll need a counterpoise wire -- several is better -- or some tuners do OK with the coax feed from the rig to the end fed bauln box if the coax is long enough and the velocity factor for that length doesn't hit a resonant frequency where you want to operate. A tuner and some experimenting with the counterpoise wires or the coax length will get you on the air. OR a loop. I often use an LNR (W4OP) loop with very good success. I also have a cheapie (about $125) minimalist loop that sets up even easier, weighs less, and performs OK. Either of them can do fine on a camera tripod that has a weight so it doesn't blow over. The trailer hitch mount for a pole is a nice idea if you do chose any of the wire antenna options. But the camera tripod is lighter and quicker to set up.
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KB1GMX

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Re: another antenna question
« Reply #8 on: April 16, 2022, 04:21:17 PM »

I'm with WB6BYU...

Your request was I want it all in scope but in practical case a few
bands done well will be better,  If you there for days battery and
charging needs to be thought out.

The key items is a collapsible pole and guys to support it.
10M is plenty tall.

A basic vertical like a PAC12 or similar with more than two radials
especially for areas of very dry soil.  I have a home brew vertical based
on  a AN271 foldable bungee antenna and a large loading coil that
assembles for the field for 80 though 10 and 6 radials as long as the
antenna  (16ft max), Rarely use it,  I reserve verticals (loaded whips)
for the truck.  Around here trees are a resource save for a few
mountain tops.  But I have kit for that rare case,

Myself a good pole such as the TMC mentioned for 10M height and a
Dipole or Endfed fed multiband  I happen to like the Vibroplex/LNR/PAR
EF40/20/10  and can use it as sloper or inverted V setup as that covers
 a lot of tree and no tree cases.  For the other bands precut wires for
17, 15, and 12M are in the kit they are easy to switch out,  That and light
rope and stakes (or pitons) to anchor the ropes.

If I plan a 6M outing I use a K6STI full wave loop for 6M and a 20ft
plastic pole our lift into a tree on a rope.  Its easily rolled up to make
a 43" long bag to carry,  Other choices can be yagis or Moxon big
and time consuming but from the truck fine as it has a mast mount 
and they can just lay in the 6ft bed.   I rarely bother with that if the
goal is activity as usually 40 and 20 can supply more than enough.
I will only bring 80/75M if a low location (valley) for NVIS and use
what can be had (or short poles) to get it 6 to 10 ft up.  NVIS is MUF
limited so higher bands like 40 are poor for that.  NOTE: valleys are
bad for most VHF work.

IC705 is low power so thick or bulky antennas for higher power buy
you nothing,  They may break your wallet and back,

Band choices, bands that are active is where you find people.
With current sunspot activity that means 40 and 20 is a good bet
and higher is maybe.

For 6M ops unless high and you use a horizontal beam its going to
be sketchy, Small beam of 2-3 elements or maybe a moxon is a good
choice.  Height, if your on a mountain 6-8ft is plenty, any place lower
higher is better.  Generally reserve VHF for mountain tops as low spots
are less thena optimal.  The times when 6M is active is during
Sporatic E season and contests.  The last few years here in W1 land
6M has been better than 70% data (FT8) during active times,

MIL antenna or copies of them are poor choices as the military
requirement are known coverage, pattern, and what the heck is DX.
They carry satellite radios for when distance is needed.  That and
for that money I can make  a lot of wires and have dinner and a
motel money left.  Price does not buy performance that is has
been limited by physics.


Allison
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AB7R

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Re: another antenna question
« Reply #9 on: April 17, 2022, 12:45:18 PM »

Thanks for all the input.  I have not operated portable before except for Field Days.

I will be using a few different Ununs and a choke balun along with various lengths of 26 ga wire.  I ordered 500ft of the wire so I have plenty for radials as well.  The mast will go into a hitch mount for flags (should fit).  I may also end up with the heavy duty 33ft mast from TMC.    This should provide good options for various configurations as needed.

73
Greg
AB7R
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