[QRP] Usable, accessible portable antenna?

[Darrell Shandrow]

Hi Daniel,

Thanks for your excellent ideas.  I might be able to run a thin long wire;
I'm just not sure right now.  I definitely need to obtain some additional
local assistance with a project like that.  I've also thought about a thin
28-gauge copper wire loop of some kind.  I'm not sure about the internal
construction of this apartment; it was built in 1998 or so.  I'm surprised
that I can get some good play on VHF/UHF from deep inside my apartment using
just a rubber duck on an HT, while I can't get or receive much of a signal
at all on HF from the patio!

I'm thinking about trying a few projects.  Another commercial antenna like
the Buddipole, if I could figure out a way to use it effectively as a blind
person.  A horizontal thin-wire loop run along the ceiling of the other
bedroom not used as the office.

Thanks/73





----- Original Message ----- 
From: "Daniel Reynolds" <aa0ni@yahoo.com>
To: <qrp@mailman.qth.net>
Sent: Saturday, April 10, 2004 11:23 PM
Subject: Re: [QRP] Usable, accessible portable antenna?


> Hi Darrell,
>
> How much space do you have to work with for an antenna? How high can you
string
> a wire? How long of a wire can you put up? If you can, try to get a four
to one
> balun that will tie into the back end of the radio, and then run 450 Ohm
> twinlead to a long wire, an off center dipole, or a center fed dipole like
a
> G5RV.
>
> I live in an apartment. What I've been trying lately is an 85 foot end fed
long
> wire with a 15 foot counterpoise attached directly to the balun which is
hooked
> up right to the output of my K2 (which has the tuner option included). If
the
> IC-703 tuner can handle most SWR's, the Balun will further improve its
ability.
> Most baluns can be had for around $30 or more. I've been using 22 gauge
wire
> for temporary antennas strung from my 2nd story balcony and tied off to a
fence
> 85 feet away (the counterpoise just droops over the balcony).
>
> If you get a chance to read eham.com, you might be able to find out what
folks
> say about the various antennas you've mentioned so far. A compromise
antenna
> might do a good job at 100 Watts, but that's because it is 20% efficient
(80%
> turns into heat) - so in effect, you have a signal that is still better
than
> QRP. If you run QRP into the same antenna, you are effectively operating
QRPp
> (1 Watt out with a 5 Watt signal into the antenna).
>
> I use the Buddipole antenna most of the time since I try to operate away
from
> my apartment. It's a great antenna, and I am very fond of it. Compared to
the
> outbacker antennas, it is not quite as simple to configure. This is
because you
> can move any of the buddipole coil taps where ever you want on the coils.
Also,
> the coil taps can become loose, fall off, and dissappear in the grass
(they
> aren't much bigger than the fleshy end of my pinky finger which is under
my
> fingernail). If you knew you were going to always use the stock buddipole
> antenna and Budd and company had a way to make their coil form with
permanent
> taps like the outbacker antennas, then it would be much easier to set up
for
> the various bands it can handle. However, you wouldn't have the
flexibility of
> design which would allow you to add more antenna arms, or use the new
longer
> shock-cord/section whips. This isn't a big issue for operation on most
bands
> like 20m and up since the stock Buddipole does a great job on those bands.
On
> the lower bands like 40m, you'll need to retune the coils or adjust the
> telescoping whips if you change from the CW and Data portion of the 40m
band to
> the voice portion of the 40m band.
>
> The key for compromise antennas like the Buddipole is to get a low SWR by
> tuning the antenna, NOT by using an antenna tuner in your radio. The tuner
in
> the radio only makes the transmitter happy - it doesn't make the antenna
more
> efficient.
>
> However, using the same tuner into a less-of-a-compromise antenna like a
long
> wire actually has a positive effect since it enables the radio to transfer
more
> power into a mismatched load (Although - I'm sure those who are more
technical
> will set me straight if I need correction).
>
> Because you want to run QRP - you may want to also specify which bands are
more
> important to you, and what time of day you will be doing most of your
> operating?
>
> I understand your frustration about the outbacker. I recently set up a
couple
> slinkies with some aluminum tape in my radio room. The slinkies were
stretched
> out about 11 feet each, and the tape was another 5 feet added to the end
of
> each slinky. This antenna, which by all means appeared to be much grander
than
> any mobile 80m antenna (and also had a bandwidth of almost 200-300
kHz!!! - can
> you say dummy load?), netted zero contacts in the half dozen times I tried
to
> use it. The last week I had it up, I tried to check into the Four States
QRP
> net - and the net control station couldn't hear my signal running through
this
> magnificently 'broadband' and efficient looking compromise antenna. The
week
> after the slinkies came down, I snuck out that 85 foot wire I mentioned
> previously, and got a decent report from the net control station.
>
> If you have a good idea of your surroundings, or if you have another ham
who is
> experienced with stealth antennas, you will hopefully be able to determine
just
> how high you can get a wire. The higher you can get it (for example, 30-40
feet
> up), the better chance you will have of getting your QRP signal off the
> continent on bands like 20-15m. If you run a random length wire along a
wooden
> fence line which is less than 10 feet tall - it may tune up on all the
bands,
> but your contacts will be relegated to primarily stateside contacts on
bands
> like 20-15m, and states in your region on 80-30m. That's because the
closer
> your wire is to the ground, the more of the signal that goes up (instead
of out
> ward and low to the horizon).
>
> I hope this information helps. Setting up an apartment antenna can be
pretty
> tricky.
>
> - Daniel/AA0NI
> Oklahoma City
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