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Author Topic: Which portable antenna wouls you get?  (Read 7681 times)
KA4NMA
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Posts: 357




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« on: May 27, 2011, 10:01:31 PM »

I am in need of a cheap ultra portable antenna and would like opinions and users to comment on the following antenna's:
 
1 Mfj Walkabout Antenna 80m-6m, MFJ-1899T
2. Mfj Single Band walkabout (40m, 20m, 17m, 10m, 6m)
3. MFJ mini bugcatcher antenna (MFJ-1624)
4. MFJ Apartment antenna (MFJ-1622)
5. MFJ Short mobile antenna (MFJ-23xxT)
6. SuperAntenna MP-1.
 
I'm primarily intersted in the higher HF bands with 80m and 40m sometimes used. Antenna donations accepted :-).  I am homebound and outside antenna's are not possible.
 
I know most of these antenna's are about as efficient as a wet noodle.
 Randy Ka4nma
« Last Edit: May 27, 2011, 10:49:58 PM by KA4NMA » Logged
N4OI
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Posts: 214




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« Reply #1 on: May 28, 2011, 02:36:53 AM »

Wire: Lightweight dipole or random length with tuner.
73 ES GOD BLESS U ES URS DE KEN N4OI
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W8JX
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Posts: 6685




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« Reply #2 on: May 28, 2011, 05:41:12 AM »

I would agree that a dipole or random wire and tuner is best here. When you are QRP, you want to make best antenna possible to help low power.
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You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
WB6BYU
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Posts: 13578




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« Reply #3 on: May 28, 2011, 08:04:49 AM »

When considering vertical antennas such as those you listed there are three general principles to keep in mind:

(1) the performance will depend more on your ground system than on the choice of antenna itself.

(2) longer antennas are capable of higher efficiency than shorter ones for the same ground system.

(3) Any such system will need fine tuning to account for changes in environment and/or ground system.


The next thing to decide is whether you want multi-band coverage or just one band.  I think you'll find
that the higher bands tend to be more efficient for indoor operation (but not always), so being able to
try 17, 15 or 12m as they open up can be a lot of fun.  A simple system (commercial or homebrew)
that consists of a vertical section (as tall as practical in your application) and an efficient matching
coil should do the job for you.  The coil can be either at the base or in the middle of the vertical.
If you run radial wires under the rug and put the base of the antenna at floor level, making adjustments
in the center of the radiator may be more convenient as it doesn't require bending over.

While you can feed such an antenna using an antenna tuner, a simple coil wound with, say, #14 wire
is probably more convenient, and quite likely will be more efficient.  If you use a mobile antenna for
the highest band (say, 10m, possibly with an old CB whip) then you can add a loading coil at the
base for the lower bands, but trying to tune a 20m Hamstick on 15m really doesn't work as well.

Note that a similar method can be used with a wire hanging from the ceiling, in which case you could
run a couple wires across the ceiling to act as a capacity hat and get more efficient operation on 40m.


The ground system should consist of at least one, and preferably two or more, quarter wave wire radials
for each band you want to operate.  (Requirements may be different if the floor is immediately over a
cement slab foundation.)  Run them under the rug, or tucked around the edges of the floor out of the
way.  You can use thin insulated wire or magnet wire to keep them unobtrusive.
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WB8YYY
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Posts: 159


WWW

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« Reply #4 on: May 28, 2011, 03:44:36 PM »

Keep in mind the basics - an antenna much shorter than a half wave dipole will be very inefficient unless high attention is given to minimizing ohmic loss. 

One excellent portable antenna you did not mention is the Buddipole, another is the Pacific Antenna PAC-12.  Both have build your own instructions also BTW. 

If antennas are legit at your QTH, don't rule out members of your local ham club putting up a wire for you. 

73 Curt


 
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M0JHA
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Posts: 646




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« Reply #5 on: May 29, 2011, 08:49:28 AM »

Hi Randy , as already said there are better antennas out there , i do a lot of experimenting with short vert antennas all qrp. One i do like is the atx walkabout. Now i know it's limitations but i must admit this antenna performs very well indeed.

As already stated the earth is the key, the atx can be a pig to tune and the counterpoise is the key with this antenna. i have a page on my site re my findings www.m0jha.com..

i have made many a contact on this little antenna all 5 watts or less.. if you can't get an antenna outside this may be for you , that or i can reccommend the MP1 also..

The miracle antenna mixed mode dipole may be an option as you could hang it out your window..
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KE3WD
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Posts: 5689




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« Reply #6 on: May 29, 2011, 03:55:50 PM »

Or look into homebrewing Small Magnetic Loop antennas on the web (google search). 

*Low Noise pickup, even in today's EMI/RFI environment.

*Yes, you have to tune the capacitor any time you change frequency, but that is actually a plus because the antenna always operates at the high Q point. 

*VERY popular antenna for use indoors, even at ground level, by QRPers outside the USA. 

Use more than one to cover all bands, sizing the main loop and capacitor accordingly. 

In my personal testing, the well designed Small Magnetic Loop, when used indoors hanging on a stick held upright by an old lamp stand far outperforms any of those wound verticals. 

There is less signal, but that is to be expected on *any* compromise antenna system, the advantage of the Small Magnetic Loop is that there is also lots less noise, which means that a signal that might be S9 on a full dipole but is only S7 on your Magloop is still often easier to copy. 

They are also rather easy to homebrew and the capacitor needed for QRP levels will not break the bank.  I use scrap air tuning caps taken out of old fashioned tube and transistor AM radios. 

Just threw together a portable one where the loop is made from coax, using the shield as the conductor.  Comes apart and fits in the suitcase that way, plus I have two different sized coax loops to cover more bands with the same matching loop and capacitor setup. 

http://www.aa5tb.com/loop.html

http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm

Don't buy. 

BUILD

Be a ham and not only save money, but LEARN and have lots of fun on the way. 

And enjoy being able to say, "Antenna here is homebrew..." 

73
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KB1GMX
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Posts: 830




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« Reply #7 on: May 30, 2011, 10:33:33 AM »

Me I vote for none of the above.

I'd build (you may buy) a random wire tuner such as the Hendricks QRP kits SLT+
(antenna tuner+SWR) and two pieces of wire.  Cheap, multiband and efficient.

I also use PAR endfed antennas specifically the EF40/20/10 as it covers 3 bands
as is and that plus 25ft of RG58 is all thats needed.  It's only 40FT long too.   
If trees are in short supply I bring a 20FT crappie pols (fiberglass collapsible
pole).  The wire can be run as vertical, inverted L, inverted V, or with two
supports horizontal.

The first using random wire tuner, or second are more or less interchangeable
for my use.

Allison
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K1WJ
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Posts: 464




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« Reply #8 on: June 01, 2011, 04:10:51 PM »

I run a 20m MFJ Hamtenna (8ft tall) with a single 1/4w (16.5ft+-)counterpoise wire 2 ft above the ground.
Also have the same set up for 10m. Check pic on QRZ (K1WJ) pic on top right - click on it - gets bigger.
Worked all over with 100w. 73 K1WJ David
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WB6RQN
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Posts: 484




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« Reply #9 on: June 01, 2011, 05:00:23 PM »

I have become a real aficionado of the single-wire loop. If the loop is greater than 1/2-wave it seems to work quite well. Normally I feed it with my SG-231 tuner. For QRP operation I use an SG-211 but that requires a larger loop before it will tune, probably because the tuning range on the low impedance end of the SG-211 is much less than the SG-231.

A year ago I spent two months on the island of Dominica in the Caribbean. I quickly put up a 10m rectangular loop fed at the bottom in the middle just to make sure everything was working before I went to the effort of setting up my end-fed wires. With the SG-231 the loop worked well on 40m down to 6m. I never ended up changing it.

So, I recommend trying out a loop with a good tuner.

My QRP backpack-portable station consists of a Flex 1500, my laptop, an SG-211 tuner, and 100' of 14AWG insulated flexible wire. The ideal is to create a loop or a folded dipole/doublet, depending on the amount of space I have.

BTW, if you use a bias-tee to bring 12V to the tuner and then a common-mode choke on the feed line right at the tuner, the tuner effectively becomes a balanced tuner.
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KATEKEBO
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Posts: 117




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« Reply #10 on: June 02, 2011, 06:44:44 AM »

If you can (have enough space), I would recommend PAR End Fedz EF-10/20/40.  Very good performer, no tuner needed, low SWR across all three bands, and no re-tuning necessary when changing bands.  The only limitations are that you don't have 12, 15 and 17 m, and that it needs to be hang either vertically or horizontally high above the ground for optimum performance.  If strung horizontally less then 1/2 wavelength above the ground, it will act as NVIS antenna and be useless for DX-ing.

My second choice would be a set of hamsticks - one for each band.  Once you tune them, all you have to do is to swap the "sticks" when changing bands.

I don't think the MFJ small antennas are very good.

I have used the MP-1 and it works well, about the same performance as the hamsticks, but I got tired of the tuning process.  It is cumbersome and takes time.  I found that swapping sticks is much more convenient.
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WB6RQN
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Posts: 484




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« Reply #11 on: June 02, 2011, 04:09:45 PM »

You can use a pair of hamsticks back-to-back to make a compact loaded dipole. It doesn't need a ground or counterpoise. It is also twice the feedpoint impedance of a single hamstick which is good because the shortened antenna is generally fairly low impedance.

73 de Brian, WB6RQN/J79BPL
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KD5TXX
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Posts: 82




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« Reply #12 on: June 03, 2011, 07:55:17 PM »

I have a Par End fed 10-20-40.  I have talked to DX stations on 17m on it also so don't count it out.  My 817 and tuner...If I can tune it.. I'll try to work it.
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N0SYA
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Posts: 369




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« Reply #13 on: June 04, 2011, 01:31:01 PM »

Hi
Hard to beat the portability, mounting options, and most importantly the efficiency of a simple wire dipole.
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If you have a clumsy child, you make them wear a helmet. If you have death prone children, you keep a few clones of them in your lab.
WY3X
Member

Posts: 768




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« Reply #14 on: June 07, 2011, 06:22:16 AM »

Sounds like you're in a condo-like situation. No outdoor rules out any physically long antenna. My personal favorite for your situation is to drop down from the ceiling with ceramic fence insulators around the perimeter of the room. Run a loop of wire through the insulators. These insulators have a "lag bolt" sticking out the backside (screw them into your ceiling) and have a honking big ceramic insulator with a hole in it on the other end. At some convenient point (over your operating position) break the loop of wire, and connect a piece of 450 ohm window line to it there. Keep the ladder line as short as possible, and tie it directly to your HF antenna tuner. Don't let metal objects come close to the window line. Don't hang your laundry on the loop to dry (coat hangers made of metal will affect your SWR and radiation pattern). Tune up and enjoy! Not all that portable, but you'll make plenty of contacts!

73, -WY3X
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