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Author Topic: Mars Antennas  (Read 8424 times)
KE7UAF
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Posts: 36




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« on: June 08, 2008, 03:06:27 PM »

I recently applied for membership to Army MARS, and I had a few preliminary questions regarding antennas.

Since the MARS frequencies are all off the amateur bands,  do most people make their antennas or use commercially made antennas? This goes for both HF and VHF/UHF antennas. Would your standard amateur antennas work for operating out of band?
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W3LK
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« Reply #1 on: June 08, 2008, 04:45:15 PM »

Eric:

<<do most people make their antennas or use commercially made antennas? This goes for both HF and VHF/UHF antennas.>>

The average VHF antenna needs no modification for MARS usage; it's broadband enough. As for HF, the answer is both. Most commercial antennas can be used on those MARS frequencies that are just outside the amateur bands with the use of an antenna matcher (sometimes called an antenna tuner). Frequencies not close to amateur allocations ( more than 250kHz away) generally require separate antennas (mostly dipoles) cut for the specific frequencies involved.

A very popular option is the B&W Terminated Folded Dipole. This antenna generally has a 2.5:1 or less SWR over it's entire operating range. It is less efficient than a single-band dipole, but it is excellent for the frequency hopping often done in MARS operations. This is the very purpose it was designed for - military communications on multiple frequencies without the need for any antenna matching device. There is nothing to prevent you using a tuner with it to keep the SWR lower, if you are running a solid-state rig. If you are using a tube amp following the rig, virtually all tube amps will handle a 3:1 or higher with no problem.

I normally drive a B&W with an AL-80A (running about 500w) for all MARS operations. It's mounted as a very shallow inverted V with the apex at 15' and the ends at 12' for an NVIS pattern. I have no problem covering a 400+ mile operating radius with the installation.

I have also used my Butternut HF6V for MARS for longer hauls down into the deep South and into the Mid-West and Texas.

Even though you are joining Army MARS, Welcome Aboard! Smiley

Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve


http://bwantennas.com/ama/fdipole.ama.htm







 
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KE7UAF
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Posts: 36




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« Reply #2 on: June 08, 2008, 05:26:24 PM »

Right now I've got a G5RVjr with a MFJ-993b automatic tuner. I also have a hustler 6btv but I haven't put it up yet. I've also got a Diamond X510HDM for 2m/70cm and a Cuschraft Ringo for 6m, but I doubt they'll be much use.

I've been doing some research and reading on the forum and I'm thinking about looking into the Navy MARS instead. I'm mostly interested in learning and getting some training, as well as just more reason to get on the air. With this in mind, would you have any specific recommendations?
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W3LK
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« Reply #3 on: June 09, 2008, 02:09:14 PM »

Eric:

The G5RV/tuner combo might work OK. All you can do it try it. The same with the Hustler; try it and see what happens. Smiley

As for joining Navy MARS, I'll be happy to continue that discussion via email, rather than on the forum. I try to keep discussions about the different services off the forum. Despite the same basic operating procedures, there are definite differences between the services.

Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve
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KE7UAF
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« Reply #4 on: June 10, 2008, 11:36:15 AM »

Somehow I managed to unsubscribe from this thread. Sorry for taking so long to respond.

My email is huntley.eric.a@gmail.com, I didn't see yours listed anywhere or I would have emailed you.
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W3LK
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« Reply #5 on: June 10, 2008, 03:46:34 PM »

It's in my profile. Smiley

73,

Lon - W3LK
Naugatuck, Connecticut
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W3LK
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« Reply #6 on: June 10, 2008, 03:47:58 PM »

Well guess what? It ISN'T. Sad

majorlk@att.net

73,

Lon - W3LK
Naugatuck, Connecticut
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W4LTX
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Posts: 9




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« Reply #7 on: June 17, 2008, 04:23:11 PM »

I use an alpha delta DX-CC for the amateur and MARS bands with an autotuner in the feedline.
Welcome to Army MARS.
God bless,
Pudge AAR3RF  
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W4FID
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Posts: 138




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« Reply #8 on: June 18, 2008, 07:08:38 AM »

I have used a Buddipole not even 10 feet high but physically adjusted for the MARS operating frequency I wanted. Had a delta loop 22 feet on a sidefed with an SGC237 coupler successfully on the Army MARS nets above 75 meters. Also the MFJ 1788 hi Q loop will tune anywhere from 7 to about 22 MHz and it's a resonant antenna that will work nicely even as low as about 10 feet high and great if in the clear. Some MARS nets are in that range.

If you can physically do it and the MARS nets you want are on one or only a few close frequencies a dedicated dipole in the clear is great.

Mobile whips don't seem to do too well. Most wil be tough to tune very far outide the ham band and at best they are a big compromise in efficiency so that's probably a last choice.

73
John
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N9ESH
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Posts: 27




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« Reply #9 on: June 24, 2008, 11:02:28 PM »

You find some great ideas and some good pointers here.

http://www.netcom.army.mil/mars/training/docs/DOCUMENT%20NUMBER%201%202007%20REV%201.pdf

It’s the Army Antenna Seminar.

73,
Jim
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KA1MDA
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Posts: 543




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« Reply #10 on: June 26, 2008, 08:03:57 PM »

"A very popular option is the B&W Terminated Folded Dipole"

I wouldn't wish this antenna on my worst enemy! I have one, got it for free from someone that was getting out of MARS. If I include the time and labor to install it, I feel I overpaid. It's totally deaf. Compared to my 2nd hand Hustler 6BTV, stations that are S-0 to S-1 on the B&W are S-7 to S-9 on the Hustler. I couldn't even hear the HARP experiment on 7 Mhz with that lame antenna. If you have a KW, and want to work a few hundred miles, I guess it's ok, but there has to be a better choice! The day I replaced the B&W with the Hustler was the first time I could ever turned off the preamp on me receiver and still hear something!

73, de Tom, KA1MDA
www.ka1mda.org

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K3WVU
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Posts: 491




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« Reply #11 on: June 27, 2008, 07:38:26 AM »

Tom,

I think you're missing the point here.  You're quite correct about the B&W antenna if your primary purpose is working DX.  For MARS, it is a very good antenna, because most MARS HF comms are local or regional. The B&W antenna is also capable of working over a wide range of frequencies that a non-MARS ham never uses, which is a paramount concern for MARS. Your Hustler 6BTV, with a good radial system, is great for DX, but would be nearly useless for most MARS work.

73

Dwight NNN0TPR/NNN0GCP2

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W3LK
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« Reply #12 on: June 27, 2008, 12:00:52 PM »

<< I wouldn't wish this antenna on my worst enemy! >>

No one asked you to. Smiley

Yes, tom, you missed the point.

For it's designed purpose, it's an excellent antenna. As a general purpose ham antenna, no. There is little else that is as frequency-agile and does not require any kind of coupler, as is often the case in military and MARS communications. I don't know how you installed it, but having use several over the years, I didn't find it deaf, by any means.

It's called using the right tool for the job - and for typical 100-200 mile MARS operations, your Hustler ain't the right tool - and neither is my Butternut HF6V.

I'm curious as to what MARS experience, if any, you have.

Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve
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AB5KT
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Posts: 1




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« Reply #13 on: July 24, 2008, 07:51:36 PM »

W3LK,

I read your post about asking people about their MARS experience and with your three line signature block, I am almost afraid to ask a question.

Then what would be a good antenna recommendation for those of us who do not have many years of MARS tucked under out belts?

Educate rather than tear people down!
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W3LK
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Posts: 5639




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« Reply #14 on: July 24, 2008, 08:25:16 PM »

I don't understand your comments, but if you are referring to my response to Tom, the man simply doesn't know what he is talking about. He has made the same statements in other forums and has been shot down by several hams who DO know what they are talking about.

The best antenna for MARS is a dipole cut to the specific frequency you plan to operate on, but if you operate on several, as most MARS members do, that's not very practical.

Just about any multi-band dipole and a wide-range tuner will do. That's what most MARS members use. If you don't want to use a tuner, the B&W is a good choice, albeit it is down 4-6 dB from a single-band resonant dipole.

Verticals are a poor choice for state-wide or regional operations due to the low takeoff angle. What you need is the high takeoff angle of a dipole and even better is one in an NVIS configuration - 12 to 15 feet off the ground. I used one for a few years and did fine on the Southeastern regional nets but often couldn't be heard 20 miles away. In my present location, the B&W is 6-8 dB over my Butternut HF6V under three hundred miles.

I hope this answers your question.

Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve
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