Small Antennas

[Bacon, WA3WDR]

Robert Vincent of the University of Rhode Island says that the US Navy seems to like the 7 MHz plano spiral top hat "Super DLM" (Distributed Load Monopole) spiral-top antenna.  I haven't had time to check this out, but here is the link:

http://www.uri.edu/news/releases/?id=3126

[N9NEO]

Yea, I heard that some guy down the road chanting "size doesn't matter... size doesn't matter"  Heheh, ya know what they say bout those guys.

I'm going to take the skeptical stance as well.

I'm putting some plans together for a 160m shortened dipole that I'm going to stuff in a thimble.   I hit my head on the concrete floor last night and came up with the idea.  I know you guys will really like me when I publish that paper.  I haven't got all the math worked out yet, but I got the whole summer to figure it out.

73
NEO

[W3SLK]

Neo said:

I'm putting some plans together for a 160m shortened dipole that I'm going to stuff in a thimble. I hit my head on the concrete floor last night and came up with the idea. I know you guys will really like me when I publish that paper.

Yeah, you can sell the plans to MFJ and they will build it cheap and market it to the hamdom-public. You could probably convince a boat-load of Sloppbucketeers to fall ass-over-tin-cups to buy one.

[k4kyv]

Yeah, you can sell the plans to MFJ and they will build it cheap and market it to the hamdom-public. You could probably convince a boat-load of Sloppbucketeers to fall ass-over-tin-cups to buy one.

Yes, I remember the infamous Maxcom antenna matcher.

[WA1GFZ]

Don,
wasn't it MAX-CON

[km1r]

looks surprisingly similar to a HY-Gain hustler.

Good to know that academia is re-inventing the dipole (again). Right up there in technology with the "NVIS" (very low dipole - duh) and the "Inverted U Beam" (beam with the ends bent down to fit!)

fancy names for simple things... yep it keeps us smiling and the vendors happy!

73 have a good weekend...

KM1R

[Jack-KA3ZLR-]

Hi Bacon,

 Nice article, was a good read, and the facility is Technicians Paradise, but I think like the others here the author is somewhat Lost in his product, and falling Short of "Forward Momentum"...  oh well End users can be Sold anything if the performance figures add up to their "Knowledge Shortcomings" i guess....

Nice place...

[c. mac neill w8znx]

hello
yes it works
nothing like

big big counterpose
in salt water
or
over 18k tons of steel ship
floating in salt water
help very short antenna

mac

[nq5t]

Yes, I remember the infamous Maxcom antenna matcher.

These yahoos are still in business.  Dummy load with a wire attached

http://www.maxx-com.com/index.html

You can tell by some of the praise of these things on eHam that QST needs to rerun its expose of this piece of crap.

[Glenn K2KL]

Has anyone else noticed how many products there are in the ham catalogs these days that can turn RF into heat?

What about that B&W folded dipole antenna with the big "matching" resistor? Military used 'em, gotta be good, right?

Was that a Gotham vertical I saw on that battleship?  :lol:  :lol:

Yes, I remember the infamous Maxcom antenna matcher.

These yahoos are still in business.  Dummy load with a wire attached

http://www.maxx-com.com/index.html

You can tell by some of the praise of these things on eHam that QST needs to rerun its expose of this piece of crap.

[Glenn K2KL]

"smaller is better"? What a load of crap!.... Did someone change the laws of physics?.....

Hey Don! you can take down that full size 160m vertical now....


Small antennas make small signals...  

[WA1GFZ]

"IT AIN"T THE MEAT IT"S THE MOTION" ca mon

[K1JJ]

The Isotron - 160-10M -
http://www.isotronantennas.com/index.htm

If John Wayne [with a black wig] says they work, then they work!


Every Sanford and Son ham should have one on their tower:  

[W1GFH]

Whee! Here's my new 75 meter antenna!

[Glenn K2KL]

Now that's funny!!!!!...... Notice the NASA shirt?

and what a waste of a tower, eh Tom?

The Isotron - 160-10M -
http://www.isotronantennas.com/index.htm

If John Wayne [with a black wig] says they work, then they work!
Every Sanford and Son ham should have one on their tower:  

[wa2zdy]

"If the military says it's good, it must be, right?"  

Yeah and the military says claw hammers and toilet seats are worth $600.

Uh huh.

I've actually never heard of that antenna range on Fisher's Island, NY.  Then again, I'd never heard of Fisher's Island either.  No matter, I'm sure the military has their minimum acceptable standards and I'm sure this miniature antenna meets them.

But so do that Maxcom and B&W "dipole."  So what's that tell us?  It tells ME I know what the military is going to be spending money on shortly.

[WA1GFZ]

When I lived in L.A. there was a guy pushing that antenna at every TRW
flea market. What a Tom Vu sales pitch. I used to get close and listen just for a good laugh. He claimed the plates had the same surface area as a full size dipole so it worked as good as a full sized dipole.
It aint the it's the motion

[WD8BIL]

AS the HUZMAN says;
You can't change the laws of physics !

And Dad;

If it sounds too good to be true ......

[Steve - WB3HUZ]

Military users have different requirements than amateurs. Thus, they may use an antenna like the broadband dipole from B&W and be perfectly happy with it. One example is the ALE systems used by the military. These systems can operate over much of the HF spectrum, depending on time of day, propagation conditions and the path to be covered. As such, a broadband antenna is required and a 3 to 6 dB loss is an acceptable tradeoff to obtain the required bandwidth with only one antenna. It has nothing to do with $600 toilet seats, even though such comments make for a good laugh.

Engineering is about considering and balancing various performance tradeoffs with the associated costs, complexity, maintenance, and production issues.

[WA1GFZ]

Also a lot easier to live with a little loss when the operator can't be trusted to operate an antenna tuner every time the operating frequency is changed. Then there is the hopping mode that needs a broad band resistive load.
A little heat is the KISS approach.

[K1JJ]

Hard to beat a log periodic for broadbanded 2.5:1 freq
coverage with flat f-b and gain.  Like 13-32 mhz or so.

I notice the military uses them quite a bit for fixed,
directive rotary use.  I don't see many Yagis - or even
Gothams or Isotrons these days...  

The homebrew JJ Log stack - top at 100' has 60' boom, 400 pounds -
It ain't done, but it's still fun!

[WA1GFZ]

A log antenna seems like you are cheating I've never seen such a flat load. They even work close to the ground.
My third contact was a KH6 running 50 watts with the antenna 6 feet in the air.

[Steve - WB3HUZ]

The A in ALE is for automatic. If the operator needs to select a frequency, tune an antenna, or rotate an antenna, it's no long automatic. All the operator needs to do is compose his message and hit send. The ALE system picks the frequency or frequencies and which node or nodes (other ALE stations) to send the message. This is not much different than what you do when you send an email via the Internet. All you do is put in the address of of the recipient(s). You don't care how it get there, as long as it makes it. The DNS system and routers take care of this for you behind the scenes. ALE is similar but the "Internet" connections are RF on HF.

The mil does like logs. But they don't rotate them a whole lot. Many installations are fixed directions. The B&W dipole is "flat" over a 20:1 frequency range. That would make for a mightly big Log to cover such a range at HF. Logs (really multiple logs off one feed) with 100:1 frequency coverage are available at VHF/UHF and microwave frequencies. Most have no more than 6 dB gain though.

[K1JJ]

Yep, agreed.

I'm not sure why the antenna manufacturers go thru all the
effort to make those "interlaced" Yagis - booms loaded with
parasitic elements for 6 bands, all interacting...gads.   Then
there's the TRAP multi-band Yagis for 6 bands... makes me shiver.

The log is a waste for 40M-160M - too large and better done
wid single Yagis for ham use.  But for 20-10M, a stacked log
set has so many advantages.  Flat swr, flat f-b, flat gain, driven
array so little problem with detuning from towers/guys, etc,  
doesn't have associated interaction problems like trying to do
10-20M wid multiple Yagis on same tower....  They will take
unlimited power - no traps/matches to blow out.  Mechanically
easier to turn, construct and support than the equivalent in
single band Yagis.

The disadvantage is they're down a db or so from an optimized
Yagi stack for a single freq, and the stacking height between
logs is a compromise for the center freq..  


T

[Steve - WB3HUZ]

Right on. It is surprising why manufacurers continue to mess with the complex matching and tuning tricks for nested/trapped/crapped yagis and the like. I would think it would be less expensive to manufacture a log. Also no tuning or tweaking needed at the factory or by the user. And they could still charge as much and up their profits.