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Stock Maco gamma vs off-the-shelf beta match CHALLENGE!

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  #1  
Old 05-12-2007, 08:16 PM
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Default Stock Maco gamma vs off-the-shelf beta match CHALLENGE!


I submit the following:

It's MY opinion that the same 3-element Maco, one fed with a gamma match and one fed with a beta match, will perform better with the beta match.

I'm also willing to put my money where my mouth is.

I'll supply the stock Maco M103C antenna. You (who ever you are) supply the DX Engineering "hairpin match". I already own the DXE-BEB-2.

I'll model the antenna using "Yagi for Windows" which is supplied in the 20 edition of the ARRL Handbook. This software allows modeling for both a gamma and a hairpin match.

I'll build and tune the antenna using both matching networks, taking readings with my Bird 4030 relative field strength meter.

Once we agree on what "better" means, the winner takes all.

My investment will be $100.00+. Your investment will be $30.00 plus shipping.

Who's willing?!


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Old 05-13-2007, 05:48 PM
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OK, a little thread cleaning was in order. There is a challenge on the table, who will accept?

My argument is that the beta match is better. I don't set a limit on the amount of efficiency, only that it performs better.

I won't argue a db or a tenth of one; only the feedpoint that performs better.

And there seemed to be a bit of confusion so let me add that the arrangement of the elements on the boom will be IDENTICAL. Front to back, rejection and forward gain is not the issue here. ONLY THE FEEDPOINT! Please keep to the subject at hand.

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Old 05-13-2007, 05:55 PM
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P.S. No thread hyjacking on this one. If you want to call me names, start your own thread and be able to back up your statements.

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Old 05-13-2007, 07:02 PM
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I like 1/4 wave matching networks. They are narrow banded but work well for feeding a quad.

However, I'm talking about the gamma vs the hairpin so I need to ask, what's your point?

Tell me, what do YOU think works better, the gamma or the hairpin? Go ahead and say it, I know you want to , its OK, we all know the answer already, just say it.

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Old 05-14-2007, 10:37 AM
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Quote:
Originally Posted by Blanket
All the alternative matching networks all do the exact same thing, the hairpin is simpler to use and construct than the gamma. It has about .04 db less loss than a gamma match.
They are only similar in the fact that they provide a match at the feedpoint. How they do it is very different. .04db less loss tells me it is "better" than a gamma. Good enough for me. Your point is taken about the little difference between the two.

Quote:
Originally Posted by Blanket
I dont use a gamma on a 5/8 wave antenna you know the one where you say the Hairpin is far more efficient when there isnt any data to back up your claim other than one cber saying he is getting a better signal on his radio.
I don't think anyone, other than Jay and Steve, have done any real comparisons and tests between various feedpoints for 5/8 wave antennas. But this is a totally different subject from the beam challenge above.

Most 5/8 antennas used some sort of a coil or shunt feed. Some were etched on very small circuit boards. Other than the Sigma IV (not a 5/8, but a vertical nonetheless), Wolf's .64 wave, and the Son-of-a-Gunn, I haven't seen a gamma on a 5/8 wave vertical. The real world tests of the I-10K is excellent proof that it is a great performing antenna.

But the "hairpin" on the Penetrator or the I-10K (trombone) is NOT a BETA MATCH! Don't confuse the two because some people call these "hairpins". As far as the Penetrator goes, it only LOOKS like a hairpin, hence the name.

Quote:
Originally Posted by Blanket
Honestly if a hairpin/beta was that much more efficient it would be used more often and classified a proven better performer, but it isn't.
It was used, and is still used by Hy-Gain. I'm sure their earlier patent prevented other manufacturers from using it. Again, this "hairpin" is NOT the same hairpin you find on the verticals above.

Quote:
Originally Posted by Blanket
What do I think is better? they each have there place but I don't think anyone on a receiving end will know if you used the gamma or the hairpin on any style antenna
I disagree. There is case after case where people have seen a big improvement when using an I-10K over any other antenna (again, not the same "hairpin" as a beam). Are they all wrong? The performance of beams have been good enough for people to look into and study different type of matching networks. There must be a reason nobody uses gamma matches anymore.

Quote:
Originally Posted by Blanket
that is the whole argument that DaveGrntsr I believe was trying to make and I agree there isn't any difference, as antenna gain etc is more a function of element length and spacing etc where you can add any type of matching network to the antenna yes even the 1/4 wave transformer, btw who cares about the bandwidth the point is performance/efficiency.
Gain is a function of antenna design. We agree. My argument is that you will get MORE energy into your antenna design with a beta match than with a gamma match. In other words, same antenna with same layout, but with different feed systems will work differently. I say the beta will win and am willing to prove it.

Quote:
Originally Posted by Blanket
What is the definition of better you still haven't been able to arrive at that, since you have tapped danced around putting a number or figure on it so I cant answer what is better?
No tap dancing here. I already defined what I thought was better, I only stated that we need to AGREE what the definition of "better" is. .04db is better as far as I'm concerned.

I like direct feed antennas. What I mean by this is that the center conductor of the coax makes a physical and electrical connection to the main radiating element. This happens with T-match, Beta-match, 1/4 wave transformers, and a few others.

This does NOT happen with a gamma match. It is a capacitive coupling like the thru-glass antennas that everyone runs out and buys because they are "just as good" as a roof mount. Do they work? Yep! Can you do "better"? Yep Yep!

That's all I'm trying to say.

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Old 05-15-2007, 08:53 AM
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MC, I ran some examples on a three element yagi using YW and when changing from HP to Gamma all I see is a bit broader bandwidth with a little better SWR at center frequency using the gamma. There is no difference noted with the gain or F\B between the two using this software.

Is this what you might expect if you did it?

You must have something other than just a thought/idea that leads you to claim the HP is superior over the gamma. Comparing the gamma to a little short thru glass mobile antenna is pretty also. You have to do better than that.

I also notice that it seems the Gamma design ends up inductively load while the HP is typically capactively loaded when good results are obtained at resonance. This is probably what 'Doc was talking about saying they worked differently. I did not compare the element spacing and length measurements but I notice the HP boom was longer. Is there some way to print out the product of the Elements spreadsheet figures?

I read what Blanket provided us in a link to Cebik's work in comparing several matching devices and he doesn't seem to support your claim either to any substantial degree.

I am not good at understanding this software maybe, so I could have done something in error. I will try to post my results soon. Would you take a look and advise. I wish I had saved the two files, but I didn't think to do that before I exited the program. I might go back and see if I can didle those results again.
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Old 05-15-2007, 10:03 AM
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See if this works MC.




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Old 05-15-2007, 02:01 PM
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Well, you noticed that the Peak Elevation Angles were different. The HP was 5 degrees and the Gamma was 9 degrees. True, there was a difference in height also. I mess up there and that will have to be checked out to be fair. I suspect that I had made some adjustments to the spacing also and that made the boom on the HP model longer.

I am also going to try and get a better match with the HP too.
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