The Gamma Match (
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- Опубликовано: 17 окт 2024
- Today Dave will be explaining the Gamm Match.
Hello Oggies, we apologize for the lack of videos lately. This video will appear out of order since Ask Dave #535 came out last week. We are working on ways to get videos prepared in advance for your convenience.
Also don't forget the Livestream tomorrow; We will be doing the September Giveaway drawing. Like always, 73.
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I've wanted a gamma match explained to me for 10 years. Thanks!
Wish you also showed tuning it in. That woulda been nice. Love yer vids Dave!
Not clear to me for sure: sliding tube over wire (capacitance) controls resonance and sliding shorting strap controls impedance?? Also it looks like driven element is directly attached (connected) to Yagi mast, not insulated electrically, right?
DAVID, I teach Amateur Radio at our Church, and I have referred your videos to help my students understand how things work. I can talk, show diagrams, refer to the antenna handbook, but you show how it works (whatever they question or someday want to build). I tell them it is much cheaper to build it themselves from discrete parts, or a kit than to buy it off the shelf. This teaches them how it works and how they can fix it when it lets the "smoke out" and breaks down. Thanks for your videos from an old Ham trying to teach his knowledge before I become a "silent key".
73's de W4FJF.
Thanks for helping bring people into the hobby!
Again! Thank you very much for your explanation... I'm just getting into the hobby and trying to understand all these concepts by reading is becoming a chore. Thanks you for your videos.
Dave, Thanks for all you do for the hobby!
Thanks for the explanation! Remembering the different types of matches were difficult when studying for the Extra.
Hello Dave, thx for another great content. My V-Quad Delta Loop for 10 / 11m has a gamma match system. I have seen many yagi beams for shortwave running gamma match. Simple to adjust and works just fine. Easy to home brew from left over aluminum pipes and shrink hose. 73's de Your Friend Uncle Guenter
I always appreciate how Mr Cassler explains how to ham radio.
Thanks for the info & great job explaining. Hope to see more projects soon to.
I wonder how low I could get the impedance on a 3-wire folded dipole by tuning the gamma match.
I wanted to know what is Gama match and had asked a senor ham. The response I got was very disappointing saying that sing you have just got your ticket understanding such complex things will take you ages to learn. But after watching this video the whole concept of Gama match made it so easy to understand. Perhaps, I would now be able to apply and experiment such Gama match while building certain antennas.
Dave you are simply brilliant in explaining/teaching most complex things in a lucid way. I am so indepted to your other videos which has enlightened me on various topics centering Ham Radio. Please continue the good work and do take care of your health too
73
New Delhi
How bro, watching from Jamaica west Indies, can you tell me the specification for a vector 4000 antenna, an a maco m104C gamma match, am try to make both antenna at home, please an thanks !!
How would you calculate a gamma match for a magloop? 🤔
Any pros / cons for this approach contrary a 'normal' exciter loop?
To me it 'looks' like a gamma match would be more efficient but it's just a 'hunch'. Any input on the subject would be much appreciated. 🇳🇴
Howdy.
I built a mag. loop for my CB radio. Using a circular driver loop I could not get under 1,5 SWR. Kevin Loughin has a clip where he experimented with different driver geometries and found that the driver should be oval. I tried that and got down to about 1,2. I tried a gamma match and got 1 on the spot. And the best. It tays 1 all over the CB band. I only need to tweak the capacitor to resonate at a channel.
So yes. I warmly recommend gamma matching.
Regards.
thats an Arrow antenna..I believe made in Loveland. nice video. NC2L
Hi Dave, Im struggling to understand why, and I'm guessing it does not matter, but that none of the elements/driver are not isolated from each other plus the boom. Why is this?
They are not isolated at DC. At RF, the boom is perpendicular to the flow of RF, so it doesn't really get into the equation. The centerpoint of all elements is at zero volts.
How is the formula for determining the length of gamma mach for antena delta loop..frequency 14.200 mc..thanks
Where do you get your tubing for making antennas?
another ham wizardry simplified thanks dave 👍👍
I like your 2 meter Yagi, I have a question, could you also write exact measurements, thanks in advance 55, 73
What's better to use, hairpin or gamma match?
Thank for this! It looks like a very simple, sturdy antenna you have, although I'm not sure of the brand. The way I understand it, is you basically have a tuner that's ON the antenna. The sliding potion is the inductor and you've mentioned the capacitor. The 38 inch half wave driven element can ONLY be resonant on the 1/2 wave it's cut for (145 Mhz). The match is just for adjusting the feedpoint impedance. I'm trying to fully grasp this concept myself. A good antenna to practice understanding the concept of feedpoint impedance is a J- pole for two meters or a UHF frequency (even better). You feed it in the end, it's 300 ohms, you feed it a little ways up, the impedance is 50 ohms. In this process you've NEVER changed the resonant frequency of the antenna. A copper pipe (or tubing) J- pole is also an excellent driven element for a beam! :) I'm going to try to feed a 2 meter beam with 300 ohm open wire line just to say I've done it. 73's- Ryan.
The gamma rod steps up the impedance. Look at it as a portion of a folded dipole. The variable capacitor is then utilised to cancel out the added inductance.
I'm with, Mr.FoxBox.
Thanks Dan.
Good video!
I'm sure there are many new Hams that benefit greatly from these videos, and right here on RUclips!
Hi Sir ,can you gave me a exact measurement of 7 elements for 2 meter..thanks 73
Hi Dave, thank you for this video.
Excellent explanation.
The tower version is often called "shunt fed" perhaps, or am I confused here too? 73.
You are correct.
A video on hairpin match would be highly apprecited. I feel don't quite understand yagi hairpin match.
Does it need a grounding cable? If it does how can I do it ? And thanks a lot for you !
No it does not. The game a match will connect your unbalance cable to the balance due antenna. I don’t know what language my iPad knows but it certainly isn’t English. Sorry about the misspellings. You don’t need an extra ground connection for a game at Mitch
Dave, I've heard that the gamma match will yield a non-symmetrical lobe coming off the front of the antenna, due to the match being only on one side of the driven element. Is that accurate, and if so, does it matter?
I believe it does. It makes sense considering it's physically not symmetrical. Personally, I think it's better to build yagis with a direct 50 ohm feed instead of these plumber's delight type antennas. Some say it's a much more complicated build. However, you don't have to construct a matching device, and they will outperform these old school, compromised antennas. Feed it with a coaxial choke at minimum. The LFA is the one to build, you'll never go back.
Nicely explained. Thank you.
Wonderful video
Do you have any antennas with the hairpin match and shorting bar? Does it do the same as the Gama match? The old hygain antennas used to use them on their beams years ago.
The hairpin match is balanced to balanced, whereas the gamma is unbalanced to balanced.
But... why don't you explain what is varied by adjusting the elements of the gamma match, and the extent to which they interact? If I want to move the lowest SWR frequency, how do I do that? And how do I then adjust the impedance seen by the feedline to 50 ohms?
He probably didn't explain it because he doesn't know. I did read a good step by step approach once, but can't remember it. I haven't played with gammas for a while, but I know a good systematic approach is the key to getting your antenna tuned quickly.
When you move the tapping point out you're stepping up the impedance, and with this, adding inductance. So I imagine you have to slide the capacitor component in (increase the capacitance) to cancel this inductance out. Find the area where the tap dips the SWR, and go back and forth with the cap in small increments. I suppose you could begin with the cap half way and figure out the direction in the beginning (whether you have too much capacitance or not enough). But this depends on dimensions. There are examples of gammas in the ARRL which you could scale yours to, and this may also get you in the ballpark for initial tuning position. I'm sure there's plenty online too, showing the measurements to adjust it to, so just scale it for your design frequency.
What does the adjustable shorting bar, adjust?
Is the driven element a one piece element like the reflector and directors would be?
yes one piece right through the boom, all director and reflector also 1 piece of material
Thanks Excelent
Wow what a terrific tutorial. So I assume that the reflector and the director elements are at ground potential, so if this is the case does the driven element’s radiated power excite the other elements?
The center of each element is at ground potential (voltage) but the current is quite high. Yes, the driven element's radiated power pattern is shaped by the other elements.
I need to make a gama match for a v qaud antenna 27mhz any help
Can you give the formule for calculating the gamma match?
Salam, gud day to you sir, it s very interesting and educating your sharing sir, it would be highly appreciated if you could share to us basic computation or measurement of a gamma match,,, god bless
How does the gama match works?
Maco m105c having issues hitting 28.4
Let’s blow that up a little bigger to 160 meters so I can see without my glasses.
I can't wait dave, but tomorrow I'll be out of commission because I am having Heart surgery to replace my Aortic valve.
Good luck and speedy recovery!
Hope everything goes smoothly and all my best to you!
Good luck!
Wow. Best of luck and a speedy recovery. You will be in my thoughts and prayers.
Which coax should I use for gamma match??
something with the thicker core (the inner) but i have used 5mm copper pipe with 2 spacers on it , pushing into the thicker 10 mm pipe in my case, 2.5mm spacing can carry 2000 volt so no problems .
Thank you, Dave. N0QFT
I love videos Dave. Thanks. I need to get my HF going. I'd love to make you a contact on HF
Then it would match to any ANY ANTENNA? @nybody makin some expirements....I watch gamma match 3 years ago by Eprahaim Garaguez
Boleh info gambar gmatch vhf&uhf transmiter boefeng wt
👍🏻
i am PU1AAB