Yagi gamma match

[Moleculo]

With a gamma match (and also other types of matching systems), the driven element is solid. The taper of the element isn't important...usually that's just done for mechanical reasons. If you taper it as it extends, it puts less stress on the element and keeps it from drooping.



Moleculo


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[tejanodrum]

I noticed on the Maco antenna yagis that the drive element is solid and there isnt a break in the middle of the element. The gamma just attaches and tunes. I am puzzled. I thought there was supposed to be some sort of insulator between the element halves. I am in the process of building a yagi and i want to make some sort of Gamma Match. Also is the taper of the elements critical or can i use a larger diameter tubing?

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[byder]

i made a gamma match and i put a foam from coaxial cable as insulator and work's great
!if you want a pic just email me to pololr@hotmail.com

 

[Henry HPSD]

Although element diameter is indeed done for ..strength and transportation.

Element diameter is quite important as it influences everything.
Gain/FB/SWR etc..
Especially with "high"gain critical yagi's (often low impedance)
Ofcourse a nail thickness of difference wont hurt,and your probarbly not going to see any difference as we as humans are normaly only are capable of seeing a difference as soon as it reaches 2..3 dB.

However, when one writes down: one antenna performance 1..2 dB down the other every body is conficed the other one is "better". And that is what that nail thickness does.
You wont hear/see it but one can measure it.
A bigger change in diameter say...10..20 procent would be in my opinion to much without verification through the modeling programms or field testing.

Kind regards,

Henry

 

[wavrider]

A yagi using a gamma is more or less a plumbers dream, all is connected electrically shorted, the only thing isolated is the feed point of the gamma, the gamma "rod" which is the variable cap is shorted to the radiating element, parasitic element, driven element or whatever flavor you want to call it.

as far as homebrewing gammas? I use CPVC as the insulator, visit the local hardware store and look at the hoses/waterlines for icemakers, they also have many different varieties/sizes of hose clamps, not the automotive type but the type for running/installing water supply for the icemakers in the refrigerators, these work perfect for connecting to the aluminum tubing on the yagi.