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Hack a Yagi

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jonGjack

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#1
I was just wondering and I dont know if it would work, but you can get those cheap yagi antennas on ebay that are made out of solid aluminum. I read an article somewhere that the elements are parasitic except for the driver. So I was thinking about using some heat shrink wire insulation and drilling out the rivets to insulate the elements. Im not sure if it would but it might make it (more)directional.
 
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#2
I was just wondering and I dont know if it would work, but you can get those cheap yagi antennas on ebay that are made out of solid aluminum. I read an article somewhere that the elements are parasitic except for the driver. So I was thinking about using some heat shrink wire insulation and drilling out the rivets to insulate the elements. Im not sure if it would but it might make it (more)directional.
What ??? If you insulate the elements you may as well just throw them away because they will do nothing.
 
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#3
jonGjack,

What you are talking about doing will just detune the array. The element lengths are selected when the antenna is designed depending on whether or not the elements are to be insulated from the boom or not. It will likely not make it more directional, if anything it will detune it from the design frequency.

Parasitic elements will work in a yagi array whether or not they are insulated from the boom. At higher frequencies whether or not they are insulated has a greater effect on the length of each element.
 
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#4
The reflector and directors are parasitic but the formula for their lengths depend on if they are in an insulated boom or grounded to the boom and the boom diameter also affect the element length.
That means you will detune the Yagi by insulating the elements that were designed to be grounded to the boom.

For gonfishin1's comment, you can make a Yagi with metal elements hanging in the air by strings, they done need to attach to anything metal or not. I believe Dr. Yagi's original lab antenna had floating elements.
prcguy

I was just wondering and I dont know if it would work, but you can get those cheap yagi antennas on ebay that are made out of solid aluminum. I read an article somewhere that the elements are parasitic except for the driver. So I was thinking about using some heat shrink wire insulation and drilling out the rivets to insulate the elements. Im not sure if it would but it might make it (more)directional.
 
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#5
I was just wondering and I dont know if it would work, but you can get those cheap yagi antennas on ebay that are made out of solid aluminum. I read an article somewhere that the elements are parasitic except for the driver. So I was thinking about using some heat shrink wire insulation and drilling out the rivets to insulate the elements. Im not sure if it would but it might make it (more)directional.
No, it wouldn't work that way. If anything, it would make it less than directional.

You are correct that the director elements are parasitic, and they are attached to the grounded boom. Same as the reflector element. Many years ago I built my own VHF yagi for use on 2 meters. I used a length of PVC pipe for the boom, and while it didn't bond the reflector and director elements together, it still worked well.

Usually the way you make a Yagi more directional (tighter pattern) and better front to back ratio, is by adding more elements. Isolating elements from the grounded boom isn't going to help. What you'd want is more director elements.

Yagis can be really easy to build. I know some of the ones on line are cheap, and they may be a good source of materials, but you can brew your own pretty easily.
 
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