Conducting vs Non-conducting Yagi Boom

[clunker]

I decided to build another Yagi antenna so I can pull in the only station that broadcasts my sports team. It appears that I didn't build the last one with a high enough frequency. Since I will be mounting this one on the roof instead of in the attic, I want to use more rigid materials to cope with the strong winds and/or heavy snow we get several times every year. I built the last boom with a ABS pipe, but I want to use aluminum this time, and I keep seeing conflicting information about whether electrically isolating the directors from a conducting boom is the same as using a non-conducting boom. It makes a big difference in making dimensional calculations. For example, if I have an aluminum boom and I use aluminum pipe directors that feed through the boom but are isolated from it by rubber grommets, is this a conducting or non-conducting boom? Also, the grommets may stick out as much as 1/4" from the aluminum boom. Does the grommet count as part of the boom diameter? Any help would be greatly appreciated.

 

[chief21]

I can't say that I've built any textbook Yagi antennas lately, but you don't appear to be getting any answers, so I'll give you an answer based on my understanding of antenna physics.

In my view, the primary purpose of the boom on a Yagi is to provide the correct separation between the antenna elements. If you're using grommets to isolate the elements from the boom, I would consider that a non-conducting boom. I would also say that the size of the gromments should have no bearing on the boom diameter.

(Now let's see if anyone corrects my answer.)

 

[merlin]

I have used both wood, PVC, and aluminum, the boom makes little difference. The spacing, element length, and element diametr are significant factors,