HI:Not true. See
In addition to neglecting the ferrite bead at the feedpoint (not listed as optional), your element diameters are wrong. The pattern of this design, which has no backlobes worse than 21 dB down when correctly implemented, is sensitive to element lengths, element diameters, element spacing, and pickup of signals by the outside of the coax shield.
This is a fine example of how not to build a high-performance Yagi.
Once again thank you for your antenna plans and your advice. I guess your a perfectionist and that's a good thing in a theoretician. When I discovered this site and read about the SBGH Gen1 antenna I wanted to build one but I started to obsess over the minutae of if I could build it to the right tolerances with the right materials and all that kind of stuff. What I found was that that kind of thinking prevented me from trying anything because I was worrying more about getting it totally right than getting anything at all. I also figured that if I had to spend pretty well as much to make an antenna compared to buying one then it would make more sense to just buy it ready made and be done with it. So I came to the conclusion that if I was going to build an antenna that it only made sense if I could build it for next to nothing. However going this route entailed that I would have to scrounge for materials and that that would probably mean that I couldn't make it perfectly because you're limited to what materials you can scrounge up. So I told myself that if I could make it good enough with free materials rather than perfectly with paid for materials then that would be a fair tradeoff. So once I got over that hurdle I was finally able to move forward with actually doing something. That's how I approached building your antenna. Guess what, it works GOOD ENOUGH. It brought a marginal signal in my attic from about 15 % on the signal meter upto the 45 to 55 % region, with 40% needed for decode. I was finally able to watch a channel that I wasn't able to watch before. So it may not be a perfect build but she still drives! Just for the record the signal is 2-edge on rf10 at 37 miles with a NM of 13. The antenna is in my attic.
Now as to the ferrite choke, I totally forgot about that. In fact I have one around here somewhere that I bought a few years ago. If I read you right then adding the choke should help better in rejecting signals from the back, right? Would it also help with increasing the gain on more marginal signals from the front? I might try with the one I have and see but i'm not going go hunting for a new one. If it doesn't work correctly with what I have then no problem since the antenna performs adequately as is.
So, once again thanks.
P.S. I added the following comment at the end of the comment in my picture album for that picture you were referencing,
P.S. Member K6STI informs me that a ferrite choke is is required on the feedline and that my build is "a fine example of how not to build a high-performance Yagi". You can see his full comment here
You can see my response a couple of comments down. Essentially my position is that it works good enough so i'm happy. You can see his plans for his Yagi at the following website.