For current UHF real channels 14 to 51. 8.5"-9" should work fine.
Is there a calculator/chart that one could use to make the diameter in the middle range of the frequency of the channels in their area or is it that critical? The Radio Shack 15-1868 models I have now, have a 4.5" hold in the middle of a plastic triangle. I one set apart a while back to fix the male coax connector that was spinning and found that there was a thin wire in the middle of the loop that connected to the adjustment knob. I'm guessing that the wire circle itself was only around 6". Maybe the hole size doesn't matter in this design.?? https://www.radioshack.com/products/radioshack-indoor-hdtv-antenna?gclid=Cj0KEQjwx96-BRDyzY3GqcqZgcgBEiQANHd-nrhTXLQqbmG47NxV9ZzaP8xTWOeNIcxo9txXYBKQf3kaAqn28P8HAQ&variant=5716990021
I'm hoping to replace my cheap Chinese antenna before the end of the year and I don't think I'll be looking at Stellar Labs equipment now.
In the mean time, I am going to stick with my rabbit ears and keep looking for either another model or perhaps one to build that can go in the attic.
Oh..and let's get rid of Soria! It seems every time I listen to the game, he is doing poorly. He was good the first time we had him but not since he has been back. It's all but over for the boys in blue this year.