Salutations, been trying to find what the part I circled in the picture is called since I'm going being a cell signal booster direction antenna was going to make a pole mount for it just need to know what the middle bits are called so I can buy them. Not sure if this is the correct sub topic for this. So sorry in advance and thank you for any help. 
Maybe a 'mouth clamp' or 'two piece clamp' don't hold me to that though lol
Typed in "mouth clamp" on google I get "mouth chlamydia" as a suggestion. Seeeeeeeems legit.
Saddle clamp?
Looks similar to an automotive "C" clamp. Used to secure axles and stuffs.
Reverse Image Search
google images > click camera > paste photo = easy
http://www.superstore4less.com/WILSON_ELECTRONICS_Fixed_Antenna_Mount_Kit_16369.html
I know what the whole thing is called I mean just the clamp part.
crop first > go to step 1
That's not a bad idea.
Enhance!
Ubolt Plate?
Close but no Mr. Crabs.
Pipe Mount.
That gets you what it is and others like it.