Hi, They are simple flag pole brackets that I got at WalMart for about $2 each. They worked very well with the exception of the 3/4 PVC that I used would not fit in them, so I had to put a reducer in the 3/4 PVC to join a 1/2 piece on the end to fit in the bracket! Was not a big deal at all though.
What is the buttom bracket and where did you find it ?
Here are pics of the clamps I used on the roof to snap the awning onto. I used 3 of them and can easily put it up myself... plus, it held tight over the downpouring rain we have had in Maine recently and the wind too! Very cheap and easy project!