Here is how I did it:

https://imgur.com/fM7R6Lz

https://imgur.com/wfaAFUy

https://imgur.com/S5C3WLD

I think it is a 2" pole... (I honestly forget the size.)

Used the pipe adapter for the top.

and 2 of these for the bottom (Could not reach any higher...):

https://www.amazon.com/gp/product/B079WTQ4CM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

These exact braces probably won't work for you as your horizontal sections are smaller, but may give you an idea.

Just enough clearance above the broken antenna at the top. (All old antennas are from WAY before me.)