Formula for flare angle of the bowtie antenna

what is the formula for calculating the flare angle of the bowtie antenna.

Are you asking about the bowtie antenna provided (years ago) with television sets for UHF reception? An alternate shape was a simple loop. Both types were several inches across. They needed to receive a wide range of frequencies, therefore they did not need selectivity. They could have a lot of shapes and still work, I believe.

It was convenient to make it a bowtie shape, to create a center hub for a:
* junction point for the 300-ohm twin lead
* clamp to grip the rabbit ears (VHF antenna)

This antenna is the bowtie antenna .i want the formula for flare angle