I want to build a fat dipole antenna for FM listening for my
brother-in-law, who refuses to get an antenna rotator.

He is located with antenna's all around him but not on top of him.

I would of course orient it vertically and use 75 ohm coax from where
it is mounted to his tuner.

Does the ARRL Antenna Handbook have directions on building one of
these?

I would be using 8 inches as the diameter. Is the math to figure out
the length gonna get me - I've been out of college for 30 years and
have only done business math since....

Thanks,

Brad