AC6LA has come up with a really nice tool that will show you graphically the effects of your local terrain on antenna performance. For the details, see:

https://forums.qrz.com/index.php?threads/seeing-the-effects-of-local-terrain-on-radiation-patterns.733041/

This is a great tool to predict what your coverage will be for various takeoff angles. It also confirms that the 3000' mountain due west of me is going to make it really hard to work into VK and ZL for me.

73...
Randy, W8FN