This book is widely regarded as one of the best resources for people interested in understanding how antennas work.
If you are a beginner in the field, you will learn about radiation patterns, impedance matching, antenna efficiency, and so much more. And the good news is that complex theorical concepts are explained thoroughly using examples and practical applications. I promise that you are going to love the illustrations and diagrams in the book!
"Antenna Physics: An Introduction" starts with basic electromagnetic theory, but covers advanced stuff as well. So, if you are a veteran radio amateur, there are quite a few things for you in this book as well...
You’d better know your math and physics, though, because some sections of the book make heavy use of them. Truth be told, the author has included a "You already Know Calculus" section. Here’s a site that may help: https://www.antenna-theory.com/
All in all, Robert Zavrel has done a great job with "Antenna Physics: An Introduction." If you want to deepen your understanding of how antennas work, this book should be on your list for sure.