Electromagnetism is a hard subject for many people, including myself. The best approach is to get a few good books on the subject rather than rely on one book. After doing a survey, I finally bought the following books suitable for my level: (i) Introductory Electromagnetics by Popovic and Popovic; (ii) Field and Wave Electromagnetics by Cheng; (iii) Electromagnetics with Applications by Kraus; (iv) Schaums Outline of Electromagnetics by Edminister. I give five stars to all these books. (There is another book which I will not review or identify, because it turned out to be unsatisfactory.)
I am reviewing these four books in one go because they are interrelated. Each of these book is strong in its own unique area.
Introductory Electromagnetics by Popovic and Popovic is the best of these book for gaining an intuitive understanding of the difficult subject of electromagnetism. Its clarity and elegance reminds me of Feynman's Lectures in Physics. Every chapter is a work of inspiration. The carefully chosen examples are designed to impart understanding of electromagnetic principles rather than calculation skills. The book is excellent for those who are new to the subject. It is also excellent for those who have already learned some electromagnetics, but who feel that their understanding is still shaky.
Field and Wave Electromagnetics by Cheng is the best of these books in terms of the mathematical development of electromagnetics. Although this approach may seem difficult at first glance, ironically the mathematical rigour makes the subject much easier to grasp. That is because mathematical precision goes a long way towards illuminating subtle principles of electromagnetism. As a result, this book, more so than any other book, has given me the confidence to handle the difficult subject of electromagnetism.
Electromagnetics With Application by Kraus is the least systematic of these books, with some of the discussions being disjoint and abrupt. It is, however, valuable for its interesting and practical examples. It is a must-have book for anyone who is serious about electromagnetism.
Schaums Outline of Electromagnetics, by Edminister, is an outstanding collection of problems and solutions, as well as summaries. It mirrors the excellence of Edminister's other Schaums Outline, namely, Electric Circuits.
In summary, these four books have different strengths, respectively the following: (i) intuitive development; (ii) systematic development; (iii) practical application; and (iv) problem solving. These books form an awesome quartet, covering all the bases, and will provide you with a good foundation for advanced studies. A useful supplement for these books is Schaums Mathematical Handbook of Formulas and Tables.