Quadrature hybrids are passive circuit elements that are used in a wide range of RF and microwave applications, and this cutting-edge book is the first resource to provide engineers with a solid understanding of their characteristics and design. The book helps professionals use lumped element quadrature hybrids to achieve extremely wide bandwidth operation. This hands-on volume provides detailed construction techniques with worked examples, and describes the synthesis of circuits using practical circuit topologies. Moreover, the book discusses a wide-range of related topics, including active circuits, weak couplers, non-quadrature dividers, and tips on using graphical techniques. This comprehensive reference is thoroughly supported with over 225 illustrations and more than 200 equations.