Microwave filters are essential components in the vast majority of wireless communication and radar systems with a number of applications including military, satellite, remote sensing, mobile communications, and many more. Helical resonator filter technology offers a valuable trade-off between electrical performance and size. This new resource is a contemporary and comprehensive approach to the design of microwave filters with helical resonators. The very detailed step-by-step approach used throughout the book allows readers to quickly familiarize with the basic concepts of microwave filter design and confidently engage with the design of helical resonator filters. The implications of utilizing helical resonator filters for high power space applications are rigorously investigated and techniques for mitigating the power-handling limitations are discussed. In addition, examples by means of numerical and experimental results are presented throughout to illustrate the performance.