This book introduced microstrip bandpass filters using a Stepped Impedance Resonators (SIR) which are widely used to simulate bandpass filters. These filters have been designed with coupling feeding technologies. The excited bands characteristics and their position of the designed filters have been optimized. Further optimization of the filter's performance was carried out through proper modifications in the filter dimensions, using different techniques based on simulated current distributions on the surfaces of the filter structure. The designed filter responses were covers the Industrial Scientific Medical(ISM), Closed Circuit Television (CCTV), and Wireless Local Area Network (WLANs) applications.