Approximate Analytical Expressions for Calculation of Transmission Characteristics of Stub Branchings of Microwave Devices on coupled Rectangular Waveguides

Microwave devices on rectangular waveguides (RW) coupled along a wide wall by means of stub branchings allowing ensuring strong coupling of channels find a wide practical application in microwave engineering. Complex cross-section shaped waveguides (CCSW) having higher values of dominant mode cutoff wavelength, broader bandwidth and smaller sizes than RW satisfy requirements to stubs the most completely. Method of equivalent networks application allows improving the technique of approximate analytical calculation of transition characteristics of stub branchings of microwave devices on RW coupled along wide wall by means of CCSW in computer-aided design of such systems. Pilot scaled microwave device on coupled collinear RW with CCSW as coupling elements was investigated experimentally in order to verify validity of considered technique of approximate analytical calculation of such systems. Comparison of theoretical and experimental transition attenuation characteristics confirms a possibility of using considered approximate analytical expressions for engineering calculation of transition characteristics of stub branchings of microwave devices on RW coupled by means of CCSW.