Scattering matrix of junctions between rectangular waveguides

The scattering matrices of junctions between rectangular waveguides are investigated for waveguides either below or above cutoff. The convergence properties of the `moment-¿¿ and `point-matching¿¿ numerical methods are compared. A `perturbation¿¿ algorithm is developed for the case when, in the double junction, the distance between planes is large. Data for the design of single and double junctions are provided, and checked experimentally.