Comparison of reduced analytic models for six-port modulators with different characteristics

This article is focused on expression of transfer function for six-port modulators in different level of simplification. Generally, complex transfer function definition of six-port system requires a consideration of all possible paths among ports and also applied impedances of all connected loads. In the following text is evaluated a comparison of transfer functions for two six-ports with very different parameters (expressed by scattering parameters). The first one is a representative of substrate integrated waveguide (SIW) technology and the second one is realized as microstrip circuit. The simulations based on expressed equations are also compared with real measured results using a set of fixed loads in the final part of the paper.