An Effective Mixed Extracting Method for Electromagnetic Parameters of Periodically Loaded Substrate Integrated Waveguide Units and Its Applications

In this article, we propose an effective mixed extracting method for anisotropic constitutive parameters of periodically loaded substrate integrated waveguide (SIW). This method takes the advantage of both scattering parameters retrieval theory and the equivalent homogeneous medium dispersion analysis, which could accurately and effectively extract the equivalent constitutive parameters of the periodically loaded SIW. With this method, the corresponding constitutive parameters of the six typical patterns of periodically loaded SIW schemes are accurately extracted, verified, explained, and compared for their performance. It can be used to quantitatively predict the miniaturization potential of each unit cell and sequentially evaluate the performance as an integrated component. In addition, in terms of application, with the aid of equivalent parameters extracted by the proposed method, a slow-wave SIW evanescent mode filter centered at 12.64 GHz with a frequency bandwidth of 300 MHz is synthesized, fabricated, and measured. In the meanwhile, the theory of slow-wave evanescent mode filter is further consummated, by introducing the dual factors of enhanced permittivity and permeability, as well as analyzing respective advantages in filter synthesis. Measurements and simulation results show good agreement, which embodies the role of the method in guiding the design of actual microwave devices.