DFW vs SIW: Dielectric Filled Waveguide and Substrate Integrated Waveguide

This article explores the distinctions between Dielectric Filled Waveguides (DFW) and Substrate Integrated Waveguides (SIW). As frequencies increase, wavelengths shrink. This makes microstrip manufacturing challenging due to the need for extremely tight tolerances, reducing efficiency. Consequently, waveguide devices often become the preferred choice over microstrips.

DFW: Dielectric Filled Waveguide

Figure 1 illustrates a DFW, or Dielectric Filled Waveguide. It’s composed of three layers, with a dielectric material sandwiched in between.

SIW: Substrate Integrated Waveguide

Figure 2 shows an SIW, or Substrate Integrated Waveguide.

The process of converting a DFW to an SIW involves using via holes along the sidewalls of the rectangular waveguide. This grounding is achieved by top and bottom planes. The use of these via holes eliminates the TM mode, leaving only the TE mode active within the SIW. Specifically, the TE10 mode is commonly employed as the dominant mode in SIW structures.