SIW Mode: Substrate Integrated Waveguides Explained

This page discusses the SIW mode (Substrate Integrated Waveguides Mode). As TM mode doesn’t exist, SIW utilizes TE10 as its dominant mode.

SIW is the abbreviation for Substrate Integrated Waveguides Mode. The structure of SIW, along with the propagation of EM waves, is depicted in Figure 1 below. It’s analogous to a rectangular waveguide.

It comprises three layers: top and bottom planes that are grounded, and a dielectric in the middle. Via holes connect the top and bottom planes at the sidewalls.

The presence of these via holes prevents the existence of the TM (Transverse Magnetic) mode.

TE10 mode is the operational mode in SIW (Substrate Integrated Waveguides Mode). TE stands for Transverse Electric Wave mode. In TE mode, the electric field (E-field) is entirely transverse to the waveguide, meaning it’s perpendicular to the broad dimension of the SIW.

The following equation (Equation 1) is a generic equation for cutoff frequency calculation in a rectangular waveguide:

TE10 is employed as the dominant mode in SIW (Substrate Integrated Waveguide) Mode. By setting m = 1 and n = 0 in Equation 1, we arrive at the following expression (Equation 2):

Equation 2 is used to calculate the cutoff frequency of the SIW.