Single Mode Operation of Substrate Integrated Non-Radiative Dielectric Waveguide and an Excitation Scheme of ${\rm LSE}_{11}$ Mode

It is shown that a substrate integrated non-radiative dielectric (SINRD) waveguide supports only the fundamental longitudinal-section-electric mode (LSE
₁₁
) over a frequency band determined by the radius of air holes. The single mode operation eliminates the need of a mode suppressor which is a potential advantage of using LSE
₁₁
mode compared to the use of the other fundamental mode, namely the longitudinal-section-magnetic mode (LSM
₁₁
). The conditions for obtaining the maximum single mode operation bandwidth are investigated. An excitation scheme of the LSE
₁₁
mode using a rectangular waveguide is presented and the measurement results of a fabricated back-to-back transition at 94 GHz are provided.