Analysis and Design of Broadband Transitions from Microstrip-to-CV-WSIW for mm-Wave Applications

The concept of the corrugated via-wall substrate-integrated waveguide (CV-WSIW) reported by the same authors earlier has now been extended to the mm-wave frequency range, and the transitions for this category of SIWs from microstrip line (ML) are presented in this work. A new design of enhanced CV-WSIW for 18-40 GHz frequency range is proposed. The design includes a tapered section of the microstrip line and two rows of metallic vias with the gap between them. They are providing a better impedance match and reduced overall loss. The proposed design offers improved performance in terms of broadband, return loss (RL), insertion loss (IL), and total loss (TL). The laboratory prototypes are developed, and the obtained simulation results show a close agreement with the measured results. The experimental results show the minimum RL of 22dB, IL of 0.22-0.42dB, a fractional bandwidth of 75.80%, a figure-of-merit of 967.9, and the TL below 20% for ML/CV-WSIW transition within 18-40GHz range. Three additional ML/CV-WSIW transitions were also designed and tested, so that four tested transitions cover 8-60GHz range; an additional fifth transition was simulated only in 60-140GHz range.