Low-Cost Narrowed Dielectric Microstrip Line-A Three-Layer Dielectric Waveguide Using PCB Technology for Millimeter-Wave Applications

We investigated a dielectric transmission line consisting of three dielectric substrate layers for millimeter-wave (mmW) applications. This line is referred to as a narrowed dielectric microstrip line (N-DML). The effective dielectric constant method is used to analyze the propagation characteristics of the N-DML. The result of the analysis of the normalized phase constant is consistent with the simulation. For demonstration, two J-band N-DML prototypes of different lengths with transitions to rectangular waveguides were designed, fabricated, and measured. Good agreement between the simulated and measured results is observed. In particular, due to its nonmetal structure, the N-DML shows a low average attenuation constant of only 0.52 dB/cm over 220-280 GHz in the experiment. Due to its good performance, ease of fabrication, low loss, and low cost, the N-DML is a suitable candidate for various mmW applications.