Compact Microwave Circuit Design With Short Wavelength on Via-Guided Microstrip Lines

In this paper, a via-guided microstrip line is proposed for minimized microwave circuit designs. The via-guided microstrip line is qualified for a general transmission line requirement of lossless, linear phase, a quasi-TEM mode, and analytical modeling. The equivalent circuit model and element values are provided to compute the characteristic impedance and guided wavelength analysis of the new transmission line. The proposed via-guide microstrip line with a short via-spacing and a distance to microstrip shows a shorter electric wavelength on a thicker and higher dielectric substrate, which is attributed to additional coupling capacitance. The characteristics analysis shows that a via-guided microstrip branch-line hybrid coupler has been successfully designed and implemented with a size reduction of 36.8% when compared to the same circuit on a conventional microstrip line.