Design of an Ultra-Wideband Microstrip-to-Slotline Transition on Low-Permittivity Substrate

Abstract

Analysis and design of an ultra-wideband microstrip-to-slotline transition on a low permittivity substrate is presented. Cross-sectional structures along the proposed transition are analyzed using conformal mapping assuming quasi-TEM modes, attaining one analytical line impedance formula with varying design parameters. Although the slotline is a non-TEM transmission line, the transitional structures are configured to have quasi-TEM modes before forming into the slotline. The line impedance is optimally tapered using the Klopfenstein taper, and the electric field shapes are smoothly transformed from microstrip line to slotline. The analytical formula is accurate within 5% difference, and the final transition configuration can be designed without parameter tuning. The implemented microstrip-to-slotline transition possesses insertion loss of less than 1.5 dB per transition and return loss of more than 10 dB from 4.4 to over 40 GHz.

Simple, Fast, and Accurate Broadband Complex Permittivity Characterization Algorithm: Methodology and Experimental Validation from 140 GHz up to 220 GHz

“…Accurate complex permittivity characterization has attracted a lot interest in various research fields and in enormous engineering applications [1,2]. For instance, with the development of 5G technology, the accurate characterization of substrate parameters, especially at millimeter and terahertz frequencies, is highly important [3][4][5]. Permittivity measurement is also playing an increasingly important role in agriculture, the food industry, material science, and biomedical engineering in the last few years [6][7][8][9], due to its obvious advantages of being direct, label-free, sensitive, nondestructive, etc.…”