An Ultra-Broadband Conductor-Backed Coplanar Waveguide with Sine Edges.

Area of Science:

• Electrical Engineering
• Electromagnetics
• Microwave Engineering

Background:

• High-frequency transmission lines (TLs) are crucial for millimeter-wave and terahertz (THz) applications.
• Traditional TLs often require complex impedance matching networks, increasing system complexity and loss.
• Maintaining signal integrity and minimizing dispersion are critical challenges at these frequencies.

Purpose of the Study:

• To propose and characterize a novel conductor-backed coplanar waveguide with sine edges (CBCPW-SE).
• To demonstrate the CBCPW-SE's capability for constant 50 Ω impedance over a broad frequency spectrum.
• To evaluate the performance of the CBCPW-SE in terms of insertion loss, reflection coefficient, and group velocity dispersion (GVD).

Main Methods:

• Design and fabrication of the CBCPW-SE transmission line.
• Experimental characterization using S-parameter measurements from 10 MHz to 100 GHz.
• Analysis of insertion loss, reflection coefficient, group delay, and GVD.

Main Results:

• The fabricated CBCPW-SE maintained a constant 50 Ω input impedance without impedance matching transitions.
• Measured insertion loss was below 0.1 dB/mm and reflection coefficient better than -10 dB across the tested frequency range.
• Minimal signal degradation was observed, with S21 (dB) < -5 dB for a 50 mm section and near-zero GVD.

Conclusions:

• The CBCPW-SE is a promising transmission line for millimeter-wave and THz frequencies due to its inherent 50 Ω impedance and low loss.
• The design simplifies high-frequency systems by eliminating the need for impedance matching circuits.
• The minimal GVD ensures excellent signal integrity for high-speed data transmission.