Analysis and Design of a New Capacitive-Loaded LCRLH Transmission Line for Stop-Band Control

This paper presents the design and simulation of a novel transmission line met material cell incorporating a loaded-inductor composite right/left-handed (LCRLH) metamaterial structure. The proposed design integrates a CR-loaded LCRLH unit cell to achieve enhanced stop-band control while maintaining compact dimensions of 4.1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{mm} \times 9.3\ \text{mm}$</tex>. The cell operates over a frequency range of 3 GHz to 6 GHz, exhibiting superior performance with S21 transmission coefficient of approximately −0.2 dB. Additionally, the return loss <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{S}_{11})$</tex> varies between −10 dB and −25 dB, indicating effective impedance matching and minimized signal reflections. The overall footprint of the transmission line measures <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$9.3\ \text{mm} \times 14.1\ \text{mm}$</tex>, making it a highly efficient and compact solution for modern RF and microwave applications. The design is implemented using a Rogers substrate with a dielectric constant <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\varepsilon\mathrm{r})$</tex> of 3.55 and a substrate height of 1.52 mm, ensuring low loss and high performance. The integration of metamaterial-inspired elements enables better control over dispersion characteristics and enhances miniaturization compared to conventional designs. Furthermore, the proposed new cell offers a promising approach for next-generation wireless communication systems, where size reduction and performance optimization are critical. Simulation results validate the proposed design, demonstrating its potential for advanced communication and signal distribution networks. The proposed unit cell is analyzed using both full-wave electromagnetic simulations in CST Microwave Studio and circuit-level simulations in Advanced Design System (ADS). The results demonstrate a well-defined left-handed transmission behavior with controlled stopband characteristics, making it suitable for advanced RF and microwave applications. The inclusion of the capacitive load enhances the frequency response by effectively shaping the transmission properties. This study offers valuable insights into the development of compact and efficient metamaterial-based components for next-generation communication and signal-processing systems, as they are essential components for power dividers and diplexers that support various systems. The main applications to use are radar systems, superheterodyne receivers.