Design of Miniaturized Microwave Filtering-Balun Component for Wireless Applications

¹ Communication Engineering Department, Al-Furat Al-Awsat Technical University, Technical Engineering College of Najaf
² Laser and Optoelectronics Engineering Department, Al-Furat Al-Awsat Technical University, Technical Engineering College of Najaf

^* Corresponding author: haider.ms.etcn25@student.atu.edu.iq

Abstract

This research paper introduces a new design being Minkowski-like fractal filtering-balun MLFFB based on the dual-mode ring resonator. The structure has three ports, converting the signal from one unbalanced port to two balanced ports (i.e., 180° phase shift). The proposed design can act as a filter and balun simultaneously using one dual-mode ring resonator. The fractal curves are applied to have compact designs. The 0^th, 1^st, and 2^nd iterations of the Minkowski-like fractal curves are applied to demonstrate the miniaturization ratio obtained in the proposed work. The miniaturization ratios are 47.8% and 73% of the 1^st iteration and 2^nd iteration of the Minkowski balun-filtering components, respectively, compared to the 0^th iteration. Also, the filtering balun has a distinctive feature, which is the control of the phase error and magnitude imbalance of the two balanced ports, depending on the size of the perturbation part. Several structures have been designed, modeled, and analyzed utilizing the Advanced Design System (ADS) software. Each design iteration is evaluated and optimized to attain the best performance. The operating frequency is 2.4 GHz, and the realized transmission coefficients are S₂₁ = -7 dB and S31 = -6.5 dB, which are less than expected ideal values because the substrate is a lossy type, being FR4. The S₁₁ is less than -10 dB. The proposed design is a good candidate for narrow-band wireless applications.