Design and Fabrication of a Microstrip Low-Pass Filter with a Wide Stopband Using a Windmill-Shaped Resonator

Sobhan  Roshani; Salah I. Yahya; Shahram  Khazaei; Saeed Roshani; Babak  Karami

doi:10.14500/aro.11752

Sobhan Roshani Department of Electrical Engineering, Kermanshah Branch, Islamic Azad University,Kermanshah, Iran https://orcid.org/0000-0001-5088-499X
Salah I. Yahya (1) Department of Communication and Computer Engineering, Cihan University-Erbil, Erbil 44001, Iraq; (2) Department of Software Engineering, Faculty of Engineering, Koya University, Koya, Iraq https://orcid.org/0000-0002-2724-5118
Shahram Khazaei Department of Electrical Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran https://orcid.org/0009-0003-5577-6500
Saeed Roshani Department of Electrical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah 6718997551, Iran https://orcid.org/0000-0002-4024-2755
Babak Karami Department of Mechanical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah 6718997551, Iran https://orcid.org/0009-0006-5145-7547

Keywords: Low-pass filter, Microstrip, Resonator, Return loss, Stopband, Transition band

Abstract

In this paper, a microstrip low-pass filter (LPF) with a wide stopband and a sharp transition band is presented using a windmill-shaped resonator. Traditional LPF designs often face challenges such as narrow stopbands, high insertion loss, and large physical sizes, which limit their performance in modern communication systems. To address these challenges, the proposed filter exhibits low insertion loss, a sharp response in the transition band, a wide stopband, and a compact size. The windmill-shaped resonator is applied to achieve a sharp response in the transition band, while two suppressor cells are added to extend the stopband. The filter has a 3 dB cutoff frequency (f_c) of 1.61 GHz, with an S₁₂ parameter value of −20 dB at 1.7 GHz, resulting in a narrow transition band of 0.18 GHz, demonstrating its superior performance. In addition, the filter achieves a wide stopband that extends from 1.79 GHz to 11.26 GHz (a bandwidth of 9.47 GHz) with high attenuation. The physical size of the filter is 13.34 mm × 12.78 mm (0.097λ × 0.093λ). Overall, the proposed filter demonstrates excellent characteristics in both the passband and stopband regions, providing an effective solution for modern communication system requirements. The presented design effectively addresses key limitations in traditional LPF configurations, offering improved performance and compactness.

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Author Biographies

Sobhan Roshani, Department of Electrical Engineering, Kermanshah Branch, Islamic Azad University,Kermanshah, Iran

Sobhan Roshani is an Assistant Professor at the ‎Department of Electrical Engineering, Islamic Azad University, Kermanshah, Iran. He got the B.Sc. degree in Razi University, Kermanshah, Iran, the M.Sc. degree in Iran University of Science & Technology, Tehran, Iran and the Ph.D. degree in, Razi University, Kermanshah, Iran. His research interests are in switching power amplifiers, optimization and neural networks, artificial intelligence, and microwave circuits. Dr. Sobhan was the Head of Young Researchers and Elite Club, Islamic Azad University, Kermanshah Branch in 2021-2022.

Salah I. Yahya, (1) Department of Communication and Computer Engineering, Cihan University-Erbil, Erbil 44001, Iraq; (2) Department of Software Engineering, Faculty of Engineering, Koya University, Koya, Iraq

Salah I. Yahya is a Professor at the Department of Software Engineering, Koya University, and a Visiting Professor at Cihan University-Erbil. He has a B.Sc. degree in Electrical Engineering, M.Sc. degree in Electronics and Communication Engineering, and Ph.D. degree in Communication and Microwave Engineering. He is a Consultant at the Iraqi Engineering Union. Dr. Yahya is a senior member of the IEEE-USA and a member of AMTA-USA, SDIWC-Hong Kong. His research interest include; Antenna, Microwaves, EMW propagation, numerical dosimetry, microwave passive component design, ANN.

Shahram Khazaei, Department of Electrical Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran

Shahram Khazaei is a Lab. engineer at the Islamic Azad University, Kermanshah Branch. He received his Bachelor’s degree in Electrical and Electronic Engineering in 2011. He began his master’s studies in 2012 at the Islamic Azad University, Kurdistan Branch, specializing in Electrical and Electronic Engineering. His academic background and research interests focus on advanced electrical and electronic systems, microwave devices, and RF circuit design.

Saeed Roshani, Department of Electrical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah 6718997551, Iran

Saeed Roshani is an Associate Professor at the ‎Department of Electrical Engineering, Islamic Azad University, Kermanshah, Iran. He got the B.Sc. degree in Razi University, Kermanshah, Iran, the M.Sc. degree in Iran Shahed University, Tehran, Iran and the Ph.D. degree in, Razi University, Kermanshah, Iran. His research interests are in microwave circuits, passive and active devices, neural networks and artificial intelligence. Dr. Saeed was the Head of Faculty of Engineering, Islamic Azad University, Kermanshah Branch in 2018-2019.

Babak Karami, Department of Mechanical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah 6718997551, Iran

Babak Karami is an Associate Prof. and heading the Department of Human Resources at the Kermanshah Branch of Islamic Azad University, Iran, for a decade. He holds a Ph.D. in mechanization and has been a dedicated, full-time faculty member at the Department of Mechanical Engineering, Islamic Azad University, Kermanshah Branch, since 2004. His research interests include neural networks, mechanical engineering, modeling, and simulation, focusing on developing innovative solutions for complex engineering problems and advancing computational methods in the field.

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