Interdigital Capacitor Based Compact Microstrip Bandpass Filter with Wide Stopband

ABSTRACT

A compact, low-cost microstrip bandpass filter (BPF) with low insertion loss and wide attenuation band is presented in this article. The proposed structure consists of multiple interdigital capacitor sections and a T-shaped stub which is connected to the ground using via. The wide stopband response is achieved by the inclusion of defected ground structures (DGS). Addition of these defected ground structures also reduces the circuit size. The designed BPF of centre frequency 0.9 GHz is fabricated, measured, and its lumped equivalent circuit is also obtained. A good agreement is found among IE3D simulated results, circuit simulated results, and the measured results. The obtained results for the proposed bandpass filter (BPF) are −3 dB fractional bandwidth (FBW) of 63% and minimum insertion loss of 0.59 dB. The relative stop band (RSB) rejection is found up to 177% and the normalized circuit size (NCS) is found 0.012${\mathit{\lambda }}_{\mathit{g}}^2$. This proposed filter can be used for GSM and other microwave circuitry in wireless communication system.

KEYWORDS:

• BPF
• CSRR
• Defected ground structures
• Group delay
• Interdigital capacitor
• Microstrip technology

Additional information

Notes on contributors

Sarbani Sen

Sarbani Sen (born in 1990) received the bachelor degree (BTech in electronics and communication engineering) from SRM University, Chennai, India, in 2012, and completed the post-graduation (MTech) in the field of communication engineering from the National Institute of Technology, Agartala, India, in 2016. Currently, she is pursuing her PhD from the National Institute of Technology, Agartala, India, in the field of RF and microwave circuits in Electronics and Communication Engineering Department.

Tamasi Moyra

Tamasi Moyra (born in 1978) received the AMIE (India) degree in electronics and communication engineering from the Institution of Engineers, India, in the year of 2003. She did ME in the year of 2007 from Bengal Engineering and Science University, Shibpur, India, in the Department of Electronics and Telecommunication Engineering. She received her PhD degree in the year of 2014 from the Department of Electronics and Telecommunication Engineering at Indian Institute of Engineering Science and Technology (IIEST), Shibpur, India. Presently, she is working as an Assistant Professor in the Department of Electronics and Communication Engineering at the National Institute of Technology, Agartala. She has published more than 25 research articles in different peer-reviewed journals, international conferences and book chapters. Her current research interests include the planar circuits, microstrip filters, antenna elements, LHM, meta-materials, etc. She is a member of the Institution of Engineers and IEEE. Email: [email protected].