Design of Dual-Band Bandpass Filters for Cognitive Radio Application of TVWS Band

Kwon, Kun-An; Kim, Hyun-Keun; Yun, Sang-Won

doi:2016.16.1.19

J. Electromagn. Eng. Sci > Volume 16(1); 2016 > Article

Journal of Electromagnetic Engineering and Science 2016;16(1):19-23.
DOI: https://doi.org/10.5515/JKIEES.2016.16.1.19

Design of Dual-Band Bandpass Filters for Cognitive Radio Application of TVWS Band

Kun-An Kwon, Hyun-Keun Kim, Sang-Won Yun

Department of Electronic Engineering, Sogang University

Correspondence: Sang-Won Yun,Email: swyun@sogang.ac.kr

Abstract

This paper presents a novel design for dual-band bandpass filters. The proposed filters are applicable to the carrier aggregation of the TV white space (TVWS) band and long-term evolution (LTE) band for cognitive radio applications. The lower passband is the TVWS band (470-698 MHz) whose fractional bandwidth is 40 %, while the higher passband is the LTE band (824-894 MHz) with 8 % fractional bandwidth. Since the two passbands are located very close to each other, a transmission zero is inserted to enhance the rejection level between the two passbands. The TVWS band filter is designed using magnetic coupling to obtain a wide bandwidth, and the LTE band filter is designed using dielectric resonators to achieve good insertion loss characteristics. In addition, in the proposed design, a transmission zero is placed with cross-coupling. The proposed dual-band bandpass filter is designed as a two-port filter (one input/one output) as well as a three-port filter (one common input/two outputs). The measured performances show good agreement with the simulated performances.

Key words: Cognitive Radio, Cross Coupling, Dual-Band BPF, TV White Space