Multi-Band Bandpass Filters for Wireless Broadband Communication Systems

• Main Authors: Chien-Chi Kuo, 郭千琦
• Other Authors: Sheng-Fuh Chang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/21245969110130610947

碩士 === 國立中正大學 === 電機工程研究所 === 99 === Multi-band bandpass filters for wireless broadband communication systems were designed in this thesis. The first subject is a dual-band bandpass filter, which is formed by lumped element and microstrip resonators . Each type of resonator resonates at its own passband. Such that the dual-band response is resulted. The experimental results show that the measured insertion losses are less than 1.3 dB at 825 MHz and 1.3 dB at 2.52 GHz, respectively. The return losses are greater than 19 dB and 15dB at both bands. three transmission zeros are located at 0.35 GHz, 1.225 GHz and 3.83 GHz, respectively. The second subject is the further extension of the previous dual-band design to triple-band design by interleating different types of resonators to generate multiple passbands and numerous transmission zeros for selectivity enhancement. Each type of resonates at each passband. At the first passband, the first stepped-impedance resonator (A-SIR) is at resonance while the second resonator (B-UIR) is off resonance, working as the input/output coupling network for A-SIR. On the other hand, at the second passband, the B-UIR resonates while the A-SIR acts as inter-coupling element between B-UIR. The third band is generated by controlling the second harmonic of A-SIR. Consequently, a triple-band response is resulted. The measured insertion losses are less than 2.2 dB at 0.85 GHz, 3.9 dB at 2.6 GHz, and 1.3 dB at 3.4 GHz, respectively. The return losses are greater than 9.3 dB at 0.85 GHz, 7.4 dB at 2.55 GHz and 18.5 dB at 3.4 GHz. Seven transmission zeros are located at 0.66 GHz, 0.96 GHz, 1.28 GHz, 2.32 GHz, 2.54 GHz 3.12 GHz, and 4.2 GHz, respectively, which result in a great stopband and intra-and suppressions.