A Compact Dual-band Bandpass Filter Design Using Parallel Coupled λ/4 Resonators

• Main Authors: Tang-hao Liang, 梁唐豪
• Other Authors: Chih-Wen Kuo
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/3jy3r4

碩士 === 國立中山大學 === 電機工程學系研究所 === 102 === This paper presents a design center frequency at 2.4GHz (for WLAN) and 3.5GHz (for WIMAX) compact size dual-band band-pass filter (Bandpass Filter). This filter uses a symmetrical structure of top and high-frequency and low-frequency resonators, operated between the two resonance frequencies of resonators with almost no impact to the design after the band easy to adjust and design, not limited to 2 times the frequency of a λ/2 resonator and 3 times the frequency of a λ/4 resonator effect. In addition, the filter coupled resonators using the newer structure, two resonators by parallel coupled structure, resulting in two modes of resonance in the frequency band you want, simply by adjusting the length of coupled microstrip lines, so its resonance at the frequency you want, easy to change design and bandwidth. But this parallel coupled structure, Source-Loading effect will produce additional capacitive to help resonance frequency falls more low frequency, and to reduce the size. Also added a short branch line near the feed end (Spur-Line) defective structure, curb outside the passband insertion loss. Filter ties in Tapped Line Feed into way, and λ/4 short-circuit transmission line (λ/4 Short Circuit) and λ/4 open transmission line (λ/4 Open Stub), in passband with sides produced transmission zero points (Transmission Zeros), improving the selective of filter and has very significantly of out of band suppression performance. Finally, band-pass filter to bend (Bend) arranged in a square structure to narrow band-pass filter size.