Summary
International Symposium on Antennas and Propagation
2008
Session Number:1B02
Session:
Number:1B02-2
UWB BPF Design Using Modified Tri-Section SIR
Ching-Her Lee, Lian-Yu Chen, I-Chin Wang, Chung-I G. Hsu,
pp.-
Publication Date:2008/10/27
Online ISSN:2188-5079
Summary:
Since the U.S. Federal Communications Commission (FCC) approved the unlicensed use of the ultra-wide-band (UWB) (3.1-10.6 GHz) for commercial communication applications in February 2002, many researchers have placed their efforts on developing various UWB components and systems [1], [2]. As an important building block in a UWB communication system, UWB BPFs have been gaining favor in the area of filter design. Although UWB BPFs can be easily realized using tightly coupled microstrip lines [3], the ones in recent published work showed that using multi-mode resonators (MMR) is an effective design method [4], [5]. In [4], the UWB BPF aiming at transmitting signals in the whole UWB band was implemented using a microstrip-line MMR together with the input/output parallel-coupled line sections. By properly locating the first three modes of the MMR and the coupling peak of the parallel-coupled lines at the two sides, one can realize a five-transmission-pole UWB BPF with a uniform passband response. Presented in [5] was a UWB BPF similar to the one reported in [4] but with aperture-backed input/output coupled line sections. With the aperture in the ground plane, the parallel coupling between resonator and feed lines can be largely enhanced and the need of the very small coupling gap can be alleviated. All the MMRs used in the aforementioned papers are two-section SIRs. The tri-section SIR (TSSIR), as shown in [6], has tunable first three resonant frequencies. Thus it is appropriate to serve as a potential MMR for design of UWB BPFs. In this paper, a new MMR-based UWB BPF is proposed and designed using a modified TSSIR. The high-impedance line sections at the two sides of the modified TSSIR are split into two identical parallel ones to enhance the coupling with the input/output feed lines. By properly locating the first five resonant modes of the TSSIR and the coupling peak of the parallel-coupled lines at the two sides, we can obtain a seven-transmissionpole UWB BPF with a uniform in-band response. The filter design and the obtained results are presented in the following sections.