Summary
International Symposium on Antennas and Propagation
2009
Session Number:2E1
Session:
Number:2E1-1
Compact Dual-Band PCML-SIR Bandpass Filters with Edge-Capacitive Coupling
Jayaseelan Marimuthu, Mazlina Esa,
pp.596-599
Publication Date:2009/10/21
Online ISSN:2188-5079
Summary:
In recent years, compact multiband devices compatible with printed circuit board (PCB), have received great demand for advanced wireless systems with simultaneous operations at multiple frequency bands. With the advent of wireless communications, the design of many passive circuits such as the bandpass filters, are facing new design challenges including compact in size, wide bandwidth and multi-band operations. High data-rate wireless communication systems, such as worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN), require wide bandwidth up to several hundred of megahertz and flexibility of operating in multiple frequency bands. Planar bandpass filters fabricated on printed circuit board (PCB) are attractive for filter application because their low fabrication cost suits commercial application well [1?2]. The multi-band microwave components, when realized, can lead to both the size and cost reduction in the circuits used for multi-band wireless communication systems [3?4]. In this paper, a simple dual-band bandpass filter were constructed by cascading the multiple λ/2 stepped-impedance resonators (SIRs) through the distributed parallel coupled microstrip lines (PCMLs) with edge-capacitive coupling configuration. It is named PCML-SIR ECC filter. A simple PCML structure with high impedance feeding network shows dual-band characteristics. Similarly a SIR cascaded with PCML coupling also shows dual-band response. A single-stage dual-band bandpass filter was designed by cascading a simple SIR structure coupled with PCML of high impedance feeding network. The single-stage dual-band filter passband response and bandwidth are adjustable by controlling the impedance ratio of both strips and middle resonator length of SIR and also the impedance of PCML feeding network. The edge-capacitive coupling technique was introduced and incorporated in PCML-SIR filter to obtain good stopband response between two passband. The stopband response between two resonant frequencies depends on the gap of edgecapacitive coupling between two PCML structures. By suitably choosing edge-capacitive coupling gap, a perfect stopband response with two transmissions zero can be obtained between the two resonant frequencies. Various PCML-SIR single-stage dual-band bandpass filters were designed on RT/duroid 6006 of εr = 6.15 and h =1.27 mm to investigate the performance of filter in terms of bandwidth and stopband characteristics. Finally, three two-stage dual-band bandpass filters of PCML-SIR ECC are optimally designed and fabricated to demonstrate in reality the dual-band performance with controllable bandwidth and stopband parameters. It was found that the simulated and measured insertion and return losses responses showed good agreement with excellent stopband performance with two transmission zero frequencies.