An ultra-wideband (UWB) bandpass filter with microstrip-to-CPW transition and a notch-band

Zhu, He; Wong, Sai‐Wai; Wen, Shenjie; Chu, Qing Xin

doi:10.1109/ieee-iws.2013.6616756

Cited by 4 publications

(1 citation statement)

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“…Multi-mode resonators [5] are a series of resonators which can produce multiple resonant modes, using an appropriate coupling to form multi-band or ultra-wideband bandpass filters. Typical multi-mode resonators include stepped-impedance resonators [6], multi-stub-loaded resonators [7], ring resonator [8], slot-line/CPW resonators [9]- [10], coupled-line resonators [11], and so on. For multi-band filters, two resonators are coupled together with a decent coupling coefficient, and then fed with tapped feeding lines or spur-lines.…”

Section:  Other Techniquesmentioning

confidence: 99%

Multi-functional and Tunable Microwave Devices and Sub-systems for Wideband Applications

Zhu¹

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Microwave components and sub-systems have been widely investigated in recent years since they play essential roles in microwave systems. With the rapid development and explosive extension of microwave techniques, high speed, large data volume, and electromagnetic compatibility are not the only issues that concern designers, practitioners, and researchers. Features like multi-functionality, reconfigurability, portability, low energy consumption, miniaturization of circuit size and simple construction have come into focus more and more in recent years. Currently, microwave devices are suffering from several drawbacks: huge losses from a lack of integration of individual components, lack of new functionality, poor adaptability to different environments, low efficiency, flexibility and controllability, high cost and energy consumption, and insufficient miniaturization of circuit size.With these existing challenges and the huge call for innovation in microwave components and subsystems, new design approaches and structures are extremely in demand and a high point of focus.This thesis aims to solve some of the current challenges mentioned above by making four main contributions.The first contribution is the development of new design approaches to design microwave devices with multiple functions to replace cascaded devices with a single function. The main target is to reduce the overall number of components used in constructing microwave systems. With a large number of cascaded devices, huge losses will be produced which decrease systems" reliability and overall performance, not to mention the current large circuit volumes, high cost, and energy consumption. Multi-functional componentry is a suitable and proper solution to solve these problems. In wireless microwave systems, power dividers are usually cascaded with bandpass filters, to get rid of unwanted signals and transmit the desired ones. When the number of output terminations is raised, more filters are required, which makes it more difficult for design and implementation. A four-way power divider integrated with filtering characteristics is proposed to replace the cascaded structures. The proposed design shows equal power division, great selection of filtering signals and reduction in device numbers and overall cost.The second contribution is the development of multiple tunable microwave devices which can be controlled and adapted to different environments. An electrical tuning method is used by loading varactors on microstrip lines. To begin with, tunable bandpass filters were investigated to achieve high tunability of both centre frequency and bandwidth. To that end, several new designs with varactor-loaded coupled-line sections were proposed and verified. Relocatable transmission zero was realised to control the cut-off of the passband at two edges. The concept was applied in the II design of a tunable balanced bandpass filter with a wide tuning range and high common-mode suppression. Wideband power dividers with tunable power division at output termi...

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