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Author

S. Yamashita

Bio: S. Yamashita is an academic researcher. The author has contributed to research in topics: Distributed element filter & Constant k filter. The author has an hindex of 1, co-authored 1 publications receiving 743 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, approximate design formulas for bandpass filters using parallel coupled stripling stepped impedance resonators (SIR) are derived, taking into account the arbitrary coupling length as well as quarter-wavelength coupling.
Abstract: Approximate design formulas for bandpass filters using parallel coupled stripling stepped impedance resonators (SIR) are derived. The formulas take into account the arbitrary coupling length as well as quarter-wavelength coupling. Some advantages of this filter are its abilities to control spurious response and insertion loss by changing the structure of the resonator. Using the design formulas two experimental filters were designed and fabricated and their performances closely matched design data.

784 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this article, a microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiplemode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz.
Abstract: A novel microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiple-mode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz. In the design, the first three resonant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched so as to raise the frequency-dispersive coupling degree with the coupling peak near the center of the UWB. After optimization of this filter, a good UWB bandpass behavior with five transmission poles is theoretically realized and experimentally confirmed. Within the whole UWB passband, the return loss is found higher than 10dB, and the group delay variation is less than 0.23ns.

990 citations

Journal ArticleDOI
TL;DR: In this paper, the fundamental and higher order harmonics of an SIR were analyzed against the length ratio of the high-Z and low-Z segments to obtain an optimal length ratio for each high-z to low-z impedance ratio to maximize the upper rejection bandwidth.
Abstract: Bandpass filters with an optimal rejection bandwidth are designed using parallel-coupled stepped impedance resonators (SIRs). The fundamental (f/sub o/) and higher order resonant harmonics of an SIR are analyzed against the length ratio of the high-Z and low-Z segments. It is found that an optimal length ratio can be obtained for each high-Z to low-Z impedance ratio to maximize the upper rejection bandwidth. A tapped-line input/output structure is exploited to create two extra transmission zeros in the stopband. The singly loaded Q(Q/sub si/) of a tapped SIR is derived. With the aid of Q/sub si/, the two zeros can be independently tuned over a wide frequency range. When the positions of the two zeros are purposely located at the two leading higher order harmonics, the upper rejection band can be greatly extended. Chebyshev bandpass filters with spurious resonances up to 4.4f/sub o/, 6.5f/sub o/, and 8.2f/sub o/ are fabricated and measured to demonstrate the idea.

360 citations

Journal ArticleDOI
TL;DR: In this article, the fundamental characteristics of the three types of SIRs, namely, resonance conditions, resonator length, spurious (higher order) responses, and equivalent circuits are summarized.
Abstract: /spl lambda//sub g//4-,/spl lambda//sub g//2-, and /spl lambda//sub g/-type transmission-line stepped-impedance resonators (SIRs) have been proposed and various practical applications have been reported on the basis of the analysis related to each resonator. This paper standardizes these three types of SIRs and systematically summarizes their fundamental characteristics, such as resonance conditions, resonator length, spurious (higher order) responses, and equivalent circuits. Practical applications which employ features of three types of SIRs are investigated with demonstrations of specific structures. Original design formulas with respect to /spl lambda//sub g/-type dual-mode resonators are analytically derived. Advanced SIR's using composite material and multisteps are also introduced and their availability is discussed.

358 citations

Journal ArticleDOI
TL;DR: In this article, the theory and experiment of a new class of microstrip slow-wave open-loop resonator filters is presented, and two filter designs of this type are described in detail.
Abstract: This paper presents the theory and experiment of a new class of microstrip slow-wave open-loop resonator filters. A comprehensive treatment of capacitively loaded transmission line resonator is described, which leads to the invention of microstrip slow-wave open-loop resonator. The utilization of microstrip slow-wave open-loop resonators allows various filter configurations including those of elliptic or quasi-elliptic function response to be realized. The filters are not only compact size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. These attractive features make the microstrip slow-wave open-loop resonator filters promising for mobile communications, superconducting and other applications. Two filter designs of this type are described in detail. The experimental results are demonstrated and discussed.

355 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations, where the second resonant frequency can be tuned over a wide range by adjusting its structure parameters.
Abstract: This paper presents a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations. Based on resonance characteristics of a stepped impedance resonator (SIR), the second resonant frequency can be tuned over a wide range by adjusting its structure parameters. Emphasis is placed on filter synthesis for simultaneously matching in-band response and singly loaded Q by using tapped input/output couplings for the two designated passbands. Fractional bandwidth design graphs are used to determine proper geometric parameters of each coupled stage when filter specification is given. Realizable fractional bandwidths of the two passbands for a coupled SIR structure are clearly depicted in fractional bandwidth design graphs. Several experimental filters are fabricated and measured to demonstrate the design.

324 citations