Browsing by Author "Liang, Cheng-Hsien"

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Compact Microstrip Bandpass Filters Using Miniaturized Quarter-Wavelength Resonators
(2010-01-01)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel miniaturized lambda/4 microstrip resonator. The two shorted high-impedance lines not only possess the feasibility to be arranged but also provide the strong magnetic coupling between resonators easily. By applying the proposed resonator, the filter with the flexible bandwidth can be realized. Moreover, the spurious frequency can be shifted to the higher frequency by adjusting the structural parameters. The proposed lambda/4 resonator has a much smaller size compared to the conventional one. Two four-pole bandpass filters were designed and fabricated to demonstrate the practicality of the proposed resonator. Each filter occupies a small circuit area and has a good stopband response.
Compact Microstrip Bandpass Filters Using Miniaturized Slow-Wave Quarter-Wavelength Resonators
(2010-01-01)
Chang, Wei-Shin
;
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel lambda/4 microstrip slow wave resonator with interdigital capacitive fingers. The interdigital fingers provide a strong capacitive loading so as to miniaturize the resonator size. The resonant frequency is easily adjusted by varying the number of fingers and the spacing between fingers. To demonstrate the feasibility of the proposed structure, one four-pole Chebyshev and one four-pole generalized Chebyshev filter with 0.05 dB equal-ripple bandwidths of 7.5% and 5%, respectively, were designed and fabricated. An extra transmission zero can be close to the passband for high selectivity and stopband attenuation by using the proposed slow-wave resonator and the tapped input/output structure. Both filters are compact in size and exhibit good stopband rejection.
Compact Wideband Bandpass Filters Using Stepped-Impedance Resonators and Interdigital Coupling Structures
(2009-09-01)
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This letter proposes a microstrip lambda/4 interdigital stepped-impedance resonator whose impedance ratio can be very low and coupling strength between adjacent resonators can be very large. On the basis of the proposed structure, one four-pole Chebyshev and one four-pole generalized Chebyshev filter with 0.05 dB equal-ripple bandwidths of 48% and 46%, respectively, are designed and fabricated. Both implemented filters have a compact size, a wide passband, a wide upper stopband, and a high spurious passband at near 5.1 times the center frequency. Good agreement between measurements and simulations is observed.
Design of Microstrip Ultrabroadband Multisection Quadrature Hybrid
(2012)
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
傳播研究所
;
Institute of Communication Studies
This paper proposes a three-and a five-section microstrip 3-dB quadrature hybrid. Two types of enhanced coupling structures, both with a rectangular ground-plane aperture and two inserted signal strips in the aperture, are used in the quadrature hybrid not only to achieve tight coupling but also to minimize the junction effect between coupling sections. The designed circuits have a fully planar structure. They were fabricated on a single-layer substrate by the standard printed circuit board (PCB) manufacturing process.
Enhanced Coupling Structures for Tight Couplers and Wideband Filters
(2011-03-01)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Tightly coupled lines are difficult to realize on the conventional printed circuit board (PCB). This paper proposes two types of novel enhanced coupled-line structures appropriate for tightly coupled directional couplers and wideband filters. The proposed coupled-line structures both have a rectangular ground-plane aperture and two inserted signal strips in the aperture to increase the coupling strength significantly. No fine lines and narrow gaps are required so as to fit the conventional PCB fabrication process. More importantly, the proposed structures only need a single-layer substrate. To demonstrate the feasibility of the proposed structures, one 3-dB directional coupler and two four-pole Chebyshev filters with 0.05-dB equal-ripple bandwidths of 40% and 37% are designed and realized. The coupler and filters are fabricated on a PCB substrate with a dielectric constant of 3.58 and a thickness of 0.508 mm. Good agreement between measurements and simulations is observed.
Fabrication-Tolerant Microstrip Quarter-Wave Stepped-Impedance Resonator Filter
(2009-05-01)
Liang, Cheng-Hsien
;
Chen, Chin-Hsiung
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
The etching error causes serious frequency drift of a microstrip stepped-impedance resonator (SIR). This paper proposes a novel microstrip quarter-wave SIR structure, which is insensitive to fabrication tolerances. Inserting several ground strips in the low-impedance section of the resonator keeps the impedance ratio almost constant in spite of inaccurate fabrication. As an additional benefit, the resonator size would be miniaturized because the characteristic impedance of the microstrip line in the low-impedance section is mainly controlled by the signal strips and the inserted ground strips in a coplanar manner. The concepts and characteristics of this modified resonator structure are discussed in detail. The filters constructed by the conventional microstrip SIR were also designed and fabricated at the same frequency band to compare with the proposed ones. Measured results show that each proposed filter has compact size, wide stopband, and high tolerance to fabrication errors. Two four-pole cross-coupled filters were designed and fabricated to demonstrate the feasibility.
Novel Low-Impedance Microstrip Structures for Miniaturized Microstrip Quarter-Wave Stepped-Impedance Resonator Filters
(2008)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Novel Microstrip Stepped-Impedance Resonator for Compact Wideband Bandpass Filters
(2009)
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
A novel lambda/4 microstrip stepped-impedance resonator with interdigital coupling elements is presented in this paper. By combining the merits of these two structures, strong coupling between adjacent resonators for wideband bandpass filters can be easily obtained and the size of the filter can be largely reduced. More importantly, only a single-sided fabrication process is required in the implementation of the proposed filter. Two four-pole bandpass filters with 0.1 dB equal-ripple bandwidths of 38% and 55%, respectively, are designed and fabricated. Both filters have the advantages of compactness, wide bandwidth, and ease of fabrication.
Slow-Wave Broadside-Coupled Microstrip Lines and Its Application to the Rat-Race Coupler
(2015-06-01)
Chang, Wei-Shin
;
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
傳播研究所
;
Institute of Communication Studies
This letter proposes a type of slow-wave broadside-coupled microstrip lines. The new structure only requires a single-layer substrate and has the independently controllable even-and odd-mode impedances and slow-wave factors by adjusting the corresponding structural parameters. This property greatly simplifies the circuit design. In addition, it provides a large coupling strength. A miniaturized wideband microstrip rat-race coupler with the high isolation and perfect balances is implemented using the proposed slow-wave coupled lines.