Browsing by Author "Shih, E"

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A new compact microstrip stacked-SIR bandpass filter with transmission zeros
(2003)
Shih, E
;
Kuo, JT
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents a new class of bandpass filters based on a stacked-SIR (stepped impedance resonators) configuration. By stacking multi-coupled SIR's, the longitudinal dimension of the resulting filter is not increased despite the increase of the filter order, so that the area of the whole filter is very compact. The use of SIR's assures that the filters have a wide upper stopband. In addition, with proper tapped input and output couplings, this new bandpass filter structure is capable of generating at least two transmission zeros. Of filters of orders 2 and 4, simulated responses show three transmission zeros in the stopband. Two third-order filters with transmission zeros purposely located at twice the center passband frequency (2f(0)) are fabricated and measured to demonstrate the design.
Design of bandpass filters with parallel three-line coupled microstrips
(2001)
Kuo, JT
;
Shih, E
;
Lee, WC
;
電信工程研究所
;
Institute of Communications Engineering
Bandpass filters are designed based on parallel coupled three-line microstrip structures. The relation between the circuit parameters of a three-line coupled microstrip section and an admittance inverter is established. A design graph for substrate with epsilon(r) = 2.2 is provided. Two Chebyshev filters, of order 2 and 1dB passband ripple, with fractional bandwidths 40% and 60% are fabricated and measured. Good agreement between prediction and measurement is obtained.
Microstrip stepped impedance resonator bandpass filter with an extended optimal rejection bandwidth
(2003-05-01)
Kuo, JT
;
Shih, E
;
電信工程研究所
;
Institute of Communications Engineering
Bandpass filters with an optimal rejection bandwidth are designed using parallel-coupled stepped impedance resonators (SIRs). The fundamental (f) and higher order resonant harmonies 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(si)) of a tapped SIR is derived. With the aid of Q(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(o), 6.5f(o), and 8.2f(o) are fabricated and measured to demonstrate the idea.
Stepped impedance resonator bandpass filters with tunable transmission zeros and its application to wide stopband design
(2002)
Kuo, JT
;
Shih, E
;
電信工程研究所
;
Institute of Communications Engineering
Bandpass filters with a very wide stopband are designed using parallel coupled stepped impedance resonators (SIR), which have advantageous resonance harmonic characteristics. The singly loaded Q (e) of a tapped SIR is derived, so that the relation between Q,, and the position of tap point can be established.,It is known that a single resonator with tapped input can create an extra zero. It is found that in this paper, with proper tapping at the first and the last SIR's of a bandpass filter, two zeros can be created and tuned independently over a wide frequency range. By exploiting both the advantageous resonance characteristics of SIR and tapped-line input, a bandpass filter with high selectivity and/or wide stopband can be realized. The experimental results show a good agreement with the simulated prediction.
Wideband bandpass filter design with three-line microstrip structures
(2001)
Kuo, JT
;
Shih, E
;
電信工程研究所
;
Institute of Communications Engineering
Systematic procedure is described for designing bandpass filters with wide bandwidths based on parallel coupled three-line microstrip structures. It is found that the tight gap sizes between the resonators of end stages and feed lines, required for wideband filters based on traditional coupled line design, can be greatly released. The relation between the circuit parameters of a three-line coupling section and an admittance inverter circuit is derived. A design graph for substrate with epsilon(r) = 10.2 is provided. Two filters of orders 3 and 5 with fractional bandwidths 40% and 50%, respectively, are fabricated and measured. Good agreement between prediction and measurement is obtained.
Wideband bandpass filter design with three-line microstrip structures
(2002-10-01)
Kuo, JT
;
Shih, E
;
電信工程研究所
;
Institute of Communications Engineering
A systematic procedure is described for designing wideband bandpass filters based on parallel coupled three-fine microstrip structures. It starts with modal analysis of a three-line coupled microstrip circuit. A database of modal eigenvoltage coefficients and modal characteristic impedances for a specified value of substrate e, is established. The relation between the circuit parameters of a three-fine coupling section and an admittance inverter circuit is derived, so that the filters can be synthesised by a standard procedure. As compared with traditional parallel coupled lines, the proposed three-line design has the following two important features for the design of wideband filters: the tight line spacings of end stages can be greatly relaxed; and the stopband rejections are improved. Four filters with fractional bandwidths from 40% to 70% are fabricated on substrates with low and high dielectric constants. Prediction and measurement results are in good agreement.