Showing papers on "Stopband published in 1985"

A Design Method of Bandpass Filters Using Dielectric-Filled Coaxial Resonators (Short Papers)

Abstract: Design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified. The most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression. Its features can be obtained from the configuration using both quarter-wavelength uniform impedance resonators (UIR's) and stepped impedance resonators (SIR's).

Optimal design of linear phase FIR digital filters with very flat passbands and equiripple stopbands

Abstract: A new technique is presented for the design of digital FIR filters, with a prescribed degree of flatness in the passband, and a prescribed (equiripple) attenuation in the stopband. The design is based entirely on an appropriate use of the well-known Remez-exchange algorithm for the design of weighted Chebyshev FIR filters. The extreme versatility of this algorithm is combined with certain "maximally flat" FIR filter building blocks, in order to generate a wide family of filters. The design technique directly leads to structures that have low passband sensitivity properties.

Finline and Metal Insert Filters with Improved Passband Separation and Increased Stopband Attenuation

Abstract: A new class of optimized finline and metal insert filters is introduced. In these filters, the ladder-type insert is located in a waveguide section which is either wider or narrower than the embedding standard waveguide. A step junction at each end forms the transition to the standard waveguide and is included in the analysis. Both filter types provide a better suppression of spurious passbands and have significantly improved stop-band attenuation. Filters with enlarged sections are useful for design at the lower end of the waveguide band, whereas the narrower version is appropriate for bandend design.

Verification of the light phase effect at the facet on DFB laser properties

Abstract: The critical importance of the relative position of the reflectors and grating in InP/InGaAsP DFB laser diodes have been directly verified. The relative position was varied by etching the cleaved facet of a DFB laser with the precisely controlled ion beam etching technique. The threshold current, oscillation wavelength, stopband width, and spectral intensity ratio of both modes which form a stopband were measured. All these characteristics changed periodically, with the period being about 2400 A. This value corresponds to one half of the oscillation wavelength in the laser cavity. These characteristic variations resulting from the relative position change of the reflector and grating are theoretically analyzed by the eigenvalue equation which determines the propagation modes. The calculated results qualitatively agree with the experimental findings.

Waveguide bandpass filter

Abstract: A waveguide bandpass filter having multiple waveguide sections including alternating ridge waveguide sections and evanescent waveguide sections The ridge waveguide sections define a resonant cavity and the evanescent waveguide sections reactively load the resonant cavity thus intercoupling the ridge waveguide sections so as to provide a low loss filter having high attenuation, not only at adjacent stop band frequencies, but also at harmonics of the pass band

Bandstop Filter Design Using a Dielectric Waveguide Grating

Abstract: Precision design techniques are obtained for dieletric waveguide (DW) bandstop filters with bandwidths up into the 5-10-percent range. Dielectric waveguide bandstop filters are realized in the form of a grating in the DW image guide which utilizes notches of varying depth and length. The grating is designed from a transmission-line prototype which has a prescribed stopband and also prescribed Chebyshev passbands. An approximate synthesis procedure for such prototypes is presented. Design data for grating notches were obtained from tests on uniform gratings, while DW dispersion is compensated for by calculations based on the "effective dielectric constant" method. Excellent agreement between computed and measured attenuation response is obtained. Two such grating structures used with loads on one end and a 3-dB coupler can be used to form a bandpass filter.

Waveguide E-plane integrated-circuit diplexer

Abstract: A waveguide diplexer is introduced where optimised low-insertion-loss metal insert filters are directly integrated in the E-planes of the T-junction arms. The filters are designed by the exact method of field expansion into suitable eigenmodes which takes the influences of higher-order-mode interaction and finite thickness of the inserts into account. Computer optimised design data are given which provide a metaletching technique for reliable low-cost production. Measured minimum passband insertion losses of an R120-waveguide diplexer prototype are about 0.8 dB at 10.4 GHz, and 0.5 dB at 11.2 GHz. The stopband attenuation at 10.8 GHz is about 48 dB.

Theoretical analysis of the coupling between whispering-gallery dielectric resonator modes and transmission lines

Abstract: Whispering-gallery dielectric resonator modes coupled to one or two transmission lines form a millimetre-wave directional filter or a millimetre-wave stopband filter. The coupling is discussed and a formula for loaded Q is proposed.

E-Plane Integrated Parallel-Strip Screen Waveguide Filters (Short Papers)

Abstract: A rigorous field theory design of a class of rectangular waveguide screen fiIters is presented which achieves improved attenuation in the upper stopband. The method of field expansion into suitable eigenmodes used considers the effects of the finite rectangular E-plane grid thickness and the mutual higher order mode interaction of the single screens. Calculated results up to 55 GHz show that the peak attenuation in the upper stopband for a Ka-band (26-40-GHz) two-resonators filter example with a midband frequency of f/sub 0/= 37 GHz is about 70 dB, whereas its planar circuit single-metal-insert counterpart reaches only about 34 dB. A Ku-band (12- 18-GHz) filter prototype with three metal-etched screens yields a measured passband insertion loss of 0.8 dB at about f/sub 0/= 17 GHz and a measured attenuation in upper stopband of about 50 dB up to 25 GHz.

Waveguide E-Plane Triple-Insert Filter

Abstract: A triple planar integrated circuit filter with all-metal inserts and an additional abrupt waveguide step-wall discontinuity is introduced which achieves ultra-broadband high attenuation in the second stopband. The theory is based on field expansion into suitable eigenmodes which allows direct inclusion of both the higher-order mode interaction at all step discontinuities and the finite thickness of the metal inserts. Computer optimized design data for a four-resonator Ka-band proto-type at 27 GHz midband frequency provide a minimum stop-band attenuation of 50 dB between 28 and 42 GHz (80 dB between 30 and 41.6 GHz).

Computer-aided design of dielectric resonator filters in waveguide sections below cutoff

Abstract: The letter describes the analysis and design of a class of dielectric resonator filters in waveguide sections below cutoff. In these filters evanescent-mode coupling between the resonators can be realised by either an air-filled waveguide section or a dielectric slab-loaded waveguide section. Metallising the dielectric slab on both sides reduces the length of the coupling section and improves the stopband attenuation significantly. Filter characteristics can be predicted very accurately using a mode-matching technique to calculate the S-matrix of the filter component. This method accounts for the effect of finite metallisation thickness and higher-order modes.

A New Class of Optimized Finline and E-Plane Metal Insert Filters with Improved Characteristics

Abstract: A new class of optimized finline and metal insert filters is introduced. In these filters, the ladder-type insert is located in a waveguide section which is either wider or narrower than the embedding standard waveguide. An abrupt step junction at each end forms the transition to the standard waveguide and is included in the analysis. Both filter types provide a better suppression of spurious passbands and have significantly improved stopband attenuation. Filters with enlarged section are useful for design at the lower end of the waveguide band, whereas the narrower version is appropriate for bandend design.

Finite‐element analysis of periodically perturbed piezoelectric waveguides

Abstract: The propagation velocity of the acoustic wave can be reduced in a periodic acoustic waveguide (periodic waveguide) on which a periodic perturbation is added along the propagation direction of the acoustic wave. The passband and stopband appear in the dispersion characteristics (Brillouin diagram). The structure is used widely for the delay line, filter, reflector and resonator. The design of these devices made of periodic waveguides requires the Brillouin diagram. The objective of this paper is to develop a method that can be used to derive the Brillouin diagram of the periodic piezoelectric waveguide receiving an arbitrary mechanical or electrical perturbation. A method based on the finite element method is proposed and its formulation is presented. Further, for the periodic waveguide used as a reflector, the stopband width and the shift of the center frequency are calculated. These are important parameters for the design of the reflector. The groove reflector and the metal strip reflector are analyzed and the results are found to agree well with the experimental values.

Design of digital filters with maximally flat passband and equiripple stopband magnitude

Abstract: This paper introduces a general class of digital filters with maximally flat passband magnitude, equiripple stopband magnitude, and different order numerator and denominator. the classical Chebyschev type II (inverse Chebyschev) filters having equal numerator and denominator orders are considered as special members of this filter class. the filter types to be considered are lowpass, highpass and bandpass. the proposed filter class consists both of filters having all the zeros on the unit circle and of filters having some zeros off the unit circle to contribute to the passband shaping. An efficient iterative algorithm for the design of filters of the given type is presented. It is based on shaping the passband and stopband responses alternately until the difference between successive solutions is within given tolerance limits. Several comparisons show that in wideband applications filters with numerator order higher than denominator order present considerable advantages over equivalent Chebyschev type II designs, in terms of multiplication rate and/or frequency selectivity. In narrowband applications, in turn, filters with higher denominator order are shown to be the most effective.

Self-Suppression Effects of Spurious Transverse Modes in SAW Reflectors and Resonators with a Positive and Negative Reflectivity

Abstract: A new class of SAW grating reflector consisting of reflecting element with both a positive and negative reflectivity (PNR) previously proposed has many advantages of a large reflectivity I wide stopband, and small mode conversion loss into bulk waves1). In this paper, it is shown that an SAW resonator formed by PNR reflectors consisiting of electrically shorted and open strips has inherently the strong suppression effects of spurious resonances due to transverse modes in a grating of finite width. together with above merits. Experiments of one-port resonator on a 1280 YX LiNbOj are done. Results show that no spurious responses at frequencies other than principal mode resonance can be o bserved o ver a wide r ange o f grating guide width. The mechanism of suppression effects is described.

Filter structure constructed as branching circuit

Abstract: The basis is minimum-phase filter structures of any order which have a low-pass, high-pass, band-pass or band-stopping transfer function and in which an additional stop band is provided in the transfer functions which is implemented by using crystals. The circuit structures are constructed, and the dimensioning is selected, in such a way that no additional switching elements are required for implementing the overall circuit, the crystals being directly included in series resonant circuits which are located in longitudinal or transverse branches of the filter structure.

New Types of SAW Reflector and Resonator Consisting of Reflecting Elements with Alternative (Positive and Negative) Reflection Coefficients

Abstract: New types of SAW grating reflector and resonator configurations are proposed which consist of reflecting elements with the opposite sign of the reflection coefficients, and which have the advantages of large reflectivity, wide stopband and small mode conversion into radiative bulk waves. The principles of operation and the possible configurations of the reflector are described. It is confirmed by experiments on metal strip gratings that the proposed configurations provide very efficient reflection characteristics and a small size resonator with very small capacitance ratio.

Shunt-inductance-coupled waveguide filters with expanded second stopband

Abstract: A computer-aided design is described for inductive iris and inductive double-strip coupled filters with increased-width resonator sections. The theory includes both the higher-order-mode interaction of all discontinuities and the finite thickness of the irises and inserts. The step-wall discontinuity effect is included in the optimisation process as an additional design parameter. Design examples for midband frequencies of about 11 and 16 GHz are given; the corresponding stop-band attenuation is higher than 50 dB, or 40 dB, up to 18.5 GHz, or 24.5 GHz, respectively.

Dielectric Waveguide Band-Pass Filters with Broad Stop Bands

Abstract: Techniques for the design of band-pass filters using dielectric waveguide gratings are discussed. Direct-coupled-resonator filter theory is applied to synthesize a prescribed pass band having a Chebyshev or maximally flat characteristic, and at the same time a broad, absorptive stop band is provided through the use of parallel-coupled gratings. Experimental results are also presented which show good agreement between theoretical and measured results.

Switched-capacitor ladder filters with zero worst-case sensitivity at reflection zeros

Abstract: A method for synthesising a parasitic-compensated switched-capacitor (SC) ladder filter with the property that the worst-case sensitivity of its amplitude response is zero at every reflection zero is presented. The stopband sensitivity of this SC filter is low as well as its passband sensitivity.

Design of fir lowpass matched filter pairs with zero intersymbol interference and quasi equiripple stopband attenuation

Abstract: A method is described for designing FIR lowpass filters for receivers and transmitters in data transmission systems. Choosing both filters as a matched pair, the objective is to provide each filter with quasi-equiripple stopband attenuation and to make the overall impulse response satisfy zero intersymbol interference (zero ISI). The method consists of four steps. First, the ideal overall transfer characteristics are approximated in terms of a Fourier series, and the initial zeros of the characteristics are obtained. Second, one half of the mirror image zeros are used for finding zeros on a unit circle so that the single filter has equiripple stopband characteristics. Third, in the overall transfer function, these stopband zeros are fixed as double zeros. The overall impulse response is successively approximated by changing the mirror image zeros in the passband so that the zero ISI condition is satisfied. Finally, the obtained mirror image zeros are divided into two groups, one is allotted to the transmission filter and the other is to receiving filter so that they form a matched pair. In the zero ISI approximation in the third stage, a good initial response is obtained. Further, since the number of variables is equal to the number of zero ISI conditions, the approximation converges accurately and quickly. As a design example, a filter pair is shown in which both the transmission and receiving filters are 59th orders. The ISI is only 2.2 × 10-4% compared to 0.4% found in a different design method.

Microwave band-stop filter

Abstract: PURPOSE:To obtain a small-sized band-stop filter which has large attenuation in a stop band and small insertion loss in a normal band by projecting outward the part of an H surface close to a dielectric resonator. CONSTITUTION:The part 11H of the H surface of a waveguide 11 close to the dielectric resonator 12 is projected out of the waveguide by length b' at the upper side and by length b'' at the lower side. Consequently, the inductance L by the operation of magnetic energy at the projection part is formed and inserted in series of the parallel resonance circuit consisting of capacity CD and inductance LD corresponding to the dielectric resonator 12. Further, an E wave having an electric field in the propagation component of the wave is generated on surfaces 11A-11D as discontinuance points of the projection part and this E wave is a damped wave, so electrostatic capacity C is formed and inserted in parallel. Consequently, matching is attained in a passing band and the interval between the dielectric resonator 12 and H surface become larger to increase nonloaded Q, so the expected purpose is attained.

Design of finite-duration impulse response digital and charge-coupled device filters with arbitrary attenuation characteristics

Abstract: A novel analytic technique is given, for the derivation of finite duration impulse response transfer functions which satisfy arbitrary attenuation characteristics, with or without exact linear phase at all frequencies. The method uses a parameter for the determination of the stopband attenuation at the outset, and the rate of cutoff and the passband performance can be improved by increasing the order of the filter. The resulting solutions provide a marked improvement over the available analytic solutions, particularly where monotonic passband behaviour is required. The technique is also characterised by its simplicity and gives explicit expressions for the coefficients of the transfer function in the z-domain. This obviates the need for the various transformations commonly employed, and consequently improves the accuracy in determining the filter coefficients. The realisation of the resulting functions can be accomplished in either digital or charge-coupled device form.

IWERACTION OF HIGH-COUPLING LW SAW WITH BULK WAVES UNDER >lETAL.LIC-GRATING STRUCIUfE ON 36OYX-LiTaO j

Abstract: The paper deals with leaky SAW (LSAW) propagating under metallic-grating structure on 36OYX-LiTa03, and its interaction with bulk waves. Theoretical analysis has shown that the attenuation of LSAW unusually changes with frequency about the stopband of the grating: the attenuation is negli- gibly small at frequencies lower than the stopband, whereas it rapidly increases when the frequencies are raised above the stopband, and takes a maximum value of about O.ldB per wavelength. This suggests that the attenuation is mainly attributed to the interaction of LSAW with highly piezoelectric fast- shear waves. As to the velocity dispersion, the effect of the metallic-grating upon LSAW is quali- tatively similar to that on conventional SAW. Ex- perimental result using an open-circuited metallic- grating was in good agreement with the theoretical prediction. However, the agreement was rather poor for a short-circuited metallic-grating. This may be due to the fact that in the short-circuited grating, the effects of mass loading and electrical perturbation upon LSAW propagation cancel each other.

Narrow-Band Filter Design Using a Staggered

Abstract: Abstmct-Theoretical and experimental observations are reported on tor and transducer coupling was used in the design of the performance of a narrow-band surface acoustic wave (SAW) filter Chebyshev and Butterworth filters with 3-dB bandwidths using a resonator structure incorporating a stepped-finger interdigital transducer (IDT) as well as a stepped grating reflector. Circuit opera- of about 0.02 percent, with maximum insertion loss of 10 tion is modeled in terms of parallel-connected multimode SAW reso- dB and 60 dB out-of-band rejection. Further, O’Shea ad nators with interlaced resonances across a common Erating-reflector Rosenfeld 1121 have used two-pole SAW resonator filters stop band. Trade-off between insertion loss and filter fractional bandwidth is examined for such a filter with 0.5 percent fractional bandwidth and accompanying 10 dB insertion loss at 75 MHz, on yz-lithium niobate. A determination of the location of the effective center of reflection within the grating reflectors lends support to the validity of the model used.

New design methods for FIR filters with equiripple stopbands and prescribed degrees of passband flatness

Abstract: A technique is presented for designing linear-phase digital FIR filters, with a prescribed degree of flatness in the passband, and a prescribed (equiripple) attenuation in the stopband. The design is based entirely on appropriate use of the McClellan-Parks algorithm along with certain maximally flat building blocks.