Cuvinte cheie. Filtre, microstrip, cuplaje incrucisate, optimizare. Rezumat. Articolul prezintă u... more Cuvinte cheie. Filtre, microstrip, cuplaje incrucisate, optimizare. Rezumat. Articolul prezintă un studiu asupra posibilităţilor de imbunătăţire a proiectării filtrelor trece-bandă de microunde cu cuplaje incrucisate, utilizând o procedură hibridă de optimizare. In acest fel toate caracteristicile filtrului, incluzând aici si localizarea in frecvenţă a polilor de atenuare, pot fi precis controlate, permiţând proiectarea unor filtre trece-bandă cu selectivitate imbunătăţită. Drept exemplu, configuraţia de filtru trece-bandă considerată a fost proiectată folosind simularea electromagnetică iar performanţele sale au fost optimizate utilizând simularea de circuite liniare. Performanţele filtrului concordă bine cu specificaţia, ceea ce validează posibilităţile de proiectare mai precisă a unor filtre trece-bandă de microunde selective, utile in sistemele actuale de comunicaţii.
This paper presents the design, simulation/optimization and measured results of a 4 order microst... more This paper presents the design, simulation/optimization and measured results of a 4 order microstrip bandpass filter using open loop square resonators, with a central frequency 5.5GHz and 275MHz bandwidth. The design of microwave filters with cross-couplings is improved by applying a new multiple-steps optimization procedure. After a thorough optimization of the filter's layout by this method, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing the efficiency of the applied optimization method.
This paper is dedicated mainly to the study of couplings between planar resonators in multilayer ... more This paper is dedicated mainly to the study of couplings between planar resonators in multilayer structures with modified (defected) ground plane. Couplings between two miniaturized resonators are investigated, by full electromagnetic field simulation. Based on the results of this study, several models of planar microwave bandpass filters, with a single or with two apertures, are designed, verified by simulation, fabricated and measured. Compared to the classical filters, these novel structures show a good compactness and can offer some technological advantages.
In this paper the design of a filtering structure with improved group-delay characteristic in mic... more In this paper the design of a filtering structure with improved group-delay characteristic in microstrip technology is presented. This improvement is achieved by using pairs of equalization poles. In addition, an improved selectivity with respect to the adjacent channels is achieved by introducing two attenuation poles in the stop-band, one on each side of the pass-band. As a design example, a sixth-order quasielliptic filter with an in-band Chebyshev response, having two prescribed attenuation poles and two optimized group-delay equalization poles is designed, simulated, fabricated and tested. The measured characteristics of the experimental model are found to be in good agreement with the results anticipated through electromagneticfield simulation. In a similar way, filters acting as equalization circuits can also be obtained using a slightly different optimization procedure, in order to improve the overall group-delay of a specified communication system. Key-Words: Group-Delay, A...
Investigations on compact planar devices are presented in this paper. The proposed patch dual mod... more Investigations on compact planar devices are presented in this paper. The proposed patch dual mode filter occupies about 16% of the surface area of a conventional square patch. The six-pole filter with compact cross-coupled resonators provides an improved rejection band.
Articolul prezintă o metodă analitică de sinteză pentru filtrele trece-bandă (FTB) cuasi-eliptice... more Articolul prezintă o metodă analitică de sinteză pentru filtrele trece-bandă (FTB) cuasi-eliptice cu poli de atenuare impuşi funcţiei de transfer. În general, matricea filtrelor obţinută prin această procedură presupune existenţa unor cuplaje directe între toate rezonatoarele filtrului. Prin transformări de similitudine pot fi însă obţinute alte matrice care păstrează toate caracteristicile electrice ale filtrului corespunzător matricei iniţiale, dar care sunt mai convenabile din punct de vedere al realizării practice. Ca exemplu, în articol este prezentată proiectarea şi simularea unui FTB de ordin 4 cu rezonatoare cuplate încrucişat, care are o pereche de poli de atenuare la frecvenţe finite. Performanţele FTB obţinute prin simulare de circuit şi prin simulare electromagnetică concordă bine cu specificaţiile de proiectare, ceea ce validează metoda de calcul. This paper describes a general method for the synthesis of quasi-elliptic bandpass filters (BPF), with prescribed attenuatio...
Dual-mode, meander loop filters can provide a valid solution for narrow-band, compact and cost-ef... more Dual-mode, meander loop filters can provide a valid solution for narrow-band, compact and cost-effective devices for mobile communications. The finite-difference time-domain (FDTD) method was employed in order to obtain an accurate filter design. For the non-reflective boundary conditions, the Bérenger perfectly-matched layer (PML) was extended to a 3-D non-homogeneous PML. The computation time was reduced by five times by employing some estimation techniques after the FDTD signal was decimated and de-noised using wavelet packets.
European Conference on Circuits and Systems for Communications, 2008
In this paper a new type of dual-mode compact resonator for mobile communication systems, in the ... more In this paper a new type of dual-mode compact resonator for mobile communication systems, in the 900 MHz frequency band, is investigated. This compact planar resonator, developed on a 0.635 mm substrate with a 10.8 dielectric constant, has a square shape with an edge of 20.5 mm. For this dual resonator, several methods of modes coupling were considered. The radiation
In this paper some novel types of microwave bandpass filters using defected ground structures are... more In this paper some novel types of microwave bandpass filters using defected ground structures are investigated. In the microstrip technology the use of defected ground structures (DGS) allows designs of filters with tight couplings, without the necessity of using very narrow coupling gaps. In multilayer filters DGS can be used as coupling elements between resonators, allowing very compact filter designs.
A new topology for fourth-order microstrip bandpass filters is investigated in this paper. Compar... more A new topology for fourth-order microstrip bandpass filters is investigated in this paper. Compared to the classical quadruplet, the proposed new topology offers an extra coupling between two resonators, allowing this way the design of fourth order filters with two attenuation poles situated on the same side of the passband. A strongly asymmetric transfer characteristic can be obtained by a
Proceedings of the Second International Symposium of Trans Black Sea Region on Applied Electromagnetism (Cat. No.00TH8519), 2000
Summary form only given. Changing the polarization of a wave is a common procedure in many applic... more Summary form only given. Changing the polarization of a wave is a common procedure in many applications in the field of communication, measurement systems etc. Polarization transformers are passive and linear devices, based on the differential phase-shift generated between two orthogonal propagation modes. In this paper, a simple method for the numerical analysis of a variety of non-homogeneous waveguides is presented. Essentially, the proposed procedure is based on the application of a finite-difference method in the frequency domain (FD-FD). Versatile programs can be created using the MATLAB programming language, for use with different waveguide geometries. These programs are relatively simple and do not demand large computational efforts, so that they can represent an economic solution for the analysis of non-homogeneous propagating structures. In the paper are presented some results obtained by applying methods of this type to the analysis of a number of inhomogeneous guiding structures, in the form of dispersion characteristics, β=β(ω), and of differential phase shift per unit length characteristics versus frequency. This last form allows the determination of the working frequency band, for each type of differential phase-shift structure. As a conclusion, some new structures of differential phase-shifters with improved characteristics are presented
Cuvinte cheie. Filtre, microstrip, cuplaje incrucisate, optimizare. Rezumat. Articolul prezintă u... more Cuvinte cheie. Filtre, microstrip, cuplaje incrucisate, optimizare. Rezumat. Articolul prezintă un studiu asupra posibilităţilor de imbunătăţire a proiectării filtrelor trece-bandă de microunde cu cuplaje incrucisate, utilizând o procedură hibridă de optimizare. In acest fel toate caracteristicile filtrului, incluzând aici si localizarea in frecvenţă a polilor de atenuare, pot fi precis controlate, permiţând proiectarea unor filtre trece-bandă cu selectivitate imbunătăţită. Drept exemplu, configuraţia de filtru trece-bandă considerată a fost proiectată folosind simularea electromagnetică iar performanţele sale au fost optimizate utilizând simularea de circuite liniare. Performanţele filtrului concordă bine cu specificaţia, ceea ce validează posibilităţile de proiectare mai precisă a unor filtre trece-bandă de microunde selective, utile in sistemele actuale de comunicaţii.
This paper presents the design, simulation/optimization and measured results of a 4 order microst... more This paper presents the design, simulation/optimization and measured results of a 4 order microstrip bandpass filter using open loop square resonators, with a central frequency 5.5GHz and 275MHz bandwidth. The design of microwave filters with cross-couplings is improved by applying a new multiple-steps optimization procedure. After a thorough optimization of the filter's layout by this method, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing the efficiency of the applied optimization method.
This paper is dedicated mainly to the study of couplings between planar resonators in multilayer ... more This paper is dedicated mainly to the study of couplings between planar resonators in multilayer structures with modified (defected) ground plane. Couplings between two miniaturized resonators are investigated, by full electromagnetic field simulation. Based on the results of this study, several models of planar microwave bandpass filters, with a single or with two apertures, are designed, verified by simulation, fabricated and measured. Compared to the classical filters, these novel structures show a good compactness and can offer some technological advantages.
In this paper the design of a filtering structure with improved group-delay characteristic in mic... more In this paper the design of a filtering structure with improved group-delay characteristic in microstrip technology is presented. This improvement is achieved by using pairs of equalization poles. In addition, an improved selectivity with respect to the adjacent channels is achieved by introducing two attenuation poles in the stop-band, one on each side of the pass-band. As a design example, a sixth-order quasielliptic filter with an in-band Chebyshev response, having two prescribed attenuation poles and two optimized group-delay equalization poles is designed, simulated, fabricated and tested. The measured characteristics of the experimental model are found to be in good agreement with the results anticipated through electromagneticfield simulation. In a similar way, filters acting as equalization circuits can also be obtained using a slightly different optimization procedure, in order to improve the overall group-delay of a specified communication system. Key-Words: Group-Delay, A...
Investigations on compact planar devices are presented in this paper. The proposed patch dual mod... more Investigations on compact planar devices are presented in this paper. The proposed patch dual mode filter occupies about 16% of the surface area of a conventional square patch. The six-pole filter with compact cross-coupled resonators provides an improved rejection band.
Articolul prezintă o metodă analitică de sinteză pentru filtrele trece-bandă (FTB) cuasi-eliptice... more Articolul prezintă o metodă analitică de sinteză pentru filtrele trece-bandă (FTB) cuasi-eliptice cu poli de atenuare impuşi funcţiei de transfer. În general, matricea filtrelor obţinută prin această procedură presupune existenţa unor cuplaje directe între toate rezonatoarele filtrului. Prin transformări de similitudine pot fi însă obţinute alte matrice care păstrează toate caracteristicile electrice ale filtrului corespunzător matricei iniţiale, dar care sunt mai convenabile din punct de vedere al realizării practice. Ca exemplu, în articol este prezentată proiectarea şi simularea unui FTB de ordin 4 cu rezonatoare cuplate încrucişat, care are o pereche de poli de atenuare la frecvenţe finite. Performanţele FTB obţinute prin simulare de circuit şi prin simulare electromagnetică concordă bine cu specificaţiile de proiectare, ceea ce validează metoda de calcul. This paper describes a general method for the synthesis of quasi-elliptic bandpass filters (BPF), with prescribed attenuatio...
Dual-mode, meander loop filters can provide a valid solution for narrow-band, compact and cost-ef... more Dual-mode, meander loop filters can provide a valid solution for narrow-band, compact and cost-effective devices for mobile communications. The finite-difference time-domain (FDTD) method was employed in order to obtain an accurate filter design. For the non-reflective boundary conditions, the Bérenger perfectly-matched layer (PML) was extended to a 3-D non-homogeneous PML. The computation time was reduced by five times by employing some estimation techniques after the FDTD signal was decimated and de-noised using wavelet packets.
European Conference on Circuits and Systems for Communications, 2008
In this paper a new type of dual-mode compact resonator for mobile communication systems, in the ... more In this paper a new type of dual-mode compact resonator for mobile communication systems, in the 900 MHz frequency band, is investigated. This compact planar resonator, developed on a 0.635 mm substrate with a 10.8 dielectric constant, has a square shape with an edge of 20.5 mm. For this dual resonator, several methods of modes coupling were considered. The radiation
In this paper some novel types of microwave bandpass filters using defected ground structures are... more In this paper some novel types of microwave bandpass filters using defected ground structures are investigated. In the microstrip technology the use of defected ground structures (DGS) allows designs of filters with tight couplings, without the necessity of using very narrow coupling gaps. In multilayer filters DGS can be used as coupling elements between resonators, allowing very compact filter designs.
A new topology for fourth-order microstrip bandpass filters is investigated in this paper. Compar... more A new topology for fourth-order microstrip bandpass filters is investigated in this paper. Compared to the classical quadruplet, the proposed new topology offers an extra coupling between two resonators, allowing this way the design of fourth order filters with two attenuation poles situated on the same side of the passband. A strongly asymmetric transfer characteristic can be obtained by a
Proceedings of the Second International Symposium of Trans Black Sea Region on Applied Electromagnetism (Cat. No.00TH8519), 2000
Summary form only given. Changing the polarization of a wave is a common procedure in many applic... more Summary form only given. Changing the polarization of a wave is a common procedure in many applications in the field of communication, measurement systems etc. Polarization transformers are passive and linear devices, based on the differential phase-shift generated between two orthogonal propagation modes. In this paper, a simple method for the numerical analysis of a variety of non-homogeneous waveguides is presented. Essentially, the proposed procedure is based on the application of a finite-difference method in the frequency domain (FD-FD). Versatile programs can be created using the MATLAB programming language, for use with different waveguide geometries. These programs are relatively simple and do not demand large computational efforts, so that they can represent an economic solution for the analysis of non-homogeneous propagating structures. In the paper are presented some results obtained by applying methods of this type to the analysis of a number of inhomogeneous guiding structures, in the form of dispersion characteristics, β=β(ω), and of differential phase shift per unit length characteristics versus frequency. This last form allows the determination of the working frequency band, for each type of differential phase-shift structure. As a conclusion, some new structures of differential phase-shifters with improved characteristics are presented
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Papers by George Lojewski