Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335855
M. Ghaderi, Surinder Kumar
Quadrature ampliltude modulation has high spectral efficiency but is highly sensitive to power amplifier nonlinearities. It is shown that an adaptive predistorter usig polynomial amplitude and phase predistortion functions can be used to linearize the power amplifier. The recursive least square algorithm is employed in an estimator which uses demodulated signals to estimate the required predistortion. Computer simulation results are provided and these results show that fast convergence and high spectrum improvement can be obtained using the proposed linearization method. The results are significantly better than those reported before for other linearization techniques.
{"title":"Power Amplifier Adaptive Linearization Using Predistortion with Polynomial Functions","authors":"M. Ghaderi, Surinder Kumar","doi":"10.1109/EUMA.1992.335855","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335855","url":null,"abstract":"Quadrature ampliltude modulation has high spectral efficiency but is highly sensitive to power amplifier nonlinearities. It is shown that an adaptive predistorter usig polynomial amplitude and phase predistortion functions can be used to linearize the power amplifier. The recursive least square algorithm is employed in an estimator which uses demodulated signals to estimate the required predistortion. Computer simulation results are provided and these results show that fast convergence and high spectrum improvement can be obtained using the proposed linearization method. The results are significantly better than those reported before for other linearization techniques.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123484879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335760
A. Melloni, M. Politi, G. Gentili, G. Macchiarella
A modified mode-matching technique for the analysis of waveguide bandpass filters employing circular T E011 resonators, coupled by rectangular apertures, is presented. The technique rigorously takes into account both the thickness of the coupling irises and the angle between the irises of the same resonator, overcoming the limitations of available approximate models. By optimization procedures it is so possible to design filters having the desired frequency response without resorting to empirical adjustments. Spurious responses can be controlled too, as verified experimentally.
{"title":"Field Design of TE011-Mode Wavegude Passband Filters","authors":"A. Melloni, M. Politi, G. Gentili, G. Macchiarella","doi":"10.1109/EUMA.1992.335760","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335760","url":null,"abstract":"A modified mode-matching technique for the analysis of waveguide bandpass filters employing circular T E011 resonators, coupled by rectangular apertures, is presented. The technique rigorously takes into account both the thickness of the coupling irises and the angle between the irises of the same resonator, overcoming the limitations of available approximate models. By optimization procedures it is so possible to design filters having the desired frequency response without resorting to empirical adjustments. Spurious responses can be controlled too, as verified experimentally.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126296121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335751
T. Rozzi, G. Gerini, P. Sewell, F. Moglie, M. Ridolfi
The fundamental and the parasitic mode of coplanar guide, fig. 1), have been extensively investigated [1]. Due to its open nature, the guide also features a continuum of radiation modes both in air and in the dielectric substrate which is excited by discontinuities such as steps, bends, short circuits, etc. Various common discontinuities in the guide couple strongly to these radiation modes. Such fields propagate without attenuation a long way away from their source and are difficult to handle by standard numerical techniques. This part of the spectrum has never been investigated before. This contribution deals with the continuum of coplanar guide in full hybrid form, including the effect of finite metallisation thickness. Its simple application to the problem of scattering by transverse metal strips is also treated, providing details of the radiation patterns. Cascades of strips, including interaction via the radiation field, are currently under investigation.
{"title":"The Complete Spectrum of Coplanar Waveguide and its Application to Scattering Problems","authors":"T. Rozzi, G. Gerini, P. Sewell, F. Moglie, M. Ridolfi","doi":"10.1109/EUMA.1992.335751","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335751","url":null,"abstract":"The fundamental and the parasitic mode of coplanar guide, fig. 1), have been extensively investigated [1]. Due to its open nature, the guide also features a continuum of radiation modes both in air and in the dielectric substrate which is excited by discontinuities such as steps, bends, short circuits, etc. Various common discontinuities in the guide couple strongly to these radiation modes. Such fields propagate without attenuation a long way away from their source and are difficult to handle by standard numerical techniques. This part of the spectrum has never been investigated before. This contribution deals with the continuum of coplanar guide in full hybrid form, including the effect of finite metallisation thickness. Its simple application to the problem of scattering by transverse metal strips is also treated, providing details of the radiation patterns. Cascades of strips, including interaction via the radiation field, are currently under investigation.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131907625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335762
L. Zhao, R. Carter
A finite-difference frequency-domain algorithm has been developed in non-orthogonal curvilinear co-ordinates. The full vector Maxwell's equations are discretized on boundary-fitted meshes. Because the algorithm is formulated in a non-orthogonal co-ordinate system, it is not restricted to any a special orthogonal co-ordinate system, and can over the conventional FD-FD algorithm in the orthogonal co-ordinate system. To demonstrate the method, several of the lowest eigenvalues of waveguides with arbitrary cross-section shapes have been computed. The subspace iterative algorithm is used to solve the unsymmetric eigen-equation. Boundary-orthogonal meshes are introduced in order to eliminate the error generated by non-orthogonal meshes on which the boundary conditions for the electromagnetic fields are not satisfied.
{"title":"The Solution of Waveguides Eigenvalues with Arbitrary Shapes by FD-FD Algorithm in Curvilinear Co-Ordinates","authors":"L. Zhao, R. Carter","doi":"10.1109/EUMA.1992.335762","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335762","url":null,"abstract":"A finite-difference frequency-domain algorithm has been developed in non-orthogonal curvilinear co-ordinates. The full vector Maxwell's equations are discretized on boundary-fitted meshes. Because the algorithm is formulated in a non-orthogonal co-ordinate system, it is not restricted to any a special orthogonal co-ordinate system, and can over the conventional FD-FD algorithm in the orthogonal co-ordinate system. To demonstrate the method, several of the lowest eigenvalues of waveguides with arbitrary cross-section shapes have been computed. The subspace iterative algorithm is used to solve the unsymmetric eigen-equation. Boundary-orthogonal meshes are introduced in order to eliminate the error generated by non-orthogonal meshes on which the boundary conditions for the electromagnetic fields are not satisfied.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"08 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128305398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335806
D. Raicu
A new approach to the optimization of the output circuit for a power FET is proposed, whereby the quantity maximized is directly the saturated power delivered by the device rather than the return loss referenced to the optimal load impedance for power. Thus, the power performance of the FET is more realistically represented and additional information is obtained on the power margin necessary for broadband operation.
{"title":"Optimization of the Output Circuits of Power FETs Based on the Mismatch Power Penalty","authors":"D. Raicu","doi":"10.1109/EUMA.1992.335806","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335806","url":null,"abstract":"A new approach to the optimization of the output circuit for a power FET is proposed, whereby the quantity maximized is directly the saturated power delivered by the device rather than the return loss referenced to the optimal load impedance for power. Thus, the power performance of the FET is more realistically represented and additional information is obtained on the power margin necessary for broadband operation.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116508476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335854
V. Cojocaru, T. Brazil
A large-signal equivalent circuit model is presented for a hyperabrupt p-n junction varactor diode (HJVD), suitable for nonlinear CAD and computer simulation. A new function is proposed to describe the nonlinear dependence of the junction capacitance on the applied voltage. Experimental measurements on several commercial devices are presented, showing excellent agreement with the model proposed, over a very wide range of applied voltages. A physical investigation of the doping profile of hyperabrupt p-n junctions is made and a method to determine the doping profile parameters for an assumed type of dopant distribution is presented. Finally, validation of the model is demonstrated in two particular applications.
{"title":"A Large-Signal Equivalent Circuit Model for Hyperabrupt P-N Junction Varactor Diodes","authors":"V. Cojocaru, T. Brazil","doi":"10.1109/EUMA.1992.335854","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335854","url":null,"abstract":"A large-signal equivalent circuit model is presented for a hyperabrupt p-n junction varactor diode (HJVD), suitable for nonlinear CAD and computer simulation. A new function is proposed to describe the nonlinear dependence of the junction capacitance on the applied voltage. Experimental measurements on several commercial devices are presented, showing excellent agreement with the model proposed, over a very wide range of applied voltages. A physical investigation of the doping profile of hyperabrupt p-n junctions is made and a method to determine the doping profile parameters for an assumed type of dopant distribution is presented. Finally, validation of the model is demonstrated in two particular applications.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131214083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335839
B. Toland, T. Itoh
A full wave analysis of a transmission line with a trapezoidal cross section is described. The boundary element method (BEM) is used, and by making a convenient choice for the dyadic Green's function the method is shown to be very efficient in comparison to appropriate alternative methods of analysis. This is an innovative application of the BEM to an innovative structure. The analysis is verified by comparisons with calculated results from a vector finite element computer program.
{"title":"Full Wave Analysis of a Trapezoidal Transmission Line using the Boundary Element Method","authors":"B. Toland, T. Itoh","doi":"10.1109/EUMA.1992.335839","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335839","url":null,"abstract":"A full wave analysis of a transmission line with a trapezoidal cross section is described. The boundary element method (BEM) is used, and by making a convenient choice for the dyadic Green's function the method is shown to be very efficient in comparison to appropriate alternative methods of analysis. This is an innovative application of the BEM to an innovative structure. The analysis is verified by comparisons with calculated results from a vector finite element computer program.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131242344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335848
P. Chazan, S. Tedjini, A. Vilcot
We propose and analyse a new electrooptic phase structure using the finline technology which is well suited for narrow band millimeter wave and submillimeter wave applications. A preliminary modelling of the proposed structure is reported. A full wave analysis of the structure which takes into account the anisotropic properties of LiNbO3 has been used. A technical solution is proposed to improve the velocity matching without decreasing the microwave field.
{"title":"Spectral Domain Analysis of a Finline Optical Phase Modulator","authors":"P. Chazan, S. Tedjini, A. Vilcot","doi":"10.1109/EUMA.1992.335848","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335848","url":null,"abstract":"We propose and analyse a new electrooptic phase structure using the finline technology which is well suited for narrow band millimeter wave and submillimeter wave applications. A preliminary modelling of the proposed structure is reported. A full wave analysis of the structure which takes into account the anisotropic properties of LiNbO3 has been used. A technical solution is proposed to improve the velocity matching without decreasing the microwave field.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132591599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335827
F. Berizzi, G. Corsini
Some autofocusing techniques for the motion compensation in Inverse Synthetic Aperture Radar Imaging of object are proposed. These techniques are based on the maximization of a suitably defined contrast function which represents a measure of the degree of focus of the image. A theoretical analysis of these techniques is performed and some results achieved by means of a simulation program are presented and discussed.
{"title":"Focusing of Two Dimensional ISAR Images by Contrast Maximization","authors":"F. Berizzi, G. Corsini","doi":"10.1109/EUMA.1992.335827","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335827","url":null,"abstract":"Some autofocusing techniques for the motion compensation in Inverse Synthetic Aperture Radar Imaging of object are proposed. These techniques are based on the maximization of a suitably defined contrast function which represents a measure of the degree of focus of the image. A theoretical analysis of these techniques is performed and some results achieved by means of a simulation program are presented and discussed.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130190707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1992-10-01DOI: 10.1109/EUMA.1992.335787
S. Kawasaki, T. Itoh
The reactance of MESFETs in the active integrated antenna are controlled by illuminating with a laser or a fiber illuminator. For the slot antenna with reactive FETs operated by an external source, the optical tuning range of 110 MHz was obtained at 10 GHz. Further, for the quasi-optical oscillator using a MESFET and a slot radiator, the unoptimized optical tuning range of 10 MHz was achieved.
{"title":"Optical Control of Active Integrated Antenna","authors":"S. Kawasaki, T. Itoh","doi":"10.1109/EUMA.1992.335787","DOIUrl":"https://doi.org/10.1109/EUMA.1992.335787","url":null,"abstract":"The reactance of MESFETs in the active integrated antenna are controlled by illuminating with a laser or a fiber illuminator. For the slot antenna with reactive FETs operated by an external source, the optical tuning range of 110 MHz was obtained at 10 GHz. Further, for the quasi-optical oscillator using a MESFET and a slot radiator, the unoptimized optical tuning range of 10 MHz was achieved.","PeriodicalId":317106,"journal":{"name":"1992 22nd European Microwave Conference","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116263059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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