Pub Date : 2008-04-23DOI: 10.1109/COMITE.2008.4569947
W. Ciccognani, F. Giannini, E. Limiti, P. Longhi
Controlled attenuators are key elements in a phased array's beam forming network and generally in all those systems requiring accurate control of the RF signal's amplitude and phase. Therefore the realisation of constant- phase digital attenuators is essential to obtain advanced system performance. A reactive element has been inserted in the traditional T topology digital attenuator to obtain equiphase condition and design equations have been inferred for optimum design. A MMIC X-Band 5-BIT constant-phase attenuator system has been designed and realised as a test vehicle for the proposed methodology.
{"title":"Compensating Digital Attenuator Differential Phase Shift","authors":"W. Ciccognani, F. Giannini, E. Limiti, P. Longhi","doi":"10.1109/COMITE.2008.4569947","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569947","url":null,"abstract":"Controlled attenuators are key elements in a phased array's beam forming network and generally in all those systems requiring accurate control of the RF signal's amplitude and phase. Therefore the realisation of constant- phase digital attenuators is essential to obtain advanced system performance. A reactive element has been inserted in the traditional T topology digital attenuator to obtain equiphase condition and design equations have been inferred for optimum design. A MMIC X-Band 5-BIT constant-phase attenuator system has been designed and realised as a test vehicle for the proposed methodology.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129764014","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569952
M. Tomáška, Tibor Lalinský, G. Vanko, Martin Misun
The paper reports the properties of AlGaN/GaN HEMT fabricated on sapphire substrate. Using 2 mum length of gate electrode 6.67 GHz transition frequency as well as 24.5 GHz maximum frequency of oscillation was achieved. Small-signal model was identified. The transistor transconductance is in the range of 170 mS/mm. However the transistor was intended for structure and technology verification, it could be used in RF circuits. To improve HEMT's microwave properties, gate length and source-drain distance shortening are in progress.
{"title":"Microwave Characterization and Properties of 2μm Gate Length AlGaN/GaN HEMT Structures","authors":"M. Tomáška, Tibor Lalinský, G. Vanko, Martin Misun","doi":"10.1109/COMITE.2008.4569952","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569952","url":null,"abstract":"The paper reports the properties of AlGaN/GaN HEMT fabricated on sapphire substrate. Using 2 mum length of gate electrode 6.67 GHz transition frequency as well as 24.5 GHz maximum frequency of oscillation was achieved. Small-signal model was identified. The transistor transconductance is in the range of 170 mS/mm. However the transistor was intended for structure and technology verification, it could be used in RF circuits. To improve HEMT's microwave properties, gate length and source-drain distance shortening are in progress.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130831465","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569893
L. Golestanirad, M. Mattes, J. Mosig
For the problem of boxed printed circuits embedded within a stratified media, efficient formulations based on the Method of Moments have been suggested which involve the computation of modal series appearing in the representation of Green's functions in this context. This paper suggests an efficient truncation criterion in computing these modal series which guarantees attaining an acceptable accuracy in final results while avoiding unnecessary computational effort. Different structures are examined in the framework of printed circuits packaged in rectangular shields to verify the validity of the suggested criterion using rectangular and triangular mesh schemes.
{"title":"An Efficient Truncation Criteria for Computation of Modal Series Appearing in the Green's Function of Shielded Media","authors":"L. Golestanirad, M. Mattes, J. Mosig","doi":"10.1109/COMITE.2008.4569893","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569893","url":null,"abstract":"For the problem of boxed printed circuits embedded within a stratified media, efficient formulations based on the Method of Moments have been suggested which involve the computation of modal series appearing in the representation of Green's functions in this context. This paper suggests an efficient truncation criterion in computing these modal series which guarantees attaining an acceptable accuracy in final results while avoiding unnecessary computational effort. Different structures are examined in the framework of printed circuits packaged in rectangular shields to verify the validity of the suggested criterion using rectangular and triangular mesh schemes.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113951292","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569939
D. Markov
Article is concerned to the problem of assessment of occupational exposition to EMF of medical personnel of physiotherapy departments. The results of measurements close to the appliances and in the whole room are shown. Confirming dangerous levels of EMF near apparatus the study also aims precise exposition evaluation in real conditions of work. An attempt to represent new method of examining of complex electromagnetic situation is made.
{"title":"Electromagnetic Fields of Medical Sevices as Risk Factor for Medical Personnel","authors":"D. Markov","doi":"10.1109/COMITE.2008.4569939","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569939","url":null,"abstract":"Article is concerned to the problem of assessment of occupational exposition to EMF of medical personnel of physiotherapy departments. The results of measurements close to the appliances and in the whole room are shown. Confirming dangerous levels of EMF near apparatus the study also aims precise exposition evaluation in real conditions of work. An attempt to represent new method of examining of complex electromagnetic situation is made.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116756663","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569917
D. Kholodnyak, P. Kapitanova, S. Humbla, R. Perrone, J. Mueller, M. Hein, I. Vendik
Application of metamaterial left-handed transmission lines to design 180deg power dividers is considered. Design of microstrip and coplanar miniaturized rat-race rings based on artificial left-handed and right-handed transmission line sections is presented. The devices have been implemented as quasi-lumped-element multilayer structures on low-temperature co-fired ceramics. Novel broadband Wilkinson-type 180deg power dividers using metamaterial left-handed transmission lines are proposed.
{"title":"180° Power Dividers Using Metamaterial Transmission Lines","authors":"D. Kholodnyak, P. Kapitanova, S. Humbla, R. Perrone, J. Mueller, M. Hein, I. Vendik","doi":"10.1109/COMITE.2008.4569917","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569917","url":null,"abstract":"Application of metamaterial left-handed transmission lines to design 180deg power dividers is considered. Design of microstrip and coplanar miniaturized rat-race rings based on artificial left-handed and right-handed transmission line sections is presented. The devices have been implemented as quasi-lumped-element multilayer structures on low-temperature co-fired ceramics. Novel broadband Wilkinson-type 180deg power dividers using metamaterial left-handed transmission lines are proposed.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133804043","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569883
Z. Raida
Since 2001, an Internet textbook of electromagnetic waves and antennas has been developed at the Dept. of Radio Electronics, Brno University of Technology. In the paper, the history of the textbook is reviewed, the latest version of the textbook is described, and the experience of its development and usage are summarized.
{"title":"Internet Support of Education in Antenna and Microwave Techniques","authors":"Z. Raida","doi":"10.1109/COMITE.2008.4569883","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569883","url":null,"abstract":"Since 2001, an Internet textbook of electromagnetic waves and antennas has been developed at the Dept. of Radio Electronics, Brno University of Technology. In the paper, the history of the textbook is reviewed, the latest version of the textbook is described, and the experience of its development and usage are summarized.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129323259","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569894
Milan Polivka, M. Svanda, Petr Cerny
The paper presents study of radiation properties of low profile folded multiple-arm dipole and design of monopole antennas operating extremely closely spaced above a conductive plane (as far as to 0.003 lambda0) intended to use for radiofrequency identification of moving sportsmen in mass race in frequency band at 869 MHz. It is shown that complex conjugate matched monopole prototype can have satisfactory radiation efficiency in spite of the extremely low relative antenna height above the conductive plane used as a shielding of human body or metallic objects.
{"title":"Multiple-Arm Folded Monopole Antenna Operating Extremely Close to a Conductive Plane","authors":"Milan Polivka, M. Svanda, Petr Cerny","doi":"10.1109/COMITE.2008.4569894","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569894","url":null,"abstract":"The paper presents study of radiation properties of low profile folded multiple-arm dipole and design of monopole antennas operating extremely closely spaced above a conductive plane (as far as to 0.003 lambda0) intended to use for radiofrequency identification of moving sportsmen in mass race in frequency band at 869 MHz. It is shown that complex conjugate matched monopole prototype can have satisfactory radiation efficiency in spite of the extremely low relative antenna height above the conductive plane used as a shielding of human body or metallic objects.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125740111","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569890
T. Komljenovic, N. Burum, Z. Šipuš
The paper presents a comparison of three approaches for analyzing spherical lens antennas - spectral-domain method, ray-tracing method, and time- domain finite integration technique (FIT) implemented in commercial software CST Microwave Studioreg. The spectral-domain method takes advantage of transforming the three-dimensional problem into a set of one- dimensional problems. The spherical lens antenna is rigorously taken into account by implementing the Green's functions for the multilayer spherical structures. The ray- tracing method is a general analysis method that can be applied to all kinds of lenses with general (non-symmetric) shape. Finally, FIT implemented in commercial software is general purpose full-wave method. The results of the analysis are compared with measured radiation pattern of a 12 layer Luneburg lens antenna.
{"title":"Analysis of Spherical Lens Antennas - Comparison of Three Analysis Methods","authors":"T. Komljenovic, N. Burum, Z. Šipuš","doi":"10.1109/COMITE.2008.4569890","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569890","url":null,"abstract":"The paper presents a comparison of three approaches for analyzing spherical lens antennas - spectral-domain method, ray-tracing method, and time- domain finite integration technique (FIT) implemented in commercial software CST Microwave Studioreg. The spectral-domain method takes advantage of transforming the three-dimensional problem into a set of one- dimensional problems. The spherical lens antenna is rigorously taken into account by implementing the Green's functions for the multilayer spherical structures. The ray- tracing method is a general analysis method that can be applied to all kinds of lenses with general (non-symmetric) shape. Finally, FIT implemented in commercial software is general purpose full-wave method. The results of the analysis are compared with measured radiation pattern of a 12 layer Luneburg lens antenna.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127587177","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569915
K. Novotná, J. Vrba
Vascular diseases are the most common cause of death in present time. This project describes the design of two different types of intracavitary applicators for treatment of the atherosclerosis by microwaves. Basic principle of microwave angioplastic is, that heating gained by microwave energy irradiated into artery by microwave applicator, enables safe clear out of atherosclerotic plates in the wall of vessel.
{"title":"New Methods For Treatment Of Atherosclerosis","authors":"K. Novotná, J. Vrba","doi":"10.1109/COMITE.2008.4569915","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569915","url":null,"abstract":"Vascular diseases are the most common cause of death in present time. This project describes the design of two different types of intracavitary applicators for treatment of the atherosclerosis by microwaves. Basic principle of microwave angioplastic is, that heating gained by microwave energy irradiated into artery by microwave applicator, enables safe clear out of atherosclerotic plates in the wall of vessel.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114170686","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 : 2008-04-23DOI: 10.1109/COMITE.2008.4569940
J. Surda, E. Cocherová, O. Ondrácek
This article is devoted to an investigation of electrophysical parameters of biological tissue influence on its absorption of microwave energy. The specific absorption rate (SAR) is the dosimetric quantity for evaluation of microwave energy absorbed in biological tissue. Many parameters have effect on the SAR value, such as geometry of the part of the body, which is exposed to microwave energy, electrical parameters of body tissues, distance between the source of energy and surface of body, geometry of the antenna etc. In this article, homogeneous spherical model of the human head is modeled in CST Microwave Studio program environment. The tissue parameters variation influence on SAR values is evaluated for 900 MHz, 1800 MHz and 2450 MHz frequencies utilized in communication, medical and other applications.
{"title":"Tissue Parameters Influence on the Microwave Energy Absorption in Biological Objects","authors":"J. Surda, E. Cocherová, O. Ondrácek","doi":"10.1109/COMITE.2008.4569940","DOIUrl":"https://doi.org/10.1109/COMITE.2008.4569940","url":null,"abstract":"This article is devoted to an investigation of electrophysical parameters of biological tissue influence on its absorption of microwave energy. The specific absorption rate (SAR) is the dosimetric quantity for evaluation of microwave energy absorbed in biological tissue. Many parameters have effect on the SAR value, such as geometry of the part of the body, which is exposed to microwave energy, electrical parameters of body tissues, distance between the source of energy and surface of body, geometry of the antenna etc. In this article, homogeneous spherical model of the human head is modeled in CST Microwave Studio program environment. The tissue parameters variation influence on SAR values is evaluated for 900 MHz, 1800 MHz and 2450 MHz frequencies utilized in communication, medical and other applications.","PeriodicalId":306289,"journal":{"name":"2008 14th Conference on Microwave Techniques","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132417691","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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