Pub Date : 1996-03-19DOI: 10.1109/NRSC.1996.551109
S. Zainud-Deen
External loaded wires are used to eliminate the scattered fields from arbitrary surfaces. The values of loads depend on the length of the external wire, the distance between the wire and the surface, the shape of the surface, the relative position of the wire with respect to the surface and the direction of the incident wave. These loads may be passive or active. The method is applied to eliminate the scattered fields from a rectangular plate and an open circular cylinder structure. The moment method is used to formulate the problem and to calculate suitable values of these loads. Elimination of the scattered field may be from one or multi-direction incident plane wave of arbitrary polarization.
{"title":"Elimination of backscattering from conducting surfaces using externally loaded straight wire system","authors":"S. Zainud-Deen","doi":"10.1109/NRSC.1996.551109","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551109","url":null,"abstract":"External loaded wires are used to eliminate the scattered fields from arbitrary surfaces. The values of loads depend on the length of the external wire, the distance between the wire and the surface, the shape of the surface, the relative position of the wire with respect to the surface and the direction of the incident wave. These loads may be passive or active. The method is applied to eliminate the scattered fields from a rectangular plate and an open circular cylinder structure. The moment method is used to formulate the problem and to calculate suitable values of these loads. Elimination of the scattered field may be from one or multi-direction incident plane wave of arbitrary polarization.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125218333","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551128
F. Amer
The aim of built-in-self test (BIST) is to increase the number of test points. But there is a tradeoff between the chip area and pin overhead. An alternative novel BIST for fault diagnosis and testing of analog circuits is presented to enhance the testability of the circuit under test. This novel technique minimizes the required test points to only input/output pins. Moreover, the technique consumes less chip area and monitors the obtained data with high speed.
{"title":"A novel built-in-self test structure for analog circuits with application to filters","authors":"F. Amer","doi":"10.1109/NRSC.1996.551128","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551128","url":null,"abstract":"The aim of built-in-self test (BIST) is to increase the number of test points. But there is a tradeoff between the chip area and pin overhead. An alternative novel BIST for fault diagnosis and testing of analog circuits is presented to enhance the testability of the circuit under test. This novel technique minimizes the required test points to only input/output pins. Moreover, the technique consumes less chip area and monitors the obtained data with high speed.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122008225","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551098
S. El-Ghazaly, M. Golio
This papers reviews the commercial wireless personal communications available. The diverse systems offer a wide range of services with different quality, data types, bit rates, and coverage ranges. The salient features of the modern communications systems from cordless phones up to mobile satellite services are discussed. The key issues related to the development of active devices for commercial wireless receivers are examined. This paper focuses on the RF portion of the wireless commercial applications, and specifically on the requirements for digital pagers, cellular phones, and other commercial technologies.
{"title":"Challenges in modern wireless personal communications","authors":"S. El-Ghazaly, M. Golio","doi":"10.1109/NRSC.1996.551098","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551098","url":null,"abstract":"This papers reviews the commercial wireless personal communications available. The diverse systems offer a wide range of services with different quality, data types, bit rates, and coverage ranges. The salient features of the modern communications systems from cordless phones up to mobile satellite services are discussed. The key issues related to the development of active devices for commercial wireless receivers are examined. This paper focuses on the RF portion of the wireless commercial applications, and specifically on the requirements for digital pagers, cellular phones, and other commercial technologies.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"48 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120979061","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551108
E. Khaled
Scattered time-dependent intensities from a dielectric sphere illuminated with a very short pulsed plane wave are calculated. The time dependence of the incident pulse is considered to be a rectangular or a Gaussian function. The results are obtained for a sphere on a resonant mode. The frequency spectrum of the scattered field at a point is calculated using the incident field spectrum and the transfer function at that point. The transfer function at any frequency of the sphere at a space point is calculated using the T-matrix method. The inverse Fourier transform of the frequency spectrum is used to calculate the time-dependence of the scattered electric field. The scattered intensities are calculated for pulses of durations (/spl sim/10 ps) smaller than the resonant lifetime. The computer codes are capable of calculating the scattered intensity of a shorter pulse. The computations for such shorter pulses depend on the capacity and speed of the computer system. The main factors which affect the behavior of the scattered pulse are the incident pulse spectrum (or duration) and the lifetime of the resonant mode of the sphere.
{"title":"Time-dependence of backscattered intensities of a sphere illuminated with very short electromagnetic pulses","authors":"E. Khaled","doi":"10.1109/NRSC.1996.551108","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551108","url":null,"abstract":"Scattered time-dependent intensities from a dielectric sphere illuminated with a very short pulsed plane wave are calculated. The time dependence of the incident pulse is considered to be a rectangular or a Gaussian function. The results are obtained for a sphere on a resonant mode. The frequency spectrum of the scattered field at a point is calculated using the incident field spectrum and the transfer function at that point. The transfer function at any frequency of the sphere at a space point is calculated using the T-matrix method. The inverse Fourier transform of the frequency spectrum is used to calculate the time-dependence of the scattered electric field. The scattered intensities are calculated for pulses of durations (/spl sim/10 ps) smaller than the resonant lifetime. The computer codes are capable of calculating the scattered intensity of a shorter pulse. The computations for such shorter pulses depend on the capacity and speed of the computer system. The main factors which affect the behavior of the scattered pulse are the incident pulse spectrum (or duration) and the lifetime of the resonant mode of the sphere.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"362 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115552880","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551117
S. El-Khamy, H. Abdou
In communication networks employing spread-spectrum (SS) code-division multiple-access (CDMA), the performance of single user matched filter receivers are highly degraded when the relative powers of the interfering signals are large (the near-far problem). Optimum multiuser (maximum likelihood) receivers have been suggested to overcome the near-far problem, but they are too complex to implement, specially when the number of users is high. In addition, such multiuser detectors lacks security, which is one of the main advantages of SS techniques, as all of the users messages are detected simultaneously. We introduce a new technique for separately demodulating the packets belonging to different users using feedforward artificial neural networks. A special neural network, the neural matched filter (NMF), is trained not only to detect the spreading code of the assigned user but also to suppress the multiple-access interference caused by the waveforms of other users. This technique is shown to be highly resistant to near-far effects. A comparative performance analysis of conventional, optimum multiuser and NMF single user receivers is carried out via Monte Carlo simulation. It is shown that the proposed single user NMF detectors have a better performance than the optimum receiver in severe near-far cases. This exalted performance is due to the implicit cancellation of cross-correlation between different users codes. The suggested technique is also not sensitive to the code selection and does not necessitates the use of sophisticated optimized code families. Our suggested NMF technique solves most of the security, complexity and near-field problems associated with CDMA systems.
{"title":"Neural matched filter detection in synchronous code-division multiple-access (CDMA) systems","authors":"S. El-Khamy, H. Abdou","doi":"10.1109/NRSC.1996.551117","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551117","url":null,"abstract":"In communication networks employing spread-spectrum (SS) code-division multiple-access (CDMA), the performance of single user matched filter receivers are highly degraded when the relative powers of the interfering signals are large (the near-far problem). Optimum multiuser (maximum likelihood) receivers have been suggested to overcome the near-far problem, but they are too complex to implement, specially when the number of users is high. In addition, such multiuser detectors lacks security, which is one of the main advantages of SS techniques, as all of the users messages are detected simultaneously. We introduce a new technique for separately demodulating the packets belonging to different users using feedforward artificial neural networks. A special neural network, the neural matched filter (NMF), is trained not only to detect the spreading code of the assigned user but also to suppress the multiple-access interference caused by the waveforms of other users. This technique is shown to be highly resistant to near-far effects. A comparative performance analysis of conventional, optimum multiuser and NMF single user receivers is carried out via Monte Carlo simulation. It is shown that the proposed single user NMF detectors have a better performance than the optimum receiver in severe near-far cases. This exalted performance is due to the implicit cancellation of cross-correlation between different users codes. The suggested technique is also not sensitive to the code selection and does not necessitates the use of sophisticated optimized code families. Our suggested NMF technique solves most of the security, complexity and near-field problems associated with CDMA systems.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130185667","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551129
G. Z. El-Far, M. Nassef, A. Montasser
A two-level optimization control algorithm based on the minimum variance approach is developed to control the dynamic behaviour of large-scale interconnected subsystems under certain constraints. In the first level, the control action and adjoined parameters are obtained. In the second level, the parameters of both the coordinator and interactions between subsystems are obtained. Developments are introduced to the estimation adaptive scheme so as to determine the controller coefficients for each subsystem effectively. To show the effectiveness of the proposed algorithm, it is used successfully to control the behaviour of the head-box of a paper machine. Computer simulation results are presented to illustrate the potential of the approach proposed.
{"title":"Online multilevel controller structure for a class of dynamical systems","authors":"G. Z. El-Far, M. Nassef, A. Montasser","doi":"10.1109/NRSC.1996.551129","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551129","url":null,"abstract":"A two-level optimization control algorithm based on the minimum variance approach is developed to control the dynamic behaviour of large-scale interconnected subsystems under certain constraints. In the first level, the control action and adjoined parameters are obtained. In the second level, the parameters of both the coordinator and interactions between subsystems are obtained. Developments are introduced to the estimation adaptive scheme so as to determine the controller coefficients for each subsystem effectively. To show the effectiveness of the proposed algorithm, it is used successfully to control the behaviour of the head-box of a paper machine. Computer simulation results are presented to illustrate the potential of the approach proposed.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129744729","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551096
Y. Botros, J. Volakis, E. Ebbini
A computationally efficient hybrid ray-physical optics model is presented for the analysis and synthesis of multiple-focus ultrasound heating patterns through the human rib cage. In particular, a ray method is used to propagate the ultrasound fields from the source to the frontal plane of the rib cage. The physical optics integration method is then employed to obtain the field intensity pattern inside the rib cage. The solution of the matrix system is carried out by using the pseudo inverse technique to synthesize the desired heating pattern. This simulation model allows for the design and optimization of large-aperture phased array applicator systems for noninvasive ablative thermal surgery in the heart and the liver through the rib cage. This technology is applied for ablating cancerous malignant tissue in the liver and the treatment of life threatening cardiac arrhythmias.
{"title":"Analysis and synthesis of multiple-focus phased array heating patterns through the rib cage: a simulation model","authors":"Y. Botros, J. Volakis, E. Ebbini","doi":"10.1109/NRSC.1996.551096","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551096","url":null,"abstract":"A computationally efficient hybrid ray-physical optics model is presented for the analysis and synthesis of multiple-focus ultrasound heating patterns through the human rib cage. In particular, a ray method is used to propagate the ultrasound fields from the source to the frontal plane of the rib cage. The physical optics integration method is then employed to obtain the field intensity pattern inside the rib cage. The solution of the matrix system is carried out by using the pseudo inverse technique to synthesize the desired heating pattern. This simulation model allows for the design and optimization of large-aperture phased array applicator systems for noninvasive ablative thermal surgery in the heart and the liver through the rib cage. This technology is applied for ablating cancerous malignant tissue in the liver and the treatment of life threatening cardiac arrhythmias.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132167575","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551102
M. Mokhtar, M. A. Kader, M. Kassem
This paper discusses the application of a preprocessing discrete Fourier transform (DFT) based technique for uniform circular arrays in direction of arrival (DOA) estimation problems of wideband coherent sources. Simulation results, that illustrate the performance of the rotational signal subspace (RSS) and spatial smoothing (SS) techniques in conjunction with the MUSIC algorithm, in the case of two wideband coherent sources, are included.
{"title":"Direction of arrival estimation techniques using uniform circular array","authors":"M. Mokhtar, M. A. Kader, M. Kassem","doi":"10.1109/NRSC.1996.551102","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551102","url":null,"abstract":"This paper discusses the application of a preprocessing discrete Fourier transform (DFT) based technique for uniform circular arrays in direction of arrival (DOA) estimation problems of wideband coherent sources. Simulation results, that illustrate the performance of the rotational signal subspace (RSS) and spatial smoothing (SS) techniques in conjunction with the MUSIC algorithm, in the case of two wideband coherent sources, are included.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133230528","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551119
H. El-Bakry, M. Abo-Elsoud, H. Soliman, H. El-Mikati
Neural network implementation using analog circuits has the advantage that computational problems such as multiplication or addition can be realized with simple circuits. In addition, analog circuits are faster than digital implementation and occupy a small silicon area. A software program for simulation and realization of artificial neural nets by using the backpropagation algorithm is designed. An analog neural network is implemented for realizing XOR function using D-MOS transistors acting as synaptic weights and bipolar transistors to represent the nonlinear sigmoid function. Computer simulations for this network are performed with the Pspice program. The learning phase is done in a very fast time. Experimental results confirm the theoretical considerations.
{"title":"Design of neural networks for solving computational problems","authors":"H. El-Bakry, M. Abo-Elsoud, H. Soliman, H. El-Mikati","doi":"10.1109/NRSC.1996.551119","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551119","url":null,"abstract":"Neural network implementation using analog circuits has the advantage that computational problems such as multiplication or addition can be realized with simple circuits. In addition, analog circuits are faster than digital implementation and occupy a small silicon area. A software program for simulation and realization of artificial neural nets by using the backpropagation algorithm is designed. An analog neural network is implemented for realizing XOR function using D-MOS transistors acting as synaptic weights and bipolar transistors to represent the nonlinear sigmoid function. Computer simulations for this network are performed with the Pspice program. The learning phase is done in a very fast time. Experimental results confirm the theoretical considerations.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"185 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123578737","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551125
M. Sobhy, E. A. Hosny, M. Ng, E.A. Bakkar
A new method of modelling non-linear microwave system and subsystem is presented. Non-linear models of the subsystem are identified and then combined to solve the entire system. Throughout the procedure time domain modelling and simulation is used but frequency domain characteristics can also be obtained. Models of non-linear subsystems are identified from time domain measurement which require less measurement time compared to frequency domain measurement. Black box models are used instead of equivalent circuits. The identified models are time domain transfer functions and this offers flexibility and saving in the amount of data stored for each model.
{"title":"Time domain modelling of microwave systems and subsystems","authors":"M. Sobhy, E. A. Hosny, M. Ng, E.A. Bakkar","doi":"10.1109/NRSC.1996.551125","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551125","url":null,"abstract":"A new method of modelling non-linear microwave system and subsystem is presented. Non-linear models of the subsystem are identified and then combined to solve the entire system. Throughout the procedure time domain modelling and simulation is used but frequency domain characteristics can also be obtained. Models of non-linear subsystems are identified from time domain measurement which require less measurement time compared to frequency domain measurement. Black box models are used instead of equivalent circuits. The identified models are time domain transfer functions and this offers flexibility and saving in the amount of data stored for each model.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124492248","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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