Antoni Elias - Academia.edu (original) (raw)

Papers by Antoni Elias

International Carnahan Conference on Security Technology, 1986

Doppler Radars operatinq as conventional in-• t:uder detectors at X band have been used in severa... more Doppler Radars operatinq as conventional in-• t:uder detectors at X band have been used in several security applications. However, almost all of them utilize heavy and bulky microwave subsystems in wavequide technoloqy. This paper presents a new prototype on =icrostrip technology for a homodyne doppler radar system wich exhibits excellent performance and low cocponent cost.

This paper shows the influence of several loss factors on radar systems. It deals specially with ... more This paper shows the influence of several loss factors on radar systems. It deals specially with those loss factors which are due to atmospheric effects, such as refraction, reflexion and the rain effects on radar system performance.

Distributed detection theory is widely used in surveillance systems that recquire a large area of... more Distributed detection theory is widely used in surveillance systems that recquire a large area of coverage and a large number of targets under consideration. In this paper an optimization algorithm for distributed systems is described. The optimization criterion maximizes the probability of detection in the Data Fusion Center, keeping the overall probability of a false alarm constant. Furthermore the optimal decision rules in the Data Fusion Center are showed, in function of the sensor characteristics.

T11e recieved signa! by rhe radar receiver musr be correcred by afuncrion (Sensirivy Time Conrrol... more T11e recieved signa! by rhe radar receiver musr be correcred by afuncrion (Sensirivy Time Conrrol), rhis funcrion is applied ro maintain consrant rhe power recieved from al! rargers wirh same RCS in any arbirrary space position, in order ro compress rhe Dynamic Range of rhe received power, and adapr ir ro rhe Dynamic Range of rhe receiver. In monosraric sysrems, rhis correcrion depens only on rhe disrance berween rransmirter and rarger, bur, in bisraric sysrems, rhis correcrion depens on rhis disrance and rhe angle ojrransmission. T71is paper presents a solurion based on braking rhis correction in nvo pans, jirsrable app!ying a simple monosraJic STC, and leaving rhe second one ro rhe proccesor.

Using a single active device as a non linear element both oscillating and mixing functions are ac... more Using a single active device as a non linear element both oscillating and mixing functions are acomplished. A method of design that uses a dielectric resonator as a frequency selective network is given. INTRODUCCION La utilización en recepción de osciladores con transistores ymezcladores activos lleva consigo el tratamiento separado de proble~as no

Detection systems lvith distribued sensors and data fusion, are incresingly being used by surveil... more Detection systems lvith distribued sensors and data fusion, are incresingly being used by surveillance systems. In this paper we present an algorithm that permits for a no homogeneus system formed by N different parametrics CFAR (cell averaging or ordered statistics) detectors and a fixed level of false alarm in the data fusion center, to test the rules of rank K, with l=<K<=N and obtain the rule K that maximizes the detection probability in the fusion center.

A canonical model is examinated for generating coherent Weibull vectors wi th a desired correlati... more A canonical model is examinated for generating coherent Weibull vectors wi th a desired correlation matrix and specified parameters. Such vectors may represent samples of a correlated radar signal. Statistical and espectral estimates to value Weibull correlated vectors are also discussed.

A bistatic radar is defined as having the receivers and transmi ters widely separated by distance... more A bistatic radar is defined as having the receivers and transmi ters widely separated by distances equivalents to the target range. A monostatic radar has the receiver and transm itter collocated with a common antenna for both receive and transmit functions. Monostatic radar generally exhibits better operational performance than a bistatic radar, and except for some special cases such as an over-the-horizon (OTH) radar, it has been used in modern systems and for most classic applications. The actual revaluation of bistatic radar is being driven by an emerging operational emphasis on passive operation. The technology to perform the measurements and real-time calculations required by a bistatic system is now available, providing the capability of passive surveillance, ranging and target location. In this paper we present the features and performance study of this kind of surveillance system compared with the clasics monostatic systems .

This paper presents a new and efficient algorithm in cvlindrical coordinates for microwave diffra... more This paper presents a new and efficient algorithm in cvlindrical coordinates for microwave diffraction tomography. In comparision with algorithms in cártesian coordinates, it does not need mechanical rotation of the object and provides higher quality reconstruction with similar processing time.

The paper presents an evaluation of a high resolution technique intended to enhance the radar det... more The paper presents an evaluation of a high resolution technique intended to enhance the radar detectability of targets. The method is based on the coherent integration of the individually resolved target scatterers. The measured radar signatures of two scaled-down aircrafts are used to validate the proposed approach. Also the possibility of using this technique to identify the target has been addressed.

Studies about microwave imaging systems require complex models of biological materials to test th... more Studies about microwave imaging systems require complex models of biological materials to test the performance of prototypes in realistic situations. Tissue phantom materials have been studied and measured in order to determine their suitability to simulate biological substances around 2.45 GHz. The paper presents sorne dielectric constant data of tissues and phantom materials.A permitivity measurement system,based on an open-ended coaxial line, is also presented. Several materials and mixtures for phantom construction have been cbaracterized using this method,and the relevant measurements have been tabulated.

A cylindric microwave tomography system for biomedical applications is presented. The system oper... more A cylindric microwave tomography system for biomedical applications is presented. The system operates at 2.45 GHz. The cylindric geometry is an alternative to planar systems, which require rotation around the object. An experimental setup with a reconstuction area of 20 cm of diameter, and a total adquisition and processing time of S seconds is described.

International Carnahan Conference on Security Technology, 1986

Doppler Radars operatinq as conventional in-• t:uder detectors at X band have been used in severa... more Doppler Radars operatinq as conventional in-• t:uder detectors at X band have been used in several security applications. However, almost all of them utilize heavy and bulky microwave subsystems in wavequide technoloqy. This paper presents a new prototype on =icrostrip technology for a homodyne doppler radar system wich exhibits excellent performance and low cocponent cost.

This paper shows the influence of several loss factors on radar systems. It deals specially with ... more This paper shows the influence of several loss factors on radar systems. It deals specially with those loss factors which are due to atmospheric effects, such as refraction, reflexion and the rain effects on radar system performance.

Distributed detection theory is widely used in surveillance systems that recquire a large area of... more Distributed detection theory is widely used in surveillance systems that recquire a large area of coverage and a large number of targets under consideration. In this paper an optimization algorithm for distributed systems is described. The optimization criterion maximizes the probability of detection in the Data Fusion Center, keeping the overall probability of a false alarm constant. Furthermore the optimal decision rules in the Data Fusion Center are showed, in function of the sensor characteristics.

T11e recieved signa! by rhe radar receiver musr be correcred by afuncrion (Sensirivy Time Conrrol... more T11e recieved signa! by rhe radar receiver musr be correcred by afuncrion (Sensirivy Time Conrrol), rhis funcrion is applied ro maintain consrant rhe power recieved from al! rargers wirh same RCS in any arbirrary space position, in order ro compress rhe Dynamic Range of rhe received power, and adapr ir ro rhe Dynamic Range of rhe receiver. In monosraric sysrems, rhis correcrion depens only on rhe disrance berween rransmirter and rarger, bur, in bisraric sysrems, rhis correcrion depens on rhis disrance and rhe angle ojrransmission. T71is paper presents a solurion based on braking rhis correction in nvo pans, jirsrable app!ying a simple monosraJic STC, and leaving rhe second one ro rhe proccesor.

Using a single active device as a non linear element both oscillating and mixing functions are ac... more Using a single active device as a non linear element both oscillating and mixing functions are acomplished. A method of design that uses a dielectric resonator as a frequency selective network is given. INTRODUCCION La utilización en recepción de osciladores con transistores ymezcladores activos lleva consigo el tratamiento separado de proble~as no

Detection systems lvith distribued sensors and data fusion, are incresingly being used by surveil... more Detection systems lvith distribued sensors and data fusion, are incresingly being used by surveillance systems. In this paper we present an algorithm that permits for a no homogeneus system formed by N different parametrics CFAR (cell averaging or ordered statistics) detectors and a fixed level of false alarm in the data fusion center, to test the rules of rank K, with l=<K<=N and obtain the rule K that maximizes the detection probability in the fusion center.

A canonical model is examinated for generating coherent Weibull vectors wi th a desired correlati... more A canonical model is examinated for generating coherent Weibull vectors wi th a desired correlation matrix and specified parameters. Such vectors may represent samples of a correlated radar signal. Statistical and espectral estimates to value Weibull correlated vectors are also discussed.

A bistatic radar is defined as having the receivers and transmi ters widely separated by distance... more A bistatic radar is defined as having the receivers and transmi ters widely separated by distances equivalents to the target range. A monostatic radar has the receiver and transm itter collocated with a common antenna for both receive and transmit functions. Monostatic radar generally exhibits better operational performance than a bistatic radar, and except for some special cases such as an over-the-horizon (OTH) radar, it has been used in modern systems and for most classic applications. The actual revaluation of bistatic radar is being driven by an emerging operational emphasis on passive operation. The technology to perform the measurements and real-time calculations required by a bistatic system is now available, providing the capability of passive surveillance, ranging and target location. In this paper we present the features and performance study of this kind of surveillance system compared with the clasics monostatic systems .

This paper presents a new and efficient algorithm in cvlindrical coordinates for microwave diffra... more This paper presents a new and efficient algorithm in cvlindrical coordinates for microwave diffraction tomography. In comparision with algorithms in cártesian coordinates, it does not need mechanical rotation of the object and provides higher quality reconstruction with similar processing time.

The paper presents an evaluation of a high resolution technique intended to enhance the radar det... more The paper presents an evaluation of a high resolution technique intended to enhance the radar detectability of targets. The method is based on the coherent integration of the individually resolved target scatterers. The measured radar signatures of two scaled-down aircrafts are used to validate the proposed approach. Also the possibility of using this technique to identify the target has been addressed.

Studies about microwave imaging systems require complex models of biological materials to test th... more Studies about microwave imaging systems require complex models of biological materials to test the performance of prototypes in realistic situations. Tissue phantom materials have been studied and measured in order to determine their suitability to simulate biological substances around 2.45 GHz. The paper presents sorne dielectric constant data of tissues and phantom materials.A permitivity measurement system,based on an open-ended coaxial line, is also presented. Several materials and mixtures for phantom construction have been cbaracterized using this method,and the relevant measurements have been tabulated.

A cylindric microwave tomography system for biomedical applications is presented. The system oper... more A cylindric microwave tomography system for biomedical applications is presented. The system operates at 2.45 GHz. The cylindric geometry is an alternative to planar systems, which require rotation around the object. An experimental setup with a reconstuction area of 20 cm of diameter, and a total adquisition and processing time of S seconds is described.