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This work has been supported by the Spanish Science, Research and Innovation Plan(MINECO) with Project Codes TIN2014-55413-C2-1-P and TEC2017-85244-C2-2-P andby Unidad de Excelencia Maria de Maeztu MDM-2016-0600 financed by the Agencia Es-tatal de Investigaci ́on, Spain.

This document presents the conceptual design and analysis of a Synthetic Aperture Radar (SAR) system based on geosynchronous satellites (GEOSAR) working at Ka-band. These satellites, apparently orbiting in a fixed position relative to the Earth, are affected by slight perturbations of the perfectly geostationary orbits (small inclinations and non zero eccentricities) that may be used to generate a synthetic aperture radar for Earth Observation. The main advantage of GEOSAR is to obtain short revisit pass (daily or less) with local coverage, thus complementary to typical Low Earth Orbit SAR that achieve global coverage but with weekly or monthly revisit times. A further advantage is the look direction, mainly South-North, that is truly complementary to the LEO satellites looking at East-West. The LEO long revisit times prevent the observation of fast dynamic scenarios like natural hazards, disasters, atmosphere, etc. The GEOSAR main characteristics are presented and different configurations are proposed. Some geosynchronous orbit considerations are shown to understand the particularities in the GEOSAR geometry. The compromises between spatial resolution and sensitivity are obtained together with basic operation parameters like Doppler Analysis, power link budget and ambiguities.

In this paper we present improved techniques of unwrapping and geocoding to obtain Digital Elevation Models (DEM). These techniques have been developed in the Teoria del Senyal i Comunicacions (TSC) department. Some results are presented too.

The activity of the EEF group in the TMR European Project Radar Polarimetry: Theory and Applications will be presented in this paper. We have developed new polarimetric-interferometric retrieval algorithms and enhancement techniques. These methods will be showed briefly in the next points.

SAR Interferometry is a useful tool which allows the generation of high-precision Digital Elevation Models of the Earth surface. The paper describes an operational scheme of an interferometric processor, applicable to airborne data, which takes into account the specific nature of such platforms: observation geometry, phase characteristics or motion instabilities.

This paper shows the a student training RADAR computer to control it, simulated and introduced transformation of a non-coherent X-band RADAR in station. Using the RADAR P. P. I and a personal Rayleigh targets and clutter statistics are in base band. Raw video signals and severa! post-processing data can be represented.

An operational processor to obtain high resolution radar images of the Earth surface from an airborne platform is presented. The paper describes the problem, its geometry and the steps to obtain a reflectivity image from the echos received by an airborne SAR (Synthetic Aperture Radar) sensor, characterized by an unstable trajectory. The performance of the processor has been verified with real data from the DLR E-SAR system.

La interferometría SAR es una técnica que mediante la combinación coherente de imágenes radar de alta resolución de la superficie terrestre permite obtener patrones de interferencia de fase, los interferogramas, directamente relacionados con la geometría de la escena (el relieve). Un tratamiento posterior que involucra procesos críticos como un desenrollado de fase bidimensional y una georreferenciación considerando las efemérides del satélite y un modelo preciso de la superficie terrestre (datum) permite obtener - con algunas restricciones - un modelo digital del elevaciones del terreno (DEM) con precisiones en altura del orden de 10 m rms. Un segundo grupo de aplicaciones es la medida de pequeños movimientos de la superficie terrestre con una precisión por debajo del centímetro; estas aplicaciones diferenciales son las que han permitido estudiar el efecto de la atmósfera en los interferogramas SAR. En el artículo se muestran resultados obtenidos a partir de imágenes ERS-1 y ERS-2 de Tarragona.

This paper presents an interferometric algorithm capable of working with SAR images obtained from measurements carried out with antennas that describe a circular trajectory. The antennas are positioned on a vertical mast at a low height. Therefore, the system is very interesting for surface scattering studies and buried objects detection due to the very high spatial resolution that C-SAR (Circular SAR) images present. A summary of the analytical formulation of the C-SAR processor and a complete description of the interferometric algorithm are presented along. Some experimental results obtained in anechoic chamber are also shown.

A parallel SAR processor is presented in this paper. The target configuration is a cluster of UNIX workstations, available in most user sites. This fact allows to obtain an increased computing performance w1thout the need of dedicated hardware investment.

SAR Interferometry allows the obtention of digital elevation models (DEM) by combination of two synthetic aperture radar images acquired from slightly different viewpoints. ERS-1 SAR interferometry has already been validated over small areas. When processing wider areas, new adaptative filtering algorithms such as the short time Fourier transform are required. However, phase unwrapping is still the critical step. LMS an weighted LMS are two phase unwrapping algorithms which overcome some disadvantages of traditional residue based methods. Some results are shown obtained from ERS-1 images from Tarragona.

Un dispersómetro polarimétrico es un radar de baja potencia y corto alcance capaz de medir la matriz de dispersión de la superficie que esté iluminado. “TERPBA” (TErrestrial Radar Equipment for Scattering Analysis) es un dispersómetro terreno totalmente polarimétrico operativo de las bandas S, C, X, y Ku que utiliza el analizador de redes HP-8720C como unidad de transmisión-recepción. Su diseño ha sido orientado para obtener máximas prestaciones a la frecuencia del ERS-1. En este artículo se describen las especificaciones y la estructura del sistema, el método de calibración y la campaña de medidas prevista.

La simulación de imágenes SAR nos permite comprender algunas características de los sistemas SAR y comprobar la calidad de los algoritmos de procesado de imágenes SAR. En este artículo se presenta un simulador de señales SAR. Necesita un modelo apropiado de la reflectividad de la escena y un algoritmo para regenerar la señal producida por el SAR. El simulador se ha empleado para generar datos que han sido posteriormente procesados para dar lugar a un interferograma y a partir de éste un modelo digital del terreno. También se presenta un modelo digital del terreno obtenido a partir de datos reales. Obtención de datos e imágenes ERS-1 mediante simulación: aplicaciones en interferometría.

A polarimetric scatterometer is a short-range, low-power radar system capable of measuring the complete backscattering matrix of the surface it illuminates.

Phase noise is nowadays one of the most challenging limitations on radar systems sensitivity and its effects are specially important in remote sensing systems such as scatterometers and synthetic aperture radars. However, due to the complexity of such systems, these effects have not been deeply studied. In this paper a time-domain phase noise analysis is applied to a physical remote sensing radar system and, from the results obtained, a set of techniques for minimizing phase noise effects in this kind of systems is detailed.

This document presents an algorithm for the reconstruction of 3D radar reflectivity images using spherical-wave ISAR techniques. The target is illuminated with an spherical wave and near-field backscatterig measurements are obtained using an spherical exploration geometry. The solution proposed by this method is described and the results of some simulations are shown for its validation.

A new method for motion compensation has been developed for radar imaging of moving targets (ISAR). Phase shifts (due to target motion) among adjacent pulses from a STEPPED FREQUENCY signal, are removed with a parabolic compensation method. The simulated ISAR images below show the improvement achieved after motion compensation.

A new method for motion compensation has been developed for radar imaging of moving targets (ISAR). Phase shifts (due to target motion) among adjacent pulses from a STEPPED FREQUENCY signal, are removed with a parabolic compensation method. The simulated ISAR images below show the improvement achieved after motion compensation.

Pulse to pulse staggering in the pulse reference interval (PRI), usually used to increase the radar unambiguous range and MTI blind speeds, complicates notably the synchronization of the pulsed waveform. A free running open loop technique may be used for this purpose, adjusting a stable clock at the same frequency as the transmitted pulses, which is synchronized by the received sequence during direct illumination. When the received signal can be contaminated by interferences, noise, or multipath effects, a more robust closed loop approach is desirable. This paper presents a closed loop solution to the synchronism process, based on a delay-lock loop configuration, using the special properties of the pulse to pulse staggered signal, that can be considered as a digital pseudorandom code modulation with a period equal to the PRI

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.

This paper presents the design of an emitter-receiver system for a clinical microwave tomographic scanner prototype. A new design has been considered to reduce the problems of a prior experimental prototype in the department, the electromagnetic compability and the repetibility errors. From a viability study, a protoype system has been integrated and evaluated. The design of the subsystems and the finals results are discussed in this communication.

The paper presents a numerical simulation and experimental evaluation of active microwave monitoring of temperature changes induced in human pelvis and thorax during hyperthermia treatments of cancer.

This paper presents an introduction to the study and development of a new concept of Bistatic Radar Receiver, which eliminates any kind of direct microwave or optical fiber link between them. It is based on discret phase-lock techniques to acquire and maintain all the signal parameters when the transmitter illuminates directly the receiver system.

A polarimetric compact range RCS measurement system covering 8 to 40 GHZ is presented. The sensitivity is evaluated both theoretically and experimentally. Some RCS and ISAR results are included.

The design of a polarimetric Compact Range system covering 12-40 GHz is presented. Includes a preliminar error analysis, feeder design, and plane wave evaluation.

Processing radar cross section data is possible to image sorne properties of a target. The paper presents two radar imaging algorithms allowing the reconstruction of reflectivi ty distribution of the target or i ts shape. The methods have been evaluated by numerical simulations for different measurement conditions. Sorne encouraging results are presented.

The authors examine the use of active microwave tomography as an imaging technique which gives information on the dielectric properties of the body. They show that a cylindrical system is an efficient option to obtain multiview data. The system is described and the philosophy of the reconstruction algorithm is outlined. Some experimental results are presented for the permittivity reconstruction of a human forearm cross-section

A set of algorithms and procedures to compute radar cross section (RCS) of aircraft are presented. The aircraft will be defined by a solid modelling data base. The hardware capabilities of a 3-D graphics accelerator will be used to obtain high-frequency approximation to RCS in real time. We are also developing new algorithms to approach efficiently the electromagnetic problem of scattering by large conducting bodies.

The clinical applications of a microwave tomographic system are studied. Imaging parameters are appropriate for medical use : a spatial resolution of 7mm anda contrast resolution of 1% for a measurement time of 3 seconds. Measurements on tissue-simulating numerical simulations are presented of tissue distribution and for pathological and induced changes in Introduction phantoms and volunteers, together with to assess the system for absolute imaging differential imaging of physiological, tissues.

An incremental method for diffraction analysis of metalic bodies of arbitrary shape is presented. The algorithm has been evaluated for metalic cylinders and for tridimensional bodies using a scalar approximation of the field.

Conventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of the algorithms and new reconstruction procedures suitable to high diffracting bodies, using optimization, frequency diversity, analytical continuation and matched plane wave synthesis techniques. The validity of the proposed algorithms is investigated by numerical simulations and experimentally.

La utilización de radiación de microondas para la obtención de imágenes tomográficas de cuerpos biológicos es un nuevo campo de investigación que puede englobarse dentro de los métodos de diagnóstico no invasivo. El elemento diferencial con respecto a los demás métodos en el propio sensor, lo que asegura la complementaridad con el resto de procedimientos. Las microondas, zona del espectro electromagnético comprendida entre 300 MHz y 300 GHz, no poseen la energía cuántica necesaria como para romper los enlaces intermoleculares y por tanto constituyen una radiación no ionizante. Este hecho, considerado aisladamente, hace atractivos los procedimientos de detección de imágenes biológicas basados en este tipo de radiación.

The E.M.C. of a prototype for cylindrical microwave tornography is analized, the initial design has been improved and first results are presented.

Conventional first order algorithms used in microwave tomography often fail to reconstruct biological bodies due to their high contrast in permittivity. The paper presents several methods to improve the applicability of the algorithms and new reconstruction procedures suitable to high diffracting bodies, using optimization, frequency diversity, analytical continuation and matched plane wave synthesis techniques. The validity of the proposed algorithms is investigated by numerical simulations and experimentally.

This paper presents the different contributions to the radiation measured by a radiometer, and how they can be related to the physical features of the scene. Several models ha ve been designed to simulate radiometric observationsover sea and land. Sorne radiometric images have been obtained showing the brighness temperature of earth surface and its dependence on surface characteristics, moisture, temperature, wind over sea, etc.

This document presents an algorithm for the reconstruction of 3D radar reflectivity images using spherical-wave ISAR techniques. The target is illuminated with an spherical wave and near-field backscatterig measurements are obtained using an spherical exploration geometry. The solution proposed by this method is described and the results of some simulations are shown for its validation.

Microwave diffraction tomography allows to obtain a cross-sectional image of the dielectric properties of an object, from the scattering of an incident microwave radiation. This paper presents a computational study of an imaging algorithm for cylindrical geometries based in the Born approximation. A series of homogeneous cylinders of different size and dielectric permittivity has been reconstructed in lossy media. The influence of attenuation is investigated, and the validity of the algorithm is found to be restricted to weakly scattering objects, in a similar way that in linear geometries. However differential techniques allow the reconstruction of changes in high diffracting objects.

The interferometric techniques allow the generation of digital elevation models (DEM) from data collected by synthetic aperture radars (SAR). In this paper a geocoding method applied to ERS-1/2 data is proposed. It is based on an exact knowledge of the orbits, a step from phase to height in slantrange and, finally, a projection and interpolation to generate a final map in UTM coordinates. Next, a technique evaluated in the airborne case is also presented. It is able to relate directly the interferometric phase of every point of the image to its position in a global reference system.

The surface clutter becames a interference in a radar system that makes it warse. So, ir was built a personal computer tool that obtains the surface clutter power. This tool takes imo consideration the orographic and geographic effects and tries ro get a easy and quick use, everybody can run it wirhout need ro use a handbook.

Microwaves have been considered for medical applications involving the detection of organ movements and changes in tissue water content. More particularly cardiopulmonary interrogation via microwaves has resulted in various sensors monitoring ventricular volume change or movement, arterial wall motion, respiratory movements, pulmonary oedema, etc. In all these applications, microwave sensors perform local measurements and need to be displaced for obtaining an image reproducing the spatial variations of a given quantity. Recently, advances in the area of inverse scattering theory and microwave technology have made possible the development of microwave imaging and tomographic instruments. This paper provides a review of such equipment developed at Suplec and UPC Barcelona, within the frame of successive French-Spanish PICASSO cooperation programs. It reports the most significant results and gives some perspectives for future developments. Firstly, a brief historical survey is given. Then, both technological and numerical aspects are considered. The results of preliminary pre-clinical assessments and in-lab experiments allow to illustrate the capabilities of the existing equipment, as well as its difficulty in dealing with clinical situations. Finally, some remarks on the expected development of microwave imaging techniques for biomedical applications are given.