http://hdl.handle.net/2117/659 2013-06-19T01:16:55Z http://hdl.handle.net/2117/19341 Title: Real time 100 GHz MST imaging retina Authors: Alonso del Pino, María; Garg, V.; Garcia Guerra, Carlos Enrique; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís Abstract: A real time tomographic imaging system at 100 GHz based on a retina and Modulated Scattered Technique (MST) is presented in this paper. It consists in applying a low frequency modulation to each probe of an array of antennas in order to coherently detect the electric field by a collector. This system just requires low frequency wiring and reduces the RF equipment necessary for each pixel for a planar surface. The aim of this paper is to analyze the performance of different tomographic imaging processes for the imaging system described. 2013-05-17T13:52:47Z http://hdl.handle.net/2117/19292 Title: MM-wave scattering measurements for imaging and channel characterization Authors: Toda, A.P.; de Flaviis, Franco; Jofre Roca, Lluís; Romeu Robert, Jordi Abstract: In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained. 2013-05-16T12:23:28Z http://hdl.handle.net/2117/18564 Title: Tomographic imaging retina at 100 GHz Authors: Alonso, Maria; Garg, V; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís Abstract: This paper presents a tomographic system at 100 GHz for imaging based on MST technique. At 100 GHz, a good compromise is obtained between penetration and reso- lution for biomedical and non-destructive testing applications. Moreover, this system just requires low frequency wiring and reduces the RF equipment necessary for performing real-time imaging. The system has been built and successfully validated with a set of measurements for a canonical scenario. 2013-04-03T10:47:28Z http://hdl.handle.net/2117/18563 Title: Optical cross-correlation of millimeter wave signals applied to interferometric radiometry Authors: Nova, Enrique; Romeu Robert, Jordi; Torres Torres, Francisco; Broquetas Ibars, Antoni; Jofre Roca, Lluís Abstract: This paper presents a method to perform in the opti- cal domain the correlations required when processing millimeter wave interferometric radiometer signals. The main problem when addressing the design of an interferometric radiometer working at W-band resides on the distribution and correlation of large bandwidth signals acquired by each radiometer receiver. In order to avoid the necessity of baseband processing of signals with large relative bandwidths, the signals coming from the radiometric receivers are up-converted to the optical domain using LiNbO3 optical phase modulators. The modulated signals from each receiver pairs are added and and detected by a photodiode. The correlation is obtained from the resulting photocurrent. 2013-04-03T10:43:31Z http://hdl.handle.net/2117/18562 Title: UWB Magnitude combined realistic breast model imaging capabilities Authors: Guardiola Garcia, Marta; Jofre Roca, Lluís; Romeu Robert, Jordi Abstract: Breast cancer is the leading cancer killer among women. Early stage detection has been recognized to be best solution to reduce mortality rates. A non-ionizing, economical screening system based on microwave imaging is being investigated, but it is still a long way towards clinical ready system. In this paper, the validation of UWB-MC tomographic algorithm is performed using realistic breast models. 2013-04-03T10:38:48Z http://hdl.handle.net/2117/18561 Title: Retina design for 100GHz MST imaging system Authors: Alonso, Maria; Garg, V.; Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís Abstract: A near field imaging system for THz tomographic imaging based on a MST retina (an array of real antennas) has been designed. The main adva ntage of this implementation is the absence of microwave transmission line distribution networks and the capability to perform high speed imaging. The aim of this paper is to describe the design of the retina in order to maximize the performance of this im aging system. 2013-04-03T10:32:05Z http://hdl.handle.net/2117/18560 Title: Input impedance measurements of cell phone antennas using backscattering modulation Authors: Monsalve, Beatriz; Blanch Boris, Sebastián; Romeu Robert, Jordi Abstract: This contribution presents an overview of the backscattering modulation applied to input impedance measurements of cell phone antennas. 2013-04-03T10:28:47Z http://hdl.handle.net/2117/18318 Title: Interference rejection using frequency and pattern reconfigurable antennas Authors: Rodrigo López, Daniel; Romeu Robert, Jordi; Jofre Roca, Lluís Abstract: Interference rejection by taking advantage of the radiation pattern diversity of a reconfigurable antenna is considered. It is proposed to use simultaneously frequency and radiation reconfiguration to extend interference rejection capabilities to large bandwidths. A small-size low-complexity pixel antenna is used to provide interference rejection capabilities over an octave bandwidth. An average signal-to-interference ratio of 24 dB is achieved and interference rejections above 15 dB are reliably provided over the whole frequency bandwidth and an angular range of 120o 2013-03-14T17:40:20Z http://hdl.handle.net/2117/18172 Title: Sparsified ACA for accelerated iterative solution of the MoM linear system Authors: Heldring, Alexander; Rius Casals, Juan Manuel; Úbeda Farré, Eduard; Tamayo Palau, José María Abstract: A new algorithm, the Sparsified Adaptive Cross Approximation (SPACA) is presented for fast iterative solution of the Method of Moments linear system. Like ordinary ACA, it is a completely kernel-independent method, but it is faster and yields a higher compression rate than ordinary ACA, without compromising the accuracy. As an example, the RCS of a perfectly conducting sphere is computed using up to 786,432 basis functions. It is shown that SPACA exhibits close to NlogN complexity for this problem. 2013-03-11T12:16:47Z http://hdl.handle.net/2117/18036 Title: Validation of a sea surface model for simulations of dynamic maritime SAR images Authors: Yam Ontiveros, Luis Eduardo; Mallorquí Franquet, Jordi Joan; Rius Casals, Juan Manuel Abstract: Controllable maritime scenarios have become a central issue in the research of new applications of SAR imaging to vessel monitoring systems. Numerical tools such as GRECOSAR, a SAR simulator of complex targets, are able to provide suitable test-beds as long as the model of the targets (vessels) and the sea surface resemble to what is expected in real maritime scenes. This paper presents the validation of SAR simulated images from GRECOSAR while using a dynamic and multi-harmonic elevation model of the sea surface. The simulations are carried out for generic C- and X-band SAR sensors. The results of the co-polar cha nnels are compared with K,lognormal, Weibull and Rayleigh distributions, which are commonly used to describe statistics of real SAR images of the sea surface. The results show that the clutter has statistics clos er to the K and Weibull distributions, suggesting that the elevation model presented can provide a more realistic approach in simulating SAR images of maritime scenarios 2013-03-01T13:46:52Z http://hdl.handle.net/2117/16214 Title: Passive RFID based sensing Authors: Capdevila Cascante, Santiago; Jofre Roca, Lluís; Romeu Robert, Jordi; Bolomey, J.Ch. Abstract: The principle of communication of passive RFID, which relies on the Modulated Scattering Technique (MST) to transmit the information from the tag to the reader, opens a way to enable conventional RFID for sensing purposes, without any additional circuitry. In this paper a short description of the physical principle behind the sensing is presented along with measurements of RFID tags used for sensing in multiple applications, such as electromagnetic field measurement temperature or presence detection. 2012-07-09T16:14:58Z http://hdl.handle.net/2117/16213 Title: The “challenging” world of Terahertz radiation and imaging Authors: Jofre Roca, Lluís; Romeu Robert, Jordi; Capdevila Cascante, Santiago; Abril, Jordi; Nova, Enrique; Alonso, Maria Abstract: THz propagation through materials may reveal unique macroscopic and physical properties of their internal structure without the damage associated with ionizing radiation. The generation, radiation, and detection of THz signals relays into an intermediate region between microwave and optical frequencies seen as a transition in device physics from classical transport to quantum transition. The physical properties and parameters of the antennas and electronic devices at these frequencies (0.1-10THz) will we compared with their microwave and optical counterparts, the important differences highlighted and its significance in terms of spectral bandwidth and signal-to-noise ratio for near and short range imaging systems reviewed. Finally, some of the recent significant developments in the field will be summarized and the potential applications and future challenges and opportunities identified. 2012-07-09T16:12:12Z http://hdl.handle.net/2117/16212 Title: 100 GHz retina for THz tomographic imaging Authors: Alonso, Maria; Guerra, C.; Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Llombart, Nuria; Jofre Roca, Lluís Abstract: In a tomographic imaging system, the key is to collect a sufficient number of scattered field points to recover the currents in the inverse scattering problem. This can be accomplished by using a real array of multiplexed antennas for real time imaging. In this paper, a W-Band Retina for Terahertz tomographic imaging is presented. A system based on a retina, a collector and an illuminator is described and the results of a fabricated retina are shown. 2012-07-09T16:08:56Z http://hdl.handle.net/2117/16193 Title: Characterization of a 94 GHz radiometric imager with mechanical beam-scanning Authors: Nova, Enrique; Abril, Jordi; Romeu Robert, Jordi; Broquetas Ibars, Antoni; Torres Torres, Francisco; Jofre Roca, Lluís Abstract: This paper presents the characterization in terms of spatial resolution and radiometric sensitivity of a W-band Total Power Radiometer (TPR). The TPR is based on a heterodyne receiver with 64 dB of gain and 6.5 dB of noise figure. An antenna system consisting on a pan-tilt scanner has been designed and built in order to aim a 100 mm offset parabolic reflector. With this system, relative temperature images of targets at a 1 m standoff range are obtained in indoor environments with an spatial resolution of 4 cm. 2012-07-06T15:50:44Z http://hdl.handle.net/2117/16192 Title: Micrometric deformation imaging at W-Band Authors: Abril, Jordi; Nova, Enrique; Broquetas Ibars, Antoni; Aguasca Solé, Alberto; Romeu Robert, Jordi; Jofre Roca, Lluís Abstract: The measurement of scattered signals at W Band can be exploited to form images of small deformations with precisions in the order of tenths of micrometers. In this paper an Interferometric Synthetic Aperture Radar setup is proposed to form high resolution reflectivity images and deformation maps of dielectric or metallic surfaces. First, the system geometry of observation based on a linear motion of the radar antennas is described. A CW frequency domain measurement provides the wide band required for high resolution imaging. The scattered field data is focused on the surface spatial domain using a combination of range compression based on Inverse Fourier Transform combined with a backprojection algorithm to form the synthetic aperture with a high cross range resolution. The focusing performance has been assessed by numerical simulations and experimental measurements of simple scattering objects like spheres and trihedrals. Interferometric images of controlled displacements have been obtained showing a good agreement between real and measured displacements. A representative surface deformation test has been also carried out using a metallic rough surface. The interferometric phase difference between acquisitions can be used to image local deformations in the order of tens of micrometers from a range of several meters. Likewise the interferogram coherence shows the degree of decorrelation of the radar reflectivity which provides valuable information for surface random change assessment. 2012-07-06T15:46:47Z