ANTENNALAB - Grup d'Antenes i Sistemes Radio
http://hdl.handle.net/2117/657
2024-03-29T12:14:43ZFast analysis and optimization of sparsely distributed partial modification problems
http://hdl.handle.net/2117/376102
Fast analysis and optimization of sparsely distributed partial modification problems
Fang, Xiaoxing; Heldring, Alexander; Rius Casals, Juan Manuel; Cao, Qunsheng
This article addresses the efficient numerical analysis of sparsely distributed small modifications in a large structure, that is, the sparsely distributed partial modification problem (SDPMP). A hierarchical matrix (H-matrix)-based fast direct solver is adopted to solve the SDPMP in a very short time for each new set of modifications. The main idea of this method is to reuse the parts of the compressed inverse matrix operator that do not change and only recompute the modified parts. In contrast with already existing algorithms designed to tackle a single localized modification, this new approach is still very fast for sparsely distributed small modifications, so it becomes a very attractive option to solve optimization problems efficiently, due to the very cheap analysis of the modified structure at each iteration of the optimization procedure. The efficiency of the solution of SDPMP is demonstrated for several cases involving passive and active metasurfaces and a reconfigurable antenna. As a practical example, a programmable metasurface reflector is optimized with particle swarm optimization to obtain a prescribed reflection pattern.
2022-11-11T09:29:21ZFang, XiaoxingHeldring, AlexanderRius Casals, Juan ManuelCao, QunshengThis article addresses the efficient numerical analysis of sparsely distributed small modifications in a large structure, that is, the sparsely distributed partial modification problem (SDPMP). A hierarchical matrix (H-matrix)-based fast direct solver is adopted to solve the SDPMP in a very short time for each new set of modifications. The main idea of this method is to reuse the parts of the compressed inverse matrix operator that do not change and only recompute the modified parts. In contrast with already existing algorithms designed to tackle a single localized modification, this new approach is still very fast for sparsely distributed small modifications, so it becomes a very attractive option to solve optimization problems efficiently, due to the very cheap analysis of the modified structure at each iteration of the optimization procedure. The efficiency of the solution of SDPMP is demonstrated for several cases involving passive and active metasurfaces and a reconfigurable antenna. As a practical example, a programmable metasurface reflector is optimized with particle swarm optimization to obtain a prescribed reflection pattern.Microwave-microfluidic measurement system optimization for bio-particle-sensing with coplanar-electrodes
http://hdl.handle.net/2117/374686
Microwave-microfluidic measurement system optimization for bio-particle-sensing with coplanar-electrodes
Palacios Arias, César Augusto; Jofre Cruanyes, Marc; Jofre Cruanyes, Lluís; Trabal Pou, Arnau; Coll Beltran, Mercè; Rodríguez Gargallo, Marta; Romeu Robert, Jordi; Jofre Roca, Lluís
Microwave and microfluidic techniques may enable wireless monitoring and interaction with bio-particles, yet still is a largely uncharted territory. Fortunately, the requirements of microfluidics and microwave techniques converge to the need of system miniaturization for reaching the sensitivity levels required. Accordingly, in this work, it is presented the design and optimization of a measurement setup for the system-level characterization of different designs of bio-particle-sensing coplanar-electrodes on a microfluidic-platform.
The design of the signal-chain of the measurement setup is optimized for a RF Phase-Sensitive Homodyne Receiver. In addition, the signal-integrity is achieved with a microwave-shielded-chamber, protecting from electromagnetic interference the coplanar electrodes on a microfluidic platform. As well, experimental validation of the system-level performance of the measurement setup are provided, for different coplanar-electrodes designs.
2022-10-19T14:47:35ZPalacios Arias, César AugustoJofre Cruanyes, MarcJofre Cruanyes, LluísTrabal Pou, ArnauColl Beltran, MercèRodríguez Gargallo, MartaRomeu Robert, JordiJofre Roca, LluísMicrowave and microfluidic techniques may enable wireless monitoring and interaction with bio-particles, yet still is a largely uncharted territory. Fortunately, the requirements of microfluidics and microwave techniques converge to the need of system miniaturization for reaching the sensitivity levels required. Accordingly, in this work, it is presented the design and optimization of a measurement setup for the system-level characterization of different designs of bio-particle-sensing coplanar-electrodes on a microfluidic-platform.
The design of the signal-chain of the measurement setup is optimized for a RF Phase-Sensitive Homodyne Receiver. In addition, the signal-integrity is achieved with a microwave-shielded-chamber, protecting from electromagnetic interference the coplanar electrodes on a microfluidic platform. As well, experimental validation of the system-level performance of the measurement setup are provided, for different coplanar-electrodes designs.Microstrip-fed 3D-printed H-sectorial horn phased array
http://hdl.handle.net/2117/373688
Microstrip-fed 3D-printed H-sectorial horn phased array
Zhou, Ivan; Pradell i Cara, Lluís; López Villegas, José María; Vidal Martínez, Neus; Albert Gali, Miquel; Jofre Roca, Lluís; Romeu Robert, Jordi
A 3D-printed phased array consisting of four H-Sectorial horn antennas of 200 g weight with an ultra-wideband rectangular-waveguide-to-microstrip-line transition operating over the whole LMDS and K bands (24.25–29.5 GHz) is presented. The transition is based on exciting three overlapped transversal patches that radiate into the waveguide. The transition provides very low insertion losses, ranging from 0.30 dB to 0.67 dB over the whole band of operation (23.5–30.4 GHz). The measured fractional bandwidth of the phased array including the transition was 20.8% (24.75–30.3 GHz). The antenna was measured for six different scanning angles corresponding to six different progressive phases α, ranging from 0° to 140° at the central frequency band of operation of 26.5 GHz. The maximum gain was found in the broadside direction α = 0°, with 15.2 dB and efficiency η = 78.5%, while the minimum was found for α = 140°, with 13.7 dB and η = 91.2%.
2022-09-29T14:14:21ZZhou, IvanPradell i Cara, LluísLópez Villegas, José MaríaVidal Martínez, NeusAlbert Gali, MiquelJofre Roca, LluísRomeu Robert, JordiA 3D-printed phased array consisting of four H-Sectorial horn antennas of 200 g weight with an ultra-wideband rectangular-waveguide-to-microstrip-line transition operating over the whole LMDS and K bands (24.25–29.5 GHz) is presented. The transition is based on exciting three overlapped transversal patches that radiate into the waveguide. The transition provides very low insertion losses, ranging from 0.30 dB to 0.67 dB over the whole band of operation (23.5–30.4 GHz). The measured fractional bandwidth of the phased array including the transition was 20.8% (24.75–30.3 GHz). The antenna was measured for six different scanning angles corresponding to six different progressive phases α, ranging from 0° to 140° at the central frequency band of operation of 26.5 GHz. The maximum gain was found in the broadside direction α = 0°, with 15.2 dB and efficiency η = 78.5%, while the minimum was found for α = 140°, with 13.7 dB and η = 91.2%.Preliminary phantom-based dynamic calibration techniques assessment for microwave colonoscopy systems
http://hdl.handle.net/2117/373612
Preliminary phantom-based dynamic calibration techniques assessment for microwave colonoscopy systems
Garrido Atienza, Alejandra; Dghoughi, Walid; Romeu Robert, Jordi; Guardiola Garcia, Marta
Early detection and resection of colon polyp is the best way to reduce colorectal cancer (CRC) mortality. The current method for early detection is colonoscopy, which has a limited field of view, and its efficacy is highly dependant on the endoscopist's experience and colon preparation. This work presents a device for combining microwave imaging with optical colonoscopy. The challenges of this new microwave imaging system are presented, such as the unknown distance to the colon mucosa, which leads to undesired scattered fields and, the antenna size limitations. Four dynamic calibration techniques are proposed to remove the effects of the undefined distance from the imaging region to colon mucosa. These calibration methods are based on averaging the colonoscopy trajectory frames and subtracting the calibration set from the current frame. The phantom preliminary results show that these calibration methods completely delete the undesired scatter.
2022-09-29T07:54:52ZGarrido Atienza, AlejandraDghoughi, WalidRomeu Robert, JordiGuardiola Garcia, MartaEarly detection and resection of colon polyp is the best way to reduce colorectal cancer (CRC) mortality. The current method for early detection is colonoscopy, which has a limited field of view, and its efficacy is highly dependant on the endoscopist's experience and colon preparation. This work presents a device for combining microwave imaging with optical colonoscopy. The challenges of this new microwave imaging system are presented, such as the unknown distance to the colon mucosa, which leads to undesired scattered fields and, the antenna size limitations. Four dynamic calibration techniques are proposed to remove the effects of the undefined distance from the imaging region to colon mucosa. These calibration methods are based on averaging the colonoscopy trajectory frames and subtracting the calibration set from the current frame. The phantom preliminary results show that these calibration methods completely delete the undesired scatter.In-cabin 120 GHz radar system for functional human breathing monitoring in a 3D scenario
http://hdl.handle.net/2117/370191
In-cabin 120 GHz radar system for functional human breathing monitoring in a 3D scenario
López Montero, María José; Aguasca Solé, Alberto; Romeu Robert, Jordi; Jofre Roca, Lluís
Driving is one of the activities that takes a significant part of a person’s time, that is why monitoring vital signs is useful for the wellness of the occupants of the vehicle. One of the vital signs that provides more information about the state of the person, is the functional breathing. Compared to other vital signs indicators, breathing is more sensitive to cardiovascular events, emotional stress, physical exertion, or fatigue induced by long time driving, seen as variations in chest and abdomen elongation modes. Functional monitoring is a tool that can transcend, from measurement and detection to emotional changes through feedback of sounds, images, or videos to the driver. In this regard, this work proposes an imaging radar system to generate a topographic map with elongation modes of the driver’s chest and abdomen, at 120 GHz. Numerical simulations have been deployed in order to reconstruct the image from the receiver signal in the radar using spatial convolution.
Furthermore, a metronome has been used to calibrate the radar for elongations measuring with respect to time, and finally, the system has been tested experimentally in an adult person, to generate a preliminary topographic map that allows matching the chest elongation modes to breathing patterns.
2022-07-14T10:00:41ZLópez Montero, María JoséAguasca Solé, AlbertoRomeu Robert, JordiJofre Roca, LluísDriving is one of the activities that takes a significant part of a person’s time, that is why monitoring vital signs is useful for the wellness of the occupants of the vehicle. One of the vital signs that provides more information about the state of the person, is the functional breathing. Compared to other vital signs indicators, breathing is more sensitive to cardiovascular events, emotional stress, physical exertion, or fatigue induced by long time driving, seen as variations in chest and abdomen elongation modes. Functional monitoring is a tool that can transcend, from measurement and detection to emotional changes through feedback of sounds, images, or videos to the driver. In this regard, this work proposes an imaging radar system to generate a topographic map with elongation modes of the driver’s chest and abdomen, at 120 GHz. Numerical simulations have been deployed in order to reconstruct the image from the receiver signal in the radar using spatial convolution.
Furthermore, a metronome has been used to calibrate the radar for elongations measuring with respect to time, and finally, the system has been tested experimentally in an adult person, to generate a preliminary topographic map that allows matching the chest elongation modes to breathing patterns.Vector spherical harmonic analysis and experimental validation of spherical shells illuminated with broadband, millimeter wave Gaussian beams: applications to corneal sensing
http://hdl.handle.net/2117/370142
Vector spherical harmonic analysis and experimental validation of spherical shells illuminated with broadband, millimeter wave Gaussian beams: applications to corneal sensing
Zarrinkhat, Faezeh; Lamberg, Joel; Tamminen, Aleksi; Baggio, Mariangela; Nefedova, Irina; Ala-Laurinaho, Juha; Khaled, Elsayed E. M.; Romeu Robert, Jordi; Rius Casals, Juan Manuel; Taylor, Zachary
Coupling to longitudinal modes of thin spherical shells, under Gaussian-beam illumination, was explored with a theoretical method based on Fourier-optics analysis and vector spherical harmonics and was scrutinized with an experimental setup. For the theory part, the illumination frequency band was fixed between 100–600 GHz and the outer spherical shell radius of curvature and thickness are 7.5 mm and 0.5 mm, respectively. The shell material was either the lossless cornea or an aqueous effective media representing the cornea. Six different beam-target strategies were introduced being potential candidates for maximum coupling. Two dispersion-tuned beam ensembles with strongly frequency-dependent phase center location have been created with a fixed incident beam 1/e radius and radius of curvature called forward strategies. These computations of different alignments were continued with four beam ensembles of frequency-invariant phase center, constructed from fits to experimental data, oriented at four different axial locations with respect to the spherical shell center of curvature, they are called reverse strategies. Coupling efficiency for all strategies was calculated for different targets including perfect electrical conductor (PEC) sphere, PEC core covered by a cornea loss-free layer and cornea. All scattering strategies contrasted to scattering from equivalent planar targets as a reference with maximum coupling. The results show that, under an ideal calibration, forward strategies are a closer approximation to the plane-wave condition for the cornea. An experimental setup was assembled to explore the simulation approach in a frequency range between 220 GHz to 330 GHz. Two different quartz samples with permittivity of 4.1 were mounted on a water core, acting for a cornea. The first and second quartz radius and thickness were 7.5 mm and 0.5 mm and 8 mm and 1 mm, respectively. An adequate agreement between theory and experiment was confirmed. A particle optimisation swarm algorithm was applied to extract the thickness and permittivity of quartz from the measured back-scattered field for reverse strategies.
2022-07-13T11:01:29ZZarrinkhat, FaezehLamberg, JoelTamminen, AleksiBaggio, MariangelaNefedova, IrinaAla-Laurinaho, JuhaKhaled, Elsayed E. M.Romeu Robert, JordiRius Casals, Juan ManuelTaylor, ZacharyCoupling to longitudinal modes of thin spherical shells, under Gaussian-beam illumination, was explored with a theoretical method based on Fourier-optics analysis and vector spherical harmonics and was scrutinized with an experimental setup. For the theory part, the illumination frequency band was fixed between 100–600 GHz and the outer spherical shell radius of curvature and thickness are 7.5 mm and 0.5 mm, respectively. The shell material was either the lossless cornea or an aqueous effective media representing the cornea. Six different beam-target strategies were introduced being potential candidates for maximum coupling. Two dispersion-tuned beam ensembles with strongly frequency-dependent phase center location have been created with a fixed incident beam 1/e radius and radius of curvature called forward strategies. These computations of different alignments were continued with four beam ensembles of frequency-invariant phase center, constructed from fits to experimental data, oriented at four different axial locations with respect to the spherical shell center of curvature, they are called reverse strategies. Coupling efficiency for all strategies was calculated for different targets including perfect electrical conductor (PEC) sphere, PEC core covered by a cornea loss-free layer and cornea. All scattering strategies contrasted to scattering from equivalent planar targets as a reference with maximum coupling. The results show that, under an ideal calibration, forward strategies are a closer approximation to the plane-wave condition for the cornea. An experimental setup was assembled to explore the simulation approach in a frequency range between 220 GHz to 330 GHz. Two different quartz samples with permittivity of 4.1 were mounted on a water core, acting for a cornea. The first and second quartz radius and thickness were 7.5 mm and 0.5 mm and 8 mm and 1 mm, respectively. An adequate agreement between theory and experiment was confirmed. A particle optimisation swarm algorithm was applied to extract the thickness and permittivity of quartz from the measured back-scattered field for reverse strategies.A parallel Monte Carlo method for solving electromagnetic scattering in clusters of dielectric objects
http://hdl.handle.net/2117/370122
A parallel Monte Carlo method for solving electromagnetic scattering in clusters of dielectric objects
López Menchón, Héctor; Úbeda Farré, Eduard; Heldring, Alexander; Rius Casals, Juan Manuel
In this work, we develop a novel Monte Carlo method for solving the electromagnetic scattering problem for clusters of photonic particles. The method is based on a formal solution of the scattering problem as a modified Born series whose coefficients are found by a conformal transformation. The terms of the Born series are approximated by sampling random elements of its matrix representation, computed by the Method of Moments. Unlike other techniques like the Fast Multiple Method, this Monte Carlo method does not require communication between processors, which makes it suitable for large parallel executions.
2022-07-13T09:32:55ZLópez Menchón, HéctorÚbeda Farré, EduardHeldring, AlexanderRius Casals, Juan ManuelIn this work, we develop a novel Monte Carlo method for solving the electromagnetic scattering problem for clusters of photonic particles. The method is based on a formal solution of the scattering problem as a modified Born series whose coefficients are found by a conformal transformation. The terms of the Born series are approximated by sampling random elements of its matrix representation, computed by the Method of Moments. Unlike other techniques like the Fast Multiple Method, this Monte Carlo method does not require communication between processors, which makes it suitable for large parallel executions.Calibration alignment sensitivity in corneal terahertz imaging
http://hdl.handle.net/2117/368200
Calibration alignment sensitivity in corneal terahertz imaging
Zarrinkhat, Faezeh; Baggio, Mariangela; Lamberg, Joel; Tamminen, Aleksi; Nefedova, Irina; Ala-Laurinaho, Juha; Khaled, Elsayed E. M.; Rius Casals, Juan Manuel; Romeu Robert, Jordi; Taylor, Zachary
Improving the longitudinal modes coupling in layered spherical structure contributes significantly to corneal terahertz sensing, which plays a crucial role in the early diagnosis of cornea dystrophies. Using a steel sphere to calibrate reflection from the cornea sample assists in enhancing the resolution of longitudinal modes. The requirement and challenges toward applying the calibration sphere are introduced and addressed. Six corneas with different properties are spotted to study the effect of perturbations in the calibration sphere in a frequency range from 100 GHz to 600 GHz. A particle-swarm optimization algorithm is employed to quantify corneal characteristics considering cases of accurately calibrated and perturbed calibrated scenarios. For the first case, the study is carried out with signal-to-noise values of 40 dB, 50 dB and 60 dB at waveguide bands WR-5.1, WR-3.4, and WR-2.2. As expected, better estimation is achieved in high-SNR cases. Furthermore, the lower waveguide band is revealed as the most proper band for the assessment of corneal features. For perturbed cases, the analysis is continued for the noise level of 60 dB in the three waveguide bands. Consequently, the error in the estimation of corneal properties rises significantly (around 30%).
2022-06-09T09:12:55ZZarrinkhat, FaezehBaggio, MariangelaLamberg, JoelTamminen, AleksiNefedova, IrinaAla-Laurinaho, JuhaKhaled, Elsayed E. M.Rius Casals, Juan ManuelRomeu Robert, JordiTaylor, ZacharyImproving the longitudinal modes coupling in layered spherical structure contributes significantly to corneal terahertz sensing, which plays a crucial role in the early diagnosis of cornea dystrophies. Using a steel sphere to calibrate reflection from the cornea sample assists in enhancing the resolution of longitudinal modes. The requirement and challenges toward applying the calibration sphere are introduced and addressed. Six corneas with different properties are spotted to study the effect of perturbations in the calibration sphere in a frequency range from 100 GHz to 600 GHz. A particle-swarm optimization algorithm is employed to quantify corneal characteristics considering cases of accurately calibrated and perturbed calibrated scenarios. For the first case, the study is carried out with signal-to-noise values of 40 dB, 50 dB and 60 dB at waveguide bands WR-5.1, WR-3.4, and WR-2.2. As expected, better estimation is achieved in high-SNR cases. Furthermore, the lower waveguide band is revealed as the most proper band for the assessment of corneal features. For perturbed cases, the analysis is continued for the noise level of 60 dB in the three waveguide bands. Consequently, the error in the estimation of corneal properties rises significantly (around 30%).Multi-antenna 3D pattern design for millimeter-wave vehicular communications
http://hdl.handle.net/2117/367194
Multi-antenna 3D pattern design for millimeter-wave vehicular communications
Ballesteros Sánchez, Christian; Montero Bayo, Luca; Ramírez Arroyave, Germán Augusto; Jofre Roca, Lluís
The transformation of the automotive industry towards ubiquitous connection of vehicles with all kind of external agents (V2X) motivates the use of a wide range of frequencies for several applications. Millimeter-wave (mmWave) connectivity represents a paramount research field in which adequate geometries of antenna arrays must be provided to be integrated in modern vehicles, so 5G-V2X can be fully exploited in the Frequency Range 2 (FR2) band. This paper presents an approach to design mmWave vehicular multi-antenna systems with beamforming capabilities considering the practical limitations of their usage in real vehicular environments. The study considers both the influence of the vehicle itself at radiation pattern level and the impact of the urban traffic on physical layer parameters. Connectivity parameters such as Signal-to-Interference-plus-Noise Ratio (SINR) and outage probability are optimized based on the array topology. A shaped beam in the vertical plane based on three preset radiating elements is proven to be robust enough against self-scattering effects on the vehicle body. Regarding the horizontal geometry, four panels on the roof's edges provide good coverage and link quality. The number of horizontal antennas per panel tightly depends on the required values of the link quality metrics, potentially leading to a non-uniform geometry between sides and front or back panels.
2022-05-10T15:45:16ZBallesteros Sánchez, ChristianMontero Bayo, LucaRamírez Arroyave, Germán AugustoJofre Roca, LluísThe transformation of the automotive industry towards ubiquitous connection of vehicles with all kind of external agents (V2X) motivates the use of a wide range of frequencies for several applications. Millimeter-wave (mmWave) connectivity represents a paramount research field in which adequate geometries of antenna arrays must be provided to be integrated in modern vehicles, so 5G-V2X can be fully exploited in the Frequency Range 2 (FR2) band. This paper presents an approach to design mmWave vehicular multi-antenna systems with beamforming capabilities considering the practical limitations of their usage in real vehicular environments. The study considers both the influence of the vehicle itself at radiation pattern level and the impact of the urban traffic on physical layer parameters. Connectivity parameters such as Signal-to-Interference-plus-Noise Ratio (SINR) and outage probability are optimized based on the array topology. A shaped beam in the vertical plane based on three preset radiating elements is proven to be robust enough against self-scattering effects on the vehicle body. Regarding the horizontal geometry, four panels on the roof's edges provide good coverage and link quality. The number of horizontal antennas per panel tightly depends on the required values of the link quality metrics, potentially leading to a non-uniform geometry between sides and front or back panels.Experimental exploration of longitudinal modes in spherical shells at 220 GHz – 330 GHz: applications to corneal sensing
http://hdl.handle.net/2117/366621
Experimental exploration of longitudinal modes in spherical shells at 220 GHz – 330 GHz: applications to corneal sensing
Zarrinkhat, Faezeh; Lamberg, Joel; Baggio, Mariangela; Tamminen, Aleksi; Ala-Laurinaho, Juha; Khaled, Elsayed E. M.; Rius Casals, Juan Manuel; Romeu Robert, Jordi; Taylor, Zachary
Submillimeter-wave and THz sensing of cornea leverage the layered tissue structure for assessments of corneal water content and thickness. The cornea is bounded by air on the anterior and an optically thick body of water on the posterior and thus presents as a lossy thin film lying atop a lossy termination. Resolution of the cornea’s lossy longitudinal modes via frequency domain reflectometry in a band sufficiently low (e.g. 220 GHz – 330 GHz) for significant penetration allows simultaneous estimates of corneal tissue water content (CTWC) and central corneal thickness (CCT). However, since the cornea is spherical, efficient coupling to longitudinal modes requires normal incidence across the interrogated area and thus a converging spherical phase front whose curvature matches the corneal surface curvature [1, 2].
2022-04-29T15:16:10ZZarrinkhat, FaezehLamberg, JoelBaggio, MariangelaTamminen, AleksiAla-Laurinaho, JuhaKhaled, Elsayed E. M.Rius Casals, Juan ManuelRomeu Robert, JordiTaylor, ZacharySubmillimeter-wave and THz sensing of cornea leverage the layered tissue structure for assessments of corneal water content and thickness. The cornea is bounded by air on the anterior and an optically thick body of water on the posterior and thus presents as a lossy thin film lying atop a lossy termination. Resolution of the cornea’s lossy longitudinal modes via frequency domain reflectometry in a band sufficiently low (e.g. 220 GHz – 330 GHz) for significant penetration allows simultaneous estimates of corneal tissue water content (CTWC) and central corneal thickness (CCT). However, since the cornea is spherical, efficient coupling to longitudinal modes requires normal incidence across the interrogated area and thus a converging spherical phase front whose curvature matches the corneal surface curvature [1, 2].