Juan Heredia Juesas

A Single-Transceiver Compressive Reflector Antenna for High-Sensing-Capacity Imaging

This letter presents the simulated design and signal processing algorithms of a novel single-transceiver compressive reflector antenna for high-sensing-capacity imaging. The compressive reflector antenna (CRA) generates a spatial code in the imaging region, which is dynamically changed by using a mechanical rotation of the reflector. The scattered data measured by the single transceiver is processed using compressive sensing techniques in order to perform a 3-D reconstruction of the object under test. Preliminary results show that the CRA outperforms traditional reflector antennas in terms of sensing capacity and reconstruction accuracy.

Consensus-based imaging using ADMM for a Compressive Reflector Antenna

This paper describes a novel norm-one-regularized, consensus-based imaging algorithm, based on the Alternating Direction Method of Multipliers (ADMM), that can be used by a high-sensing-capacity Compressive Reflector Antenna (CRA). The proposed method outperforms current state of the art iterative reconstruction algorithms in terms of computational cost; and it ultimately enables the use of a CRA in quasi-real-time, compressive sensing imaging applications.

Imaging breast cancer in a hybrid DBT / NRI system using compressive sensing

This work presents an improved imaging algorithm for use in a hybrid Digital Breast Tomosynthesis (DBT) / microwave Nearfield Radar Imaging (NRI) system. By using compressive sensing techniques, this new algorithm is capable of reconstructing the dielectric constant and conductivity of breast cancer with a small number of measurements.

Miniaturized UWB Antipodal Vivaldi Antenna for a mechatronic breast cancer imaging system

Digital Breast Tomosynthesis (DBT) can be fused with microwave Nearfield Radar Imaging (NRI) in order to improve breast cancer detection. This paper presents the design of a new miniaturized ultra-wideband Antipodal Vivaldi Antenna (AVA), which can be used in such a hybrid DBT/NRI mechatronic imaging device. The antenna is miniaturized by using a coupling media and a substrate that have a high effective dielectric constant. Preliminary results show that the designed antenna has a return loss above 9 dB in a 2.5 GHz frequency band.

Active imaging using a metamaterial-based compressive reflector antenna

This paper presents a new high-sensing-capacity system for active imaging. The proposed system consists of a Compressive Reflector Antenna (CRA) coated with Metamaterial Absorbers (MMA). The Compressive Reflector Antenna creates a spatial codification in the imaging domain, while the MMA creates a frequency codification in the spectral domain. To solve the inverse problem, we built the sensing matrix using a high frequency method based on Physical Optics; and an iterative Compressive Sensing algorithm (ADMM) is used to perform the inversion. Numerical simulations consisting on PEC targets in the reconstruction domain are carried out. The performance of the proposed system is compared to that of the Compressive Reflector Antenna without metamatrial absorbers. Preliminary results show that a better imaging performance and higher channel capacity is achieved for the metamaterial-based CRA than the CRA configuration.

Norm-1 Regularized Consensus-based ADMM for Imaging with a Compressive Antenna

This letter presents a novel norm-1-regularized, consensus-based imaging algorithm, based on the alternating direction method of multipliers (ADMM). This algorithm is capable of imaging metallic targets by using a limited amount of data. The distributed capabilities of the algorithm enable a fast imaging convergence. Recently, a compressive reflector antenna (CRA) has been proposed as a way to provide high sensing capacity with a minimum cost and complexity in the hardware architecture. The ADMM algorithm applied to the imaging capabilities of the CRA outperforms current state-of-the-art iterative reconstruction algorithms, such as Nesterov-based methods, in terms of computational cost, enabling the use of the CRA in quasi-real-time, compressive sensing imaging applications.

Single-pixel mm-wave imaging using 8-bits metamaterial-based compressive reflector antenna

This paper presents a single-pixel millimeter-wave (mm-wave) imaging system, capable of performing spectral coding by using a Compressive Reflector Antenna (CRA). The CRA is designed by coating the surface of a parabolic reflector with 8-bits metamaterial absorbers (MMAs). By specially designing the codes, the mutual information between successive measurements is reduced, leading to an enhanced sensing capacity. The imaging performance of the proposed mm-wave imaging system is evaluated using synthetic data. Preliminary results show that the proposed 8-bits metamaterial-based CRA system outperforms the equivalent one without MMAs in terms of imaging quality and sensing capacity.

A bilayer ELC metamaterial for multi-resonant spectral coding at mm-Wave frequencies

Metamaterial-based spectral coding is of special interest in high capacity sensing and imaging applications. This paper presents the design, fabrication and performance evaluation of a bilayer, multi-resonant ELC metamaterial that may be used for those applications at mm-Wave frequencies. The S21 response of both fabricated and simulated bilayer metamaterial are in good agreement within the used 60–90 GHz frequency range; and they show the desired narrow-band, double resonances at 78 GHz and 82 GHz.

Compressive Reflector Antenna Phased Array

Conventional phased array imaging systems seek to reconstruct a target in the imaging domain by employing many transmitting and receiving antenna elements. These systems are suboptimal, due to the often large mutual information existing between two successive measurements. This chapter describes a new phased array system, which is based on the use of a novel compressive reflector antenna (CRA), that is capable of providing high sensing capacity in different imaging applications. The CRA generates spatial codes in the imaging domain, which are dynamically changed through the excitation of multiple-input-multiple-output (MIMO) feeding arrays. In order to increase the sensing capacity of the CRA even further, frequency dispersive metamaterials can be designed to coat the surface of the CRA, which ultimately produces spectral codes in nearand farfields of the reflector. This chapter describes different concepts of operation, in which a CRA can be used to perform active and passive sensing and imaging.

Charachterization of two Antipodal Vivaldi Antennas for breast cancer Near-field Radar Imaing

This letter assesses the performance of two Antipodal Vivaldi Antennas, which have been previously designed for a fused DBT/NRI breast imaging system, through two simple experiments. In the first experiment, the s-parameters of both antennas, when they are positioned front-to-front, are obtained and compared with simulations. In the second experiment, the capability of the antennas in detecting a metallic bearing ball submerged in sunflower oil is evaluated. A mechatronic system is used to move the antennas over the bearing ball, and the scattered field is measured using a vector network analyzer operating in the 1-3 GHz frequency band. The s-parameters of the fabricated antennas are in good agreement with those predicted by the simulations, and they are capable of measuring the scattered field from the metallic ball when they move over it.