Model-based Optimization of Compressive Antennas for High-Sensing-Capacity Applications

This paper presents a novel, model-based compressive antenna design method for high sensing capacity imaging applications. Given a set of design constraints, the method maximizes the sensing capacity of the compressive antenna by varying the constitutive properties of scatterers distributed along the antenna. Preliminary 2D design results demonstrate the new method's ability to produce antenna configurations with enhanced imaging capabilities

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 near- and far- fields 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

On the Use of Passive Reflecting Surfaces and Compressive Sensing Techniques for Detecting Security Threats at Standoff Distances

This work presents a new radar system concept, capable of detecting explosive related threats at standoff distances. The system consists of a two-dimensional aperture of randomly distributed transmitting/receiving antenna elements and a set of passive reflecting surfaces (PRS) positioned in the vicinity of the target. The PRS act as a mirror that enhances the field of view of the radar system, thus increasing its resolution. A 3D imaging algorithm, based on novel compressive sensing techniques, is used in this work. This system configuration provides a resolution of 7.1 mm in cross-range and 25 mm in range, when the target is at 10 m range, and the radar works at 60 GHz center frequency and has 6 GHz bandwidth

The OTELO survey: A case study of [O III] lambda 4959,5007 emitters at z=0.83

Context. The OSIRIS Tunable Filter Emission Line Object (OTELO) survey is a very deep, blind exploration of a selected region of the Extended Groth Strip and is designed for finding emission-line sources (ELSs). The survey design, observations, data reduction, astrometry, and photometry, as well as the correlation with ancillary data used to obtain a final catalogue, including photo-z estimates and a preliminary selection of ELS, were described in a previous contribution. Aims. Here, we aim to determine the main properties and luminosity function (LF) of the [O III] ELS sample of OTELO as a scientific demonstration of its capabilities, advantages, and complementarity with respect to other surveys. Methods. The selection and analysis procedures of ELS candidates obtained using tunable filter pseudo-spectra are described. We performed simulations in the parameter space of the survey to obtain emission-line detection probabilities. Relevant characteristics of [O III] emitters and the LF ([O III]), including the main selection biases and uncertainties, are presented. Results. From 541 preliminary emission-line source candidates selected around z = 0.8, a total of 184 sources were confirmed as [O III] emitters. Consistent with simulations, the minimum detectable line flux and equivalent width in this ELS sample are ∼5 × 10−19 erg s−1 cm2 and ∼6 Å, respectively. We are able to constrain the faint-end slope (α = −1.03 ± 0.08) of the observed LF ([O III]) at a mean redshift of z = 0.83. This LF reaches values that are approximately ten times lower than those from other surveys. The vast majority (84%) of the morphologically classified [O III] ELSs are disc-like sources, and 87% of this sample is comprised of galaxies with stellar masses of M⋆ <  1010 M⊙

Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years

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