Structure-Based Evolutionary Design Applied to Wire Antennas

A new design technique for antennas, namely the Structure-based Evolutionary Design (SED), is introduced and described in detail. SED is a new global random search method derived by the “genetic programming”, a strategy proposed by Koza. The proposed technique will be compared with the genetic algorithms (GA), a widely used design technique, showing the numerous advantages of our approach with respect to standard ones. SED assumes no “a priori” structure, but it builds up the structure of the individuals as the procedure evolves. Therefore SED is able to determine both the structure shape and dimensions as an outcome of the procedure (infinite-dimensional solution space), acting on subparts of the whole structure, and allowing to explore effectively the far more vast solution space. We thoroughly discuss both the general features of SED and its application to wire antenna design. The antenna internal representation, which is a key to the successful implementation of SED, and the construction of fitness functions from the antenna specifications will be described in detail. The proposed approach has been assessed with many different cases, using as design requirements both Gain and VSWR in a frequency band as wide as possible, and with the smallest size. The results obtained with SED are finally compared with other popular algorithms like Particle Swarm Optimization (PSO) and Differential Evolution (DE), showing that both the computational cost and the complexity are of the same order of magnitude, but the performances obtained by SED are significantly higher

Asymmetric Architecture for Heralded Single Photon Sources

Single photon source represent a fundamental building block for optical implementations of quantum information tasks ranging from basic tests of quantum physics to quantum communication and high-resolution quantum measurement. In this paper we investigate the performance of a multiplexed system based on asymmetric configuration of multiple heralded single photon sources. {To compare the effectiveness of different designs we introduce a single-photon source performance index that is based on the value of single photon probability required to achieve a guaranteed signal to noise ratio.} The performance and scalability comparison with both currently existing multiple-source architectures and faint laser configurations reveals an advantage the proposed scheme offers in realistic scenarios. This analysis also provides insights on the potential of using such architectures for integrated implementation.Comment: 11 pages, 13 figure

A numerical estimation of a RFID reader field and SAR inside a blood bag at UHF

In this paper, the effects of UHF electromagnetic fields produced by a RFID reader on a blood bag are evaluated numerically in several configurations. The results of the simulation, field level and distribution, specific absorption rate (SAR), and heating time show that an exposure to a typical reader field leads to a temperature increase smaller than 0.1 C and to a SAR smaller than 1 W/kg. As a consequence, no adverse biological effects occur during a typical UHF RFID reading cycle on a blood bag. Therefore, the blood contained in a bag traced using UHF-RFID is as safe as those traced using barcodes. The proposed analysis supports the use of UHF RFID in the blood transfusion supply chain

Structure-Based Evolutionary Programming Design of Broadband Wire Antennas

A design technique for wire antennas, based on the Structure-Based Evolutionary Programming, is used to design a broadband antenna with an end-fire radiation pattern and a very simple geometry, operating in the 3–16 GHz frequency band, namely, from the S band to the Ku band. The antenna has been analyzed with NEC-2 during the evolutionary process, looking for high gain, good input match, and robustness with respect to realization tolerances. The outcome of our design procedure shows a very good performance

Design of Shaped-Beam Planar Arrays of Waveguide Longitudinal Slots

The Elliott's procedure for the design of a pencil beam waveguide longitudinal slot array has been generalized to encompass the design of shaped beam planar slot arrays. An extended set of design equations, taking into account in an operative way the feeding part of the array, has been devised. From this set of equations, a general and effective design procedure has been set up, shedding light on the constraints posed by a complex aperture distribution. The results of the proposed synthesis procedure have been validated through comparison with a commercial FEM software

A Truncated Waveguide Fed by a Microstrip as a Radiating Element for High-Performance Automotive Anticollision Radars

A small truncated waveguide fed by a microstrip line through a transverse coupling slot is proposed and assessed as a high-performance antenna and array element in the K band and above. This antenna allows to obtain a high radiated power, with a very low cross-polar component in the radiated field. It is therefore particularly suitable for application in automotive anticollision radars. The proposed radiating element has been analyzed by a numerical code based on an in-house method of moments, and the microstrip feeding line has been modeled by its equivalent magnetic-wall waveguide. A linear array of such elements has been designed and matched with a BPF-inspired matching network allowing an in-band behavior suitable for anti-collision radar use, with an out-of-band rejection large enough to avoid the first receiving BPF

Secondary mechanisms of anti-HER2 resistance in breast cancer: NF1 as an actionable target

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A review on improved design techniques for high performance planar waveguide slot arrays

Planar waveguide slot arrays (WSAs) have been used since 1940 and are currently used as performing antennas for high frequencies, especially in applications such as communication and RADAR systems. We present in this work a review of the most typical waveguide slot array configurations proposed in the literature, describing their main limitations and drawbacks along with possible effective countermeasures. Our attention has been focused mainly on the improved available design techniques to obtain high performance WSAs. In particular, the addressed topics have been reported in the following. Partially filled WSAs, or WSAs covered with single or multilayer dielectric slabs, are discussed. The most prominent second-order effects in the planar array feeding network are introduced and accurately modeled. The attention is focused on the T-junction feeding the array, on the effect of interaction between each slot coupler of the feeding network and the radiating slots nearest to this coupler, and on the waveguide bends. All these effects can critically increase the first sidelobes if compared to the ideal case, causing a sensible worsening in the performance of the arra

Synthesis of Artificial Magnetic Conductors Using Structure-Based Evolutionary Design

An evolutionary programming approach, the so-called structure based evolutionary design, is applied to the synthesis of planar periodic electronic band gap in order to obtain an artificial magnetic conductor surface. We show that this strategy, in conjunction with a flexible aperture-oriented approach, allows for obtaining new and effective structures. This almost unique ability is exploited to obtain an artificial magnetic conductor periodic surface with a bandwidth larger than the most popular surfaces known so far