Perfect Anomalous Reflection with a Binary Huygens' Metasurface

In this paper we propose a new metasurface that is able to reflect a known incoming electromagnetic wave into an arbitrary direction, with perfect power efficiency. This seemingly simple task, which we hereafter call perfect anomalous reflection, is actually highly non-trivial due to the differing wave impedances and complex interference between the incident and reflected waves. Heretofore, proposed metasurfaces which achieve perfect anomalous reflection require complicated, deeply subwavelength and/or multilayer element structures which allow them to couple to and from leaky and/or evanescent waves. In contrast, we demonstrate that using a Binary Huygens' Metasurface (BHM) --- a passive and lossless metasurface with only two cells per period --- perfect anomalous reflection can be achieved over a wide angular and frequency range. Through simulations and experiments at 24 GHz, we show that a properly designed BHM can anomalously reflect an incident electromagnetic wave from $\theta_i = 50^\circ$ to $\theta_r = -22.5^\circ$, with perfect power efficiency to within experimental precision

On the use of bianisotropic huygens' metasurfaces to build leaky-wave antennas

The Electromagnetics AcademyHuygens' metasurfaces are considered a powerful tool to achieve anomalous electromagnetic field transformations. They consist of an artifcial surface built of pairs of collocated electric and magetic dipoles that force the boundary conditions for the desired transformation to be ful lled [1]. Despite their possibilities, the achievable transformations must ful l some conditions. In [2] it was shown that Huygens' metasurfaces with passive and lossless particles can achieve an arbitrary field transformation provided that the power is conserved at each point of the metasurface and there is wave impedance matching. However, it was shown in [3], that by introducing bianisotropy of the omega-type, the matching condition can be suppressed, which allows the control of both the transmission and rejection coe cients on the metasurface.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A spatially shifted beam approach to subwavelength focusing

Although negative-refractive-index metamaterials have successfully achieved subwavelength focusing, image resolution is limited by the presence of losses. In this Letter, a metal transmission screen with subwavelength spaced slots is proposed that focuses the near-field beyond the diffraction limit and furthermore, is easily scaled from microwave frequencies to the optical regime. An analytical model based on the superposition of shifted beam patterns is developed that agrees very well with full-wave simulations and is corroborated by experimental results at microwave frequencies.Comment: 5 pages, 7 figures. Content updated following reviewer comments to match final published pape

Progress in integrated-circuit horn antennas for receiver applications. Part 2: A 90 GHz quasi-integrated horn antenna receiver

A receiver belonging to the family of integrated planar receivers has been developed at 90 GHz. It consists of a planar Schottky-diode placed at the feed of a dipole-probe suspended inside an integrated horn antenna. The measured planar mixer single-sideband conversion loss at 91.2 GHz (LO) with a 200 MHz IF frequency is 8.3dB plus or minus 0.3dB. The low cost of fabrication and simplicity of this design makes it ideal for millimeter and submillimeter-wave receivers

Progress in integrated-circuit horn antennas for receiver applications. Part 1: Antenna design

The purpose of this work is to present a systematic method for the design of multimode quasi-integrated horn antennas. The design methodology is based on the Gaussian beam approach and the structures are optimized for achieving maximum fundamental Gaussian coupling efficiency. For this purpose, a hybrid technique is employed in which the integrated part of the antennas is treated using full-wave analysis, whereas the machined part is treated using an approximate method. This results in a simple and efficient design process. The developed design procedure has been applied for the design of a 20, a 23, and a 25 dB quasi-integrated horn antennas, all with a Gaussian coupling efficiency exceeding 97 percent. The designed antennas have been tested and characterized using both full-wave analysis and 90 GHz/370 GHz measurements

A novel approach to FAME biodiesel production by means of reactive distillation

Includes bibliographical references (leaves 109-111).A novel concept of reactive distillation is examined in this dissertation. The design and construction of a rig to test the novel set-up were executed. The design of the rig was based on residence times selected for the rig's three main sections; the pre-reactor, the column and the reboiler. The rig was designed as a continuous process, provided feed could be supplied constantly even in the case of small scale users. The reactor was designed to perform around a flowrate of 5l/hr. The main aim of the design was to produce biodiesel by using a stoichiometric feed ratio

Congenital Cystic Adenomatoid Malformation: Is There a Need for Pregnancy Termination?

Aim. Congenital cystic adenomatoid lung malformation is a rare unilateral dysplasia of the lung. Three pathologic types are described in the literature: type I with cysts >2 cm, type II with cysts <1 cm, and type III with microcysts. The aim of this paper is to present a case of a fetus with congenital cystic adenomatoid lung malformation and discuss the necessity for pregnancy termination according to its prognosis and future mortality. Case. A 36-year-old pregnant woman (para: 1, gravida: 1) presented in our department for anatomy ultrasound screening at 20 + 1 weeks of gestation. The ultrasound detected a cystic adenomatoid right lung malformation measuring 1.45 × 1.67 cm which caused mediastinal shift of the heart and the lung to the left side. Other findings were cysts of the choroid plexus and echogenic intracardiac foci. The parents after genetic counseling decided pregnancy termination. The pregnant received cabergoline for ablactation. Conclusion. Congenital cystic adenomatoid lung malformation has different prognosis according to the type (69% in type I, 0% in types II and III). Fetal hydrops, cardiac and skeletal anomalies, Potter's syndrome, and gastrointestinal atresia are common cofindings. Genetic counseling is necessary, and pregnancy termination is proposed to the cases with poor prognosis

Unidirectional Invisibility and PT-Symmetry with Graphene

We investigate the reflectionlessness and invisibility properties in the transverse electric (TE) mode solution of a linear homogeneous optical system which comprises the $\mathcal{PT}$-symmetric structures covered by graphene sheets. We derive analytic expressions, indicate roles of each parameter governing optical system with graphene and justify that optimal conditions of these parameters give rise to broadband and wide angle invisibility. Presence of graphene turns out to shift the invisible wavelength range and to reduce the required gain amount considerably, based on its chemical potential and temperature. We substantiate that our results yield broadband reflectionless and invisible configurations for realistic materials of small refractive indices, usually around $\eta = 1$, and of small thickness sizes with graphene sheets of rather small temperatures and chemical potentials. Finally, we demonstrate that pure $\mathcal{PT}$-symmetric graphene yields invisibility at small temperatures and chemical potentials.Comment: 20 pages, 1 table 17 figure