DOCSLIB.ORG

Transformation-Optics-Based Design of a Metamaterial Radome For

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Transformation-Optics-Based Design of a Metamaterial Radome For IEEE JOURNAL ON MULTISCALE AND MULTIPHYSICS COMPUTATIONAL TECHNIQUES, VOL. 2, 2017 159 Transformation-Optics-Based Design of a Metamaterial Radome for Extending the Scanning Angle of a Phased-Array Antenna Massimo Moccia, Giuseppe Castaldi, Giuliana D’Alterio, Maurizio Feo, Roberto Vitiello, and Vincenzo Galdi, Fellow, IEEE Abstract—We apply the transformation-optics approach to the the initial focus on EM, interest has rapidly spread to other design of a metamaterial radome that can extend the scanning an- disciplines [4], and multiphysics applications are becoming in- gle of a phased-array antenna. For moderate enhancement of the creasingly relevant [5]–[7]. scanning angle, via suitable parameterization and optimization of the coordinate transformation, we obtain a design that admits a Metamaterial synthesis has several traits in common technologically viable, robust, and potentially broadband imple- with inverse-scattering problems [8], and likewise poses mentation in terms of thin-metallic-plate inclusions. Our results, some formidable computational challenges. Within the validated via finite-element-based numerical simulations, indicate emerging framework of “metamaterial-by-design” [9], the an alternative route to the design of metamaterial radomes that “transformation-optics” (TO) approach [10], [11] stands out does not require negative-valued and/or extreme constitutive pa- rameters. as a systematic strategy to analytically derive the idealized material “blueprints” necessary to implement a desired field- Index Terms—Metamaterials, phased-array antennas, radomes, manipulation interpreted as a local distortion of the coordinate transformation optics (TO). reference frame. Several extensions have also been proposed in order to accommodate effects (e.g., nonlinear, nonreciprocal, I. INTRODUCTION bianisotropic, magnetoelectric, artificial moving, space time, nonlocal, non-Hermitian, topological) and observables (e.g., HE past two decades have witnessed an exponentially resonances, optical forces, density of states) not encompassed growing interest in electromagnetic (EM) “metamateri- T by the original formulation (see, e.g., [12]–[26]). Moreover, a als” [1]–[3]. These are artificial materials, typically consisting variety of mechanisms can be exploited in order to reconfigure of electrically small inclusions in a host medium, engineered the metamaterial response [27]. The reader is also referred to so as to attain unconventional EM responses, not necessarily [4], [28], and [29] (and references therein) for recent reviews of limited by the material properties available in nature. EM applications as well as extensions to other disciplines. From the computational viewpoint, the analysis and design In this paper, we apply the TO approach to the design of a of metamaterials represent quintessential multiscale problems, metamaterial radome capable of extending the scanning angle of characterized by several characteristic sizes spanning orders of a phased-array antenna. It is well known that, in typical phased magnitude: from the electrically large size of many operational arrays, the scanning angle is practically limited to ∼±60o from scenarios of practical interest, through the wavelength-sized spa- the broadside direction [30]. In this context, a suitably designed tial variations of the effective constitutive parameters required metamaterial radome appears as an attractive alternative to typi- in typical designs, up to the deeply subwavelength sizes of in- cal mechanical-augmentation systems, in terms of size, weight, clusions utilized for practical implementations. Moreover, after and complexity. A first metamaterial-based radome for extend- ing the scanning angle was proposed and successfully realized Manuscript received March 3, 2017; revised May 2, 2017; accepted May 27, by Lam et al. [31], [32]. Such design is heavily based on brute- 2017. Date of publication June 8, 2017; date of current version October 25, 2017. This work was supported in part by the Italian Ministry of Education, force numerical optimization, which results in a nonlinear (and University and Research (MIUR) through the Campania Aerospace District difficult to control) relationship between the input and output within the framework of the TELEMACO project (PON03PE-00112-1) “En- angles. Moreover, it relies on negative-index media [33], whose abling Technologies and Innovative Electronic Scanning Systems in Millimeter and Centimeter Bands for Avionic Radar Applications.” (Corresponding author: metamaterial implementations [34] are known to be highly dis- Vincenzo Galdi.) persive and prone to losses; this inherently curtails bandwidth M. Moccia, G. Castaldi, and V. Galdi are with the Fields and Waves and efficiency. In [35], Sun et al. proposed a different, TO-based Laboratory, Department of Engineering, University of Sannio, I-82100 Ben- evento, Italy (e-mail: [email protected]; [email protected]; approach to design 2-D arbitrarily shaped metamaterial radomes [email protected]). yielding a desired (e.g., linear) relationship between the input G. D’Alterio, M Feo, and R. Vitiello are with MBDA Italia s.p.a., and output angles. To overcome the significant complexity of the I-80070 Bacoli, Italy (e-mail: [email protected]; maurizio.feo@ mbda.it; [email protected]). resulting (anisotropic, inhomogeneous) transformation medium Digital Object Identifier 10.1109/JMMCT.2017.2713826 to be implemented, the same authors subsequently put forward 2379-8793 © 2017 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information. 160 IEEE JOURNAL ON MULTISCALE AND MULTIPHYSICS COMPUTATIONAL TECHNIQUES, VOL. 2, 2017 confined to a finite region nearby the aperture. Even though arbitrary shapes are possible, for simplicity, we assume such region to be the annular domain R1 <r<R2 , −π/2 <θ< π/2. The aforementioned mapping belongs to the general class of “finite embedded coordinate transformations” introduced in [39]. As conceptually illustrated in Fig. 1(b), it locally distorts the energy flow so that the impinging beam [cf., Fig. 1(a)] is gradually steered and exits the annular region with a different direction θo = αθi (2) with α>1 denoting a desired enhancement factor. Fig. 1. Schematic of our approach. (a) In an auxiliary vacuum space, the beam Following the TO approach [11], and invoking the form- radiated by a phased array (indicated by a thick red arrow) is directed along invariance properties of Maxwell’s equations, the aforemen- an angle θi . (b) In the transformed space, a coordinate mapping embedded in R <r<R −π/2 <θ<π/2 tioned effects can be equivalently obtained by filling the annular the annular region 1 2 , (delimited by the blue- R <r<R −π/2 <θ<π/2 dashed contours) locally distorts the metric so that the same impinging beam is domain 1 2 , with an anisotropic, steered toward a different angle θo >θi . inhomogeneous medium characterized by relative permittivity and permeability tensors a modified approach [36], whose implementation relies on the ε (r)=μ (r) = det Λ (r) Λ−1 (r) · Λ−T (r) previously introduced “optical null medium” [37]. Though sim- (3) plified, this implementation still requires material constituents −1 −T where det, and denote the determinant, inverse, and in- with extreme parameters: one with very high permittivity and verse transpose, respectively, whereas Λ ≡ ∂F/∂r is the Ja- permeability, and the other with near-zero permittivity and per- cobian matrix associated with the coordinate transformation in meability. (1). From the aforementioned discussion, it appears that a prac- In what follows, we address the judicious choice of the coor- tical, broadband implementation is not at hand, and there dinate transformation, as well as the practical implementation is still considerable room for research. Accordingly, we of the TO-based constitutive “blueprints” in (3). propose here an alternative TO-based approach that yields constitutive parameters without extreme values (with possibly III. METAMATERIAL RADOME DESIGN nonmagnetic character) and with moderate anisotropy, which admit a potentially broadband implementation in terms of in- A. Coordinate Transformation clusions made of thin metallic plates [38]. More specifically, in To implement the manipulation schematized in Fig. 1, we Section II, we describe the problem geometry and outline its con- choose a 2-D coordinate transformation ceptual formulation. In Section III, we detail the metamaterial radome design, from the analytically derived, TO-based consti- r = Fr (r) (4a) tutive blueprints to the actual implementation. In Section IV, θ = Fθ (r) θ (4b) we illustrate some representative results, and validate our ap- proach via rigorous full-wave numerical simulations. Finally, in z = z (4c) Section V, we provide some closing remarks and perspectives. with the following boundary conditions: II. PROBLEM GEOMETRY AND FORMULATION Fr (R1 )=R1 (5a) The geometry and general idea underlying our approach Fr (R2 )=R2 (5b) are schematized in Fig. 1. Throughout this paper, we assume F (R )=1 an implicit exp (−iωt) time-harmonic excitation, and a 2-D θ 1 (5c) scenario, with all fields and quantities independent of z, and 1 F (R )= . transverse-magnetic (TM) polarization (i.e., z-directed mag- θ 2 α (5d) netic field). We begin considering an auxiliary vacuum space In particular, (5a) and (5c) ensure that the transformation re- with coordinates r ≡ (x,y,z) [and associated
Load more

Recommended publications
  • Transformation Optics for Thermoelectric Flow
    J. Phys.: Energy 1 (2019) 025002 https://doi.org/10.1088/2515-7655/ab00bb PAPER Transformation optics for thermoelectric flow OPEN ACCESS Wencong Shi, Troy Stedman and Lilia M Woods1 RECEIVED 8 November 2018 Department of Physics, University of South Florida, Tampa, FL 33620, United States of America 1 Author to whom any correspondence should be addressed. REVISED 17 January 2019 E-mail: [email protected] ACCEPTED FOR PUBLICATION Keywords: thermoelectricity, thermodynamics, metamaterials 22 January 2019 PUBLISHED 17 April 2019 Abstract Original content from this Transformation optics (TO) is a powerful technique for manipulating diffusive transport, such as heat work may be used under fl the terms of the Creative and electricity. While most studies have focused on individual heat and electrical ows, in many Commons Attribution 3.0 situations thermoelectric effects captured via the Seebeck coefficient may need to be considered. Here licence. fi Any further distribution of we apply a uni ed description of TO to thermoelectricity within the framework of thermodynamics this work must maintain and demonstrate that thermoelectric flow can be cloaked, diffused, rotated, or concentrated. attribution to the author(s) and the title of Metamaterial composites using bilayer components with specified transport properties are presented the work, journal citation and DOI. as a means of realizing these effects in practice. The proposed thermoelectric cloak, diffuser, rotator, and concentrator are independent of the particular boundary conditions and can also operate in decoupled electric or heat modes. 1. Introduction Unprecedented opportunities to manipulate electromagnetic fields and various types of transport have been discovered recently by utilizing metamaterials (MMs) capable of achieving cloaking, rotating, and concentrating effects [1–4].
    [Show full text]
  • Windshear Radar Calibration: Transmitter Power and Receiver Gain Stability
    NASA Technical Memorandum 107589 Windshear Radar Calibration: Transmitter Power and Receiver Gain Stability Anne I. Mackenzie June 1992 National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23665-5225 I . INTRODUCT ION During 1991, the Antenna and Microwave Research Branch began its Windshear Radar Experiment flights onboard the Boeing 737 airplane owned by NASA Langley. Experiment team members used a radio frequency (RF) test set to check the radar transmitter power and receiver gain on the airplane before and after flights. This document contains the results of power measurements and gain and noise calculations done to characterize the radar stability over a period of months. The RF test set was manufactured by IFR Inc. and shall be referred to here as the IFR test unit. The test unit performed two functions: it measured the radar transmitter power and provided known signal inputs to the radar receiver. Upon receiving the test signal inputs, the windshear radar recorded the automatic gain control (AGC) attenuation applied to the signal and the resulting in-phase and quadrature ( I,Q) detected voltages of the signal. From those recorded values, receiver gain and receiver noise power have been calculated. I,Q CHASSIS 2 MHz ori IFR TEST COLLINS 7 MHz- i IF i VIDEO i I,Q TAPE > R/T ~BANDPASS[SECTION~SECTION~DETECTOR~RECORDER FILTER j G=30dB CONSTANT RECEIVER GAIN CALCULATED LRECEIVER NO ISE POWER CALCULATED Figure 1.-Simplified block diagram of the Windshear Radar receiver showing the portions characterized by the system gain and noise. Figure 1 shows major portions of the receiver system which are characterized by the gain and noise power calculations described here.
    [Show full text]
  • Controlling the Wave Propagation Through the Medium Designed by Linear Coordinate Transformation
    Home Search Collections Journals About Contact us My IOPscience Controlling the wave propagation through the medium designed by linear coordinate transformation This content has been downloaded from IOPscience. Please scroll down to see the full text. 2015 Eur. J. Phys. 36 015006 (http://iopscience.iop.org/0143-0807/36/1/015006) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 128.42.82.187 This content was downloaded on 04/07/2016 at 02:47 Please note that terms and conditions apply. European Journal of Physics Eur. J. Phys. 36 (2015) 015006 (11pp) doi:10.1088/0143-0807/36/1/015006 Controlling the wave propagation through the medium designed by linear coordinate transformation Yicheng Wu, Chengdong He, Yuzhuo Wang, Xuan Liu and Jing Zhou Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing 100875, People’s Republic of China E-mail: [email protected] Received 26 June 2014, revised 9 September 2014 Accepted for publication 16 September 2014 Published 6 November 2014 Abstract Based on the principle of transformation optics, we propose to control the wave propagating direction through the homogenous anisotropic medium designed by linear coordinate transformation. The material parameters of the medium are derived from the linear coordinate transformation applied. Keeping the space area unchanged during the linear transformation, the polarization-dependent wave control through a non-magnetic homogeneous medium can be realized. Beam benders, polarization splitter, and object illu- sion devices are designed, which have application prospects in micro-optics and nano-optics.
    [Show full text]
  • Transformation Magneto-Statics and Illusions for Magnets
    OPEN Transformation magneto-statics and SUBJECT AREAS: illusions for magnets ELECTRONIC DEVICES Fei Sun1,2 & Sailing He1,2 TRANSFORMATION OPTICS APPLIED PHYSICS 1 Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, JORCEP, East Building #5, Zijingang Campus, Zhejiang University, Hangzhou 310058, China, 2Department of Electromagnetic Engineering, School of Electrical Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm, Sweden. Received 26 June 2014 Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theory Accepted of transformation optics to transformation magneto-statics, which can design magnets through coordinate 28 August 2014 transformations. Some novel DC magnetic field illusions created by magnets (e.g. rescaling magnets, Published cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Our 13 October 2014 research will open a new door to designing magnets and controlling DC magnetic fields. ransformation optics (TO), which has been utilized to control the path of electromagnetic waves1–7, the Correspondence and conduction of current8,9, and the distribution of DC electric or magnetic field10–20 in an unprecedented way, requests for materials T has become a very popular research topic in recent years. Based on the form-invariant of Maxwell’s equation should be addressed to under coordinate transformations, special media (known as transformed media) with pre-designed functionality have been designed by using coordinate transformations1–4. TO can also be used for designing novel plasmonic S.H. ([email protected]) nanostructures with broadband response and super-focusing ability21–23. By analogy to Maxwell’s equations, the form-invariant of governing equations of other fields (e.g.
    [Show full text]
  • Design Method for Transformation Optics Based on Laplace's Equation
    Design method for quasi-isotropic transformation materials based on inverse Laplace’s equation with sliding boundaries Zheng Chang1, Xiaoming Zhou1, Jin Hu2 and Gengkai Hu 1* 1School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China 2School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, P. R. China *Corresponding author: [email protected] Abstract: Recently, there are emerging demands for isotropic material parameters, arising from the broadband requirement of the functional devices. Since inverse Laplace’s equation with sliding boundary condition will determine a quasi-conformal mapping, and a quasi-conformal mapping will minimize the transformation material anisotropy, so in this work, the inverse Laplace’s equation with sliding boundary condition is proposed for quasi-isotropic transformation material design. Examples of quasi-isotropic arbitrary carpet cloak and waveguide with arbitrary cross sections are provided to validate the proposed method. The proposed method is very simple compared with other quasi-conformal methods based on grid generation tools. 1. Introduction The form invariance of Maxwell’s equations under coordinate transformations constructs the equivalence between the geometrical space and material space, the developed transformation optics theory [1,2] is opening a new field that may cover many aspects of physics and wave phenomenon. Transformation optics (TO) makes it possible to investigate celestial motion and light/matter behavior in laboratory environment by using equivalent materials [3]. Illusion optics [4] is also proposed based on transformation optics, which can design a device looking differently. The attractive application of transformation optics is the invisibility cloak, which covers objects without being detected [5].
    [Show full text]
  • A Unified Approach to Nonlinear Transformation Materials
    www.nature.com/scientificreports OPEN A Unifed Approach to Nonlinear Transformation Materials Sophia R. Sklan & Baowen Li The advances in geometric approaches to optical devices due to transformation optics has led to the Received: 9 October 2017 development of cloaks, concentrators, and other devices. It has also been shown that transformation Accepted: 9 January 2018 optics can be used to gravitational felds from general relativity. However, the technique is currently Published: xx xx xxxx constrained to linear devices, as a consistent approach to nonlinearity (including both the case of a nonlinear background medium and a nonlinear transformation) remains an open question. Here we show that nonlinearity can be incorporated into transformation optics in a consistent way. We use this to illustrate a number of novel efects, including cloaking an optical soliton, modeling nonlinear solutions to Einstein’s feld equations, controlling transport in a Debye solid, and developing a set of constitutive to relations for relativistic cloaks in arbitrary nonlinear backgrounds. Transformation optics1–9, which uses geometric coordinate transformations derive the materials requirements of arbitrary devices, is a powerful technique. Essentially, for any geometry there corresponds a material with identi- cal transport. With the correct geometry, it is possible to construct optical cloaks10–12 and concentrators13 as well as analogues of these devices for other waves14–18 and even for difusion19–26. While many interpretations and for- malisms of transformation optics exist, such as Jacobian transformations4, scattering matrices27–31, and conformal mappings3, one of the most theoretically powerful interpretations comes from the metric formalism32. All of these approaches agree that materials defne an efective geometry, however the metric formalism is important since it allows us to further interpret the geometry.
    [Show full text]
  • A Review Paper on Metamaterial Antenna and Its Application Shalini, Roopali Student, ECE, Rayat & Bahra Institute of Engineering & Bio-Technology, Mohali, India
    IJRECE VOL. 3 ISSUE 2 APR-JUNE 2015 ISSN: 2393-9028 (PRINT) | ISSN: 2348-2281 (ONLINE) A Review Paper on Metamaterial Antenna and its Application Shalini, Roopali Student, ECE, Rayat & Bahra Institute of Engineering & Bio-Technology, Mohali, India Abstract - In this paper a brief review about II. ANTENNA SUBSTRATE metamaterials is given. Here we discuss different type of Metamaterials are promising candidates as antenna metamaterials composite structure used in antenna substrates for miniaturization, sensing, bandwidth engineering. Compared with the conventional materials, enhancement and for controlling the direction of radiation metamaterials exhibits some specific features which are not [3]. These substrates have great potential for improving found in conventional material. After that metamaterials antenna or other RF device performances. Metamaterial based antenna, also describe the parameter of antenna like substrate can be used for a variety of applications. It can be gain and bandwidth which can improve by using designed to act as a high impedance substrate that can be metamaterials and discuss future scope and application of used to integrated low-profile antennas in various metamaterials. Moreover, novel applications of components and packages. In general any antenna, printed metamaterials composite structure in antenna engineering on a high dielectric constant substrate has a low resonance have been considered. Some unique applications of these frequency. This property contributes to miniaturization of composite structures as an antenna substrate, superstrate, the device. Metamaterial substrates can be designed to act as feed networks, phased array antennas, ground planes, a very high dielectric constant substrate at given frequency antenna radome and struts invisibility have been discussed.
    [Show full text]
  • Roadmap on Transformation Optics 5 Martin Mccall 1,*, John B Pendry 1, Vincenzo Galdi 2, Yun Lai 3, S
    Page 1 of 59 AUTHOR SUBMITTED MANUSCRIPT - draft 1 2 3 4 Roadmap on Transformation Optics 5 Martin McCall 1,*, John B Pendry 1, Vincenzo Galdi 2, Yun Lai 3, S. A. R. Horsley 4, Jensen Li 5, Jian 6 Zhu 5, Rhiannon C Mitchell-Thomas 4, Oscar Quevedo-Teruel 6, Philippe Tassin 7, Vincent Ginis 8, 7 9 9 9 6 10 8 Enrica Martini , Gabriele Minatti , Stefano Maci , Mahsa Ebrahimpouri , Yang Hao , Paul Kinsler 11 11,12 13 14 15 9 , Jonathan Gratus , Joseph M Lukens , Andrew M Weiner , Ulf Leonhardt , Igor I. 10 Smolyaninov 16, Vera N. Smolyaninova 17, Robert T. Thompson 18, Martin Wegener 18, Muamer Kadic 11 18 and Steven A. Cummer 19 12 13 14 Affiliations 15 1 16 Imperial College London, Blackett Laboratory, Department of Physics, Prince Consort Road, 17 London SW7 2AZ, United Kingdom 18 19 2 Field & Waves Lab, Department of Engineering, University of Sannio, I-82100 Benevento, Italy 20 21 3 College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano 22 Science and Technology, Soochow University, Suzhou 215006, China 23 24 4 University of Exeter, Department of Physics and Astronomy, Stocker Road, Exeter, EX4 4QL United 25 26 Kingdom 27 5 28 School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, 29 United Kingdom 30 31 6 KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden 32 33 7 Department of Physics, Chalmers University , SE-412 96 Göteborg, Sweden 34 35 8 Vrije Universiteit Brussel Pleinlaan 2, 1050 Brussel, Belgium 36 37 9 Dipartimento di Ingegneria dell'Informazione e Scienze Matematiche, University of Siena, Via Roma, 38 39 56 53100 Siena, Italy 40 10 41 School of Electronic Engineering and Computer Science, Queen Mary University of London, 42 London E1 4FZ, United Kingdom 43 44 11 Physics Department, Lancaster University, Lancaster LA1 4 YB, United Kingdom 45 46 12 Cockcroft Institute, Sci-Tech Daresbury, Daresbury WA4 4AD, United Kingdom.
    [Show full text]
  • Harnessing Transformation Optics for Understanding Electron Energy Loss and Cathodoluminescence
    Harnessing transformation optics for understanding electron energy loss and cathodoluminescence Yu Luo 1, 2 *, Matthias Kraft 1 *, and J. B. Pendry1 1 The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, United Kingdom 2 School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue 639798, Singapore * These authors contributed equally Abstract As the continual experimental advances made in Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) open the door to practical exploitations of plasmonic effects in metal nanoparticles, there is an increasing need for precise interpretation and guidance of such experiments. Numerical simulations are available but lack physical insight, while traditional analytical approaches are rare and limited to studying specific, simple structures. Here, we propose a versatile and efficient method based on transformation optics which can fully characterize and model the EELS problems of nanoparticles of complex geometries. Detailed discussions are given on 2D and 3D nanoparticle dimers, where the frequency and time domain responses under electron beam excitations are derived. Significance Statements Critical to the wide applications of nanoplasmonics is the ability to probe the near-field electromagnetic interactions associated with the nanoparticles. Electron microscope technology has been developed to image materials at the subnanometer level, leading to experimental and theoretical breakthroughs in the field of plasmonics
    [Show full text]
  • Review Article Metamaterials for Microwave Radomes and the Concept of a Metaradome: Review of the Literature
    Hindawi International Journal of Antennas and Propagation Volume 2017, Article ID 1356108, 13 pages https://doi.org/10.1155/2017/1356108 Review Article Metamaterials for Microwave Radomes and the Concept of a Metaradome: Review of the Literature E. ÖziG,1 A. V. Osipov,1 andT.F.Eibert2 1 German Aerospace Center (DLR), Microwaves and Radar Institute, Oberpfaffenhofen, Germany 2Chair of High-Frequency Engineering, Department of Electrical and Computer Engineering, Technical University of Munich, Munich, Germany Correspondence should be addressed to E. Ozis¨ ¸; [email protected] Received 20 January 2017; Revised 23 March 2017; Accepted 9 April 2017; Published 20 July 2017 Academic Editor: Scott Rudolph Copyright © 2017 E. Ozis¨ ¸ et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A radome is an integral part of almost every antenna system, protecting antennas and antenna electronics from hostile exterior conditions (humidity, heat, cold, etc.) and nearby personnel from rotating mechanical parts of antennas and streamlining antennas to reduce aerodynamic drag and to conceal antennas from public view. Metamaterials are artificial materials with a great potential for antenna design, and many studies explore applications of metamaterials to antennas but just a few to the design of radomes. This paper discusses the possibilities that metamaterials open up in the design of microwave radomes and introduces the concept of metaradomes. The use of metamaterials can improve or correct characteristics (gain, directivity, and bandwidth) of the enclosed antenna and add new features, like band-pass frequency behavior, polarization transformations, the ability to be switched on/off, and so forth.
    [Show full text]
  • Gallery of USAF Weapons Note: Inventory Numbers Are Total Active Inventory Figures As of Sept
    Gallery of USAF Weapons Note: Inventory numbers are total active inventory figures as of Sept. 30, 2015. By Aaron M. U. Church, Senior Editor ■ 2016 USAF Almanac BOMBER AIRCRAFT B-1 Lancer Brief: Long-range bomber capable of penetrating enemy defenses and de- livering the largest weapon load of any aircraft in the inventory. COMMENTARY The B-1A was initially proposed as replacement for the B-52, and four proto- types were developed and tested before program cancellation in 1977. The program was revived in 1981 as B-1B. The vastly upgraded aircraft added 74,000 lb of usable payload, improved radar, and reduced radar cross section, but cut maximum speed to Mach 1.2. The B-1B first saw combat in Iraq during Desert Fox in December 1998. Its three internal weapons bays accommodate a substantial payload of weapons, including a mix of different weapons in each bay. Lancer production totaled 100 aircraft. The bomber’s blended wing/ body configuration, variable-geometry design, and turbofan engines provide long range and loiter time. The B-1B has been upgraded with GPS, smart weapons, and mission systems. Offensive avionics include SAR for tracking, B-2A Spirit (SSgt. Jeremy M. Wilson) targeting, and engaging moving vehicles and terrain following. GPS-aided INS lets aircrews autonomously navigate without ground-based navigation aids Dimensions: Span 137 ft (spread forward) to 79 ft (swept aft), length 146 and precisely engage targets. Sniper pod was added in 2008. The ongoing ft, height 34 ft. integrated battle station modifications is the most comprehensive refresh in Weight: Max T-O 477,000 lb.
    [Show full text]
  • Countermeasures Against Snow Accretion and Icing on Radomes
    Countermeasures Against Snow Accretion and Icing on Radomes Michiya Suzuki, Kokusho Sha and Tomohiro Tsukawàki, Faculty of Engineering, Yamagata University Daisuke Kuroiwa, Institute of Low Temperature Science, Hokkaido University Television broadcasting through an artificial the radome from snow accretion. satellite calls for a task of solving various Y. Asami et al. (1) investigated microwave problems of propagation of electromagnetic waves propagation in 1958 in snowy districts in Japan, in snowy countries, where serious problems of whereby showed that snow or rime deposited on attention is paled to removal of snow accreted antennas did not cause any significant trouble for on the surface of a radome covering a receiving the propagation of microwaves unless accreted snow aerial. Since the wavelengths of electromagnetic or rime contained much free water in it. This waves to be used in satellite broadcasting are suggests that, if wet snow accretes or deposited extremely short, they are easily absorbed by dry snow begins to melt on the surface of a radome, liquid phase existing in wet snow. The rate of the energy of a microwave received by an antenna attenuation of a 24-GHz wave was measured as a may be significantly reduced by the absorption of function of thickness of a water film and found free water existing in snow. The purpose of this to be 18 dB/mm. One of the most convenient and paper is to show the rate of attnuation of an economical devices to remove wet snow deposited electromagnetic wave ranged in 10-30 GHz by ab- on a radome surface was to rotate the radome at sorption of the free water and to find a convenient the rate of 100\.'1100 r.p.m.
    [Show full text]