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Chapter 22 Fundamentalfundamental Propertiesproperties Ofof Antennasantennas
ChapterChapter 22 FundamentalFundamental PropertiesProperties ofof AntennasAntennas ECE 5318/6352 Antenna Engineering Dr. Stuart Long 1 .. IEEEIEEE StandardsStandards . Definition of Terms for Antennas . IEEE Standard 145-1983 . IEEE Transactions on Antennas and Propagation Vol. AP-31, No. 6, Part II, Nov. 1983 2 ..RadiationRadiation PatternPattern (or(or AntennaAntenna Pattern)Pattern) “The spatial distribution of a quantity which characterizes the electromagnetic field generated by an antenna.” 3 ..DistributionDistribution cancan bebe aa . Mathematical function . Graphical representation . Collection of experimental data points 4 ..QuantityQuantity plottedplotted cancan bebe aa . Power flux density W [W/m²] . Radiation intensity U [W/sr] . Field strength E [V/m] . Directivity D 5 . GraphGraph cancan bebe . Polar or rectangular 6 . GraphGraph cancan bebe . Amplitude field |E| or power |E|² patterns (in linear scale) (in dB) 7 ..GraphGraph cancan bebe . 2-dimensional or 3-D most usually several 2-D “cuts” in principle planes 8 .. RadiationRadiation patternpattern cancan bebe . Isotropic Equal radiation in all directions (not physically realizable, but valuable for comparison purposes) . Directional Radiates (or receives) more effectively in some directions than in others . Omni-directional nondirectional in azimuth, directional in elevation 9 ..PrinciplePrinciple patternspatterns . E-plane . H-plane Plane defined by H-field and Plane defined by E-field and direction of maximum direction of maximum radiation radiation (usually coincide with principle planes of the coordinate system) 10 Coordinate System Fig. 2.1 Coordinate system for antenna analysis. 11 ..RadiationRadiation patternpattern lobeslobes . Major lobe (main beam) in direction of maximum radiation (may be more than one) . Minor lobe - any lobe but a major one . Side lobe - lobe adjacent to major one . -
Radiometry and the Friis Transmission Equation Joseph A
Radiometry and the Friis transmission equation Joseph A. Shaw Citation: Am. J. Phys. 81, 33 (2013); doi: 10.1119/1.4755780 View online: http://dx.doi.org/10.1119/1.4755780 View Table of Contents: http://ajp.aapt.org/resource/1/AJPIAS/v81/i1 Published by the American Association of Physics Teachers Related Articles The reciprocal relation of mutual inductance in a coupled circuit system Am. J. Phys. 80, 840 (2012) Teaching solar cell I-V characteristics using SPICE Am. J. Phys. 79, 1232 (2011) A digital oscilloscope setup for the measurement of a transistor’s characteristic curves Am. J. Phys. 78, 1425 (2010) A low cost, modular, and physiologically inspired electronic neuron Am. J. Phys. 78, 1297 (2010) Spreadsheet lock-in amplifier Am. J. Phys. 78, 1227 (2010) Additional information on Am. J. Phys. Journal Homepage: http://ajp.aapt.org/ Journal Information: http://ajp.aapt.org/about/about_the_journal Top downloads: http://ajp.aapt.org/most_downloaded Information for Authors: http://ajp.dickinson.edu/Contributors/contGenInfo.html Downloaded 07 Jan 2013 to 153.90.120.11. Redistribution subject to AAPT license or copyright; see http://ajp.aapt.org/authors/copyright_permission Radiometry and the Friis transmission equation Joseph A. Shaw Department of Electrical & Computer Engineering, Montana State University, Bozeman, Montana 59717 (Received 1 July 2011; accepted 13 September 2012) To more effectively tailor courses involving antennas, wireless communications, optics, and applied electromagnetics to a mixed audience of engineering and physics students, the Friis transmission equation—which quantifies the power received in a free-space communication link—is developed from principles of optical radiometry and scalar diffraction. -
Section 1: Introduction (PDF)
SECTION 1: Introduction SECTION 1: INTRODUCTION Section 1 Contents The Purpose and Scope of This Guidance ....................................................................1-1 Relationship to CZARA Guidance ....................................................................................1-2 National Water Quality Inventory .....................................................................................1-3 What is Nonpoint Source Pollution? ...............................................................................1-4 Watershed Approach to Nonpoint Source Pollution Control .......................................1-5 Programs to Control Nonpoint Source Pollution...........................................................1-7 National Nonpoint Source Pollution Control Program .............................................1-7 Storm Water Permit Program .......................................................................................1-8 Coastal Nonpoint Pollution Control Program ............................................................1-8 Clean Vessel Act Pumpout Grant Program ................................................................1-9 International Convention for the Prevention of Pollution from Ships (MARPOL)...................................................................................................1-9 Oil Pollution Act (OPA) and Regulation ....................................................................1-10 Sources of Further Information .....................................................................................1-10 -
Precollimator for X-Ray Telescope (Stray-Light Baffle) Mindrum Precision, Inc Kurt Ponsor Mirror Tech/SBIR Workshop Wednesday, Nov 2017
Mindrum.com Precollimator for X-Ray Telescope (stray-light baffle) Mindrum Precision, Inc Kurt Ponsor Mirror Tech/SBIR Workshop Wednesday, Nov 2017 1 Overview Mindrum.com Precollimator •Past •Present •Future 2 Past Mindrum.com • Space X-Ray Telescopes (XRT) • Basic Structure • Effectiveness • Past Construction 3 Space X-Ray Telescopes Mindrum.com • XMM-Newton 1999 • Chandra 1999 • HETE-2 2000-07 • INTEGRAL 2002 4 ESA/NASA Space X-Ray Telescopes Mindrum.com • Swift 2004 • Suzaku 2005-2015 • AGILE 2007 • NuSTAR 2012 5 NASA/JPL/ASI/JAXA Space X-Ray Telescopes Mindrum.com • Astrosat 2015 • Hitomi (ASTRO-H) 2016-2016 • NICER (ISS) 2017 • HXMT/Insight 慧眼 2017 6 NASA/JPL/CNSA Space X-Ray Telescopes Mindrum.com NASA/JPL-Caltech Harrison, F.A. et al. (2013; ApJ, 770, 103) 7 doi:10.1088/0004-637X/770/2/103 Basic Structure XRT Mindrum.com Grazing Incidence 8 NASA/JPL-Caltech Basic Structure: NuSTAR Mirrors Mindrum.com 9 NASA/JPL-Caltech Basic Structure XRT Mindrum.com • XMM Newton XRT 10 ESA Basic Structure XRT Mindrum.com • XMM-Newton mirrors D. de Chambure, XMM Project (ESTEC)/ESA 11 Basic Structure XRT Mindrum.com • Thermal Precollimator on ROSAT 12 http://www.xray.mpe.mpg.de/ Basic Structure XRT Mindrum.com • AGILE Precollimator 13 http://agile.asdc.asi.it Basic Structure Mindrum.com • Spektr-RG 2018 14 MPE Basic Structure: Stray X-Rays Mindrum.com 15 NASA/JPL-Caltech Basic Structure: Grazing Mindrum.com 16 NASA X-Ray Effectiveness: Straylight Mindrum.com • Correct Reflection • Secondary Only • Backside Reflection • Primary Only 17 X-Ray Effectiveness Mindrum.com • The Crab Nebula by: ROSAT (1990) Chandra 18 S. -
25. Antennas II
25. Antennas II Radiation patterns Beyond the Hertzian dipole - superposition Directivity and antenna gain More complicated antennas Impedance matching Reminder: Hertzian dipole The Hertzian dipole is a linear d << antenna which is much shorter than the free-space wavelength: V(t) Far field: jk0 r j t 00Id e ˆ Er,, t j sin 4 r Radiation resistance: 2 d 2 RZ rad 3 0 2 where Z 000 377 is the impedance of free space. R Radiation efficiency: rad (typically is small because d << ) RRrad Ohmic Radiation patterns Antennas do not radiate power equally in all directions. For a linear dipole, no power is radiated along the antenna’s axis ( = 0). 222 2 I 00Idsin 0 ˆ 330 30 Sr, 22 32 cr 0 300 60 We’ve seen this picture before… 270 90 Such polar plots of far-field power vs. angle 240 120 210 150 are known as ‘radiation patterns’. 180 Note that this picture is only a 2D slice of a 3D pattern. E-plane pattern: the 2D slice displaying the plane which contains the electric field vectors. H-plane pattern: the 2D slice displaying the plane which contains the magnetic field vectors. Radiation patterns – Hertzian dipole z y E-plane radiation pattern y x 3D cutaway view H-plane radiation pattern Beyond the Hertzian dipole: longer antennas All of the results we’ve derived so far apply only in the situation where the antenna is short, i.e., d << . That assumption allowed us to say that the current in the antenna was independent of position along the antenna, depending only on time: I(t) = I0 cos(t) no z dependence! For longer antennas, this is no longer true. -
Sources and Emissions of Air Pollutants
© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION Chapter 2 Sources and Emissions of Air Pollutants LEArning ObjECtivES By the end of this chapter the reader will be able to: • distinguish the “troposphere” from the “stratosphere” • define “polluted air” in relation to various scientific disciplines • describe “anthropogenic” sources of air pollutants and distinguish them from “natural” sources • list 10 sources of indoor air contaminants • identify three meteorological factors that affect the dispersal of air pollutants ChAPtEr OutLinE I. Introduction II. Measurement Basics III. Unpolluted vs. Polluted Air IV. Air Pollutant Sources and Their Emissions V. Pollutant Transport VI. Summary of Major Points VII. Quiz and Problems VIII. Discussion Topics References and Recommended Reading 21 2 N D R E V I S E 9955 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION 22 Chapter 2 SourCeS and EmiSSionS of Air PollutantS i. IntrOduCtiOn level. Mt. Everest is thus a minute bump on the globe that adds only 0.06 percent to the Earth’s diameter. Structure of the Earth’s Atmosphere The Earth’s atmosphere consists of several defined layers (Figure 2–1). The troposphere, in which all life The Earth, along with Mercury, Venus, and Mars, is exists, and from which we breathe, reaches an altitude of a terrestrial (as opposed to gaseous) planet with a per- about 7–8 km at the poles to just over 13 km at the equa- manent atmosphere. The Earth is an oblate (slightly tor: the mean thickness being 9.1 km (5.7 miles). Thus, flattened) sphere with a mean diameter of 12,700 km the troposphere represents a very thin cover over the (about 8,000 statute miles). -
Introduction to Radio Astronomy
Introduction to Radio Astronomy Greg Hallenbeck 2016 UAT Workshop @ Green Bank Outline Sources of Radio Emission Continuum Sources versus Spectral Lines The HI Line Details of the HI Line What is our data like? What can we learn from each source? The Radio Telescope How do we actually detect this stuff? How do we get from the sky to the data? I. Radio Emission Sources The Electromagnetic Spectrum Radio ← Optical Light → A Galaxy Spectrum (Apologies to the radio astronomers) Continuum Emission Radiation at a wide range of wavelengths ❖ Thermal Emission ❖ Bremsstrahlung (aka free-free) ❖ Synchrotron ❖ Inverse Compton Scattering Spectral Line Radiation at a wide range of wavelengths ❖ The HI Line Categories of Emission Continuum Emission — “The Background” Radiation at a wide range of wavelengths ❖ Thermal Emission ❖ Synchrotron ❖ Bremsstrahlung (aka free-free) ❖ Inverse Compton Scattering Spectral Lines — “The Spikes” Radiation at specific wavelengths ❖ The HI Line ❖ Pretty much any element or molecule has lines. Thermal Emission Hot Things Glow Emit radiation at all wavelengths The peak of emission depends on T Higher T → shorter wavelength Regulus (12,000 K) The Sun (6,000 K) Jupiter (100 K) Peak is 250 nm Peak is 500 nm Peak is 30 µm Thermal Emission How cold corresponds to a radio peak? A 3 K source has peak at 1 mm. Not getting any colder than that. Synchrotron Radiation Magnetic Fields Make charged particles move in circles. Accelerating charges radiate. Synchrotron Ingredients Strong magnetic fields High energies, ionized particles. Found in jets: ❖ Active galactic nuclei ❖ Quasars ❖ Protoplanetary disks Synchrotron Radiation Jets from a Protostar At right: an optical image. -
Development of Earth Station Receiving Antenna and Digital Filter Design Analysis for C-Band VSAT
INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 3, ISSUE 6, JUNE 2014 ISSN 2277-8616 Development of Earth Station Receiving Antenna and Digital Filter Design Analysis for C-Band VSAT Su Mon Aye, Zaw Min Naing, Chaw Myat New, Hla Myo Tun Abstract: This paper describes the performance improvement of C-band VSAT receiving antenna. In this work, the gain and efficiency of C-band VSAT have been evaluated and then the reflector design is developed with the help of ICARA and MATLAB environment. The proposed design meets the good result of antenna gain and efficiency. The typical gain of prime focus parabolic reflector antenna is 30 dB to 40dB. And the efficiency is 60% to 80% with the good antenna design. By comparing with the typical values, the proposed C-band VSAT antenna design is well optimized with gain of 38dB and efficiency of 78%. In this paper, the better design with compromise gain performance of VSAT receiving parabolic antenna using ICARA software tool and the calculation of C-band downlink path loss is also described. The particular prime focus parabolic reflector antenna is applied for this application and gain of antenna, radiation pattern with far field, near field and the optimized antenna efficiency is also developed. The objective of this paper is to design the downlink receiving antenna of VSAT satellite ground segment with excellent gain and overall antenna efficiency. The filter design analysis is base on Kaiser window method and the simulation results are also presented in this paper. Index Terms: prime focus parabolic reflector antenna, satellite, efficiency, gain, path loss, VSAT. -
Find Your Telescope. Your Find Find Yourself
FIND YOUR TELESCOPE. FIND YOURSELF. FIND ® 2008 PRODUCT CATALOG WWW.MEADE.COM TABLE OF CONTENTS TELESCOPE SECTIONS ETX ® Series 2 LightBridge ™ (Truss-Tube Dobsonians) 20 LXD75 ™ Series 30 LX90-ACF ™ Series 50 LX200-ACF ™ Series 62 LX400-ACF ™ Series 78 Max Mount™ 88 Series 5000 ™ ED APO Refractors 100 A and DS-2000 Series 108 EXHIBITS 1 - AutoStar® 13 2 - AutoAlign ™ with SmartFinder™ 15 3 - Optical Systems 45 FIND YOUR TELESCOPE. 4 - Aperture 57 5 - UHTC™ 68 FIND YOURSEL F. 6 - Slew Speed 69 7 - AutoStar® II 86 8 - Oversized Primary Mirrors 87 9 - Advanced Pointing and Tracking 92 10 - Electronic Focus and Collimation 93 ACCESSORIES Imagers (LPI,™ DSI, DSI II) 116 Series 5000 ™ Eyepieces 130 Series 4000 ™ Eyepieces 132 Series 4000 ™ Filters 134 Accessory Kits 136 Imaging Accessories 138 Miscellaneous Accessories 140 Meade Optical Advantage 128 Meade 4M Community 124 Astrophotography Index/Information 145 ©2007 MEADE INSTRUMENTS CORPORATION .01 RECRUIT .02 ENTHUSIAST .03 HOT ShOT .04 FANatIC Starting out right Going big on a budget Budding astrophotographer Going deeper .05 MASTER .06 GURU .07 SPECIALIST .08 ECONOMIST Expert astronomer Dedicated astronomer Wide field views & images On a budget F IND Y OURSEL F F IND YOUR TELESCOPE ® ™ ™ .01 ETX .02 LIGHTBRIDGE™ .03 LXD75 .04 LX90-ACF PG. 2-19 PG. 20-29 PG.30-43 PG. 50-61 ™ ™ ™ .05 LX200-ACF .06 LX400-ACF .07 SERIES 5000™ ED APO .08 A/DS-2000 SERIES PG. 78-99 PG. 100-105 PG. 108-115 PG. 62-76 F IND Y OURSEL F Astronomy is for everyone. That’s not to say everyone will become a serious comet hunter or astrophotographer. -
The E-MERLIN Notebook
The e-MERLIN Notebook IRIS Collaboration F2F Meeting - 4 April 2019 Dr. Rachael Ainsworth Jodrell Bank Centre for Astrophysics University of Manchester @rachaelevelyn Overview ● Motivation ● Brief intro to e-MERLIN ● Pieces of the puzzle: ○ e-MERLIN CASA Pipeline ○ Data Archive ○ Open Notebooks ● Putting everything together: ○ e-MERLIN @ IRIS Motivation (Whitaker 2018, https://doi.org/10.6084/m9.figshare.7140050.v2 ) “Computational science has led to exciting new developments, but the nature of the work has exposed limitations in our ability to evaluate published findings. Reproducibility has the potential to serve as a minimum standard for judging scientific claims when full independent replication of a study is not possible.” (Peng 2011; https://doi.org/10.1126/science.1213847) e-MERLIN (e)MERLIN ● enhanced Multi Element Remotely Linked Interferometer Network ● An array of 7 radio telescopes spanning 217 km across the UK ● Connected by a superfast optical fibre network to its headquarters at Jodrell Bank Observatory. ● Has a unique position in the world with an angular resolution comparable to that of the Hubble Space Telescope and carrying out centimetre wavelength radio astronomy with micro-Jansky sensitivities. http://www.e-merlin.ac.uk/ (e)MERLIN ● Does not have a publicly accessible data archive. http://www.e-merlin.ac.uk/ Radio Astronomy Software: CASA ● The CASA infrastructure consists of a set of C++ tools bundled together under an iPython interface as data reduction tasks. ● This structure provides flexibility to process the data via task interface or as a python script. ● https://casa.nrao.edu/ Pieces of the puzzle e-MERLIN CASA Pipeline ● Developed openly on GitHub (Moldon, et al.) ● Python package composed of different modules that can be run together sequentially to produce calibration tables, calibrated data, assessment plots and a summary weblog. -
Optimum Partitioning of a Phased-MIMO Radar Array Antenna
Optimum Partitioning of a Phased-MIMO Radar Array Antenna Ahmed Alieldin, Student Member, IEEE; Yi Huang, Senior Member, IEEE; and Walid M. Saad as it can significantly improve system identification, target Abstract—In a Phased-Multiple-Input-Multiple-Output detection and parameters estimation performance when (Phased-MIMO) radar the transmit antenna array is divided into combined with adaptive arrays. It can also enhance transmit multiple sub-arrays that are allowed to be overlapped. In this beam pattern design and use available space efficiently which paper a mathematical formula for optimum partitioning scheme is most suitable for airborne or ship-borne radars [7]. is derived to determine the optimum division of an array into sub-arrays and number of elements in each sub-array. The main However, because the antennas are collocated, the main concept of this new scheme is to place the transmit beam pattern drawback is the loss of space diversity that is needed to nulls at the diversity beam pattern peak side lobes and place the mitigate the effect of target fluctuations. This problem could diversity beam pattern nulls at the transmit beam pattern peak be solved using phased-MIMO radar [3]. But the main side lobes. This is compared with other equal and unequal question is how to divide array elements into sub-arrays to schemes. It is shown that the main advantage of this optimum achieve the optimum performance. partitioning scheme is the improvement of the main-to-side lobe levels without reduction in beam pattern directivity. Also signal- This paper proposes an optimum partitioning scheme for to-noise ratio is improved using this optimum partitioning phased-MIMO radar and is organized as follows: Section II scheme. -
Resolving Interference Issues at Satellite Ground Stations
Application Note Resolving Interference Issues at Satellite Ground Stations Introduction RF interference represents the single largest impact to robust satellite operation performance. Interference issues result in significant costs for the satellite operator due to loss of income when the signal is interrupted. Additional costs are also encountered to debug and fix communications problems. These issues also exert a price in terms of reputation for the satellite operator. According to an earlier survey by the Satellite Interference Reduction Group (SIRG), 93% of satellite operator respondents suffer from satellite interference at least once a year. More than half experience interference at least once per month, while 17% see interference continuously in their day-to-day operations. Over 500 satellite operators responded to this survey. Satellite Communications Overview Satellite earth stations form the ground segment of satellite communications. They contain one or more satellite antennas tuned to various frequency bands. Satellites are used for telephony, data, backhaul, broadcast, community antenna television (CATV), internet, and other services. Depending on the application, each satellite system may be receive only or constructed for both transmit and receive operations. A typical earth station is shown in figure 1. Figure 1. Satellite Earth Station Each satellite antenna system is composed of the antenna itself (parabola dish) along with various RF components for signal processing. The RF components comprise the satellite feed system. The feed system receives/transmits the signal from the dish to a horn antenna located on the feed network. The location of the receiver feed system can be seen in figure 2. The satellite signal is reflected from the parabolic surface and concentrated at the focus position.