Antennas and Feedlines
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ECE 5011: Antennas
ECE 5011: Antennas Course Description Electromagnetic radiation; fundamental antenna parameters; dipole, loops, patches, broadband and other antennas; array theory; ground plane effects; horn and reflector antennas; pattern synthesis; antenna measurements. Prior Course Number: ECE 711 Transcript Abbreviation: Antennas Grading Plan: Letter Grade Course Deliveries: Classroom Course Levels: Undergrad, Graduate Student Ranks: Junior, Senior, Masters, Doctoral Course Offerings: Spring Flex Scheduled Course: Never Course Frequency: Every Year Course Length: 14 Week Credits: 3.0 Repeatable: No Time Distribution: 3.0 hr Lec Expected out-of-class hours per week: 6.0 Graded Component: Lecture Credit by Examination: No Admission Condition: No Off Campus: Never Campus Locations: Columbus Prerequisites and Co-requisites: Prereq: 3010 (312), or Grad standing in Engineering, Biological Sciences, or Math and Physical Sciences. Exclusions: Not open to students with credit for 711. Cross-Listings: Course Rationale: Existing course. The course is required for this unit's degrees, majors, and/or minors: No The course is a GEC: No The course is an elective (for this or other units) or is a service course for other units: Yes Subject/CIP Code: 14.1001 Subsidy Level: Doctoral Course Programs Abbreviation Description CpE Computer Engineering EE Electrical Engineering Course Goals Teach students basic antenna parameters, including radiation resistance, input impedance, gain and directivity Expose students to antenna radiation properties, propagation (Friis transmission -
The Bruene Directional Coupler and Transmission Lines Abstract
Bruene Coupler and Transmission lines. Version 1.3 October 18, 2009 1 The Bruene Directional Coupler and Transmission Lines Gary Bold, ZL1AN. [email protected] Abstract The Bruene directional coupler indicates \forward" and “reflected” power. Its operation is invariably explained using transmission line concepts, which leads some to wrongly believe that it must always be connected directly to a line. There are also many misconceptions about what happens on a transmission line, and in particular, what happens at the source end. This document addresses these misconceptions. Unfortunately, many derivations require complex exponential notation, phasor representations of voltage and current, and network theorems. There isn't any alternative if rigor is to be maintained. Section 1 gives some background on the Bruene coupler. Section 2 explains its operation when terminated in a resistance. Section 3 works a simple numerical example on a matched transmission line and load. Section 3 repeats this calculation for a mismatched line and load. Section 4 explains the correct interpretation of the powers read by the Bruene meter. Section 5 explains that a mismatched source always generates additional reflections, and shows how the steady-state waves on the line build up by summing these reflections. Section 6 develops the theory of section 6 further, and shows how the ¯nal waves build up in the mismatched line example given in section 4. Five appendices follow: Appendix A develops the general theory of line reflection where both source and load are mismatched, and the line may be lossy. Appendix B works a simple example to illustrate appendix A. -
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. -
Evaluation of Short-Term Exposure to 2.4 Ghz Radiofrequency Radiation
GMJ.2020;9:e1580 www.gmj.ir Received 2019-04-24 Revised 2019-07-14 Accepted 2019-08-06 Evaluation of Short-Term Exposure to 2.4 GHz Radiofrequency Radiation Emitted from Wi-Fi Routers on the Antimicrobial Susceptibility of Pseudomonas aeruginosa and Staphylococcus aureus Samad Amani 1, Mohammad Taheri 2, Mohammad Mehdi Movahedi 3, 4, Mohammad Mohebi 5, Fatemeh Nouri 6 , Alireza Mehdizadeh3 1 Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Medical Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran 3 Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 4 Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran 5 School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 6 Department of Pharmaceutical Biotechnology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran Abstract Background: Overuse of antibiotics is a cause of bacterial resistance. It is known that electro- magnetic waves emitted from electrical devices can cause changes in biological systems. This study aimed at evaluating the effects of short-term exposure to electromagnetic fields emitted from common Wi-Fi routers on changes in antibiotic sensitivity to opportunistic pathogenic bacteria. Materials and Methods: Standard strains of bacteria were prepared in this study. An- tibiotic susceptibility test, based on the Kirby-Bauer disk diffusion method, was carried out in Mueller-Hinton agar plates. Two different antibiotic susceptibility tests for Staphylococcus au- reus and Pseudomonas aeruginosa were conducted after exposure to 2.4-GHz radiofrequency radiation. The control group was not exposed to radiation. -
A Guide for Radio Operators BROCHURE RADIO TRANSM ANG 3/27/97 8:47 PM Page 2
BROCHURE RADIO TRANSM ANG 3/27/97 8:47 PM Page 17 A Guide for Radio Operators BROCHURE RADIO TRANSM ANG 3/27/97 8:47 PM Page 2 Aussi disponible en français. 32-EN-95539W-01 © Minister of Public Works and Government Services Canada 1996 BROCHURE RADIO TRANSM ANG 3/27/97 8:47 PM Page 3 CUTTING THROUGH... INTERFERENCE FROM RADIO TRANSMITTERS A Guide for Radio Operators This brochure is primarily for amateur and General Radio Service (GRS, commonly known as CB) radio operators. It provides basic information to help you install and maintain your station so you get the best performance and the most enjoyment from it. You will learn how to identify the causes of radio interference in nearby electronic equipment, and how to fix the problem. What type of equipment can be affected by radio interference? Both radio and non-radio devices can be adversely affected by radio signals. Radio devices include AM and FM radios, televisions, cordless telephones and wireless intercoms. Non-radio electronic equipment includes stereo audio systems, wired telephones and regular wired intercoms. All of this equipment can be disturbed by radio signals. What can cause radio interference? Interference usually occurs when radio transmitters and electronic equipment are operated within close range of each other. Interference is caused by: ■ incorrectly installed radio transmitting equipment; ■ an intense radio signal from a nearby transmitter; ■ unwanted signals (called spurious radiation) generated by the transmitting equipment; and ■ not enough shielding or filtering in the electronic equipment to prevent it from picking up unwanted signals. What can you do? 1. -
Compact Integrated Antennas Designs and Applications for the Mc1321x, Mc1322x, and Mc1323x
Freescale Semiconductor Document Number: AN2731 Application Note Rev. 2, 12/2012 Compact Integrated Antennas Designs and Applications for the MC1321x, MC1322x, and MC1323x 1 Introduction Contents 1 Introduction . 1 With the introduction of many applications into the 2 Antenna Terms . 2 2.4 GHz band for commercial and consumer use, 3 Basic Antenna Theory . 3 Antenna design has become a stumbling point for many 4 Impedance Matching . 5 customers. Moving energy across a substrate by use of an 5 Antennas . 8 RF signal is very different than moving a low frequency 6 Miniaturization Trade-offs . 11 voltage across the same substrate. Therefore, designers 7 Potential Issues . 12 who lack RF expertise can avoid pitfalls by simply 8 Recommended Antenna Designs . 13 following “good” RF practices when doing a board 9 Design Examples . 14 layout for 802.15.4 applications. The design and layout of antennas is an extension of that practice. This application note will provide some of that basic insight on board layout and antenna design to improve our customers’ first pass success. Antenna design is a function of frequency, application, board area, range, and costs. Whether your application requires the absolute minimum costs or minimization of board area or maximum range, it is important to understand the critical parameters so that the proper trade-offs can be chosen. Some of the parameters necessary in selecting the correct antenna are: antenna © Freescale Semiconductor, Inc., 2005, 2006, 2012. All rights reserved. tuning, matching, gain/loss, and required radiation pattern. This note is not an exhaustive inquiry into antenna design. It is instead, focused toward helping our customers understand enough board layout and antenna basics to aid in selecting the correct antenna type for their application as well as avoiding the typical layout mistakes that cause performance issues that lead to delays. -
Performance Expectations for Reduced-Size Antennas
High Frequency Design From February 2010 High Frequency Electronics Copyright © 2010 Summit Technical Media, LLC SMALL ANTENNAS Performance Expectations for Reduced-Size Antennas By Gary Breed Editorial Director λ very device that L/ = 0.167 and RRad = 5.5 ohms. The feed- This month’s tutorial article transmits and/or point impedance will be 5.5 –jX, where X is a presents a summary of Ereceives radio sig- large capacitance, as high as 1500 ohms in the the advantages and limita- nals needs an antenna. case of thin dipole. This 5.5 –j1500 ohm tions of electrically-small When that device has a impedance must be matched to the system antennas like those used in small size or limited impedance, typically 50 ohms. many wireless devices space for a classic reso- Small loops and monopoles have similarly nant antenna, various low radiation resistance with high reactance. techniques are used to implement reduced- Matching to highly reactive loads is inherent- size antennas. Those techniques may include ly narrow bandwidth, since the magnitude of inductive or capacitive loading, meandered or the reactance changes rapidly with frequency. spiral construction, high dielectric constant Achieving a broader bandwidth match materials to slow down wave propagation, and requires either complex networks or the intro- embedded structures incorporated into the duction of lossy components. packaging. Each of these methods imposes The use of meandered lines, spirals, fractal some type of limitation when compared to patterns effectively distribute the required monopole, dipole, or resonant loop antennas. inductance over the length of the antenna, This tutorial looks at the key limitations of and can result in higher radiation resistance small antennas, with the intention of illus- and lower loss matching networks. -
Radio and Electronics Cookbook
Radio and Electronics Cookbook Radio and Electronics Cookbook Edited by Dr George Brown, CEng, FIEE, M5ACN OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI Newnes An imprint of Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd A member of the Reed Elsevier plc group First published 2001 © Radio Society of Great Britain 2001 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 0LP. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 0 7506 5214 4 RSGB Lambda House Cranborne Road Potters Bar Herts EN6 3JE Composition by Genesis Typesetting, Laser Quay, Rochester, Kent Printed and bound in Great Britain Contents Preface ix 1. A medium-wave receiver 1 2. An audio-frequency amplifier 4 3. A medium-wave receiver using a ferrite-rod aerial 9 4. A simple electronic organ 12 5. Experiments with the NE555 timer 17 6. -
A Modern Directional Power/SWR Meter Every Ham Needs an RF Power Meter
A Modern Directional Power/SWR Meter Every ham needs an RF power meter. Here’s a high performance unit to build at home. Bill Kaune, W7IEQ first got the idea of designing and build- ing a power meter from a construction I article in The 1997 ARRL Handbook entitled “The Tandem Match — An Transceiver Directional Coupler Tuner Accurate Directional Wattmeter” by John 7:,13%7 32:(5 TRANSMITTER ANTENNA $17 86% INDUCTANCE 0 7 3 ANTENNA Grebenkemper, KI6WX. John described the SELECTION *(1( 9)2$ 3+21(6 &+ 92; %.,1 3$03 $*& 63/,7 15 7; 5; 021, ) 1% $1) /2&. 6&3 67(3 POWER difficulties of building an accurate power N 0,& ) ) ) ) ) METER meter using diodes to convert RF to dc because of the diode’s inherent nonlinearity. He describes a fairly complicated (at least it looked complicated to me) analog circuit that corrects for this nonlinear behavior and Reflected Power Forward Power that also calculates and displays SWR. Shortly after reading this article, I noticed 3(3: 6:5 several articles in QST that described a new $9*: Power Meter integrated circuit, the Analog Devices AD8307, that converts a low level RF signal QS1101Kaune01 into a voltage proportional to the logarithm of the signal’s power. I became intrigued Figure 1 — W7IEQ station setup, including the power meter being described here. with this device because it eliminated the difficulties associated with the use of diodes and would work over a wide range of pow- RF power flowing from the transmitter to over the two sections of RG-8 until they were 1 ers, from milliwatts to the legal limit. -
Range Calculation for 300Mhz to 1000Mhz Communication Systems
APPLICATION NOTE Range Calculation for 300MHz to 1000MHz Communication Systems RANGE CALCULATION Description For restricted-power UHF* communication systems, as defined in FCC Rules and Regula- tions Title 47 Part 15 Subpart C “intentional radiators*”, communication range capability is a topic which generates much interest. Although determined by several factors, communica- tion range is quantified by a surprisingly simple equation developed in 1946 by H.T. Friis of Denmark. This paper begins by introducing the Friis Transmission Equation and examining the terms comprising it. Then, real-world-environment factors which influence RF commu- nication range and how they affect a “Link Budget*” are investigated. Following that, some methods for optimizing RF-link range are given. Range-calculation spreadsheets, including the special case of RKE, are presented. Finally, information concerning FCC rules govern- ing “intentional radiators”, FCC-established radiation limits, and similar reference material is provided. Section 7. “Appendix” on page 13 includes definitions (words are marked with an asterisk *) and formulas. Note: “For additional information, two excel spreadsheets, RKE Range Calculation (MF).xls and Generic Range Calculation.xls, have been attached to this PDF. To open the attachments, in the Attachments panel, select the attachment, and then click Open or choose Open Attachment from the Options menu. For addi- tional information on attachments, please refer to Adobe Acrobat Help menu“ 9144C-RKE-07/15 1. The Friis Transmission Equation For anyone using a radio to communicate across some distance, whatever the type of communication, range capability is inevitably a primary concern. Whether it is a cell-phone user concerned about dropped calls, kids playing with their walkie- talkies, a HAM radio operator with VHF/UHF equipment providing emergency communications during a natural disaster, or a driver opening a garage door from their car in the pouring rain, an expectation for reliable communication always exists. -
Antennas Transmission Lines and Waveguides Are Devices Used To
Antennas Transmission lines and waveguides are devices used to transmit signals in the form of guided electromagnetic waves from a source (generator) to a load. Antennas may be used to transmit signals from a source to a load in the form of directed but unguided waves. Guided Wave Source-Load Connection Examples - power transmission lines, long-haul communications (optical fiber systems), cable television/internet Unguided Wave Source-Load Connection Examples - all wireless applications (phones, Wi-Fi networks, etc.), broadcast television/radio, satellite TV, GPS, radar Antenna - a device used to radiate and/or receive electromagnetic waves. Major Classes of Antennas Wire Antennas - monopole, dipole, loop, helical Aperture Antennas - horn, slot, microstrip patch Reflector Antennas - parabolic dish, corner reflector Antenna Characteristics Antenna impedance - an antenna must be matched to the connecting transmission line or waveguide for efficient radiation or reception. Radiated power - the amount of power radiated by a transmit antenna will limit the separation distance between the transmit and receive antennas. Directivity - the direction in which an antenna radiates or receives power will dictate how the transmit and receive antennas should be positioned (the radiation pattern of the antenna defines the antenna radiated power as a function of direction). Efficiency (losses) - the amount of power dissipated by the antenna should be small in comparison to the amount of power radiated in order to minimize the source power requirements. Reciprocity - most antennas are reciprocal (radiation characteristics are equivalent to the reception characteristics). Examples of non-reciprocal antennas are those containing nonlinear materials. Polarization - the orientation of the fields radiated by the antenna define the antenna polarization. -
Principles of Radiation and Antennas
RaoCh10v3.qxd 12/18/03 5:39 PM Page 675 CHAPTER 10 Principles of Radiation and Antennas In Chapters 3, 4, 6, 7, 8, and 9, we studied the principles and applications of prop- agation and transmission of electromagnetic waves. The remaining important topic pertinent to electromagnetic wave phenomena is radiation of electromag- netic waves. We have, in fact, touched on the principle of radiation of electro- magnetic waves in Chapter 3 when we derived the electromagnetic field due to the infinite plane sheet of time-varying, spatially uniform current density. We learned that the current sheet gives rise to uniform plane waves radiating away from the sheet to either side of it. We pointed out at that time that the infinite plane current sheet is, however, an idealized, hypothetical source. With the ex- perience gained thus far in our study of the elements of engineering electro- magnetics, we are now in a position to learn the principles of radiation from physical antennas, which is our goal in this chapter. We begin the chapter with the derivation of the electromagnetic field due to an elemental wire antenna, known as the Hertzian dipole. After studying the radiation characteristics of the Hertzian dipole, we consider the example of a half-wave dipole to illustrate the use of superposition to represent an arbitrary wire antenna as a series of Hertzian dipoles to determine its radiation fields.We also discuss the principles of arrays of physical antennas and the concept of image antennas to take into account ground effects. Next we study radiation from aperture antennas.