University of Groningen. The logistic design of the LOFAR radio telescope Schakel, L.P.

Size: px
Start display at page:

Download "University of Groningen. The logistic design of the LOFAR radio telescope Schakel, L.P."

Transcription

1 University of Groningen The logistic design of the LOFAR radio telescope Schakel, L.P. IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2009 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Schakel, L. P. (2009). The logistic design of the LOFAR radio telescope: an operations Research Approach to optimize imaging performance and construction costs Enschede: PrintPartners Ipskamp B.V., Enschede, The Netherlands Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 Chapter 2 Radio Telescopes 2.1 Introduction This chapter explains the basics of radio telescopes, the types of radio telescopes that exist, and what they can observe in the universe. It is included to provide the reader background information on radio telescopes and to introduce concepts which will be used in later chapters. We start our discussion with the notion of radio telescope. A radio telescope is an observation instrument consisting of one or more antenna systems to study the universe through the measurement of electromagnetic radiation in the radio spectrum. We give an interpretation of the above definition by explaining its keywords: observation instrument, antenna system, electromagnetic radiation, and radio spectrum. The outline of this chapter is as follows. Section 2.2 describes the basic system of a radio telescope and its properties. Section 2.3 explains the instrumentation that has been developed in the last century. Section 2.4 discusses radio wave detection. 2.2 Basics of Radio Telescopes The basic system of a radio telescope consists of three components: (1) an antenna system (i.e., simple receptor, dish antenna, or multi-sensor station), (2) a receiving system (i.e., a system being composed of a mechanism for noise reduction and a mechanism for amplifying and measuring the signal), and (3) a device for recording, monitoring, and displaying the output from the system (i.e., a computer system). Conventional radio telescopes consist of a base with a single fully steerable parabolic dish antenna. The dish antenna has a small antenna placed on its aperture. This antenna is called the feed and can be described as a horn-shaped antenna. The dish antenna acts as a radio reflector focusing the incoming radiation onto the feed. The reflected radiation is then transferred from the feed to the receiving system. Figure 2.1 shows the components and functioning of a conventional radio telescope. 11

3 12 Chapter 2. Radio Telescopes Figure 2.1. A conventional radio telescope A radio telescope is usually indicated by its size and name, the latter depending on the type of the instrumentation or its location. A radio telescope can also be described by a list of properties, which are listed below. Frequency range. The frequency range is the range of frequencies, expressed by a lower and upper frequency, within which radio waves are observed by the instrument. Angular resolution. The angular resolution is the distance, in angular units, between two close objects that can be separated by instrument. It is also called spatial resolution or resolving power. Sensitivity. The sensitivity is the ability to observe radio sources emitting low level radio signals. Collecting area. The collecting area is the area of an instrument capable of collecting electromagnetic radiation. The collecting area is positively related with the instrument s sensitivity. There is a close relationship between the angular resolution of an instrument and the observing frequency, which is inversely proportional to the observing wavelength (see Section 2.4). The angular resolution (ρ) of a radio telescope is approximated by dividing the wavelength of the observed radiation (λ) by the diameter of the telescope (D). Equation (2.1) gives this relationship. In this equation, λ and D are measured in the same length units and the angular resolution ρ is measured in arcseconds (see glossary, p. 259). ( ) ( ) λ 180 ρ 3600 (2.1) D π

4 2.3. Types of Radio Telescopes Types of Radio Telescopes In this section we discuss the types of radio telescopes that have been developed in the twentieth century. The contents of this section is mainly based on Malphrus (1996), Kellermann and Moran (2001), Thompson et al. (2001), and Burke and Graham-Smith (2002) Individual Radio Telescopes The first radio telescope built was the 175-meter long wire antenna of Charles Nordmann in The design of the telescope turned out to be effective, however, Nordmann failed to observe extraterrestrial radio signals due to a sunspot minimum (see glossary, p. 259). Another early radio telescope was constructed by Karl Guthe Jansky in 1930; see Figure 2.2. He built a rotate-able, horizontal and vertical wire skeleton to observe radio signals of 20.5 MHz. Jansky was the first person to discover cosmic radiation. Figure 2.2. The early radio telescope of Karl Jansky c NRAO The first parabolic dish antenna was developed by Grote Reber in 1937; see Figure 2.3. His 9.45-meter paraboloid became the prototype for a whole range of paraboloids radio telescopes. The radio telescope of Reber permitted observations at different frequencies. Reber operated the radio telescope at a wavelength of one centimeter, and later also at wavelengths of 33 centimeters and 1.87 meters. To see deeper and deeper into the universe, and with enhanced angular resolution and sensitivity, the size of single-dish paraboloids was enlarged (see formulae (2.1)). The postwar years initiated the race to build the world s largest radio

5 14 Chapter 2. Radio Telescopes Figure 2.3. Grote Reber and his 9.45-meter paraboloid c NRAO telescope. The first large paraboloid was the 66.5-meter transit telescope, a fixed paraboloid built at Jodrell Bank in the United Kingdom circa The size limitation of paraboloids with a fully steerable base was already encountered in mid It turned out that dish sizes larger than 100 meters were not possible from an engineering point of view. Solutions were found in the base of radio telescopes and the shape of the reflectors. Examples of radio telescopes to which these solutions have been applied are the 305-meter Arecibo telescope (Puerto Rico, USA) and the 2-reflector Kraus telescope (Ohio, USA). The Arecibo telescope consists of a spherical dish built inside a karst depression and hangs on eighteen cables strung from three solid poles. The Kraus telescope consists of a non-steerable parabolic rectangular reflector (109.8 x meters) and a semi-steerable flat rectangular reflector (103.7 x 91.5 meters). The flat reflector of the Kraus telescope reflects the incoming radio signals towards the parabolic reflector where it is focused on the feed. Currently, the largest individual radio telescope is the RATAN-600 telescope. It consists of 895 rectangular reflectors (2 x 7.4 meters) which are arranged along the boundary of a circle with a diameter of 576 meters. RATAN-600 is located in the North Caucasus, Russia. Table 2.1 gives the properties of large individual radio telescopes constructed in the twentieth century.

6 2.3. Types of Radio Telescopes 15 Table 2.1. Large individual twentieth-century radio telescopes Year Name Location Steerability Wavelengths meter Transit Telescope Jodrell Bank, United Kingdom partially steerable 1.87 m meter Dwingeloo Antenna Dwingeloo, The Netherlands fully steerable 3, 6, 18, 21 cm meter Lovell Telescope Jodrell Bank, United Kingdom fully steerable 18 cm - 25 cm 1960 Kraus 2-Reflector Telescope Delaware, Ohio USA partially steerable 21 cm meter Arecibo Telescope Arecibo, Puerto Rico non-steerable 3 cm - 6 m meter Effelsberg Telescope Effelsberg, Germany fully steerable 0.35 mm - 15 m meter RATAN-600 Telescope North Caucasus, Russia fixed location 1 cm - 50 cm meter Green Bank Telescope 1 Green Bank, West Virginia USA fully steerable 3 mm - 3 m The original Green Bank Telescope (GBT) was built in However, due to a lack of maintenance, the telescope collapsed on Tuesday the 15th of November The loss of the 100-meter telescope resulted in the GBT project, a project concerned with the construction of world s largest fully steerable radio telescope. The new radio telescope has roughly the same size as the original telescope; the dimensions of the dish antenna are 100 by 110 meters. The GBT project has been completed in Source: Barrett (2002).

7 16 Chapter 2. Radio Telescopes Radio Arrays In order to improve the angular resolution beyond the size of the instrument the socalled sea interferometer was developed (Pawsey et al., 1946). A sea interferometer is a radio telescope consisting of one antenna system located along the coast side that observes radio signals directly from the sky as well as radio signals that are reflected by the sea surface. The technique of using the sea as reflector of radio signals is known as sea interferometry. Martin Ryle and Derek Vonberg provided a method of combining two or more radio telescopes electronically to simulate one large telescope (Ryle and Vonberg, 1946). The technique is known as radio interferometry. It combines the radio signals from a pair of antenna systems by performing corrections for the time delay resulting from the corresponding separation. Radio interferometry enabled further improvements in the angular resolution. The improvements in angular resolution were realized by radio arrays (or interferometer arrays). A radio array is a radio telescope consisting of two or more separate antenna systems which observe radio waves from the universe. The received radio signals are sent to a base station where they are combined and processed. The first radio array was built by Martin Ryle and Derek Vonberg in Cambridge, England (Ryle and Vonberg, 1946). In a radio array each pair of antenna systems defines a baseline (or interferometer). The baseline has a length (the distance between the two antenna systems) and an orientation (the angle between the line through the two antenna systems and a reference axis). The length of a baseline indicates the ability to resolve nearby objects in the sky (i.e., baseline resolution). The orientation of a baseline gives a directional dimension to the resolution of the object. Figure 2.4 gives an illustration of the baseline induced by two antenna systems A and B in the Euclidean plane. The length and orientation of the baseline are indicated by r AB and θ AB, respectively. Note that the baseline orientation is measured relative to the Y-axis. Figure 2.4. The baseline induced by two antenna systems A and B

8 2.3. Types of Radio Telescopes 17 The imaging performance of a radio array strongly depends on the baselines of the array. It indicates the quality of the images that can be produced by the system. An array should have many baselines of different lengths and orientations in order to have a high-quality resolution standard. The distribution of the baseline lengths across the radio array determines the sensitivity profile of the system. The ideal distribution for the baseline lengths should be determined on the basis of the scientific purposes of the instrument. The size of a radio array is measured by the baseline of maximum length. It determines the angular resolution of the instrument. The angular resolution of a radio array is approximated by replacing the diameter (D) in formulae (2.1) by the length of the maximum baseline (L max ). Data Transmission The transmission of radio signals from the antenna systems to the base station is performed by transmission lines, radio links, or by the shipment of magnetic tapes or hard disks. The type of data transmission to be used mainly depends on the separations between the antenna systems, the wavelength of the transmitted signals, and the required speed of the transmission. In case of physical connections, the transmission speed is measured in terms of data transfer rate which is the number of bits that can be sent in one second. Next, we briefly review the types of data transmission used in radio arrays. Transmission lines are coaxial cables and fiber optic cables. Coaxial cables are used for the transmission of high-frequency radio signals over short distances (i.e., distances up to 500 meters). They allow data transfer rates from 10 to 100 megabit per second. Fiber optic cables are used for the transmission of radio signals of different frequencies. Multi-mode optical fibers allow data transfer rates of 100 megabit per second for distances up to two kilometers, one gigabit per second for distances up to 500 meters, and ten gigabit per second for distances up to 300 meters. Single-mode optical fibers carry light waves with a data transfer rate of ten gigabits per second over distances up to 60 kilometers. Radio links are used for the transmission of high-frequency radio signals over long distances (i.e., distances up to 200 kilometers). The data transfer rate is limited to about 128 megabits per second. An example of a radio array using radio links is the Multi-Element Radio-Linked Interferometer Network (MERLIN) located at Jodrell Bank, United Kingdom. Transmission lines and radio links put restrictions on the size of a radio array. In order to enable arbitrarily long, variable-length baselines the technique of very long baseline interferometry (VLBI) was developed; see Matveenko et al. (1965). VLBI is a technique that records the observations of each antenna system on magnetic tapes or hard disks with timing information. They are later shipped to a base station where the information is combined and synchronized. An example of a radio array using VLBI is the Very Long Baseline Array (VLBA) which is a radio telescope of 10 dish antennas located throughout the whole of the United States.

9 18 Chapter 2. Radio Telescopes Synthesis Techniques The sources in the universe observed by radio telescopes are usually at very remote distances. The radio waves emitted from these sources may be considered as parallel when they arrive at the earth s surface. Since a baseline is in general not normal to the source direction, the actual spacings by which a source is observed is less than the length of the baseline. Therefore, the actual imaging performance of a radio array depends on a mapping of the baselines into a plane normal to the observing direction, which is called the UV plane. A large number of spacings in the UV plane is required to form high-resolution images. A radio array with N A antenna systems gives at most ( N A ) 2 unique baselines. Solutions to the problem have been found in synthesis techniques which are techniques to increase the number of spacings in the UV plane. Next, we discuss several of these techniques. Aperture synthesis (AS) is a technique to generate supplementary baselines by moving antenna systems in two dimensions relative to one another (Blythe, 1957). It can be applied to radio arrays with transportable antenna systems. The technique was first decribed by O Brien, who used a variable spacing two-element interferometer to observe the sun (O Brien, 1953). Nowadays, the notion of aperture synthesis is also used to indicate the type of interferometry that combines signals from two or more static antenna systems to produce images having the same angular resolution as an individual instrument with the same size. Earth rotation synthesis (ERS) is a technique to generate supplementary baselines using the diurnal motion of the earth (Ryle and Hewish, 1960). A source can be studied once, but also over an elongated period when it is above the horizon. In the latter case, the observing direction of the radio array is adjusted over time to observe the same source from different directions. The earth s rotation sweeps the baselines through three-dimensional space thereby causing new spacings with different length and orientation in the UV plane. Figure 2.5 illustrates the concept of ERS for a north-south baseline AB. This baseline has different locations over times, i.e., A t B t is the location of baseline AB at time t and A t+1 B t+1 is its location at time t + 1. We assume that baseline AB receives radiation from a source that emits radio waves parallel to the earth s equator. This radiation is depicted by the double-headed arrows. For convenience, the UV plane is shown on the other side of the earth. Since baseline AB is never perpendicular to the source direction, the projected baselines A tb t and A t+1b t+1 have smaller spacings in the UV plane. Note that projected baselines also have different orientations. Multi-frequency synthesis (MFS) is a technique to generate supplementary spacings in the UV plane by varying the observing frequency (Conway et al., 1990). We will see, in Chapter 5, that the length of a projected baseline in the UV plane also depends on the observing frequency. The effect of varying the observing frequency is that a source is observed over a narrow set of radio frequencies instead of a single one. Therefore, MFS can be considered as a technique that multiplies the number of spacings in the UV plane by changing the lengths of the projected baselines.

10 2.4. Electromagnetic Radiation 19 Figure 2.5. Earth rotation synthesis for a north-south baseline This section ends with an overview of the main characteristics of some wellknown radio arrays. Table 2.2 gives this overview. Each row of Table 2.2 corresponds to one radio array with the entries indicating the name of the instrument, the year of establishment, the location, the cardinality, the size, the type of data transmission, the applied synthesis techniques, and the frequency range, respectively. 2.4 Electromagnetic Radiation An electromagnetic wave is a self-propagating wave in space that exists due to an electric field and a magnetic field. The fields are oriented perpendicular to each other and mutually alternate causing a wave that travels in a direction normal to both the fields. An electromagnetic wave can be described by its wavelength (λ), frequency (f), and energy (E). The wavelength of an electromagnetic wave is defined as the distance between two adjacent crests of the wave. It is measured in units of length. The frequency of an electromagnetic wave is the number of oscillations that it makes per second. It is measured in Hertz (Hz). The energy of an electromagnetic wave is measured in Joules. The three physical properties are directly connected by the speed of light (c) and Planck s constant (h; see glossary, p. 259): f = c λ and E = hf. The first relationship is known as the frequency-wavelength relationship. The collection of all possible types of electromagnetic waves is called the electromagnetic spectrum (EMS). It consists of gamma-rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

11 20 Chapter 2. Radio Telescopes Table 2.2. Characteristics of well-known radio arrays Name Year Location # Systems Size Data transmission Synthesis Freq. range WSRT 1970 The Netherlands 14 3 km Coaxial cables AS/ERS 117-1,200 MHz VLA 1980 New Mexico (USA) km Fiber optic cables AS/ERS 74-50,000 MHz MERLIN 1980 United Kingdom km Radio links AS/ERS ,000 MHz EVN 1980 Intercontinental km VLBI AS/ERS ,214 MHz ATCA 1988 Australia 6 6 km Coaxial cables AS/ERS 1,250-9,200 MHz VLBA 1993 United States km VLBI AS/ERS ,000 MHz GMRT 1999 India km Fiber optic cables AS/ERS 50-1,500 MHz

12 2.4. Electromagnetic Radiation Visibility of the Electromagnetic Spectrum Many sources in the universe emit electromagnetic radiation that can be detected by observation facilities. Examples of sources that emit radio waves are neutral hydrogen and carbon monoxide which are usually found in spiral galaxies and quasars. The visibility of electromagnetic radiation at the earth s surface strongly depends on the atmosphere and the ionosphere. That is, most of the extraterrestrial radiation is absorbed by the atmosphere (i.e., nitrogen, oxygen, ozone, vapor, and carbon dioxide) or blocked by the ionosphere. The optical and radio window are the only parts of the EMS that are completely transparent (Burke and Graham-Smith, 2002). Figure 2.6 shows the terrestrial visibility of the EMS. Figure 2.6. The electromagnetic spectrum and its terrestrial visibility Radio Spectrum Radio telescopes observe the universe through the measurement of electromagnetic radiation in the radio spectrum. The radio spectrum is the frequency range from about several hundreds of hertz to roughly one thousand of gigahertz (i.e., the wavelength varies from 1 millimeter to 100 kilometer). The bounds of the radio spectrum are fairly arbitrary since each scientific field uses its own interpretation. Table 2.3 shows a decomposition of the radio spectrum. Radio telescopes are also limited by the opaqueness of the ionosphere. In fact, terrestrial radio telescopes cannot detect extraterrestrial radio waves when the radio frequency is below 20 MHz or above 300 GHz. These radio frequencies can only be observed by extraterrestrial radio telescopes like the Space Radio Telescope (SRT) (ASC, 2007).

13 22 Chapter 2. Radio Telescopes Table 2.3. The radio spectrum (Wikipedia, 2007) Band name Abbrev. Frequencies Wavelengths Extremely low frequency ELF 3-30 Hz 10, ,000 km Super low frequency SLF Hz 1,000-10,000 km Ultra low frequency ULF Hz km Very low frequency VLF 3-30 khz km Low frequency LF khz 1-10 km Medium frequency MF khz 100-1,000 m High frequency HF 3-30 MHz m Very high frequency VHF MHz 1-10 m Ultra high frequency UHF MHz 100-1,000 mm Super high frequency SHF 3-30 GHz mm Extremely high frequency EHF GHz 1-10 mm

Introduction to Radio Astronomy

Introduction to Radio Astronomy Introduction to Radio Astronomy The Visible Sky, Sagittarius Region 2 The Radio Sky 3 4 Optical and Radio can be done from the ground! 5 Outline The Discovery of Radio Waves Maxwell, Hertz and Marconi

More information

Data and Computer Communications Chapter 4 Transmission Media

Data and Computer Communications Chapter 4 Transmission Media Data and Computer Communications Chapter 4 Transmission Media Ninth Edition by William Stallings Data and Computer Communications, Ninth Edition by William Stallings, (c) Pearson Education - Prentice Hall,

More information

KULLIYYAH OF ENGINEERING

KULLIYYAH OF ENGINEERING KULLIYYAH OF ENGINEERING DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING ANTENNA AND WAVE PROPAGATION LABORATORY (ECE 4103) EXPERIMENT NO 3 RADIATION PATTERN AND GAIN CHARACTERISTICS OF THE DISH (PARABOLIC)

More information

Radio Propagation Fundamentals

Radio Propagation Fundamentals Radio Propagation Fundamentals Concept of Electromagnetic Wave Propagation Mechanisms Modes of Propagation Propagation Models Path Profiles Link Budget Fading Channels Electromagnetic (EM) Waves EM Wave

More information

Introduction to Radio Astronomy. Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn

Introduction to Radio Astronomy. Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn Introduction to Radio Astronomy Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn 1 Contents Radio Waves Radio Emission Processes Radio Noise Radio source names and catalogues Radio telescopes

More information

A bluffer s guide to Radar

A bluffer s guide to Radar A bluffer s guide to Radar Andy French December 2009 We may produce at will, from a sending station, an electrical effect in any particular region of the globe; (with which) we may determine the relative

More information

ELECTROMAGNETIC SPECTRUM ELECTROMAGNETIC SPECTRUM

ELECTROMAGNETIC SPECTRUM ELECTROMAGNETIC SPECTRUM LECTURE:2 ELECTROMAGNETIC SPECTRUM ELECTROMAGNETIC SPECTRUM Electromagnetic waves: In an electromagnetic wave the electric and magnetic fields are mutually perpendicular. They are also both perpendicular

More information

Radio Astronomy for Amateurs. Presented by Keith Payea AG6CI

Radio Astronomy for Amateurs. Presented by Keith Payea AG6CI Radio Astronomy for Amateurs Presented by Keith Payea AG6CI Outline Radio Astronomy Basics: What, How, Why How Amateurs can participate and contribute What is Radio Astronomy? The Study of the non-visible

More information

Computer Networks Lecture -4- Transmission Media. Dr. Methaq Talib

Computer Networks Lecture -4- Transmission Media. Dr. Methaq Talib Computer Networks Lecture -4- Transmission Media Dr. Methaq Talib Transmission Media A transmission medium can be broadly defined as anything that can carry information from a source to a destination.

More information

Antenna & Propagation. Basic Radio Wave Propagation

Antenna & Propagation. Basic Radio Wave Propagation For updated version, please click on http://ocw.ump.edu.my Antenna & Propagation Basic Radio Wave Propagation by Nor Hadzfizah Binti Mohd Radi Faculty of Electric & Electronics Engineering hadzfizah@ump.edu.my

More information

More Radio Astronomy

More Radio Astronomy More Radio Astronomy Radio Telescopes - Basic Design A radio telescope is composed of: - a radio reflector (the dish) - an antenna referred to as the feed on to which the radiation is focused - a radio

More information

Radio Interferometry. Xuening Bai. AST 542 Observational Seminar May 4, 2011

Radio Interferometry. Xuening Bai. AST 542 Observational Seminar May 4, 2011 Radio Interferometry Xuening Bai AST 542 Observational Seminar May 4, 2011 Outline Single-dish radio telescope Two-element interferometer Interferometer arrays and aperture synthesis Very-long base line

More information

Antenna Engineering Lecture 0: Introduction

Antenna Engineering Lecture 0: Introduction Antenna Engineering Lecture 0: Introduction ELC 405a Fall 2011 Department of Electronics and Communications Engineering Faculty of Engineering Cairo University 2 Outline 1 Why Study Antenna Engineering?

More information

Fundamentals of Radio Interferometry

Fundamentals of Radio Interferometry Fundamentals of Radio Interferometry Rick Perley, NRAO/Socorro Fourteenth NRAO Synthesis Imaging Summer School Socorro, NM Topics Why Interferometry? The Single Dish as an interferometer The Basic Interferometer

More information

Antenna Engineering Lecture 0: Introduction

Antenna Engineering Lecture 0: Introduction Antenna Engineering Lecture 0: Introduction ELCN405 Fall 2011 Communications and Computer Engineering Program Faculty of Engineering Cairo University 2 Outline 1 Electromagnetic Spectrum Recent Advances

More information

Contents. ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications. Transmission Media and Spectrum.

Contents. ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications. Transmission Media and Spectrum. 2 ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 3 August 2015

More information

ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications

ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications ITS323: Introduction to Data Communications CSS331: Fundamentals of Data Communications Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 3 August 2015

More information

Introduction to Interferometry. Michelson Interferometer. Fourier Transforms. Optics: holes in a mask. Two ways of understanding interferometry

Introduction to Interferometry. Michelson Interferometer. Fourier Transforms. Optics: holes in a mask. Two ways of understanding interferometry Introduction to Interferometry P.J.Diamond MERLIN/VLBI National Facility Jodrell Bank Observatory University of Manchester ERIS: 5 Sept 005 Aim to lay the groundwork for following talks Discuss: General

More information

Chapter 1 Introduction

Chapter 1 Introduction Wireless Information Transmission System Lab. Chapter 1 Introduction National Sun Yat-sen University Table of Contents Elements of a Digital Communication System Communication Channels and Their Wire-line

More information

Section 1 Wireless Transmission

Section 1 Wireless Transmission Part : Wireless Communication! section : Wireless Transmission! Section : Digital modulation! Section : Multiplexing/Medium Access Control (MAC) Section Wireless Transmission Intro. to Wireless Transmission

More information

William Stallings Data and Computer Communications 7 th Edition. Chapter 4 Transmission Media

William Stallings Data and Computer Communications 7 th Edition. Chapter 4 Transmission Media William Stallings Data and Computer Communications 7 th Edition Chapter 4 Transmission Media Overview Guided - wire Unguided - wireless Characteristics and quality determined by medium and signal For guided,

More information

Phased Array Feeds & Primary Beams

Phased Array Feeds & Primary Beams Phased Array Feeds & Primary Beams Aidan Hotan ASKAP Deputy Project Scientist 3 rd October 2014 CSIRO ASTRONOMY AND SPACE SCIENCE Outline Review of parabolic (dish) antennas. Focal plane response to a

More information

Class Overview. Antenna Fundamentals Repeaters Duplex and Simplex Nets and Frequencies Cool Radio Functions Review

Class Overview. Antenna Fundamentals Repeaters Duplex and Simplex Nets and Frequencies Cool Radio Functions Review Class Overview Antenna Fundamentals Repeaters Duplex and Simplex Nets and Frequencies Cool Radio Functions Review Antennas Antennas An antenna is a device used for converting electrical currents into electromagnetic

More information

Liquidmetal Electromagnetic Properties & RF Shielding Overview

Liquidmetal Electromagnetic Properties & RF Shielding Overview Liquidmetal Electromagnetic Properties & RF Shielding Overview Liquidmetal alloy is more transparent to RF signals than many similar materials 1 Introduction H ow a material interacts with radio frequency

More information

Wave Behavior and The electromagnetic Spectrum

Wave Behavior and The electromagnetic Spectrum Wave Behavior and The electromagnetic Spectrum What is Light? We call light Electromagnetic Radiation. Or EM for short It s composed of both an electrical wave and a magnetic wave. Wave or particle? Just

More information

Radio Interferometers Around the World. Amy J. Mioduszewski (NRAO)

Radio Interferometers Around the World. Amy J. Mioduszewski (NRAO) Radio Interferometers Around the World Amy J. Mioduszewski (NRAO) A somewhat biased view of current interferometers Limited to telescopes that exist or are in the process of being built (i.e., I am not

More information

Vehicle Networks. Wireless communication basics. Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl

Vehicle Networks. Wireless communication basics. Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl Vehicle Networks Wireless communication basics Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl Outline Wireless Signal Propagation Electro-magnetic waves Signal impairments Attenuation Distortion

More information

TSEK02: Radio Electronics Lecture 6: Propagation and Noise. Ted Johansson, EKS, ISY

TSEK02: Radio Electronics Lecture 6: Propagation and Noise. Ted Johansson, EKS, ISY TSEK02: Radio Electronics Lecture 6: Propagation and Noise Ted Johansson, EKS, ISY 2 Propagation and Noise - Channel and antenna: not in the Razavi book - Noise: 2.3 The wireless channel The antenna Signal

More information

TSEK02: Radio Electronics Lecture 6: Propagation and Noise. Ted Johansson, EKS, ISY

TSEK02: Radio Electronics Lecture 6: Propagation and Noise. Ted Johansson, EKS, ISY TSEK02: Radio Electronics Lecture 6: Propagation and Noise Ted Johansson, EKS, ISY 2 Propagation and Noise - Channel and antenna: not in the Razavi book - Noise: 2.3 The wireless channel The antenna Signal

More information

Lecture Outlines Chapter 25. Physics, 3 rd Edition James S. Walker

Lecture Outlines Chapter 25. Physics, 3 rd Edition James S. Walker Lecture Outlines Chapter 25 Physics, 3 rd Edition James S. Walker 2007 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors in

More information

UNIT Derive the fundamental equation for free space propagation?

UNIT Derive the fundamental equation for free space propagation? UNIT 8 1. Derive the fundamental equation for free space propagation? Fundamental Equation for Free Space Propagation Consider the transmitter power (P t ) radiated uniformly in all the directions (isotropic),

More information

Technician License Course Chapter 2 Radio and Signals Fundamentals

Technician License Course Chapter 2 Radio and Signals Fundamentals Technician License Course Chapter 2 Radio and Signals Fundamentals Handling Large and Small Numbers Electronics and Radio use a large range of sizes, i.e., 0.000000000001 to 1000000000000. Scientific Notation

More information

3C5 Telecommunications. what do radios look like? mobile phones. Linda Doyle CTVR The Telecommunications Research Centre

3C5 Telecommunications. what do radios look like? mobile phones. Linda Doyle CTVR The Telecommunications Research Centre 3C5 Telecommunications what do radios look like? Linda Doyle CTVR The Telecommunications Research Centre ledoyle@tcd.ie Oriel/Dunlop House 2009 mobile phones talk is cheap.. bluetooth 3G WLAN/802.11 GSM

More information

PRINCIPLES OF COMMUNICATION SYSTEMS. Lecture 1- Introduction Elements, Modulation, Demodulation, Frequency Spectrum

PRINCIPLES OF COMMUNICATION SYSTEMS. Lecture 1- Introduction Elements, Modulation, Demodulation, Frequency Spectrum PRINCIPLES OF COMMUNICATION SYSTEMS Lecture 1- Introduction Elements, Modulation, Demodulation, Frequency Spectrum Topic covered Introduction to subject Elements of Communication system Modulation General

More information

WiFi Lab Division C Team #

WiFi Lab Division C Team # Team Name: Team Number: Student Names: & Directions: You will be given up to 30 minutes to complete the following written test on topics related to Radio Antennas, as described in the official rules. Please

More information

Interferometry I Parkes Radio School Jamie Stevens ATCA Senior Systems Scientist

Interferometry I Parkes Radio School Jamie Stevens ATCA Senior Systems Scientist Interferometry I Parkes Radio School 2011 Jamie Stevens ATCA Senior Systems Scientist 2011-09-28 References This talk will reuse material from many previous Radio School talks, and from the excellent textbook

More information

WIRELESS TRANSMISSION

WIRELESS TRANSMISSION COMP 635: WIRELESS NETWORKS WIRELESS TRANSMISSION Jasleen Kaur Fall 205 Outline Frequenc Spectrum Ø Usage and Licensing Signals and Antennas Ø Propagation Characteristics Multipleing Ø Space, Frequenc,

More information

Transmission Media. Beulah A L/CSE. 2 July 2008 Transmission Media Beulah A. 1

Transmission Media. Beulah A L/CSE. 2 July 2008 Transmission Media Beulah A. 1 Transmission Media Beulah A L/CSE 2 July 2008 Transmission Media Beulah A. 1 Guided Transmission Media Magnetic Media A tape can hold 7 gigabytes. A box can hold about 1000 tapes. Assume a box can be delivered

More information

Chapter-15. Communication systems -1 mark Questions

Chapter-15. Communication systems -1 mark Questions Chapter-15 Communication systems -1 mark Questions 1) What are the three main units of a Communication System? 2) What is meant by Bandwidth of transmission? 3) What is a transducer? Give an example. 4)

More information

Figure 4-1. Figure 4-2 Classes of Transmission Media

Figure 4-1. Figure 4-2 Classes of Transmission Media Electromagnetic Spectrum Chapter 4 Transmission Media Computers and other telecommunication devices transmit signals in the form of electromagnetic energy, which can be in the form of electrical current,

More information

Introduction to Radio Astronomy!

Introduction to Radio Astronomy! Introduction to Radio Astronomy! Sources of radio emission! Radio telescopes - collecting the radiation! Processing the radio signal! Radio telescope characteristics! Observing radio sources Sources of

More information

Allocation of electromagnetic spectrum

Allocation of electromagnetic spectrum Allocation of electromagnetic spectrum λ= = f 1 In the figure, λ = c/f, where: λ is the wavelength in meters; c is the propagation speed of light (identical to that of a radio wave) in meters per second

More information

Richard Dodson 1/28/2014 NARIT-KASI Winter School

Richard Dodson 1/28/2014 NARIT-KASI Winter School Goals: Technical introduction very short So what to cover? Things which are essential: How radio power is received - I How an interferometer works -II Antenna Fundamentals Black Body Radiation Brightness

More information

Chapter 1: Telecommunication Fundamentals

Chapter 1: Telecommunication Fundamentals Chapter 1: Telecommunication Fundamentals Block Diagram of a communication system Noise n(t) m(t) Information (base-band signal) Signal Processing Carrier Circuits s(t) Transmission Medium r(t) Signal

More information

Unit 1.5 Waves. The number waves per second. 1 Hz is 1waves per second. If there are 40 waves in 10 seconds then the frequency is 4 Hz.

Unit 1.5 Waves. The number waves per second. 1 Hz is 1waves per second. If there are 40 waves in 10 seconds then the frequency is 4 Hz. Unit 1.5 Waves Basic information Transverse: The oscillations of the particles are at right angles (90 ) to the direction of travel (propagation) of the wave. Examples: All electromagnetic waves (Light,

More information

Propagation effects (tropospheric and ionospheric phase calibration)

Propagation effects (tropospheric and ionospheric phase calibration) Propagation effects (tropospheric and ionospheric phase calibration) Prof. Steven Tingay Curtin University of Technology Perth, Australia With thanks to Alan Roy (MPIfR), James Anderson (JIVE), Tasso Tzioumis

More information

Electromagnetic (Light) Waves Electromagnetic Waves

Electromagnetic (Light) Waves Electromagnetic Waves Physics R Date: Review Questions 1. An ocean wave traveling at 3 m/s has a wavelength of 1.6 meters. a. What is the frequency of the wave? b. What is the period of the wave? Electromagnetic (Light) Waves

More information

Physics 476LW. Advanced Physics Laboratory - Microwave Optics

Physics 476LW. Advanced Physics Laboratory - Microwave Optics Physics 476LW Advanced Physics Laboratory Microwave Radiation Introduction Setup The purpose of this lab is to better understand the various ways that interference of EM radiation manifests itself. However,

More information

Unguided Transmission Media

Unguided Transmission Media CS311 Data Communication Unguided Transmission Media by Dr. Manas Khatua Assistant Professor Dept. of CSE IIT Jodhpur E-mail: manaskhatua@iitj.ac.in Web: http://home.iitj.ac.in/~manaskhatua http://manaskhatua.github.io/

More information

Random Phase Antenna Combining for SETI SETICon03

Random Phase Antenna Combining for SETI SETICon03 Random Phase Antenna Combining for SETI SETICon03 Marko Cebokli S57UUU ABSTRACT: Since the direction from which the first ETI signal will arrive is not known in advance, it is possible to relax the phasing

More information

COMMUNICATION SYSTEMS -I

COMMUNICATION SYSTEMS -I COMMUNICATION SYSTEMS -I Communication : It is the act of transmission of information. ELEMENTS OF A COMMUNICATION SYSTEM TRANSMITTER MEDIUM/CHANNEL: The physical medium that connects transmitter to receiver

More information

Chapter 3. Mobile Radio Propagation

Chapter 3. Mobile Radio Propagation Chapter 3 Mobile Radio Propagation Based on the slides of Dr. Dharma P. Agrawal, University of Cincinnati and Dr. Andrea Goldsmith, Stanford University Propagation Mechanisms Outline Radio Propagation

More information

Data and Computer Communications. Tenth Edition by William Stallings

Data and Computer Communications. Tenth Edition by William Stallings Data and Computer Communications Tenth Edition by William Stallings Data and Computer Communications, Tenth Edition by William Stallings, (c) Pearson Education - Prentice Hall, 2013 Wireless Transmission

More information

1. COMMUNICATION 10. COMMUNICATION SYSTEMS GIST The sending and receiving of message from one place to another is called communication. Two important forms of communication systems are (i) Analog and (ii)

More information

16 - INTERSTELLAR COMUNICATION

16 - INTERSTELLAR COMUNICATION NSCI 314 LIFE IN THE COSMOS 16 - INTERSTELLAR COMUNICATION Dr. Karen Kolehmainen Department of Physics, CSUSB http://physics.csusb.edu/~karen/ HOW TO SEARCH FOR LIFE IN OTHER SOLAR SYSTEMS: TRAVEL OR COMMUNICATION?

More information

Lab 12 Microwave Optics.

Lab 12 Microwave Optics. b Lab 12 Microwave Optics. CAUTION: The output power of the microwave transmitter is well below standard safety levels. Nevertheless, do not look directly into the microwave horn at close range when the

More information

Dr. Martina B. Arndt Physics Department Bridgewater State College (MA) Based on work by Dr. Alan E.E. Rogers MIT s Haystack Observatory (MA)

Dr. Martina B. Arndt Physics Department Bridgewater State College (MA) Based on work by Dr. Alan E.E. Rogers MIT s Haystack Observatory (MA) VSRT INTRODUCTION Dr Martina B Arndt Physics Department Bridgewater State College (MA) Based on work by Dr Alan EE Rogers MIT s Haystack Observatory (MA) August, 2009 1 PREFACE The Very Small Radio Telescope

More information

MODULE P6: THE WAVE MODEL OF RADIATION OVERVIEW

MODULE P6: THE WAVE MODEL OF RADIATION OVERVIEW OVERVIEW Wave behaviour explains a great many phenomena, both natural and artificial, for all waves have properties in common. The first topic introduces a basic vocabulary for describing waves. Reflections

More information

Antenna Arrays. EE-4382/ Antenna Engineering

Antenna Arrays. EE-4382/ Antenna Engineering Antenna Arrays EE-4382/5306 - Antenna Engineering Outline Introduction Two Element Array Rectangular-to-Polar Graphical Solution N-Element Linear Array: Uniform Spacing and Amplitude Theory of N-Element

More information

Basics of RFID technology Thomas Holtstiege Technical Manager EECC. October 2009

Basics of RFID technology Thomas Holtstiege Technical Manager EECC. October 2009 Basics of RFID technology Thomas Holtstiege Technical Manager EECC October 2009 About the European EPC Competence Center (EECC) First European EPCglobal accredited performance test center Active since

More information

Phased Array Feeds A new technology for multi-beam radio astronomy

Phased Array Feeds A new technology for multi-beam radio astronomy Phased Array Feeds A new technology for multi-beam radio astronomy Aidan Hotan ASKAP Deputy Project Scientist 2 nd October 2015 CSIRO ASTRONOMY AND SPACE SCIENCE Outline Review of radio astronomy concepts.

More information

Ham Radio Training. Level 1 Technician Level. Presented by Richard Bosch KJ4WBB

Ham Radio Training. Level 1 Technician Level. Presented by Richard Bosch KJ4WBB Ham Radio Training Level 1 Technician Level Presented by Richard Bosch KJ4WBB In this chapter, you ll learn about: What is a radio signal The characteristics of radio signals How modulation adds information

More information

Experiment 12: Microwaves

Experiment 12: Microwaves MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2005 OBJECTIVES Experiment 12: Microwaves To observe the polarization and angular dependence of radiation from a microwave generator

More information

Broad Principles of Propagation 4C4

Broad Principles of Propagation 4C4 Broad Principles of Propagation ledoyle@tcd.ie 4C4 Starting at the start All wireless systems use spectrum, radiowaves, electromagnetic waves to function It is the fundamental and basic ingredient of

More information

INTERFEROMETRY: II Nissim Kanekar (NCRA TIFR)

INTERFEROMETRY: II Nissim Kanekar (NCRA TIFR) INTERFEROMETRY: II Nissim Kanekar (NCRA TIFR) WSRT GMRT VLA ATCA ALMA SKA MID PLAN Introduction. The van Cittert Zernike theorem. A 2 element interferometer. The fringe pattern. 2 D and 3 D interferometers.

More information

Chapter 22. Electromagnetic Waves

Chapter 22. Electromagnetic Waves Ch-22-1 Chapter 22 Electromagnetic Waves Questions 1. The electric field in an EM wave traveling north oscillates in an east-west plane. Describe the direction of the magnetic field vector in this wave.

More information

Antennas & Propagation. CSG 250 Fall 2007 Rajmohan Rajaraman

Antennas & Propagation. CSG 250 Fall 2007 Rajmohan Rajaraman Antennas & Propagation CSG 250 Fall 2007 Rajmohan Rajaraman Introduction An antenna is an electrical conductor or system of conductors o Transmission - radiates electromagnetic energy into space o Reception

More information

RADIATIONS BEYOND THE VISIBLE. Radio UV IR Micro Gamma X-Rays

RADIATIONS BEYOND THE VISIBLE. Radio UV IR Micro Gamma X-Rays Lesson 1 Introduction 1. What name do we give the following set of waves; Radio UV IR Micro Gamma X-Rays 2. Copy the waves shown above in order of wavelength with the shortest at the top. 3. What speed

More information

4.6.1 Waves in air, fluids and solids Transverse and longitudinal waves Properties of waves

4.6.1 Waves in air, fluids and solids Transverse and longitudinal waves Properties of waves 4.6 Waves Wave behaviour is common in both natural and man-made systems. Waves carry energy from one place to another and can also carry information. Designing comfortable and safe structures such as bridges,

More information

OBJECTIVES: PROPAGATION INTRO RADIO WAVES POLARIZATION LINE OF SIGHT, GROUND WAVE, SKY WAVE IONOSPHERE REGIONS PROPAGATION, HOPS, SKIPS ZONES THE

OBJECTIVES: PROPAGATION INTRO RADIO WAVES POLARIZATION LINE OF SIGHT, GROUND WAVE, SKY WAVE IONOSPHERE REGIONS PROPAGATION, HOPS, SKIPS ZONES THE WAVE PROPAGATION OBJECTIVES: PROPAGATION INTRO RADIO WAVES POLARIZATION LINE OF SIGHT, GROUND WAVE, SKY WAVE IONOSPHERE REGIONS PROPAGATION, HOPS, SKIPS ZONES THE IONOSPHERIC LAYERS ABSORPTION AND FADING

More information

Satellite Signals and Communications Principles. Dr. Ugur GUVEN Aerospace Engineer (P.hD)

Satellite Signals and Communications Principles. Dr. Ugur GUVEN Aerospace Engineer (P.hD) Satellite Signals and Communications Principles Dr. Ugur GUVEN Aerospace Engineer (P.hD) Principle of Satellite Signals In essence, satellite signals are electromagnetic waves that travel from the satellite

More information

Polarization orientation of the electric field vector with respect to the earth s surface (ground).

Polarization orientation of the electric field vector with respect to the earth s surface (ground). Free space propagation of electromagnetic waves is often called radio-frequency (rf) propagation or simply radio propagation. The earth s atmosphere, as medium introduces losses and impairments to the

More information

14. COMMUNICATION SYSTEM

14. COMMUNICATION SYSTEM 14. COMMUNICATION SYSTEM SYNOPSIS : INTRODUCTION 1. The exchange of information between a sender and receiver is called communication. 2. The arrangement of devices to transfere the information is called

More information

Very Long Baseline Interferometry. Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn

Very Long Baseline Interferometry. Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn Very Long Baseline Interferometry Richard Porcas Max-Planck-Institut fuer Radioastronomie, Bonn 1 Contents Introduction Principles and Practice of VLBI High angular resolution of long baselines The geophysics

More information

Practicalities of Radio Interferometry

Practicalities of Radio Interferometry Practicalities of Radio Interferometry Rick Perley, NRAO/Socorro 13 th Synthesis Imaging Summer School 29 May 5 June, 2012 Socorro, NM Topics Practical Extensions to the Theory: Finite bandwidth Rotating

More information

Unguided Media and Matched Filter After this lecture, you will be able to Example?

Unguided Media and Matched Filter After this lecture, you will be able to Example? Unguided Media and Matched Filter After this lecture, you will be able to describe the physical and transmission characteristics of various unguided media Example? B.1 Unguided media Guided to unguided

More information

Antennas. Greg Taylor. University of New Mexico Spring Astronomy 423 at UNM Radio Astronomy

Antennas. Greg Taylor. University of New Mexico Spring Astronomy 423 at UNM Radio Astronomy Antennas Greg Taylor University of New Mexico Spring 2011 Astronomy 423 at UNM Radio Astronomy Radio Window 2 spans a wide range of λ and ν from λ ~ 0.33 mm to ~ 20 m! (ν = 1300 GHz to 15 MHz ) Outline

More information

Radio Telescope Antennas:

Radio Telescope Antennas: Radio Telescope Antennas: from Single Dish to Multielement Interferometer Carla Fanti IRA-INAF Bologna MCCT - SKADS 1 What is Radio Astronomy? Astronomy using Radio Waves (cm to 10 m) need a Radiotelescope

More information

Characteristics and techniques of Radio Telescopes

Characteristics and techniques of Radio Telescopes Characteristics and techniques of Radio Telescopes Soon-Joon Yoon (9931093), Hyun-Ju Rhee (9931102), and Won-Seok Choi (9931115) Department of Electrical and Electronic Engineering, Yonsei University E-MAIL:

More information

Radio Data Archives. how to find, retrieve, and image radio data: a lay-person s primer. Michael P Rupen (NRAO)

Radio Data Archives. how to find, retrieve, and image radio data: a lay-person s primer. Michael P Rupen (NRAO) Radio Data Archives how to find, retrieve, and image radio data: a lay-person s primer Michael P Rupen (NRAO) By the end of this talk, you should know: The standard radio imaging surveys that provide FITS

More information

Why Single Dish? Why Single Dish? Darrel Emerson NRAO Tucson

Why Single Dish? Why Single Dish? Darrel Emerson NRAO Tucson Why Single Dish? Darrel Emerson NRAO Tucson Why Single Dish? What's the Alternative? Comparisons between Single-Dish, Phased Array & Interferometers Advantages and Disadvantages of Correlation Interferometer

More information

Lecture 15: Fraunhofer diffraction by a circular aperture

Lecture 15: Fraunhofer diffraction by a circular aperture Lecture 15: Fraunhofer diffraction by a circular aperture Lecture aims to explain: 1. Diffraction problem for a circular aperture 2. Diffraction pattern produced by a circular aperture, Airy rings 3. Importance

More information

Phased Array Feeds A new technology for wide-field radio astronomy

Phased Array Feeds A new technology for wide-field radio astronomy Phased Array Feeds A new technology for wide-field radio astronomy Aidan Hotan ASKAP Project Scientist 29 th September 2017 CSIRO ASTRONOMY AND SPACE SCIENCE Outline Review of radio astronomy concepts

More information

Antennas. Greg Taylor. University of New Mexico Spring Astronomy 423 at UNM Radio Astronomy

Antennas. Greg Taylor. University of New Mexico Spring Astronomy 423 at UNM Radio Astronomy Antennas Greg Taylor University of New Mexico Spring 2017 Astronomy 423 at UNM Radio Astronomy Outline 2 Fourier Transforms Interferometer block diagram Antenna fundamentals Types of antennas Antenna performance

More information

Kamal M. Abood, Moretadha J. Kadhim, Mohammed I. Abd-Almajied, and Zinah F. Kadhim

Kamal M. Abood, Moretadha J. Kadhim, Mohammed I. Abd-Almajied, and Zinah F. Kadhim International Journal of Scientific & Engineering Research, Volume 5, Issue 9, September-2014 899 Improvement for Radio Jove Telescope Antenna Using Directive Angle Yagi Kamal M. Abood, Moretadha J. Kadhim,

More information

Time-of-flight PET with SiPM sensors on monolithic scintillation crystals Vinke, Ruud

Time-of-flight PET with SiPM sensors on monolithic scintillation crystals Vinke, Ruud University of Groningen Time-of-flight PET with SiPM sensors on monolithic scintillation crystals Vinke, Ruud IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you

More information

Signal Flow & Radiometer Equation. Aletha de Witt AVN-Newton Fund/DARA 2018 Observational & Technical Training HartRAO

Signal Flow & Radiometer Equation. Aletha de Witt AVN-Newton Fund/DARA 2018 Observational & Technical Training HartRAO Signal Flow & Radiometer Equation Aletha de Witt AVN-Newton Fund/DARA 2018 Observational & Technical Training HartRAO Understanding Radio Waves The meaning of radio waves How radio waves are created -

More information

Antennas and Propagation. Chapter 4: Antenna Types

Antennas and Propagation. Chapter 4: Antenna Types Antennas and Propagation : Antenna Types 4.4 Aperture Antennas High microwave frequencies Thin wires and dielectrics cause loss Coaxial lines: may have 10dB per meter Waveguides often used instead Aperture

More information

Sw earth Dw Direct wave GRw Ground reflected wave Sw Surface wave

Sw earth Dw Direct wave GRw Ground reflected wave Sw Surface wave WAVE PROPAGATION By Marcel H. De Canck, ON5AU Electromagnetic radio waves can propagate in three different ways between the transmitter and the receiver. 1- Ground waves 2- Troposphere waves 3- Sky waves

More information

Antennas and Propagation. Chapter 5

Antennas and Propagation. Chapter 5 Antennas and Propagation Chapter 5 Introduction An antenna is an electrical conductor or system of conductors Transmission - radiates electromagnetic energy into space Reception - collects electromagnetic

More information

INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad ELECTRONICS AND COMMUNIACTION ENGINEERING QUESTION BANK

INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad ELECTRONICS AND COMMUNIACTION ENGINEERING QUESTION BANK INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad - 500 04 ELECTRONICS AND COMMUNIACTION ENGINEERING QUESTION BANK Course Name : Antennas and Wave Propagation (AWP) Course Code : A50418 Class :

More information

CS441 Mobile & Wireless Computing Communication Basics

CS441 Mobile & Wireless Computing Communication Basics Department of Computer Science Southern Illinois University Carbondale CS441 Mobile & Wireless Computing Communication Basics Dr. Kemal Akkaya E-mail: kemal@cs.siu.edu Kemal Akkaya Mobile & Wireless Computing

More information

Lesson 12: Signal Propagation

Lesson 12: Signal Propagation Lesson 12: Signal Propagation Preparation for Amateur Radio Technician Class Exam Topics HF Propagation Ground-wave Sky-wave Ionospheric regions VHF/UHF Propagation Line-of-sight Tropospheric Bending and

More information

CHAPTER -15. Communication Systems

CHAPTER -15. Communication Systems CHAPTER -15 Communication Systems COMMUNICATION Communication is the act of transmission and reception of information. COMMUNICATION SYSTEM: A system comprises of transmitter, communication channel and

More information

Fig On Fig. 6.1 label one set of the lines in the first order spectrum R, G and V to indicate which is red, green and violet.

Fig On Fig. 6.1 label one set of the lines in the first order spectrum R, G and V to indicate which is red, green and violet. 1 This question is about the light from low energy compact fluorescent lamps which are replacing filament lamps in the home. (a) The light from a compact fluorescent lamp is analysed by passing it through

More information

RECOMMENDATION ITU-R F *

RECOMMENDATION ITU-R F * Rec. ITU-R F.699-6 1 RECOMMENATION ITU-R F.699-6 * Reference radiation patterns for fixed wireless system antennas for use in coordination studies and interference assessment in the frequency range from

More information

The knowledge and understanding for this unit is given below:

The knowledge and understanding for this unit is given below: WAVES AND OPTICS The knowledge and understanding for this unit is given below: Waves 1. State that a wave transfers energy. 2. Describe a method of measuring the speed of sound in air, using the relationship

More information

COURSE: ADVANCED MANUFACTURING PROCESSES. Module No. 5: OTHER PROCESSES

COURSE: ADVANCED MANUFACTURING PROCESSES. Module No. 5: OTHER PROCESSES COURSE: ADVANCED MANUFACTURING PROCESSES Module No. 5: OTHER PROCESSES Lecture No-3 Microwave Processing of Materials Microwave processing is a relatively new and emerging area in material processing.

More information

How can we define intelligence? How common are intelligent civilizations likely to be? Is it even worth trying to communicate?

How can we define intelligence? How common are intelligent civilizations likely to be? Is it even worth trying to communicate? How can we define intelligence? The Search for Extraterrestrial Intelligence (SETI) One possible definition: Civilizations that are at a similar technological level who are willing and able to communicate!

More information

Why Single Dish? Darrel Emerson NRAO Tucson. NAIC-NRAO School on Single-Dish Radio Astronomy. Green Bank, August 2003.

Why Single Dish? Darrel Emerson NRAO Tucson. NAIC-NRAO School on Single-Dish Radio Astronomy. Green Bank, August 2003. Why Single Dish? Darrel Emerson NRAO Tucson NAIC-NRAO School on Single-Dish Radio Astronomy. Green Bank, August 2003. Why Single Dish? What's the Alternative? Comparisons between Single-Dish, Phased Array

More information