Electromagnetic Spectrum • Scientists Have Found That Many Types of Wave Can Be Arranged Together Like the Notes on a Piano Keyboard, to Form a Scale
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Microwave Communications and Radar
2/26 6.014 Lecture 14: Microwave Communications and Radar A. Overview Microwave communications and radar systems have similar architectures. They typically process the signals before and after they are transmitted through space, as suggested in Figure L14-1. Conversion of the signals to electromagnetic waves occurs at the output of a power amplifier, and conversion back to signals occurs at the detector, after reception. Guiding-wave structures connect to the transmitting or receiving antenna, which are generally one and the same in monostatic radar systems. We have discussed antennas and multipath propagation earlier, so the principal novel mechanisms we need to understand now are the coupling of these electromagnetic signals between antennas and circuits, and the intervening propagating structures. Issues we must yet address include transmission lines and waveguides, impedance transformations, matching, and resonance. These same issues also arise in many related systems, such as lidar systems that are like radar but use light beams instead, passive sensing systems that receive signals emitted by the environment either naturally (like thermal radiation) or by artifacts (like motors or computers), and data recording systems like DVD’s or magnetic disks. The performance of many systems of interest is often limited in part by our ability to couple energy efficiently from one port to another, and our ability to filter out deleterious signals. Understanding these issues is therefore an important part of such design effors. The same issues often occur in any system utilizing high-frequency signals, whether or not they are transmitted externally. B. Radar, Lidar, and Passive Systems Figure L14-2 illustrates a standard radar or lidar configuration where the transmitted power Pt is focused toward a target using an antenna with gain Gt. -
Radar, Without Tears
Radar, without tears François Le Chevalier1 May 2017 Originally invented to facilitate maritime navigation and avoid icebergs, at the beginning of the last century, radar took off during the Second World War, especially for aerial surveillance and guidance from the ground or from aircraft. Since then, it has continued to expand its field of employment. 1 What is it, what is it for? Radar is used in the military field for surveillance, guidance and combat, and in the civilian area for navigation, obstacle avoidance, security, meteorology, and remote sensing. For some missions, it is irreplaceable: detecting flying objects or satellites, several hundred kilometers away, monitoring vehicles and convoys more than 100 kilometers round, making a complete picture of a planet through its atmosphere, measuring precipitations, marine currents and winds at long ranges, detecting buried objects or observing through walls – as many functions that no other sensor can provide, and whose utility is not questionable. Without radar, an aerial or terrestrial attack could remain hidden until the last minute, and the rain would come without warning to Roland–Garros and Wimbledon ... Curiously, to do this, the radar uses a physical phenomenon that nature hardly uses: radio waves, which are electromagnetic waves using frequencies between 1 MHz and 100 GHz – most radars operating with wavelength ( = c / f, being the wavelength, c the speed of light, 3.108 m/s, and f the frequency) between 300 m and 3 mm (actually, for most of them, between 1m and 1cm): wavelengths on a human scale ... Indeed, while the optical domain of electromagnetic waves, or even the ultraviolet and infrared domains, are widely used by animals, while the acoustic waves are also widely used by marine or terrestrial animals, there is practically no example of animal use of this vast part, known as "radioelectric", of the electromagnetic spectrum (some fish, Eigenmannia, are an exception to this rule, but they use frequencies on the order of 300 Hz, and therefore very much lower than the "radar" frequencies). -
Band Radar Models FR-2115-B/2125-B/2155-B*/2135S-B
R BlackBox type (with custom monitor) X/S – band Radar Models FR-2115-B/2125-B/2155-B*/2135S-B I 12, 25 and 50* kW T/R up X-band, 30 kW I Dual-radar/full function remote S-band inter-switching I SXGA PC monitor either CRT or color I New powerful processor with LCD high-speed, high-density gate array and I Optional ARP-26 Automatic Radar sophisticated software Plotting Aid (ARPA) on 40 targets I New cast aluminum scanner gearbox I Furuno's exclusive chart/radar overlay and new series of streamlined radiators technique by optional RP-26 VideoPlotter I Shared monitor utilization of Radar and I Easy to create radar maps PC systems with custom PC monitor switching system The BlackBox radar system FR-2115-B, FR-2125-B, FR-2155-B* and FR-2135S-B are custom configured by adding a user’s favorite display to the blackbox radar package. The package is based on a Furuno standard radar used in the FR-21x5-B series with (FURUNO) monitor which is designed to comply with IMO Res MSC.64(67) Annex 4 for shipborne radar and A.823 (19) for ARPA performance. The display unit may be selected from virtually any size of multi-sync PC monitor, either a CRT screen or flat panel LCD display. The blackbox radar system is suitable for various ships which require no specific type approval as a SOLAS compliant radar. The radar is available in a variety of configurations: 12, 25, 30 and 50* kW output, short or long antenna radiator, 24 or 42 rpm scanner, with standard Electronic Plotting Aid (EPA) and optional Automatic Radar Plotting Aid (ARPA). -
Microwave Radar/Radiometer for Arctic Clouds (Mirac): First Insights from the ACLOUD Campaign
Atmos. Meas. Tech., 12, 5019–5037, 2019 https://doi.org/10.5194/amt-12-5019-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Microwave Radar/radiometer for Arctic Clouds (MiRAC): first insights from the ACLOUD campaign Mario Mech1, Leif-Leonard Kliesch1, Andreas Anhäuser1, Thomas Rose2, Pavlos Kollias1,3, and Susanne Crewell1 1Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany 2Radiometer-Physics GmbH, Meckenheim, Germany 3School of Marine and Atmospheric Sciences, Stony Brook University, NY, USA Correspondence: Mario Mech ([email protected]) Received: 12 April 2019 – Discussion started: 23 April 2019 Revised: 26 July 2019 – Accepted: 11 August 2019 – Published: 18 September 2019 Abstract. The Microwave Radar/radiometer for Arctic vertical resolution down to about 150 m above the surface Clouds (MiRAC) is a novel instrument package developed is able to show to some extent what is missed by Cloud- to study the vertical structure and characteristics of clouds Sat when observing low-level clouds. This is especially im- and precipitation on board the Polar 5 research aircraft. portant for the Arctic as about 40 % of the clouds during MiRAC combines a frequency-modulated continuous wave ACLOUD showed cloud tops below 1000 m, i.e., the blind (FMCW) radar at 94 GHz including a 89 GHz passive chan- zone of CloudSat. In addition, with MiRAC-A 89 GHz it is nel (MiRAC-A) and an eight-channel radiometer with fre- possible to get an estimate of the sea ice concentration with a quencies between 175 and 340 GHz (MiRAC-P). -
24 Electromagnetic Waves.Pdf
CHAPTER 24 | ELECTROMAGNETIC WAVES 861 24 ELECTROMAGNETIC WAVES Figure 24.1 Human eyes detect these orange “sea goldie” fish swimming over a coral reef in the blue waters of the Gulf of Eilat (Red Sea) using visible light. (credit: Daviddarom, Wikimedia Commons) Learning Objectives 24.1. Maxwell’s Equations: Electromagnetic Waves Predicted and Observed • Restate Maxwell’s equations. 24.2. Production of Electromagnetic Waves • Describe the electric and magnetic waves as they move out from a source, such as an AC generator. • Explain the mathematical relationship between the magnetic field strength and the electrical field strength. • Calculate the maximum strength of the magnetic field in an electromagnetic wave, given the maximum electric field strength. 24.3. The Electromagnetic Spectrum • List three “rules of thumb” that apply to the different frequencies along the electromagnetic spectrum. • Explain why the higher the frequency, the shorter the wavelength of an electromagnetic wave. • Draw a simplified electromagnetic spectrum, indicating the relative positions, frequencies, and spacing of the different types of radiation bands. • List and explain the different methods by which electromagnetic waves are produced across the spectrum. 24.4. Energy in Electromagnetic Waves • Explain how the energy and amplitude of an electromagnetic wave are related. • Given its power output and the heating area, calculate the intensity of a microwave oven’s electromagnetic field, as well as its peak electric and magnetic field strengths Introduction to Electromagnetic Waves The beauty of a coral reef, the warm radiance of sunshine, the sting of sunburn, the X-ray revealing a broken bone, even microwave popcorn—all are brought to us by electromagnetic waves. -
RADAR Steve Krar Radar Is a System That Uses Radio Waves That Can See
1 RADAR (Radio Detection And Ranging) Steve Krar Radar is a system that uses radio waves that can see hundreds of miles in fog, rain, snow, clouds and darkness. It can identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and ground formation. A transmitter sends radio waves that are aimed at a target and deflected back to a receiver. Although the radio signal returned is usually very weak, radio signals can easily be amplified. Radar is used in many areas such as weather prediction, air traffic control, police detection of speeding traffic, and by the armed forces to detect incoming planes and missiles. The term RADAR was coined in 1941 as an acronym for Radio Detection And Ranging. The concept of using radio waves to detect objects goes back as far as 1902, but the practical system we know as radar began in the late 1930s. British inventors, aided by research from other countries, developed a warning system that could detect airplanes or missiles moving toward England. Basic Principles The basic principle of radar can be easily demonstrated. Imagine facing the side of a mountain or large wall somewhere in the distance. You have a very accurate stopwatch and 'super hearing' to help you. If a person would shout at the top of their voice and accurately time between the voice leaving and the first echo returning, this time is recorded in a radar device. You have now become a basic radar unit. Instead of one person screaming, a powerful radio beam is sent out. -
Management in the Protection from Ionizing Radiation
Management in the Protection from Ionizing Radiation Miodrag Radunovića*, MD, PhD, Krsto Nikolića, MD, Goran Rakićb, BSc aMinistry of Health, Labour and Social Welfare in the Government of Montenegro, Rimski trg 46, 81000, Podgorica, Montenegro. bProving Ground, Seljanovo 36, 85320, Tivat, Montenegro. Abstract. There are numerous types and forms of endangering working and living environment, ranging from natural disasters to nuclear accidents. Challenges of the New Age determined that most of the countries reviewed its strategic decisions in the system of protection from ionizing radiation and nuclear safety and defined in a new way the threats, which could considerably imperil health of the population and national interests as well. Excessive radiation of the pouplation became a serious and actual problem in the era of increasingly mass application of ionizing radiation, especially in medicine. The goal of this work is to reduce the risk through using knowledge and exisitng experiences, in particular when it comes to ionizing radiation in medicine. Optimization of the protcetion in radiology actually means an effort to find the compromise between quality information provided by diagnostics procedure and quality effects of therapy procedure on one side and dose of radiation received by patients on the other. Criteria for the quality management in the protection from ioniizing radiation used in diagnostic radiology was given by the European Commission: European Guidelines on Quality Criteria for Diagnostic Radiographic Images, EUR, 16260. KEYWORDS: Ionizing Radiation, Medicine, Radiology, Risk Management, Protection from Ionizing Radiation 1. Introduction The effects of ionizing and non-ionizing radiation can be expressed directly on the radiated person by means of somatic effects or indirectly, on offspring, by genetic effects. -
The Concept of a Microwave Radar with an Asymmetric Knifelike Beam for the Remote Sensing of Ocean Waves
NOVEMBER 2005 K A R A E V E T A L . 1809 The Concept of a Microwave Radar with an Asymmetric Knifelike Beam for the Remote Sensing of Ocean Waves V. YU.KARAEV,M.B.KANEVSKY, AND G. N. BALANDINA Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia P. CHALLENOR,C.GOMMENGINGER, AND M. SROKOSZ Southampton Oceanography Centre, Southampton, United Kingdom (Manuscript received 2 December 2004, in final form 10 April 2005) ABSTRACT The features of near-nadir probing of the ocean surface from a satellite are investigated, and a new configuration of a microwave radar for the surface slopes measurement is proposed. Numerical modeling is used to examine the feasibility of a spaceborne implementation, to devise a measuring technique, and to develop a data processing algorithm. It is shown that the radar with a knifelike beam (1° ϫ 25°–30°) can be used to measure the variance of surface wave slopes. Using range selection and a new processing procedure to synthesize data, it is possible to achieve the spatial resolution required to study wave processes on the ocean surface from satellites. A new approach to wind speed retrieval at and near nadir is also discussed. 1. Introduction shortcomings, and new radars are constantly being de- veloped (e.g., Lin et al. 2000; Moccia et al. 2000; Hauser Remote sensing is widely used for oceanographic re- et al. 2001). These new systems aim to measure ocean search. At present, spaceborne radars allow us to ob- parameters more precisely or to obtain data across a tain a global overview of the ocean surface state and to wider swath to improve sampling. -
Radar Wind Profiler (RWP) and Radio Acoustic Sounding System (RASS) Instrument Handbook
DOE/SC-ARM-TR-044 Radar Wind Profiler (RWP) and Radio Acoustic Sounding System (RASS) Instrument Handbook P Muradyan R Coulter March 2020 DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. DOE/SC-ARM-TR-044 Radar Wind Profiler (RWP) and Radio Acoustic Sounding System (RASS) Instrument Handbook P Muradyan R Coulter Both at Argonne National Laboratory March 2020 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research P Muradyan and R Coulter, March 2020, DOE/SC-ARM-TR-044 Acronyms and Abbreviations ACAPEX ARM Cloud Aerosol Precipitation Experiment AMF ARM mobile facility ARM Atmospheric Radiation Measurement AT Acceptance Test BBSS balloon-borne sounding system BSRWP beam-steered radar wind profiler CF Central -
RADIATION the Fundamentals of Electromagnetic Radiation Principles
RADIATION The Fundamentals of Electromagnetic Radiation Principles Contents 1. Physics of radiation. 2. Interaction of light with matter. 3. Rayleigh and Mie scattering. 4. Laws of radiation and their implication for radiative processes on earth and its environment. 5. UV radiation and Ozone depletion problem. Physics of Radiation 1. Transport of Radiant Energy (EMW): Electromagnetic radiation is a form of energy derived from oscillating magnetic and electrostatic fields and is capable of transmission through empty space where its velocity is equal to speed of light. 2. Radiation Environment: Almost all the energy for physical and biological processes at the earth’s surface comes from the sun and much of environmental physics is concerned with ways in which this energy is dispersed or stored in thermal, mechanical, or chemical form. Electromagnetic Radiation (i) Electromagnetic Radiation: consists of waves of electric and magnetic energy moving together through space. (ii) All electromagnetic radiation can be classified by frequency from the extremely low to extremely high frequencies. (iii) Extremely high frequency radiation such as Ultraviolet (UV) and X-rays is called “Ionizing Radiation” because it is powerful enough to effect changes in the atoms of matter it strikes, by breaking chemical bonds (ionization) , thus altering their chemical and biological nature. (iv) Electromagnetic radiation at those frequencies below the UV band are generally classified as “Non-Ionizing Radiation” because they typically lack the energy to effect -
Active Phased Array Antenna Development for Modern Shipboard Radar Systems
A. K. AGRAWAL et al. Active Phased Array Antenna Development for Modern Shipboard Radar Systems Ashok K. Agrawal, Bruce A. Kopp, Mark H. Luesse, and Kenneth W. O’Haver Current and future Navy radar requirements are driven by rapidly evolving threats, including both cruise missiles and tactical ballistic missiles. To address these threats, array antennas will have to operate over wider bandwidths with enhanced sensitivity, higher radiated power levels, improved stability, and improved electronic protection to address reduced target radar cross-sections. In addition, there is a growing need for reduced array signatures and a practical need to control costs, including acquisition, operational, and support costs. Active phased array antennas have emerged as a funda- mental technology for addressing these evolving Navy radar system needs. APL’s Air Defense Systems Department has long been at the forefront of phased array antenna development for shipboard radar systems, and the Department is contributing to the development of active array antennas for the new generation of Navy radar systems cur- rently under development. This article provides an overview of the emerging active array antenna technology. INTRODUCTION Shipboard radar systems typically must provide sur- required to perform discrimination and target identifi- veillance of thousands of angular locations and track cation functions. At the same time that radar demands hundreds of targets and guided missiles, all within rela- are increasing, there is a practical need to reduce tively short reaction times. These requirements can be acquisition and operation and support (O&S) costs, met only with phased array antennas that allow elec- improve reliability, and reduce manning requirements. -
Comparison of HF Radar Fields of Directional Wave Spectra Against in Situ Measurements at Multiple Locations
Journal of Marine Science and Engineering Article Comparison of HF Radar Fields of Directional Wave Spectra Against In Situ Measurements at Multiple Locations Guiomar Lopez 1,* and Daniel C. Conley 2 1 Morphodynamique Continentale et Côtière, CNRS UMR 6143, Caen University, 14000 Caen, France 2 Coastal Processes Research Group, School of Biological and Marine Sciences, Plymouth University, Plymouth PL4 8AA, UK * Correspondence: [email protected] Received: 19 June 2019; Accepted: 12 August 2019; Published: 14 August 2019 Abstract: The coastal zone hosts a great number of activities that require knowledge of the spatial characteristics of the wave field, which in coastal seas can be highly heterogeneous. Information of this type can be obtained from HF radars, which offer attractive performance characteristics in terms of temporal and spatial resolution. This paper presents the validation of radar-derived fields of directional wave spectra. These were retrieved from measurements collected with an HF radar system specifically deployed for wave measurement, using an established inversion algorithm. Overall, the algorithm reported accurate estimates of directional spectra, whose main distinctive characteristic was that the spectral energy was typically spread over a slightly broader range of frequencies and directions than in their in situ-measured counterparts. Two errors commonly reported in previous studies, namely the overestimation of wave heights and noise related to short measurement periods, were not observed in our results. The maximum wave height recorded by two in situ devices differed by 30 cm on average from the radar-measured values, and with the exception of the wave spreading, the standard deviations of the radar wave parameters were between 3% and 20% of those obtained with the in situ datasets, indicating the two were similarly grouped around their means.