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Revised multifunction phased array radar (MPAR) network siting analysis
May 26, 2015
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-425
Summary
As part of the NextGen Surveillance and Weather Radar Capability (NSWRC) program, the Federal Aviation Administration (FAA) is currently developing the solution for aircraft and meteorological surveillance in the future National Airspace System (NAS). A potential solution is a multifunction phased array radar (MPAR) that would replace some or all of the single-purpose radar types used in the NAS today. One attractive aspect of MPAR is that the number of radars deployed would decrease, because redundancy in coverage by single-mission sensors would be reduced with a multifunction system. The lower radar count might then result in overall life cycle cost savings, but in order to estimate costs, a reliable estimate of the number of MPARs is needed. Thus this report addresses the question, "If today's weather and aircraft surveillance radars are replaced by a single class of multimission radars, how many would be needed to replicate the current air space coverage over the United States and its territories?" Various replacement scenarios must be considered, since it is not yet determined which of the organizations that own today's radars (the FAA, the National Weather Service (NWS), the different branches of the U.S. military) would join in an MPAR program. It updates a previous study using a revised set of legacy systems, including 81 additional military airbase radars. Six replacement scenarios were considered, depending on the radar mission categories. Scenario 1 would replace terminal radars only, i.e., the Airport Surveillance Radars (ASRs) and the Terminal Doppler Weather Radar (TDWR). Scenario 2 would include the Scenario 1 radars plus the long-range weather radar, commonly known as NEXRAD. Scenario 3 would add the long-range aircraft surveillance radars, i.e., the Air Route Surveillance Radars (ARSRs), to the Scenario 2 radars. To each of these three scenarios, we then add the military's Ground Position Navigation (GPN) airbase radars for Scenarios 1G, 2G, and 3G. We assumed that the new multimission radar would be available in two sizes--a full-size MPAR and a scaled-down terminal MPAR (TMPAR). Furthermore, we assumed that the new radar antennas would have four sides that could be populated by one, two, three, or four phased array faces, such that the azimuthal coverage provided could be scaled from 90 degrees to 360 degrees. Radars in the 50 United States, Guam, Puerto Rico, U.S. Virgin Islands, Guantanamo Bay (Cuba), and Kwajalein (Marshall Islands) were included in the study.
Summary
As part of the NextGen Surveillance and Weather Radar Capability (NSWRC) program, the Federal Aviation Administration (FAA) is currently developing the solution for aircraft and meteorological surveillance in the future National Airspace System (NAS). A potential solution is a multifunction phased array radar (MPAR) that would replace some or all...
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The 2013 Buffalo Area Icing and Radar Study (BAIRS)
March 6, 2015
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-419
Summary
The Next Generation Weather Radar (NEXRAD) network completed a dual polarization upgrade in 2013. The radars now can be used to sense the type of scatterers that cause the radar returns. The scatterers can be hydrometeors, biologicals, or earth-sourced. The ability to reliably interpret the radar-sensed thermodynamic phase of the hydrometeors (solid, liquid, mix) in the context of cloud microphysics and precipitation physics makes it possible to assess the icing hazard potential to aviation. That assessment for Federal Aviation Administration (FAA) purposes would necessarily be performed by automated algorithms based in hydrometeor classification terms. The truth as to the icing hazard aloft (where the radar scans) is required to ascertain the value of such algorithms. The Buffalo Area Icing and Radar Study (BAIRS) of 2013 was a partnership between MIT Lincoln Laboratory (LL) and the National Research Council of Canada (NRC) to perform in situ icing missions within the surveillance range of the dual polarization NEXRAD in Buffalo, NY. The goal of these 2013 missions, and the subject of this report, was to target specific winter weather scenarios known to exhibit an aviation icing hazard for the purpose of quantifying the microphysical properties of the target zones and verifying the presence of supercooled liquid water (SLW) to support validation of hydrometeor classification algorithms. These are the first such missions to execute in situ measurements within a NEXRAD's surveillance range running with the fielded, operational NEXRAD hydrometeor classifier. NRC's Convair-580 instrumented research plane was used for three icing missions covering 14 hours. Three distinctly different winter weather scenarios were encountered. This document details the analysis of in situ data such as particle type and liquid water content (LWC) with NEXRAD dual polarization parameters for the three missions. The BAIRS analysis identified these key findings: -NEXRAD radar returns are prevalent in conditions of supercooled water, -NEXRAD classification shows positive results based on particle imagery, -NEXRAD "dry snow" class masks the presence of mixed phase potential icing hazard, -NEXRAD "unknown" class contains diverse regions of icing hazard potential, and there are methods to classify some of these regions, and -In situ aircraft observations are an important tool to both verify algorithm performance and guide further development.
Summary
The Next Generation Weather Radar (NEXRAD) network completed a dual polarization upgrade in 2013. The radars now can be used to sense the type of scatterers that cause the radar returns. The scatterers can be hydrometeors, biologicals, or earth-sourced. The ability to reliably interpret the radar-sensed thermodynamic phase of the...
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Measurements of differential reflectivity in snowstorms and warm season stratiform systems
March 1, 2015
Journal Article
Published in:
J. Appl. Meteor. Climatol., Vol. 54, No. 3, 2015, pp. 573-95.
Topic:
R&D area:
R&D group:
Summary
The organized behavior of differential radar reflectivity (ZDR) is documented in the cold regions of a wide variety of stratiform precipitation types occurring in both winter and summer. The radar targets and attendant cloud microphysical conditions are interpreted within the context of measurements of ice crystal types in laboratory diffusion chambers in which humidity and temperature are both stringently controlled. The overriding operational interest here is in the identification of regions prone to icing hazards with long horizontal paths. Two predominant regimes are identified: category A, which is typified by moderate reflectivity (from 10 to 30 dBZ) and modest +ZDR values (from 0 to 13 dB) in which both supercooled water and dendritic ice crystals (and oriented aggregates of ice crystals) are present at a mean temperature of -13 degrees C, and category B, which is typified by small reflectivity (from -10 to +10 dBZ) and the largest +ZDR values (from +3 to +7 dB), in which supercooled water is dilute or absent and both flat-plate and dendritic crystals are likely. The predominant positive values for ZDR in many case studies suggest that the role of an electric field on ice particle orientation is small in comparison with gravity. The absence of robust +ZDR signatures in the trailing stratiform regions of vigorous summer squall lines may be due both to the infusion of noncrystalline ice particles (i.e., graupel and rimed aggregates) from the leading deep convection and to the effects of the stronger electric fields expected in these situations. These polarimetric measurements and their interpretations underscore the need for the accurate calibration of ZDR.
Summary
The organized behavior of differential radar reflectivity (ZDR) is documented in the cold regions of a wide variety of stratiform precipitation types occurring in both winter and summer. The radar targets and attendant cloud microphysical conditions are interpreted within the context of measurements of ice crystal types in laboratory diffusion...
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Secondary Surveillance Phased Array Radar (SSPAR): initial feasibility study
February 6, 2014
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-416
Summary
The U.S. Federal Aviation Administration is deploying Automatic Dependent Surveillance-Broadcast (ADS-B) to provide next-generation surveillance derived through down- and cross-link of global positioning satellite (GPS) navigation data. While ADS-B will be the primary future surveillance system, FAA recognizes that backup surveillance capabilities must be provided to assure that air traffic control (ATC) services can continue to be provided when individual aircraft transponders fail and during localized, short-duration GPS outages. This report describes a potential ADS-B backup capability, Secondary Surveillance Phased Array Radar or SSPAR. SSPAR will interrogate aircraft transponders and receive replies using a sparse, non-rotating array of approximately 17 omnidirectional (in azimuth) antennae. Each array element will transmit and receive independently so as to form directional transmit beams for transponder interrogation, and support high-resolution direction finding for received signals. Because each SSPAR element is independently digitized, transponder returns from all azimuths can be equipped with Traffic Alert and Collision Avoidance System (TCAS) and ADS-B avionics to reduce spectrum usage and maintain the high surveillance update rate (~1 per second) achieved by ADS-B. Recurring costs for SSPAR will be low since it involves no moving parts and the number of array channels is small. This report describes an SSPAR configuration supporting terminal operations. We consider interrogation and receive approaches, antenna array configuration, signal processing and preliminary performance analysis. An analysis of SSPAR's impact on spectrum congestion in the beacon radar band is presented, as are concepts for integrating SSPAR and next generation primary radar to improve the efficiency and accuracy of aircraft and weather surveillance.
Summary
The U.S. Federal Aviation Administration is deploying Automatic Dependent Surveillance-Broadcast (ADS-B) to provide next-generation surveillance derived through down- and cross-link of global positioning satellite (GPS) navigation data. While ADS-B will be the primary future surveillance system, FAA recognizes that backup surveillance capabilities must be provided to assure that air traffic...
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A least mean squares approach of iterative array calibration for scalable digital phased array radar panels
October 15, 2013
Conference Paper
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Summary
This paper describes a semiautonomous approach to calibrate a phased array system, with particular use on an S-band aperture that is being developed at MIT Lincoln Laboratory. Each element of the array is controlled by an independent digital phase shifter, whose control signal may be uniquely defined. As active electronically steerable arrays (AESAs) continually evolve towards mostly digital paradigms that will support real-time computing, as opposed to look-up table approaches, then adaptive calibration approaches may be pursued for maximum AESA performance. This calibration work is being completed as one component of Lincoln Laboratory's effort within the multifunction phased array radar (MPAR) initiative.
Summary
This paper describes a semiautonomous approach to calibrate a phased array system, with particular use on an S-band aperture that is being developed at MIT Lincoln Laboratory. Each element of the array is controlled by an independent digital phase shifter, whose control signal may be uniquely defined. As active electronically...
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A method for improved cross-pol isolation based on the use of auxiliary elements
October 15, 2013
Conference Paper
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Summary
This paper describes a method to answer the following questions: can several of the elements of a phased array be employed as auxiliary (AUX) elements and how can the phase of each be adjusted so that the (1) cross-polarization (cross-pol) isolation is minimized to 40 dB, (2) the sidelobe levels of the main lobe are minimally impacted, and (3) the width and height of the main lobe are minimally impacted? This calibration work is being completed as one component of Lincoln Laboratory's effort within the multifunction phased array radar (MPAR) initiative. Devoting a few of the elements to serve as the AUX channels to specifically operate to mitigate the effects of the cross-pol influence, the distributed sidelobe levels will not suffer much impact; yet, the impact of the AUX elements will have deepened the cross-pol isolation at the peak of the co-polar beam can occur because the AUX elements can achieve a high degree of narrowband angular resolution.
Summary
This paper describes a method to answer the following questions: can several of the elements of a phased array be employed as auxiliary (AUX) elements and how can the phase of each be adjusted so that the (1) cross-polarization (cross-pol) isolation is minimized to 40 dB, (2) the sidelobe levels...
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Dual-polarization challenges in weather radar requirements for multifunction phased array radar
October 15, 2013
Conference Paper
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Summary
This paper summarizes the challenges in achieving (and even specifying) the antenna polarization accuracy requirements for the Multifunction Phased Array Radar (MPAR) and the progress that has been made towards meeting these requirements through demonstrations and theoretical investigations.
Summary
This paper summarizes the challenges in achieving (and even specifying) the antenna polarization accuracy requirements for the Multifunction Phased Array Radar (MPAR) and the progress that has been made towards meeting these requirements through demonstrations and theoretical investigations.
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Multi-lithic phased array architecture for airborne sense and avoid radar
October 15, 2013
Conference Paper
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Summary
Transmit and receive Ku-band phased array designs are described for testing an airborne sense and avoid radar. The arrays are small with a size of 24 cm x 9 cm and operate from 13 to 17 GHz with electronic scanning from plus of minus 45 degrees in azimuth and plus of minus 30 degrees in elevation. A novel design architecture allows the use of multiple multilayered printed circuit boards and simple air cooling.
Summary
Transmit and receive Ku-band phased array designs are described for testing an airborne sense and avoid radar. The arrays are small with a size of 24 cm x 9 cm and operate from 13 to 17 GHz with electronic scanning from plus of minus 45 degrees in azimuth and plus...
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On the development of a tileable LRU for the NextGen surveillance and weather radar capability program
October 15, 2013
Conference Paper
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Summary
MIT Lincoln Laboratory is working towards the development of a tileable radar panel to satisfy multimission needs. A combination of custom and commercial off-the-shelf (COTS) Monolithic Microwave Integrated Circuits (MMICs) have been developed and/or employed to achieve the required system functionality. The integrated circuits (ICs) are integrated into a low cost T/R module compatible with commercial printed circuit board (PCB) manufacturing. Sixty-four of the transmit/receive (T/R) modules are integrated onto the aperture PCB in an 8x8 lattice. In addition to the T/R elements, the aperture PCB incorporates transmit and receive beamformers, power and logic distribution, and radiating elements. The aperture PCB is coupled with a backplane PCB to form a panel, the line replaceable unit (LRU) for the multifunction phased array radar (MPAR) initiative. This report summarizes the evaluation of the second iteration LRU aperture PCB and T/R element. Support fixturing was developed and paired with the panel to enable backplane functionality sufficient to support the test objective.
Summary
MIT Lincoln Laboratory is working towards the development of a tileable radar panel to satisfy multimission needs. A combination of custom and commercial off-the-shelf (COTS) Monolithic Microwave Integrated Circuits (MMICs) have been developed and/or employed to achieve the required system functionality. The integrated circuits (ICs) are integrated into a low...
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Ultrawideband cavity-backed resistively loaded planar dipole array for ground penetrating radar
October 15, 2013
Journal Article
Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.
Topic:
R&D area:
Summary
An ultrawideband (UWB) cavity-backed resistively loaded planar dipole array antenna has been developed for the 100 to 400 MHz frequency range for ground penetrating radar applications. The antenna has been designed with a 3m aperture to perform surveys of a wide swath of ground from a moving vehicle. The performance of the UWB array is quantified by moment method simulations of the electromagnetic field penetration into lossy soil. Integration of the UWB array onto vehicle is discussed.
Summary
An ultrawideband (UWB) cavity-backed resistively loaded planar dipole array antenna has been developed for the 100 to 400 MHz frequency range for ground penetrating radar applications. The antenna has been designed with a 3m aperture to perform surveys of a wide swath of ground from a moving vehicle. The performance...
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