Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472378
N. Takeuchi, T. Yamamoto, A. Mugino, T. Omatsu, M. Gubin, A. Morinaga
Atmospheric trace gas monitoring has increased in importance, especially chloro-fluoro-methane (CFM) species, OH, HO/sub 2/, Cl and ClO radicals which have concentrations of the order of ppt (parts per trillion). Monitoring of this low level concentration is very difficult by ordinary optical methods. As a high-sensitivity optical method, frequency modulation spectroscopy (FMS) has been used. There the signal at the modulation frequency or at its overtone frequency has been measured, so that the optical thickness in the order of 10/sup -5/ or 10/sup -6/ is a technical limit of detection. On the other hand, the frequency stability technique is extraordinary developed, based on phase difference detection, where the stability of 10/sup -13/ to 10/sup -14/ has been achieved. Dual Frequency Modulation (DFM) is one of the most up-to-date technologies in this field. In this paper the authors propose application of this technique for trace gas measurement, and show an example of a simulation of high-sensitivity detection in the case of using a diode laser (LD) as a tunable light source.<>
{"title":"High sensitive detection of trace gases by dual frequency modulation","authors":"N. Takeuchi, T. Yamamoto, A. Mugino, T. Omatsu, M. Gubin, A. Morinaga","doi":"10.1109/COMEAS.1995.472378","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472378","url":null,"abstract":"Atmospheric trace gas monitoring has increased in importance, especially chloro-fluoro-methane (CFM) species, OH, HO/sub 2/, Cl and ClO radicals which have concentrations of the order of ppt (parts per trillion). Monitoring of this low level concentration is very difficult by ordinary optical methods. As a high-sensitivity optical method, frequency modulation spectroscopy (FMS) has been used. There the signal at the modulation frequency or at its overtone frequency has been measured, so that the optical thickness in the order of 10/sup -5/ or 10/sup -6/ is a technical limit of detection. On the other hand, the frequency stability technique is extraordinary developed, based on phase difference detection, where the stability of 10/sup -13/ to 10/sup -14/ has been achieved. Dual Frequency Modulation (DFM) is one of the most up-to-date technologies in this field. In this paper the authors propose application of this technique for trace gas measurement, and show an example of a simulation of high-sensitivity detection in the case of using a diode laser (LD) as a tunable light source.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117322588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472326
R. Fleming, R. Hardesty, J. Reagan
An interagency team of scientists have prepared an implementation plan for a composite water vapor observing system for atmospheric science applications. The team has a broad breadth of experience in the vertically integrated activities that could lead to a composite system producing useful fields of information-by the year 2001. This paper briefly reviews the main socioeconomic requirements which are driving these water vapor measurements; describes the planned elements for the composite system; and challenges the remote sensing community to suggest further viable improvements, subject to the constraints listed in the paper.<>
{"title":"A composite water vapor observing system for atmospheric science applications","authors":"R. Fleming, R. Hardesty, J. Reagan","doi":"10.1109/COMEAS.1995.472326","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472326","url":null,"abstract":"An interagency team of scientists have prepared an implementation plan for a composite water vapor observing system for atmospheric science applications. The team has a broad breadth of experience in the vertically integrated activities that could lead to a composite system producing useful fields of information-by the year 2001. This paper briefly reviews the main socioeconomic requirements which are driving these water vapor measurements; describes the planned elements for the composite system; and challenges the remote sensing community to suggest further viable improvements, subject to the constraints listed in the paper.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131297347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472368
P.Yu. Kostenko, Y.V. Bulka
Radar remote sensing of the sea and land surfaces is considered. Analysis of reflected waves makes it possible to derive information about electro-physical properties and geometric parameters of the surfaces under examination. A new wide practically important class of surface models is described. It is shown that if a profile of a surface relief or its complex scattering function can be approximated by a polynomial then the phase of the scattered field can be uniquely reconstructed upon registered the field magnitude, i.e. the phase problem in the one dimensional case can be successfully solved. Accordingly, a new approach to measured data processing is proposed. Only field intensity is registered and then the phase is recovered. An inverse problem is resolved by means of of well known methods.<>
{"title":"Remote sensing of scattering surface if phase information in registered data is distorted or absent","authors":"P.Yu. Kostenko, Y.V. Bulka","doi":"10.1109/COMEAS.1995.472368","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472368","url":null,"abstract":"Radar remote sensing of the sea and land surfaces is considered. Analysis of reflected waves makes it possible to derive information about electro-physical properties and geometric parameters of the surfaces under examination. A new wide practically important class of surface models is described. It is shown that if a profile of a surface relief or its complex scattering function can be approximated by a polynomial then the phase of the scattered field can be uniquely reconstructed upon registered the field magnitude, i.e. the phase problem in the one dimensional case can be successfully solved. Accordingly, a new approach to measured data processing is proposed. Only field intensity is registered and then the phase is recovered. An inverse problem is resolved by means of of well known methods.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114371482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472339
P. Foldes, F. Marinelli
An analysis is presented which, starting from the radiometric requirements to be satisfied by a parabolic antenna, gives simple guidelines to properly size the primary feed. In particular the beam efficiency and the half power beamwidth of the antenna are taken into account. A loss budget for the beam efficiency is made giving in this way the feed aperture able with its primary pattern to provide the required beam efficiencies values. All the considerations contained in the paper can be qualitatively applied to whatever antenna at the condition that it is an offset parabolic reflector. Nevertheless a quantitative analysis is given taking as a practical case the MIMR (Multifrequency Imaging Microwave Radiometer) antenna optic. Moreover the higher frequency of this radiometer (90 GHz) is taken into account for different reasons. The required tolerances related to the manufacturing of a feed with small dimensions can be met with difficulties. For the above reasons the procedure described is conservative and can be applied without difficulties to lower frequencies. The beam efficiency requirements which give the radiometer temperature resolution are specified for 2 angular zones around the antenna beam peak. It is clear that it is not sufficient to increase the edge taper of the parabola illumination with the enlargement of the feed aperture but it is necessary to take great care to not exceed certain upper limits for the feed aperture diameter to avoid a parabola half power beamwidth larger than the required value of 0.174/spl deg/. It would be preferable to have a primary pattern with a shape similar to a gaussian function and with an adequate edge taper. The degradation factors which affect the beam efficiency are listed.<>
{"title":"A preliminary design procedure to find the aperture diameter and other basic parameters of a feed able to satisfy radiometric requirements","authors":"P. Foldes, F. Marinelli","doi":"10.1109/COMEAS.1995.472339","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472339","url":null,"abstract":"An analysis is presented which, starting from the radiometric requirements to be satisfied by a parabolic antenna, gives simple guidelines to properly size the primary feed. In particular the beam efficiency and the half power beamwidth of the antenna are taken into account. A loss budget for the beam efficiency is made giving in this way the feed aperture able with its primary pattern to provide the required beam efficiencies values. All the considerations contained in the paper can be qualitatively applied to whatever antenna at the condition that it is an offset parabolic reflector. Nevertheless a quantitative analysis is given taking as a practical case the MIMR (Multifrequency Imaging Microwave Radiometer) antenna optic. Moreover the higher frequency of this radiometer (90 GHz) is taken into account for different reasons. The required tolerances related to the manufacturing of a feed with small dimensions can be met with difficulties. For the above reasons the procedure described is conservative and can be applied without difficulties to lower frequencies. The beam efficiency requirements which give the radiometer temperature resolution are specified for 2 angular zones around the antenna beam peak. It is clear that it is not sufficient to increase the edge taper of the parabola illumination with the enlargement of the feed aperture but it is necessary to take great care to not exceed certain upper limits for the feed aperture diameter to avoid a parabola half power beamwidth larger than the required value of 0.174/spl deg/. It would be preferable to have a primary pattern with a shape similar to a gaussian function and with an adequate edge taper. The degradation factors which affect the beam efficiency are listed.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114728736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472329
A. K. Arakelian, A. Hambaryan
The authors have developed a Doppler radar system for the remote sensing of near surface wind speed and for ocean surface roughness. The method also allows for the detection of anomalous atmospheric fields.<>
研制了一种用于近地面风速和海面粗糙度遥感的多普勒雷达系统。该方法还允许检测异常大气场。
{"title":"Microwave Doppler-radar system of sea surface and atmospheric formations remote sensing","authors":"A. K. Arakelian, A. Hambaryan","doi":"10.1109/COMEAS.1995.472329","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472329","url":null,"abstract":"The authors have developed a Doppler radar system for the remote sensing of near surface wind speed and for ocean surface roughness. The method also allows for the detection of anomalous atmospheric fields.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117116720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472376
M. McCormick, C. Hostetler
The first lidar in Earth orbit was recently flown aboard the Space Shuttle Discovery, September 9-20, 1994. The lidar In-space Technology Experiment (LITE) collected 45 hours of 3-wavelength atmospheric backscatter profiles during the 10-day mission. A wide variety of lidar measurements were made, including those of multi-level clouds, tropospheric and stratospheric aerosols, PBL heights, desert aerosols aloft, smoke from biomass burning, and pollution outflows from continents. This paper describes the LITE instrument and its capabilities, the worldwide correlative measurements program, and initial results.<>
{"title":"LITE-the first spaceborne lidar","authors":"M. McCormick, C. Hostetler","doi":"10.1109/COMEAS.1995.472376","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472376","url":null,"abstract":"The first lidar in Earth orbit was recently flown aboard the Space Shuttle Discovery, September 9-20, 1994. The lidar In-space Technology Experiment (LITE) collected 45 hours of 3-wavelength atmospheric backscatter profiles during the 10-day mission. A wide variety of lidar measurements were made, including those of multi-level clouds, tropospheric and stratospheric aerosols, PBL heights, desert aerosols aloft, smoke from biomass burning, and pollution outflows from continents. This paper describes the LITE instrument and its capabilities, the worldwide correlative measurements program, and initial results.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"201 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116487396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472367
O.M. Isaeva, V.A. Sarytchev
For considering the dynamics of an electromagnetic wave, a variety of presentations differing in the values being observed can be suggested. The following can be used as such values: electric intensity and magnetic induction vectors, electric and magnetic intensity vectors or vector potential. Finally, field amplitude or energetic characteristics, including, the description of the polarization state, can be used as observed values. The polarization state can be described after characteristics to be observed have been chosen. The point is that any descriptions connected by isomorphic (mutually unambiguous) transformations are completely equivalent to each other: it is possible to pass from one description to the other without losing anything from its contents.<>
{"title":"Quaternion presentations polarization state","authors":"O.M. Isaeva, V.A. Sarytchev","doi":"10.1109/COMEAS.1995.472367","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472367","url":null,"abstract":"For considering the dynamics of an electromagnetic wave, a variety of presentations differing in the values being observed can be suggested. The following can be used as such values: electric intensity and magnetic induction vectors, electric and magnetic intensity vectors or vector potential. Finally, field amplitude or energetic characteristics, including, the description of the polarization state, can be used as observed values. The polarization state can be described after characteristics to be observed have been chosen. The point is that any descriptions connected by isomorphic (mutually unambiguous) transformations are completely equivalent to each other: it is possible to pass from one description to the other without losing anything from its contents.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131816216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472372
E. Smith, M. Farrar, Xuwu Xiang, J. Turk
The upcoming Tropical Rainfall Measuring Mission (TRMM) to be launched in August, 1997, will offer a much improved instrumentation. In addition to a cloud-radiation budget instrument (CERES) and a lightning detection instrument (LIS) which were developed as part of the Earth Observing System (EOS), the TRMM satellite will carry a set of three new instruments principally devoted to rainfall estimation. This package includes a visible-infrared radiometer called VIRS, a multi-channel dual-polarization passive microwave radiometer called TMI (with a 10.7 GHz capability), and a 14 GHz radar which will represent the first use of a precipitation radar (PR) in space. The addition of the PR instrument creates a new space-based capability for rainfall measurement, particularly when coupled with the TMI radiometer. The two types of measuring systems are based on entirely different physical principles and thus generate markedly different signatures of the hydrometeor profile. Either type of measuring approach by itself presents certain difficulties in retrieving vertically distributed rainrate information, but combined together present various new approaches for more accurate rainfall estimation. This presentation outlines a new type of combined algorithm scheme being developed within the TRMM project called the "Tall Vector" algorithm, representing the emerging technology for the TRMM era insofar as rainfall and latent heating estimation. The basic framework of this approach, which can be considered as a type of physical inversion scheme using incongruent measurement vectors, is presented.<>
{"title":"Prospects for advanced radar-radiometer precipitation retrieval algorithms during the TRMM era","authors":"E. Smith, M. Farrar, Xuwu Xiang, J. Turk","doi":"10.1109/COMEAS.1995.472372","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472372","url":null,"abstract":"The upcoming Tropical Rainfall Measuring Mission (TRMM) to be launched in August, 1997, will offer a much improved instrumentation. In addition to a cloud-radiation budget instrument (CERES) and a lightning detection instrument (LIS) which were developed as part of the Earth Observing System (EOS), the TRMM satellite will carry a set of three new instruments principally devoted to rainfall estimation. This package includes a visible-infrared radiometer called VIRS, a multi-channel dual-polarization passive microwave radiometer called TMI (with a 10.7 GHz capability), and a 14 GHz radar which will represent the first use of a precipitation radar (PR) in space. The addition of the PR instrument creates a new space-based capability for rainfall measurement, particularly when coupled with the TMI radiometer. The two types of measuring systems are based on entirely different physical principles and thus generate markedly different signatures of the hydrometeor profile. Either type of measuring approach by itself presents certain difficulties in retrieving vertically distributed rainrate information, but combined together present various new approaches for more accurate rainfall estimation. This presentation outlines a new type of combined algorithm scheme being developed within the TRMM project called the \"Tall Vector\" algorithm, representing the emerging technology for the TRMM era insofar as rainfall and latent heating estimation. The basic framework of this approach, which can be considered as a type of physical inversion scheme using incongruent measurement vectors, is presented.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128160331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472386
R. Scott, Tiehan Chen, P. Krehbiel
Circularly polarized radiation propagating through regions of tropospheric clouds are depolarized by the constituents of the clouds in two ways: through backscattering and propagation effects. The propagation effects are in turn composed of two components: differential phase and differential attenuation. Tropospheric clouds can consist of water droplets, ice crystals, and liquid and solid precipitation. By coherently correlating the simultaneous signals received in the right-hand and left-hand polarization channels of a circular polarization radar the presence of aligned particles can be detected and this can be used distinguish different components of the cloud. For instance, vertical alignment of ice crystals in the upper portions of the cloud are indicative of strong electrification. The degree of the ice crystal alignment is related to the strength of the electric field. Strong alignment of these ice crystals indicates that the storm has the potential to produce lightning.<>
{"title":"Remote sensing of tropospheric clouds with a dual polarization radar","authors":"R. Scott, Tiehan Chen, P. Krehbiel","doi":"10.1109/COMEAS.1995.472386","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472386","url":null,"abstract":"Circularly polarized radiation propagating through regions of tropospheric clouds are depolarized by the constituents of the clouds in two ways: through backscattering and propagation effects. The propagation effects are in turn composed of two components: differential phase and differential attenuation. Tropospheric clouds can consist of water droplets, ice crystals, and liquid and solid precipitation. By coherently correlating the simultaneous signals received in the right-hand and left-hand polarization channels of a circular polarization radar the presence of aligned particles can be detected and this can be used distinguish different components of the cloud. For instance, vertical alignment of ice crystals in the upper portions of the cloud are indicative of strong electrification. The degree of the ice crystal alignment is related to the strength of the electric field. Strong alignment of these ice crystals indicates that the storm has the potential to produce lightning.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127252415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-04-03DOI: 10.1109/COMEAS.1995.472316
E. L. Moore
A multifrequency coboresighted antenna would be cost effective because many wavelengths utilizing different receiver technologies would be observed with one instrument. Because the size of quasioptical components is determined by wavelength, filtering the lowest frequencies from the beam first allows the system to be compact. Two calibration schemes are then possible, a conventional method for the microwave frequencies and a quasioptical method for the shorter wavelengths. The brassboard instrument described in this paper consists of an offset Cassegrain antenna with a 60/spl times/65 cm aperture and a quasioptical frequency multiplexer with 7 distinct channels at 10, 18, 22, 37, 50-58, 90, and 183 GHz. The frequency selective surfaces (FSS) include 1 dual frequency bandpass filter and 4 perforated ellipsoidal mirrors, which are high pass filters in the band of interest and focusing elements below the cutoff frequency. With the main reflector and subreflector this system is contained in a volume 175/spl times/155/spl times/68.3 cm. The multiplexer by itself has dimensions of 100/spl times/155/spl times/32 cm, which include all feeds, lenses, and fss components. In each band the power is coupled to waveguide via a scalar feed and a lens. In all channels the authors measured beam patterns, gain, cross polarization, return loss, and interchannel isolation.<>
{"title":"A 10-183 GHz common aperture antenna with a quasioptical frequency multiplexer","authors":"E. L. Moore","doi":"10.1109/COMEAS.1995.472316","DOIUrl":"https://doi.org/10.1109/COMEAS.1995.472316","url":null,"abstract":"A multifrequency coboresighted antenna would be cost effective because many wavelengths utilizing different receiver technologies would be observed with one instrument. Because the size of quasioptical components is determined by wavelength, filtering the lowest frequencies from the beam first allows the system to be compact. Two calibration schemes are then possible, a conventional method for the microwave frequencies and a quasioptical method for the shorter wavelengths. The brassboard instrument described in this paper consists of an offset Cassegrain antenna with a 60/spl times/65 cm aperture and a quasioptical frequency multiplexer with 7 distinct channels at 10, 18, 22, 37, 50-58, 90, and 183 GHz. The frequency selective surfaces (FSS) include 1 dual frequency bandpass filter and 4 perforated ellipsoidal mirrors, which are high pass filters in the band of interest and focusing elements below the cutoff frequency. With the main reflector and subreflector this system is contained in a volume 175/spl times/155/spl times/68.3 cm. The multiplexer by itself has dimensions of 100/spl times/155/spl times/32 cm, which include all feeds, lenses, and fss components. In each band the power is coupled to waveguide via a scalar feed and a lens. In all channels the authors measured beam patterns, gain, cross polarization, return loss, and interchannel isolation.<<ETX>>","PeriodicalId":274878,"journal":{"name":"Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123644600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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