The prototype of a low cost 24 GHz FM-CW-Doppler radar rain profiler operated since June 1994 by ... more The prototype of a low cost 24 GHz FM-CW-Doppler radar rain profiler operated since June 1994 by the Meteorological Institute of the University of Hamburg is described. This prototype only consists of off-the-shelf components while the signal processing electronics was developed at the Meteorological Institute. The whole system is compact and easy to transport. After a short introduction to the principle and properties of the FM-CW-Doppler radar, its use in the derivation of rain rate and liquid water content (LWC) from Doppler profiler spectra is explained. Also possible error sources are mentioned. Using a series of measurements of the 24 GHz FM-CW-Doppler profiler taken during the field campaign DROPME 94 in June 1994 at Itzehoe near Hamburg, explicit rain parameters can be derived. Drop size spectra as well as time series of rain rate and liquid water content (LWC) are shown. Finally, plans for further radar improvement and future operations are presented.
2015 8th UK, Europe, China Millimeter Waves and THz Technology Workshop (UCMMT), 2015
The activities for upgrading the Rutherford Appleton Laboratory millimetre wave radar cloud profi... more The activities for upgrading the Rutherford Appleton Laboratory millimetre wave radar cloud profiler are presented. The motivation for these activities and the approach are introduced. First results of these activities are presented.
A 94 GHz FM-CW Doppler radar with a solid state transmitter is described. The radar front end was... more A 94 GHz FM-CW Doppler radar with a solid state transmitter is described. The radar front end was designed and constructed at the Technical University in Hamburg-Harburg. The transmitted power of approximately 1.6 W is provided by five IMPATT diodes phase locked by a GUNN Voltage Controlled Oscillator (VCO). Four of the diode outputs are joined in a power combiner, which is the heart of the power generating system. The signal analyzing system contains a TI320C30 digital signal processor and uses a 10 MHz 12 bit ADC. The radar will be used to verify or improve cloud models. In addition to the vertical cloud distribution, the radar is expected to provide the vertical wind component in clouds using cloud droplets as tracers. Monitoring entrainment processes through cloud tops is the main goal. First measurements showed that the receiver noise was far above the level expected theoretically from the specifications of the mixer and other components in the receiver. Nevertheless, first Dop...
Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing
Describes a millimetre radar system for the measurement of clouds. The 94 GHz cloud profiler is a... more Describes a millimetre radar system for the measurement of clouds. The 94 GHz cloud profiler is a bistatic system with an average transmitted power of 1.6 W and it is built up using only semiconductor devices. Due to the modular design power upgrade is possible. It's size without antenna is approx. 65cmĂ—42cmĂ—22cm. The weight of the system is about 25
IEEE International Geoscience and Remote Sensing Symposium
The Institute for Tropospheric Research (IfT) in Leipzig, Germany, operates a number of airborne ... more The Institute for Tropospheric Research (IfT) in Leipzig, Germany, operates a number of airborne in situ probes for cloud microphysical properties, and ground based and airborne radiation measurement tools. To enhance information about clouds for radiative transfer calculation and research, IfT decided to add a cloud radar to its equipment. In the final state, this radar system will be applicable for dual purpose operation in ground based and airborne modes. This requirement defined a number of constraints concerning size, weight, and power supply.
Geoscience and Remote Sensing IEEE International Symposium, 2000
Continental clouds consisting of small droplets partly reveal systematic discrepancies between th... more Continental clouds consisting of small droplets partly reveal systematic discrepancies between the calculated and measured radiative properties that need to be resolved. One possible explanation is the horizontal inhomogeneities of microphysical cloud properties. A tool to characterize these is the radar technique. For clouds dominated by larger droplets, the ability of the millimeter wave radar technique to retrieve multi-dimensional microphysical
Journal of Atmospheric and Oceanic Technology, 2001
Abstract The evaluation of backscatter spectra of clouds and precipitation measured with Doppler ... more Abstract The evaluation of backscatter spectra of clouds and precipitation measured with Doppler radar profilers allows the retrieval of a number of important atmospheric parameters. This retrieval leads to inaccurate results if vertical wind parameters are not taken into account. An algorithm allowing the correction of these errors by solely using profiler spectra is introduced. The algorithm allows the retrieval of vertical wind parameters by fitting a special function to a part of the backscatter spectra. This function is derived and a sensitivity analysis on input parameters for the retrieved values is performed. Further processing of the spectra to calculate drop size distribution, liquid water content, and rain rate is described. Performance and restrictions of the retrieval algorithm are demonstrated by means of measurements taken with a unique 94-GHz frequency modulated–continuous wave Doppler radar profiler and collocated 915-MHz and 2.8-GHz profilers. The results are discussed, and operational s...
2016 IEEE 9th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT), 2016
STFC / RAL Space has been involved in the development of an extensive variety of satellite missio... more STFC / RAL Space has been involved in the development of an extensive variety of satellite mission payloads operating across a wide range of the electromagnetic spectrum. The RAL Space Millimetre-wave Technology Group (MMTG) has undertaken the development of instrumentation in support of spaceborne earth observation. Most recently, the MMTG is contributing towards a next generation of weather monitoring satellites that will utilise state-of-the-art low-noise amplifier (LNA) technology as the first reception stage of heterodyne receivers. This contribution describes the performance optimisation of an LNA used in a 183GHz receiver chain. Device optimisation includes variation in impedance transformation between waveguide and LNA millimetre-wave integrated circuit (MMIC), and under different MMIC DC bias conditions, to achieve required performance. Extensive and accurate LNA measurements have been made and, in addition to the optimisation procedures used, example results will be presen...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
The application of digital signal generation for a Radar Wind Profiler (RWP) utilising Frequency ... more The application of digital signal generation for a Radar Wind Profiler (RWP) utilising Frequency Modulated Continuous Wave (FMCW) operation is described, and the progress of the design to Technology Readiness Level 3 (TRL 3) is demonstrated. The technology and the methods for the TRL assessment are described, and results of the TRL assessment are presented. Conclusion and outlook complete this contribution.
Since many years Doppler radar profilers are known as valuable tools to retrieve profiles of rain... more Since many years Doppler radar profilers are known as valuable tools to retrieve profiles of rain rate and further rain parameters (e.g. Wakasugi et al. (1986)). Applying well established relations for terminal fall velocity, shape and backscatter cross section of rain drops allows to derive rain rate without empirical assumptions. For calculating the backscatter cross section, the flattening of rain drops (see e.g. Pruppacher and Klett (1997)) constitutes a nonnegligible error source.
The prototype of a low cost 24 GHz FM-CW-Doppler radar rain profiler operated since June 1994 by ... more The prototype of a low cost 24 GHz FM-CW-Doppler radar rain profiler operated since June 1994 by the Meteorological Institute of the University of Hamburg is described. This prototype only consists of off-the-shelf components while the signal processing electronics was developed at the Meteorological Institute. The whole system is compact and easy to transport. After a short introduction to the principle and properties of the FM-CW-Doppler radar, its use in the derivation of rain rate and liquid water content (LWC) from Doppler profiler spectra is explained. Also possible error sources are mentioned. Using a series of measurements of the 24 GHz FM-CW-Doppler profiler taken during the field campaign DROPME 94 in June 1994 at Itzehoe near Hamburg, explicit rain parameters can be derived. Drop size spectra as well as time series of rain rate and liquid water content (LWC) are shown. Finally, plans for further radar improvement and future operations are presented.
2015 8th UK, Europe, China Millimeter Waves and THz Technology Workshop (UCMMT), 2015
The activities for upgrading the Rutherford Appleton Laboratory millimetre wave radar cloud profi... more The activities for upgrading the Rutherford Appleton Laboratory millimetre wave radar cloud profiler are presented. The motivation for these activities and the approach are introduced. First results of these activities are presented.
A 94 GHz FM-CW Doppler radar with a solid state transmitter is described. The radar front end was... more A 94 GHz FM-CW Doppler radar with a solid state transmitter is described. The radar front end was designed and constructed at the Technical University in Hamburg-Harburg. The transmitted power of approximately 1.6 W is provided by five IMPATT diodes phase locked by a GUNN Voltage Controlled Oscillator (VCO). Four of the diode outputs are joined in a power combiner, which is the heart of the power generating system. The signal analyzing system contains a TI320C30 digital signal processor and uses a 10 MHz 12 bit ADC. The radar will be used to verify or improve cloud models. In addition to the vertical cloud distribution, the radar is expected to provide the vertical wind component in clouds using cloud droplets as tracers. Monitoring entrainment processes through cloud tops is the main goal. First measurements showed that the receiver noise was far above the level expected theoretically from the specifications of the mixer and other components in the receiver. Nevertheless, first Dop...
Conference Proceedings Second Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing
Describes a millimetre radar system for the measurement of clouds. The 94 GHz cloud profiler is a... more Describes a millimetre radar system for the measurement of clouds. The 94 GHz cloud profiler is a bistatic system with an average transmitted power of 1.6 W and it is built up using only semiconductor devices. Due to the modular design power upgrade is possible. It's size without antenna is approx. 65cmĂ—42cmĂ—22cm. The weight of the system is about 25
IEEE International Geoscience and Remote Sensing Symposium
The Institute for Tropospheric Research (IfT) in Leipzig, Germany, operates a number of airborne ... more The Institute for Tropospheric Research (IfT) in Leipzig, Germany, operates a number of airborne in situ probes for cloud microphysical properties, and ground based and airborne radiation measurement tools. To enhance information about clouds for radiative transfer calculation and research, IfT decided to add a cloud radar to its equipment. In the final state, this radar system will be applicable for dual purpose operation in ground based and airborne modes. This requirement defined a number of constraints concerning size, weight, and power supply.
Geoscience and Remote Sensing IEEE International Symposium, 2000
Continental clouds consisting of small droplets partly reveal systematic discrepancies between th... more Continental clouds consisting of small droplets partly reveal systematic discrepancies between the calculated and measured radiative properties that need to be resolved. One possible explanation is the horizontal inhomogeneities of microphysical cloud properties. A tool to characterize these is the radar technique. For clouds dominated by larger droplets, the ability of the millimeter wave radar technique to retrieve multi-dimensional microphysical
Journal of Atmospheric and Oceanic Technology, 2001
Abstract The evaluation of backscatter spectra of clouds and precipitation measured with Doppler ... more Abstract The evaluation of backscatter spectra of clouds and precipitation measured with Doppler radar profilers allows the retrieval of a number of important atmospheric parameters. This retrieval leads to inaccurate results if vertical wind parameters are not taken into account. An algorithm allowing the correction of these errors by solely using profiler spectra is introduced. The algorithm allows the retrieval of vertical wind parameters by fitting a special function to a part of the backscatter spectra. This function is derived and a sensitivity analysis on input parameters for the retrieved values is performed. Further processing of the spectra to calculate drop size distribution, liquid water content, and rain rate is described. Performance and restrictions of the retrieval algorithm are demonstrated by means of measurements taken with a unique 94-GHz frequency modulated–continuous wave Doppler radar profiler and collocated 915-MHz and 2.8-GHz profilers. The results are discussed, and operational s...
2016 IEEE 9th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT), 2016
STFC / RAL Space has been involved in the development of an extensive variety of satellite missio... more STFC / RAL Space has been involved in the development of an extensive variety of satellite mission payloads operating across a wide range of the electromagnetic spectrum. The RAL Space Millimetre-wave Technology Group (MMTG) has undertaken the development of instrumentation in support of spaceborne earth observation. Most recently, the MMTG is contributing towards a next generation of weather monitoring satellites that will utilise state-of-the-art low-noise amplifier (LNA) technology as the first reception stage of heterodyne receivers. This contribution describes the performance optimisation of an LNA used in a 183GHz receiver chain. Device optimisation includes variation in impedance transformation between waveguide and LNA millimetre-wave integrated circuit (MMIC), and under different MMIC DC bias conditions, to achieve required performance. Extensive and accurate LNA measurements have been made and, in addition to the optimisation procedures used, example results will be presen...
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
The application of digital signal generation for a Radar Wind Profiler (RWP) utilising Frequency ... more The application of digital signal generation for a Radar Wind Profiler (RWP) utilising Frequency Modulated Continuous Wave (FMCW) operation is described, and the progress of the design to Technology Readiness Level 3 (TRL 3) is demonstrated. The technology and the methods for the TRL assessment are described, and results of the TRL assessment are presented. Conclusion and outlook complete this contribution.
Since many years Doppler radar profilers are known as valuable tools to retrieve profiles of rain... more Since many years Doppler radar profilers are known as valuable tools to retrieve profiles of rain rate and further rain parameters (e.g. Wakasugi et al. (1986)). Applying well established relations for terminal fall velocity, shape and backscatter cross section of rain drops allows to derive rain rate without empirical assumptions. For calculating the backscatter cross section, the flattening of rain drops (see e.g. Pruppacher and Klett (1997)) constitutes a nonnegligible error source.
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