A Low-Cost Mechanically-Steered Weather Radar Concept 18 October 2018 Stefano Turso , Thomas Bertuch , Peter Knott Silke Trömel, Clemens Simmer Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR) Fraunhofer Straße, 20 53343 Wachtberg Hailstorms, rainstorms, Meteorological Institute University of Bonn Auf dem Hügel, 20 53121 Bonn Germany Folie 1 © Fraunhofer FHR Motivation Development of a cost-effective Doppler dual-polarized radar node for a short-range weather radar network Flash-floods, tornadoes, Hailstorms, rainstorms, forest fires snow © Fraunhofer FHR Motivation Nowadays, about 70% of the troposphere below 1 km cannot be observed by radar means. Being limited by the earth curvature, traditional long range weather radars (up to about 200 Km range) are unable to provide coverage of the lower part of the atmosphere. Excerpted from WakeNet-Europe 2013, by Mr. McLaughlin (UMASS) and Mr. Drake (Raytheon) “There is insufficient knowledge about what is actually happening (or is likely to happen) at the Earth’s surface where people live”, National Academy of Sciences,1998 © Fraunhofer FHR Motivation Nowadays, about 70% of the troposphere below 1 km cannot be observed by radar means. This yields inherent difficulties in the understanding, prediction and timely reaction to weather phenomena like intense convective storms and tornadoes which develops up to a height of about 3 Km in the troposphere. “There is insufficient knowledge about what is actually happening (or is likely to happen) at the Earth’s surface where people live”, National Academy of Sciences,1998 © Fraunhofer FHR Motivation Long-range weather radars suffer from orographic shielding, low space resolution and high revisit time S and C-band radar systems are known to suffer from shielding effects preventing to sound orographically complex areas like Alpine valleys and urban areas. Tropical Storm Odile Flash Flooding Excerpted from WakeNet-Europe 2013, by Mr. in Southeast Arizona, Sept. 2014 McLaughlin and Mr. Drake © Fraunhofer FHR Motivation Long-range weather radars suffer from orographic shielding, low space resolution and high revisit time Coarse resolution and high revisit time are other known limitations of a sounding approach based on a limited number of long range units, overall leading to operational maps of about 1 Km³ radar bins with a typical update time of 5 minutes. Supercell comparison Excerpted from WakeNet-Europe 2013, by Mr. (left: X-band CASA, right: S-band NEXRAD) McLaughlin and Mr. Drake © Fraunhofer FHR Motivation To overcome these limitations, the development of a network of short-range X-band dual-polarized Doppler weather radars is proposed A networked approach generates high resolution composite maps of short-range units with a typical refresh rate of one minute CASA X-band AESA experimental network Excerpted from WakeNet-Europe 2013, by Mr. McLaughlin and Mr. Drake © Fraunhofer FHR Motivation To overcome these limitations, the development of a network of short-range X-band dual-polarized Doppler weather radars is proposed A networked approach generates high resolution composite maps of short-range units with a typical refresh rate of one minute and improve monitoring of the lower troposphere. CASA X-band AESA experimental network Excerpted from WakeNet-Europe 2013, by Mr. McLaughlin and Mr. Drake © Fraunhofer FHR Fraunhofer FHR Excellence in radar research since 1957 University of Bochum RWTH Aachen University of Siegen Wachtberg Villip About 300 employees, 24M€ budget Part of Fraunhofer Gesellschaft since 2009 © Fraunhofer FHR Fraunhofer FHR business units © Fraunhofer FHR The Fraunhofer-Gesellschaft at a Glance © Fraunhofer FHR Overview Concept design Enabling technologies Manufacturing System design Feasibility Summary © Fraunhofer FHR Concept design Mechanical assembly Flat aperture 0.5 m2 array panel area Four panels framed as a flat aperture Antenna aperture connected to a rotor by an arm, mechanically adjustable elevation tilts (up to 11° in 1° step) Receiver over-elevation Distributed power generation Concept rendering mock-up, front Flat aperture © Fraunhofer FHR Concept design Mechanical assembly Flat aperture 0.5 m2 array panel area Four panels framed as a flat aperture Antenna aperture connected to a rotor by an arm, mechanically adjustable elevation tilts (up to 11° in 1° step) Receiver over-elevation Distributed power generation Concept rendering mock-up, back Flat aperture © Fraunhofer FHR Concept design Back-end AD9910 HMC785 HMC558A Tx-chain 400 MHz BW 1.7 .. 2.2 GHz 5.5 .. 14 GHz Image reject Image reject Image reject Optional Harmonics filter high pass filter, high pass filter, high pass filter conditoining VGA (EMI + isolation) mixer pre-amp (IF) mixer pre-amp (RF) (RF stage) HPF + Mixer HPF + Mixer DDS HPF RF VGA LPF Pre-Amp (IF) Pre-Amp (RF) FPGA, ADF4159 Low High Time Ref, Radar Tx 0.5 .. 13 GHz upconv. upconv. T/R Proc gen + distr Switch Reference BPF fanout x4 fanout ramp for Coupler + compression AD9530 FPGA, To LO, DAC, ADC, Feed FPGAs, VGAs, Radar Rx + Low High PLL+VCO Q-cores Net Comm Proc downconv. downconv. Mixer Mixer ADC IF Amp HPF HPF RF VGA SW (IF) (RF) Image reject Image reject high pass filter RF dynamic range Reference switch high pass filter (IF) ADL5355 (RF stage) AD9467 IF differential HMC558A Balanced mixer 16 bit, 250 MSps ADC driver, and 5.5 .. 14 GHz and RF balun Single channel anti-alias filter Rx-chain Back-end transmitter and receiver chains including on-board digital processing © Fraunhofer FHR Concept design Front-end Array To Rx-chain To Tx-chain FeedNet + T/R Switch Based on an integrated T/R front-end MMIC plus polarization switch and sub-array radiating M P F 13 61 column. E ... ... ... 1 2 3 4 16 64 Each Medium Power Front End (MPFE) feeds a SW S linear sub-array of 32 patches arranged as a u b column. A … r r 64 radiating columns for a total radiating surface a … y of about 960 x 480 mm. 13 61 ... ... Modular design based on 4 panels. 1 2 3 4 16 64 Panel 1 Panels 2,3 Panel 4 Connected to the Tx and Rx chains via a common feeding network plus T/R switch. Front-end overview Panel-based modular design © Fraunhofer FHR Concept design Front-end Dual pol sub-array Dual pol sub-array Sub-array column MPFE with polarization switch Pol. SW horizontal and vertical ports of each patch sub- array fed by a common MPFE plus polarization 1 1 layers switch on the PCB back-side. layer inner 2 2 Allows for alternate polarization modes in and transmission and reception (“Alternate Transmit Outter Alternate Receive” mode). Bottom .. .. Stacked patch design for improved bandwidth 32 32 exceeding 300 MHz. Low insertion loss switch (e.g. Analog Devices HMC1118). Patch sub-array column with polarization switch © Fraunhofer FHR Crucial components Front-end, column sub-array Column sub-array Aperture feeding detail © Fraunhofer FHR Crucial components Mechanical assembly Rotor Horizontal working position 250 kgm2 moment of inertia (max) 5.5 rpm (max) Ø 410 mm, tabletop Absolute encoder Integrated slip-ring Up to 200 kg load Remotely controllable Abound 15 K$ unitary cost FIBROTOR EM.NC.15, FIBRO GmbH Rotor © Fraunhofer FHR Enabling technologies Back-end, receiver AD9910 HMC785 HMC558A Tx-chain 400 MHz BW 1.7 .. 2.2 GHz 5.5 .. 14 GHz Image reject Image reject BalancedImage reject Mixer Optional Harmonics filter high pass filter, high pass filter, high pass filter conditoining VGA (EMI + isolation) mixer pre-amp (IF) mixer pre-amp (RF) (RF stage) HPF + Mixer HPF + Mixer DDS HPF RF VGA LPF Pre-Amp (IF) Pre-Amp (RF) Integrated RF balun Integrated differential IF amplifier FPGA, ADF4159 Low High Time Ref, Radar Tx 0.5 .. 13 GHz upconv. upconv. T/R Proc gen +1200..2500 distr MHz SwitchRF Reference BPF fanout x4 fanout ramp for Coupler + compression FPGA, AD9530 To LO, DAC, ADC, Feed FPGAs,30..450 VGAs, MHz IF Radar Rx + Low High PLL+VCO Q-cores Net Comm Proc downconv. downconv. Mixer Mixer ADC IF Amp HPF HPF RF VGA SW (IF) (RF) Suitable for early implementation of Image reject Image reject high pass filter RF dynamic range Reference switch high pass filter (IF) ADL5355 (RF stage)differential signaling. AD9467 IF differential HMC558A Balanced mixer 16 bit, 250 MSps ADC driver, and 5.5 .. 14 GHz and RF balun Single channel anti-alias filter Rx-chain Analog Devices ADL5355 Balanced mixer © Fraunhofer FHR Enabling technologies Back-end, receiver AD9910 HMC785 HMC558A Tx-chain 400 MHz BW 1.7 .. 2.2 GHz 5.5 .. 14 GHz Image reject Image reject DifferentialImage reject amplifier Optional Harmonics filter high pass filter, high pass filter, high pass filter conditoining VGA (EMI + isolation) mixer pre-amp (IF) mixer pre-amp (RF) (RF stage) HPF + Mixer HPF + Mixer DDS HPF RF VGA LPF Pre-Amp (IF) Pre-Amp (RF) High dynamic range Differential input to differential output FPGA, ADF4159 Low High Time Ref, Radar Tx 0.5 .. 13 GHz upconv. upconv. T/R Proc gen +3 distr dB bandwidth Switchof 6 GHz Reference BPF fanout x4 fanout ramp for Coupler + compression FPGA, AD9530 To LO, DAC, ADC, Feed FPGAs,2 VGAs , ns settling time Radar Rx + Low High PLL+VCO Q-cores Net Comm Proc downconv. downconv. 11 V/ns slew rate Mixer Mixer ADC IF Amp HPF HPF RF VGA SW (IF) (RF) Image reject Image reject high pass filter RF dynamic range Reference switch high pass filter (IF) ADL5355 (RF stage) AD9467 IF differential HMC558A Balanced mixer Differential ADC driver 16 bit, 250 MSps ADC driver, and 5.5 .. 14 GHz and RF balun Single channel anti-alias filter Rx-chain Analog Devices ADL5565 Differential amplifier © Fraunhofer FHR Enabling technologies Back-end, receiver AD9910 HMC785 HMC558A Tx-chain 400 MHz BW 1.7 .. 2.2 GHz 5.5 .