Sardinia Radio Telescope ALESSANDRO ORFEI, INAF-IRA National - PowerPoint PPT Presentation

A Q-band 19 pixel multifeed receiver for the Sardinia Radio Telescope ALESSANDRO ORFEI, INAF-IRA National Institute for Astrophysics – Institute of Radioastronomy Radionet Online Workshop Bonn, September 21-22 ,2020 1

SARDINIA RADIO TELESCOPE (SRT) • Primary Mirror D=64 m; Secondary Mirror D=7.9 m • Gregorian Configuration with Shaped Surfaces • Active Surface: Primary mirror with 1116 actuators (Shaped  Parabolic) • Six focal positions: Primary, Gregorian, Four Beam Wave Guide • Can host up to 20 dual polarization receivers: mono feed, dual frequency, multibeam Swapped remotely and automatically • Primary surface accuracy:  300  m RMS today, 120  m goal • Max antenna efficiency:  60 % • Pointing accuracy (RMS): 5 arcsec, 2 arcsec goal • Aim 0.3-116 GHz frequency coverage Radionet Online Workshop Bonn, September 21-22 ,2020 2

INTRODUCTION THE AIM for a Q-band MULTIFEED STARTED LONG TIME AGO PHASE 1, 2009-june12 PROVING TECHNOLOGIES (FP7 JOINT RESEARCH ACTIVITY, EU-RADIONET FUNDS) PHASE 2, 2012-2015 DESIGN/CONSTRUCTION of PASSIVE PARTS (ITALIAN FUNDS) PHASE 3, 2016-june19 DESIGN and PROTOTYPE of ACTIVE PARTS (ITALIAN FUNDS) PHASE 4, june19-2021 FINALIZING the PROJECT (ITALIAN FUNDS) Radionet Online Workshop Bonn, September 21-22 ,2020 3

PROVING TECHNOLOGIES: PASSIVE DEVICES CORRUGATED HORN & OMT: USE OF PLATELET TECHNIQUE (lower cost) OMT:Turnstyle junction POLARIZER: Pancharatnam theory <<..unprecedented performance combining extremely flat differential phase-shift across the whole band, very low losses and very low amplitude unbalance.>> (U. Manchester in collaboration with INAF-IRA, G. PISANO) Radionet Online Workshop Bonn, September 21-22 ,2020 4

PROVING TECHNOLOGIES: ACTIVE DEVICE RF IF LNA AMP x8 LO=4GHz WHEN ENGINEERING AND PROTOTYPING WE WERE NOT ABLE TO OBTAIN USABLE MODULES Radionet Online Workshop Bonn, September 21-22 ,2020 5

A Q-band MULTIFEED for the SRT 64m DISH: GOALS 1. SCIENCE : IMAGING for SPECTROSCOPY + FULL STOKES and QUIET SUN (requirement of last years) 2. RF BAND: 33-50 GHz 3. NUMBER of PIXELS: 19 , HEXAGONAL CONFIGURATION 4. POLARISATION: CIRCULAR LEFT and RIGHT 5. RF BAND AVAILABLE: 8 BASEBANDS  2GHz WIDE EACH 6. MECHANICAL ROTATOR for EARTH ROTATION COMPENSATION 7. RECEIVER NOISE TEMPERATURE < 30K 8. FIRST SIDE LOBE LEVEL ≤ -20dB 9. POLARISATION PURITY ≥ 30dB 10. NOISE MARKER VARIATION: 1dB THROUGH RF BAND 11. MAINTAINING LINEARITY UP TO QUIET SUN INPUT POWER Radionet Online Workshop Bonn, September 21-22 ,2020 6

PHASE 2: 2012-2015 (ITALIAN FUNDS) 1. DESIGN of NOISE MARKER INJECTION DEVICE (MJ) 2. REFINE OMT and POLARIZER DESIGN 3. CONSTRUCTION of the 19 HORN/MJ/POLARIZER/OMT CHAINS 4. BUY 19 NOISE GENERATOR 5. MEASURE 19 FEED SYSTEM CHAINS OMTs HORNs POLARIZERs NOISE SOURCES MJ MJ Radionet Online Workshop Bonn, September 21-22 ,2020 7

MEASUREMENTS OF THE PASSIVE PARTS: HORNs E/H-plane 33GHz, 19 horn E/H-plane 41.5GHz, 19 horn E/H-plane 50GHz, 19 horn collaboration with U. Milano ( C. FRANCESCHET ) 45 o -plane 33GHz, 19 horn 45 o -plane 41.5GHz, 19 horn 45 o -plane 50GHz, 19 horn Radionet Online Workshop Bonn, September 21-22 ,2020 8

MEASUREMENTS OF THE PASSIVE PARTS: HORNs MULTIHORN; B = 33-50 GHz; BW = 41% Obtained 33 GHz 41.5 GHz 50 GHz SIMULATED Edge taper (dB) -6.2 -10.6 -18.1 Simulated Antenna Gain (K/Jy) 0.62 0.66 0.56 HPBW (arcsec) 32 27 24 Beam Separation (arcsec) 85 MEASURED S11 (dB) ≤ -30 ≤ -30 ≤ -30 Crosspolarisation (dB) ≤ -28.9 ≤ -32.8 ≤ -30.9 SideLobeLevel (dB) -22 -21 -19 Horn/Horn Isolation (dB) ≤ -60 ≤ -60 ≤ -60 Insertion loss (dB) 0.1 0.1 0.1 MADE BY INAF- ARCETRI OBSERVATORY Radionet Online Workshop Bonn, September 21-22 ,2020 9

MEASUREMENTS OF THE PASSIVE PARTS: MARKER INJECTOR (MJ) ON 19 DEVICES MEASURED MANUFACTURED S11, S22 circular ports < -35dB S21 circular ports < 0.08dB Crosspol circular ports < -50 dB Coupling vs frequency -20.2 dB ± 0.75 dB Crosspol rectangular port < -56 dB NOISE MARKER VARIATION: EACH INDIVIDUAL CURVE WITHIN ±0.5 dB collaboration with CNR - IEIIT (TORINO) Radionet Online Workshop Bonn, September 21-22 ,2020 10

MEASUREMENTS OF THE PASSIVE PARTS: POLARIZERs MAX Ø UNBALANCE (18 over 19 devices): 3 degree (cross= -31.6dB) WORST CASE: 5 degree (cross= -27.2dB) Radionet Online Workshop Bonn, September 21-22 ,2020 11

MEASUREMENTS OF THE PASSIVE PARTS: OMTs Radionet Online Workshop Bonn, September 21-22 ,2020 12

MEASUREMENTS OF THE PASSIVE PARTS: 19 FEED SYSTEM Radionet Online Workshop Bonn, September 21-22 ,2020 13

MEASUREMENTS OF THE PASSIVE PARTS: ATTENUATOR 1. WAVEGUIDE 2. COOLED AT CRYO TEMPERATURE 3. MULTI-HOLE STYLE (directional coupler) 4. NON-FLAT TO COMPENSATE for the DECREASE of NOISE SOURCE ENR vs F 5. FIXED WAVEGUIDE with REMOVABLE DRILLED METAL SHEET RF CRYO WARM Measured Calculated Interpolation Thermal ATTENUATOR Wg NS gap MJ ALL WAVEGUIDE NOISE MARKER CIRCUIT RF+NOISE Radionet Online Workshop Bonn, September 21-22 ,2020 14

PHASE 3: 2016-june2019 (ITALIAN FUNDS) 1. PROVIDE A CONVENIENT CRYOGENIC LNA 2. DESIGN of A NEW 1 st DOWN CONVERSION MODULE (Q-CONV) 3. DESIGN/CONSTRUCTION of LO DISTRIBUTOR 4. DESIGN of THERMAL GAP 5. DESIGN of FBCB ( F ull B and C onversion/ C ontinuum B oard/ B ack-end) 33 50 WARM STAGE 20K Horn DATA CENTER ANTENNA ATTENUATOR wguide NS 600m AWAY MJ Thermal Gap 1 18 RCP Pol Qconv Omt RFoF20 Distribution LO FBCB TX RX Qconv LCP 1 18 Radionet Online Workshop Bonn, September 21-22 ,2020 15

ACTIVE PARTS: LNA COMMERCIAL DEVICE by LOW NOISE FACTORY (Sweden) - 3 wires only for bias ( save hundred of thin wires !) - very low power consumption, 10mW - very good S11, S22, Gain, Noise performance - low P1dB (-12dBm) but sufficient for quiet Sun MONITORING&CONTROL SYSTEM (INAF) Radionet Online Workshop Bonn, September 21-22 ,2020 16

ACTIVE PARTS: Q-CONV IN-HOUSE DESIGN of a DOWN CONVERSION MODULE - MMIC chip DIDN’T WORK - NEW CONVERTER USING MMIC COMMERCIAL DEVICES Mixer Image IF Low pass WG probe Amp Filter Filter 33 50 1 18 LO Filter - x2: ANALOG DEVICE x2 - MIXER: MARKI OL=16 GHz - AMPLIFIER: CUSTOM MMIC 44 53 IN-HOUSE DESIGN: - OL and IF FILTERS on 127  m TEFLON SUBSTRATE 8 - WG PROBE and IMAGE FILTER on 127  m ALUMINA SUBSTRATE Radionet Online Workshop Bonn, September 21-22 ,2020 17

Q-CONV MEASURES Image rejection ≥ 27dB NOISE FOUND ! GAIN Power consumption = 0.6W Radionet Online Workshop Bonn, September 21-22 ,2020 18

LO DISTRIBUTOR 1. DISTRIBUTE 38x16GHz LO SIGNALS 2. IN-HOUSE DESIGN 3. 8 OUTPUT ACTIVE SPLITTERS ON PCB 4. 3 LAYERS PCB. STRIPLINE ON RG4003 SUBSTRATE 5. WORKING FREQUENCY UP TO 20GHz Power consumption/board  0.6W Radionet Online Workshop Bonn, September 21-22 ,2020 19

TRIPLE WAVEGUIDE THERMAL GAP 20K STAGE WARM STAGE MJ ATTENUATOR PORT Attenuator wg NS Thermal Gap Thermal Gap RCP Qconv Qconv LCP LNA PORTS Radionet Online Workshop Bonn, September 21-22 ,2020 20

FBCB ( F ull B and C onversion/ C ontinuum B oard/ B ack-end) 1. BOARD: TWO IF INPUT 2-18GHz; 16 BASEBAND OUTPUTS+DETECTION 2. BOARD: AMPLITUDE EQUALIZATION OF THE INPUTs 3. BOARD: FULL STOKES DETECTION EMBEDDED 4. BOARD: 6 LAYERS DOUBLE EUROCARD PCB 5. BOARD: 1000+ COMPONENTS ON ROGERS 4003 508  m SUBSTRATE SYSTEM: 19 BOARDS + 2 nd LOs GENERATION and DISTRIBUTION Radionet Online Workshop Bonn, September 21-22 ,2020 21

PHASE 4: june19-2021 (ITALIAN FUNDS) 1. CRYOSTAT + MECHANICAL ROTATOR (same as K-band multifeed) 2. MASS PRODUCTION (LNA, Q-CONV, THERMAL GAP, ATTENUATOR, FBCB) 3. RECEIVER MEASUREMENTS HR500 or mylar or kapton 589 Horn MJ Polariser 657 OMT Attenuator LNA Q-CONV LO Distributors Noise source 630 Radionet Online Workshop Bonn, September 21-22 ,2020 22

MECHANICAL ROTATOR (SAME AS K-BAND MFEED) MAIN SPECIFICATIONS ± 132 STROKE (degree) SPEED ( o /s @3000 rpm) 3.276 ACCELERATION ( o /s 2 ) 2.67 MAX OUTPUT TORQUE (Nm) 550 MOTOR VOLTAGE (Vdc) 24 ABSOLUTE ENCODER LINEAR RESOLUTION (mm) 0.01 ABSOLUTE ENCODER ANGULAR RESOLUTION (degree) 0.00168 K-BAND MULTIFEED MIN DISPLACEMENT, ON SKY (arcsec) 0.013 POSITIONING ACCURACY, ON SKY (arcsec) 0.036 Radionet Online Workshop Bonn, September 21-22 ,2020 23

CALCULATION of the PERFORMANCE WARM STAGE 20K Measured Horn Simulated Attenuator wguide NS MJ Coax 4m Thermal Gap RCP Pol Qconv Omt Distribution LO FBCB RFoF20 Qconv LCP Radionet Online Workshop Bonn, September 21-22 ,2020 24

THANK YOU ! Radionet Online Workshop Bonn, September 21-22 ,2020 25