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

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

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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

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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

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2 Radionet Online Workshop Bonn, September 21-22 ,2020

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
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3 Radionet Online Workshop Bonn, September 21-22 ,2020

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)

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4 Radionet Online Workshop Bonn, September 21-22 ,2020

PROVING TECHNOLOGIES: PASSIVE DEVICES

CORRUGATED HORN & OMT: USE OF PLATELET TECHNIQUE (lower cost) 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)

OMT:Turnstyle junction

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5 Radionet Online Workshop Bonn, September 21-22 ,2020

PROVING TECHNOLOGIES: ACTIVE DEVICE

LNA

AMP

x8 RF IF LO=4GHz

WHEN ENGINEERING AND PROTOTYPING WE WERE NOT ABLE TO OBTAIN USABLE MODULES

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6 Radionet Online Workshop Bonn, September 21-22 ,2020

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
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7 Radionet Online Workshop Bonn, September 21-22 ,2020

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

HORNs POLARIZERs OMTs MJ NOISE SOURCES MJ

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8 Radionet Online Workshop Bonn, September 21-22 ,2020

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 45o-plane 33GHz, 19 horn 45o-plane 41.5GHz, 19 horn 45o-plane 50GHz, 19 horn

collaboration with U. Milano (C. FRANCESCHET)

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9 Radionet Online Workshop Bonn, September 21-22 ,2020

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

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10 Radionet Online Workshop Bonn, September 21-22 ,2020

MEASUREMENTS OF THE PASSIVE PARTS: MARKER INJECTOR (MJ)

MEASURED ON 19 DEVICES 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)

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11 Radionet Online Workshop Bonn, September 21-22 ,2020

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)

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12 Radionet Online Workshop Bonn, September 21-22 ,2020

MEASUREMENTS OF THE PASSIVE PARTS: OMTs

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13 Radionet Online Workshop Bonn, September 21-22 ,2020

MEASUREMENTS OF THE PASSIVE PARTS: 19 FEED SYSTEM

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14 Radionet Online Workshop Bonn, September 21-22 ,2020

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

Measured Calculated Interpolation

RF ALL WAVEGUIDE NOISE MARKER CIRCUIT

NS

ATTENUATOR

MJ Thermal gap

CRYO WARM

Wg

RF+NOISE

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15 Radionet Online Workshop Bonn, September 21-22 ,2020

PHASE 3: 2016-june2019 (ITALIAN FUNDS)

  • 1. PROVIDE A CONVENIENT CRYOGENIC LNA
  • 2. DESIGN of A NEW 1st DOWN CONVERSION MODULE (Q-CONV)
  • 3. DESIGN/CONSTRUCTION of LO DISTRIBUTOR
  • 4. DESIGN of THERMAL GAP
  • 5. DESIGN of FBCB (Full Band Conversion/Continuum Board/Back-end)

20K

WARM STAGE

Horn MJ Pol Omt ATTENUATOR NS Qconv Thermal Gap Qconv

FBCB

RCP LCP

LO Distribution RFoF20 TX RX wguide 33 50 1 18 1 18

ANTENNA DATA CENTER 600m AWAY

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16 Radionet Online Workshop Bonn, September 21-22 ,2020

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)

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17 Radionet Online Workshop Bonn, September 21-22 ,2020

ACTIVE PARTS: Q-CONV IN-HOUSE DESIGN of a DOWN CONVERSION MODULE

  • MMIC chip DIDN’T WORK
  • NEW CONVERTER USING MMIC COMMERCIAL DEVICES

WG probe Image Filter Amp LO Filter x2 IF Low pass Filter OL=16 GHz Mixer 33 50 1 18

  • x2: ANALOG DEVICE
  • MIXER: MARKI
  • AMPLIFIER: CUSTOM MMIC

IN-HOUSE DESIGN:

  • OL and IF FILTERS on 127m TEFLON SUBSTRATE
  • WG PROBE and IMAGE FILTER on 127m ALUMINA

SUBSTRATE

53 44 8

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18 Radionet Online Workshop Bonn, September 21-22 ,2020

Q-CONV MEASURES

Power consumption = 0.6W

FOUND !

Image rejection ≥ 27dB

NOISE GAIN

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19 Radionet Online Workshop Bonn, September 21-22 ,2020

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

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20 Radionet Online Workshop Bonn, September 21-22 ,2020

TRIPLE WAVEGUIDE THERMAL GAP

LNA PORTS MJ ATTENUATOR PORT

20K STAGE

WARM STAGE

Attenuator NS Qconv Qconv RCP LCP wg Thermal Gap Thermal Gap

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21 Radionet Online Workshop Bonn, September 21-22 ,2020

  • 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 + 2nd LOs GENERATION and DISTRIBUTION FBCB (Full Band Conversion/Continuum Board/Back-end)

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22 Radionet Online Workshop Bonn, September 21-22 ,2020

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 Horn Polariser OMT LNA Q-CONV LO Distributors Noise source MJ Attenuator

589 630 657

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23 Radionet Online Workshop Bonn, September 21-22 ,2020

MECHANICAL ROTATOR (SAME AS K-BAND MFEED)

MAIN SPECIFICATIONS STROKE (degree) ± 132 SPEED (o/s @3000 rpm) 3.276 ACCELERATION (o/s2) 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 MIN DISPLACEMENT, ON SKY (arcsec) 0.013 POSITIONING ACCURACY, ON SKY (arcsec) 0.036

K-BAND MULTIFEED

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24 Radionet Online Workshop Bonn, September 21-22 ,2020

CALCULATION of the PERFORMANCE

Measured Simulated Coax 4m 20K

WARM STAGE

Horn MJ Pol Omt Attenuator NS Qconv Thermal Gap Qconv

FBCB

RCP LCP

LO

Distribution

RFoF20

wguide

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Radionet Online Workshop Bonn, September 21-22 ,2020 25

THANK YOU !