A Q-band 19 pixel multifeed receiver for the Sardinia ... · wguide 33 50 1 18 1 18 ANTENNA DATA CENTER 600m AWAY . Radionet Online Workshop Bonn, September 21-22 ,2020 16 ACTIVE

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

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


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)


PROVING TECHNOLOGIES: PASSIVE DEVICES

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

POLARIZER: Pancharatnam theory

(U. Manchester in collaboration with INAF-IRA, G. PISANO)

OMT:Turnstyle junction


PROVING TECHNOLOGIES: ACTIVE DEVICE

LNA

AMP

x8

RF IF

LO=4GHz

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


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


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


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)


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


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)


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)


MEASUREMENTS OF THE PASSIVE PARTS: OMTs


MEASUREMENTS OF THE PASSIVE PARTS: 19 FEED SYSTEM


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


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

Th

erm

al G

ap

Qconv

FBCB

RCP

LCP

LO Distribution RFoF20

TX RX

wguide

33 50

1 18

1 18

ANTENNA DATA CENTER 600m AWAY


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)


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 127m TEFLON SUBSTRATE - WG PROBE and IMAGE FILTER on 127m ALUMINA

SUBSTRATE

53 44

8


Q-CONV MEASURES

Power consumption = 0.6W

FOUND !

Image rejection ≥ 27dB

NOISE

GAIN


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


TRIPLE WAVEGUIDE THERMAL GAP

LNA PORTS

MJ ATTENUATOR PORT

20K STAGE WARM STAGE

Attenuator NS

Qconv

Qconv

RCP

LCP

wg

Th

erm

al G

ap

T

he

rma

l G

ap


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 508m SUBSTRATE SYSTEM: 19 BOARDS + 2nd LOs GENERATION and DISTRIBUTION

FBCB (Full Band Conversion/Continuum Board/Back-end)


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

65

7


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


CALCULATION of the PERFORMANCE

Measured

Simulated

Coax 4m

20K WARM STAGE

Horn

MJ

Pol

Omt

Attenuator NS

Qconv

Th

erm

al G

ap

Qconv

FBCB

RCP

LCP

LO Distribution RFoF20

wguide

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

THANK YOU !

Documents

A Q-band 19 pixel multifeed receiver for the Sardinia ... · wguide 33 50 1 18 1 18 ANTENNA DATA CENTER 600m AWAY . Radionet Online Workshop Bonn, September 21-22 ,2020 16 ACTIVE