Hartebeesthoek Radio Astronomy Observatory (Hartrao) , South Africa 4Dtfdept
Onsala Space Observatory
Cryogenic low noise receiver for radio astronomy based on Eleven feed
Miroslav Pantaleev1 ,Jian Yang2, , Per‐Simon Kilda l2, Leif Helldner1, Benjamin Klein3, Yogesh Karadikar4, Niklas Wadefalk4
1Onsala Space Observatory, Chalmers University of Technology, Sweden 2Dept. of Signals and Systems, Chalmers University of Technology, Sweden 3Hartebeesthoek Radio Astronomy Observatory (HartRAO) , South Africa 4DtfDept. of Microt ech nol ogy and NiNanoscience, Chal mers U ni versit y of T ech nol ogy, S wed en
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Ou tline
• Introduction • Electrical and mechanical design • Feed measurement results • CiittiCryogenic integration • Measurement results • Future development
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Start in 2003: Project to Prof. Kildal from Caltech on ATA array, (500 MHz – 10 GHz)
ATA feed: Kildal’s Eleven Too large feed: & Eleven times Problem with smaller phase center & variations No problem with phase center variations
Size and complexity for fmin = 500 MHz
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
Thdhe deve lopment of mod dlels ab ove 3G Hz
210mm 280mm
68mm 68mm
2006 2009 2010 0.15-1.5GHz- 2GHz – 12GHZ 1.2GHz – 10GHZ VLBI2010 vers ion SKA version Problems with Coolable versions cooling
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Organization of the project • Prof Kildal’s antenna group, Chalmers: – electrical design of the feed (Per-Simon Kildal, Jian Yang ) – characterization measurements (Jian Yang) – descrambling board (Mojtaba Zamani, Master student) – packaging (Ashraf Uz Zaman) – twin lead line and wide band baluun (Yogesh Karandikar, Ahmed Hussain) • Onsala Space Observatory (OSO), Chalmers: – Project leadership (Miroslav Pantaleev) – mechanical design (Leif Helldner), fabrication of mechanical components (workshop at OSO), cryogenics (Christer Hermansson, Per Björklund, Miroslav Pantaleev, Leif Helldner). • Department of Microelectronics and Nanoscience (MC2), Chalmers: – didesign and dfbiti fabrication of fLNA( LNA (Niklas WdflkWadefalk, HbtHerbert Zirath , Klas EikEriksson) • Hartebeesthoek Radio Astronomy Observatory (HartRAO), South Africa: – PhD student (Benjamin Klein) working on the Feed system design
Partners
• California Institute of Technology (Caltech): – Sander Weinreb –integration of cryogenic LNA in one feed prototype • Haystack radio telescope, MIT: – Christopher Beaudoin, Arthur Niell - VLBI 2010 with Eleven Feed and Lindgren feed on two telescopes in US
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Eleven feed – Development Plan
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
Eleven f eed – PdProduct ion so far
2-12GHz (VLBI2010 versi on) • Feed #1 – Delivered to Norwegian Mapping Authority “Statkart”, March 2009 • Feed #2 – Delivered to Vertex Antennentechnik GmbH, April 2009 • Feed #3 – For cryogenic tests at OSO • Feed #4 – Spare, borrowed from NiCT, Japan for beam characterisation • Feed #5 – Delivered to Haystack Observatory, March 2010 • Feed #6 – For tests with passive balun
1.2-10GHz (SKA version) • Feed #1 – For test characterisation • Fd#2Feed #2 – Will b e shi pped to C al tech wi thi n f ew d ays
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Idea behind Eleven feed (2004)
• Two parallel dipoles over ground plane – from book by Christiansen and Högbom Radio Telescopes – equal E- and H-plane patterns – phase center is locked to the ggpround plane – low far-out sidelobes and backlobes. • Bandwidth by – Logperiodic – Folded dipoles
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Eleven feed - electrical desiggpn and performance
Six parameters are optimized: • scaling factor k, dipole length L, arm width w, and spacing da, transmission line gap dc, height above ground plane h. • 14 dipoles to cover 2-12GHz • port impedance 200 W
Feed parameters over 2-12GHz • Reflection coefficient below -10 dB • Directivity is about 11 dBi • The radi ati on patt ern i s const ant with l ow cross polarization level • Aperture efficiency is better than – 3 dB
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Feed configuration
• Possible “basic” configurations: – 4 single-ended LNAs ppper polarization 50 – 2 differential LNAs per polarization 200
• With 50 LNAs: – 4 single-ended LNAs per polarization – 2 wide band hybrids per polarisation – 1 wide band power combiner per polarisaition
• With 200 differential LNAs – 2diff2 differenti tilLNAal LNA per pol ari zati on – 1 wide band power combiner per polarisaition
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory The following choices were made during the project
• All materials MUST stand cryogenic environment •4 seppp(p)arate panels (petals) with lo g-ppperiodic dipoles • PCB technology for antenna petals • Minimize thickness of dielectric in center • 2x4 ports with no crossing lines in center puck
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Mechanical design
Components ‐ front: Components– back side: - Four Eleven Feed petals - 8-port (200 to 50ohm transition) - Center puck - Lid with pins (PMC) - Ground plane - Feeding network and LNAs - Lock with screw - Four twin lead lines
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Eleven feeds for 1.2-10GHz and 2-12GHz
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Compact1.2-10GHz Eleven feed
287 mm
92 mm
337 mm
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Simulations and Measurements at Chalmers of input reflection coefficient (power dividers and cables were calibrated away)
0
-2 measured simulated -4
-6
-8 fficient (dB) fficient ee -10
-12
-14 Reflection co
-16
-18
-20 1 3 5 7 9 11 13 15 1718 Frequency (GHz)
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
Radiation Efficiencies
0 epol > -0.2 dB -050.5 (ltt(power lost to cross-polar sidelobes), -1 eɸ > -0.1 dB )
BB -151.5 (gain reduction due to phase errors over the reflector e -2 sp aperture) e BOR1 iciencies (d
ff The higgph phase efficienc y is -252.5
Ef e pol achieved because the phase -3 e ill center of the Eleven antenna is e located almost exactly at the -353.5 ground plane, over the whole e ap frequency band. -4 3 4 5 6 7 8 9 1011121314 BOR1 efficiency is power lost in Frequency (GHz) sidelobes due to higher order variations.
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Measured and simulated Co- and crosspolar patterns in 45 deg plane 0 0 0 0 2GHz 2.5GHz 3GHz 2GHz 2.5GHz 3GHz -10 -10 -10 -10
-20 -20 -20 -20
-30 -30 -30 -30 3.5GHz-90 0 90 180-1804GHz -90 0 90 -1801805GHz-90 0 90 3.5GHz-90 0 90 -1804GHz-90 0 90 -1801805GHz-90 0 90 -10 -10 -10 -10
-20 -20 -20 -20
-30 -30 -30 -30 6GHz-90 0 90 180-1807GHz -90 0 90 -1801808GHz-90 0 90 6GHz-90 0 90 -1807GHz-90 0 90 -1801808GHz-90 0 90 -10 -10 -10 -10
-20 -20 -20 -20 plitude (dB) plitude plituide (dB) mm -30 -30 mm -30 -30 A 9GHz-90 0 90 180-18010GHz -90 0 90 -18018011GHz-90 0 90 A 9GHz-90 0 90 -18018010GHz-90 0 90 -18018011GHz-90 0 90 -10 -10 -10 -10
-20 -20 -20 -20
-30 -30 -30 -30 12GHz-90 0 90 180-18013GHz -90 0 90 -18018014GHz-90 0 90 12GHz-90 0 90 -18018013GHz-90 0 90 -18018014GHz-90 0 90 -10 -10 -10 -10
-20 -20 -20 -20
-30 -30 -30 -30 -180 -90 0 90 -180180 -90 0 90 -180180 -90 0 90 180 -180 -90 0 90 -180180 -90 0 90 -180180 -90 0 90 180 o o Patterns of the total radiation field BOR1 components of the field.
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Computed and measured directivities
14 13 12 11 10 9 ctivity (dBi) ctivity ee 8
Dir Measured 7 Simulated 6 5 4 2 3 4 5 6 7 8 9 10 11 12 13 14 Frequency (GHz)
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Radiation efficiency
0.2
0 B) dd
-0.2 Efficiency ( -0.4
Radiation measured at DTU -0.6 measured at Chalmers simulated using CST
-0.8 2 3 4 5 6 7 8 9 10 11121314 Frequency (GHz) Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
Summary of measurement results
• Matching: abs(S11) < -10 dB up to 13 GHz – measured by removing effects of power dividers and cables by calibration • Independent gain measurements at Technical University of Denmar k (TUD) – Losses smaller than 0.5 dB (Uncertainty due to multiple reflections between 180 deg hybrid, 3dB power divider and antenna, which were not calibrated out in this case) – Radiation patterns: Good between 2.5 and 9 GHz. Outside this band low BOR1 efficiency – Overall feed efficiency in reflector better than -2 dB between 2.5 and 9 GHz
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
Cryogenic integration
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Cryostat design
• Vacuum window made of Mylar • Deflection of about 25mm •The location of the Feed is determined by the deflection of the window
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Cryygogenic inte gration of the Eleven feed
The MIL infrared filter reduces the tttemperature to 25K The 70K shield has infrared window of one layer Teflon
The temperature on the Feed surface is measured with temperature sensor Lakeshore DT‐470 mounted on thin copper support soldere d at the edge of the thdhird ddlipole.
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Cryygogenic S-parameters measurements
0
without Cryostat at room temp inside Cryostat at room temp temp -5 inside Cryostat at 48 K
-10 Coefficient (dB)
Reflection -15
-20 • Calibration is done at the delta 2 4 6 8 10 12 14 Frequency (GHz) outputs of the hybrids • S11 does not change when feed is • Only one polarization is measured cooled to cryogenic temperature. • Four equal length coaxial cables are • The small variations can be connected to the Feed ports explained with the temperature • Four port VNA is used dependent permittivity.
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Noise measurements at Onsala Sppyace Observatory
Matched Cable Lengths
Load Load SMA SMA Bottom of Feed
#128D #240D PAD2 PAD4 SMA SMA LNA LNA
Load Load 3 - 3 - 3 3 4 Matched 4 116687 Cable
116695 Lengths 1 1
2 -3 -3 2
2 LNA 1 LNA
#239D #127D SMA PAD1 PAD3 SMA A A MM MM S S • 4-8GHz LNAs with GaAs Load Load transistors from GARD • Tsys of LNAs is 5-7K Dewar Output
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Tests at Haystack
• BdbdBroad band IPInP LNAs from Ca ltech • Tsys of LNAs is < 7K up to 12GHz
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory System noise measured at OSO and Haystack
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev TTeTSYS a rad ohmic TT LNA;1 ohmic eT rad PhFeed Onsala Space Observatory Measured and ppyredicted system noise temp eratures for single ended LNAs at 30K
300 T Measured 200 sys T Predicted sys 100 e T rad a
(K) T 50 LNA 40 T 30 ohmic 20 emperature emperature
TT 10
5 Noise Noise 4 3 2
1 2 3 4 5 6 7 8 9 10111213 Frequency (GHz) The measurements were done at Haystack Observatory
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev TTeTSYS a rad ohmic TT LNA;1 ohmic eT rad PhFeed Onsala Space Observatory
A/T per m 2 for single ended LNAs
0.040 0.030 • Cooled system is with Caltech 0.020 cryogenic LNA and cryostat is at
) 30 K. 2 0.010 • The feeding of the paraboloid is
/K per m with semi-subtended angles 60 2 0.005 (m
TT 00040.004 and 73 degrees Cryo-LNA ( =60) A/ 0 0.003 •for a reflector of 1 m2 area with Cryo-LNA (Optimal =73) 0.002 0 subtended half angle of 60o, i.e. 293K LNA (Optimal =60) 0 F/D = 0.433. 0,001 2 3 4 5 6 7 8 9 1011121314 Frequency (GHz)
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
On going work
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Active balun and integration
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Active balun and single ended LNA - alternatives
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory GaAs LNA developpyed by MEL at Chalmers
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory Summary • Hardware: Good. Appears solid and appealing • DiDesign f or t wo f requency b bdands • Matching: abs(S11) < -10 dB up to 13 GHz • Tsys of ~20K possible with single ended LNAs . • Extensive Tsys testing was done at OSO and Haystack
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev Onsala Space Observatory
What to do next • Redesign feed to remove surface waves ((low BOR1 efficiency above 9 GHz) • Study the effect of cryostat window and infrared filer • Design room temperature LNA • Design cryogenic LNA • More testing (patterns and noise temp.) of the cooled feed in cryostat
Annual WP2 Meeting, 27-30 October 2010 Miroslav Pantaleev