Download - Cryogenic PAF Development
Cryogenic PAF DevelopmentProgress Report
PAF WorkshopMay 3-5, 2010
Provo, UTRoger Norrod
Cryogenic PAF
PAF Workshop Provo, UT May 2010 2
• BYU/NRAO targeting noise and efficiency competitive with best single-beam receivers. i.e. 18K, 70% at L-band.
• At Green Bank, construction of cryostat for
19 element L-band PAF underway.
PAF Cryostat
PAF Workshop Provo, UT May 3-5 2010 3
With blank-off covers for leak checkApril 27
Model Drawing24 X 21 X 8 in.61 X 53 X 20 cm.
Dual LNA and Thermal Transition
PAF Workshop Provo, UT May 3-5, 2010 4
Pair of two-channel LNAs with integrated low-loss coaxial lines for transition from 15 to 300K, vacuum seal, and antenna base interface.
LNA based on: S. Weinreb, J. Bardin, H. Mani, G. Jones, “Matched wideband low-noise amplifiers for radio astronomy”, Rev. of Sci. Instr., vol. 80, 044702, 2009.
NXP SiGe transistors.Surface mount components.Thin-wall SS tubular coax.Quartz beads for vacuum seal and center conductor heat sink.
Est. input coax heat load 150 mW / chan.Bias power 17 mW / chan.
14 of 20 assembled, 8 tested cold.
LNA Measured Performance
PAF Workshop Provo, UT May 3-5, 2010 5
1300 1400 1500 1600 1700 18005
7
9
11
13
15
Dual LNA Noise8 Amps, 16 Channels Shown
Frequency (MHz)
Trx
(K)
1000 1200 1400 1600 1800 200035
37
39
41
43
45
Dual LNA Gain8 Amps, 16 Channels Shown
Frequency (MHz)
S21
(dB)
Noise Y-factor measured with LN2 cold load at room temperature SMA connector.
LNA Measured Performance
PAF Workshop Provo, UT May 3-5, 2010 6
1000 1200 1400 1600 1800 2000-20
-15
-10
-5
0
Dual LNA S118 Amps, 16 Channels Shown
Frequency (MHz)
S11
(dB)
LNA Measured Performance
PAF Workshop Provo, UT May 3-5, 2010 7
1300 1400 1500 1600 1700 18000
10
20
30
40
50
60
70
80
90
100
SN6-Y Noise vs. Physical Temperature
15K 31K 41K 51K 61K71K 81K 91K 108K 194K302K
Frequency (MHz)
Trx
(K)
0 100 200 3000
10
20
30
40
50
60
70
80
90
SN6-Y Noise vs. Physical TempAt 1660 MHz
LNA Body Temperature (K)
Trx
(K)
Dipole Ohmic Losses
PAF Workshop Provo, UT May 3-5, 2010 8
Sky noise tests Nov-Dec 2009 to determine dipole noise contribution. Measured on Ciao room-temp amps (~35K).
Dipole Ohmic Losses
PAF Workshop Provo, UT May 3-5, 2010 9
1. Measured LNA/Rx with coaxial hot/cold load.
2. Attached dipole and measured using ambient load and sky.
3. Corrected for scatter, galactic plane, etc. (Tsky = 7.5K)
1300 1400 1500 1600 1700 1800-5
-4
-3
-2
-1
0
1
2
3
4
5
Fat Dipole Noise Contribution17 Dec 09
Tdipole on SN102 Tdipole on SN124
Frequency (MHz)
Tdip
ole
(K)
Achievable Tsys?
PAF Workshop Provo, UT May 3-5, 2010 10
Contributor Noise
Receiver 9
Dipole Losses 2
Mutual Coupling 2
Spillover 5
CMB and Atm 4
Total 22 K
Next
PAF Workshop Provo, UT May 3-5, 2010 11
• Install LNA/TT assemblies.• Cooldown, measure cooling capacity.• Mount in FEB.• Sky noise tests.• Antenna (20m) tests.