Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array

Transcription

1 Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array

2 A Planar OMT for the 8-12 GHz Receiver Front-End Michael Stennes October 1, 2009 Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array

3 Acknowledgement The author wishes to thank Robert Simon for his help in wire-bonding the assemblies, Mike Hedrick and Dwayne Barker for the machining of OMT housings and chip carriers. 3

4 References [1] W. A. Tyrrell, Hybrid circuits for microwaves, PROC. IRE, vol. 35, pp ; November, [2] J. P. Shelton, Tandem couplers and phase shifters for multi-octave bandwidth, Microwaves, pp , April [3] S. B. Cohn, Shielded Coupled-Strip Transmission Line, Trans. IRE, Vol. 3, Issue 5, October [4] D. Bock, Measurements of a scale-model ortho-mode transducer, BIMA memo 74, July 7, [5] R. L. Plambeck, G. Engargiola, Tests of a planar L-band orthomode transducer in circular waveguide, Rev. Scientific Instruments, Vol. 74, No. 3, March [6] P. K. Grimes, et al, Compact broadband planar orthomode transducer, Electronics Letters, Volume 43, Issue 21 Oct Pages [7] R. W. Jackson, A planar orthomode transducer, IEEE Microwave and Wireless Components Letters, Volume 11, Issue 12, Dec Page(s):

5 OMT Goals To provide coupling to two orthogonal linear polarizations, TE11 mode in circular waveguide, diameter cm. Synthesize circular polarization by combining linear polarizations in a 90- degree hybrid. Provide for noise cal injection. Implement and integrate all of these functions in a planar transmission media, in a compact form, such that will fit in the existing VLA GHz dewar and able to be cooled by a CTI model 22 refrigerator. 5

6 X-Band Receiver Specifications From Project Book Frequency Range Noise Temperature (including feed) Circular Polarization Axial Ratio System Gain Output Power on Cold Sky Headroom above 1% Compression Point Dynamic Range Above Quiet Sun Level Circular Polarizer GHz > 20 K < 1 db 55 db -30 dbm > 30 db > 30 db (in Solar Mode) TBD 6

7 Noise Budget Cryogenic LNA 4-12 GHz LNA typical performance Gain (db) Noise (K) 15 Gain (db) Noise (K) Frequency (GHz) 0 7

8 Receiver Noise Level Analysis OMT Loss = 1 db X-Band Receiver Level Analysis M. J. Stennes 5/10/2008 C:\Documents and Settings\mstennes\Desktop\\Level Analysis Spreadsheet Note: This level analysis is for the proposed redesign of the Linear Polarization X-band receiver, using a planar OMT Page 1 of Isolator/filte Signal feed horn OMT Couplers (3) Isolator Amplifier SS Coax r Amplifier Atten Filter Atten Gain (db) Cum. Gain (db) Gain (ratio) Cum. Gain (ratio) Noise Figure (db) Cum. Noise Figure (db) Noise Figure (ratio) Cum. Noise Figure (ratio) Noise Temp (K) Cum. Noise Temp (K) GkTeB (Watts) 3.77E E E E E E E E E E E-11 GkTeB (dbm) Cum. GkTeB (Watts) 6.47E E E E E E E E E E E-08 Cum. GkTeB (dbm) Tcal (K) 5.00 Tcal (dbm) Tmax (K) Tmax (dbm) [GkTmaxB] Physical Temperature Bandwidth (GHz) T test (K) 10 P1dB (dbm) Signal Density (dbm/mhz)

9 Commercially Available Hybrid Couplers Cost, Performance 90-Degree Hybrid Manufacuter, Model No. MCLI HB-6 Mac Tech C7206 ET Indust. Q Krytar 1830 Freq. (GHz) Ampl. Bal. (+ db) Phase Bal. (+ deg) VSWR (x:1) Rtn Loss (- db) Iso (- db) I.L. (- db) Price USD not spec Deliv. (weeks) 180-Degree Hybrid Manufacuter, Model No. MCLI HJ-10 Miteq, Inc. ET Indust. J Krytar Freq. (GHz) Ampl. Bal. (+ db) Phase Bal. (+ deg) VSWR (x:1) Rtn Loss (- db) Iso (- db) I.L. (- db) Price USD Deliv. (weeks) 9

10 YBCO Surface Resistance on MgO Compare Copper & YBCO (courtesy Northrop Grumman) 10

11 New Dewar Top Plate Inventor Model 11

12 Waveguide Probe Design Single-ended approach does not have the required bandwidth 12

13 Balanced Probes Probes fed 180-degrees out of phase, s11 < -20 db over 8-12 GHz 13

14 Probe Shape Radial, Rectangular 14

15 Waveguide Probe Design CST Model 15

16 Schematic OMT 180-Degree Hybrid RCP Cal Coupler 90-Degree Hybrid LCP Cal Coupler 180-Degree Hybrid 16

17 90Degree Hybrid OMT 180-Degree Hybrid RCP Cal Coupler 90-Degree Hybrid LCP Cal Coupler 180-Degree Hybrid 17

18 OMT Probes: Prototype Copper tape supported by Ecco-Foam PS

19 Probe Design Measured Return Loss & CST Prediction S11, db Waveguide Probes: Return Loss M. Stennes 12/13/ GHz Measured Model 19

20 180-Degree Hybrid Coupler Modified Rat Race Circuit MWO Linear Circuit Model MSUB Er=9.8 H=20 m il T=0.7 mil Rh o =1 Tand=0 ErN om =9.8 Na me = SU B1 MLIN ID=TL7 W=19.94 mil L=200 mil PORT P=3 Z=50 Ohm L8 = W8=2.599 MLEF ID = T L1 0 W=W8 mil L=L8 mil MLIN ID=TL3 W=19.94 mil L=200 mil 3 2 MTE E ID=TL9 LOAD W1=W7 mil ID=Z1 W2=19.94 mil Z=33.2 Ohm W3=W8 mil 1 MTEE 2 ID=TL6 W1=W1 mil W2=19.94 mil W3=W2 mil 1 MLIN ID=TL5 W=W1 mil L=L1 mil L1 = W1=9.778 MLIN ID=TL11 2 W=W 7 mil L=L7 mil 1 L7 = W7= MLIN ID = T L 8 W=W2 mil L= L 2 m il L2=129.7 W2=12.99 MCRO SS ID=TL4 W1=W7 mil W2=W1 mil MLEF W3=W6 mil ID=TL2 W4=W1 mil W=W 6 mil L= L 6 m il 3 L6=244.9 W6=0.732 MTEE ID=TL19 W1=W2 mil W2=W4 mil W3=W3 mil MLIN ID=TL15 W=W 3 mil L= L 3 m il L3=226.4 W3=22.38 MLIN ID=TL16 W=W 4 mil L=L4 mil MLIN ID=TL24 W=W5 mil L=L5 mil L5=258.3 W5=9.387 MLIN ID=TL12 W=W1 mil L=L1 mil MTE E ID=TL1 W1=19.94 mil W2=W1 mil W3=W2 mil MLIN ID = T L 14 W=W2 mil L= L 2 m il MTEE ID = T L1 8 W1=W 4 mil W2=W 2 mil W3=W 3 mil MLIN ID=TL17 W=W 4 mil L=L4 mil L4=115.5 W4= MTE E ID=TL20 W1=19.94 mil W2=W4 mil W3=W5 mil MLIN ID=TL22 W=19.94 mil L=200 mil POR T P=1 Z=50 Ohm MLIN ID=TL13 W=19.94 mil L=200 mil POR T P=2 Z=50 Ohm 20

21 180-Degree Hybrid: Design 3D EM model, CST 21

22 180-Degree Hybrid Coupler CST Model: Amplitude Balance Degree Hybrid: Amplitude Balance (Model) M. Stennes 1/21/

23 180- Degree Hybrid Coupler CST Model: Phase Balance Degree Hybrid: Phase Difference (Model) M. Stennes 1/21/2009 Degrees GHz 23

24 90-Degree Hybrid Design Backward wave coupler, λ/4 length 24

25 90-Degree Hybrid Coupler Design Tandem pair, 8.3 db coupling 25

26 90- Degree Hybrid Coupler Design Cut and twist coupled lines 26

27 90-Degree Hybrid Coupler Design Layout of twisted tandem couplers 27

28 90-Degree Hybrid: CST Model Wire bond locations 28

29 90-Degree Hybrid Chip Inventor Model 29

30 90-Degree Hybrid: Measured Performance Amplitude Balance 2 X-Band 90-Deg Hybrid Coupler Amplitude Balance M. Stennes 2/21/2009 Sij, db Measured Model Frequency, GHz 30

31 90-Degree Hybrid: Measured Performance Phase Balance -86 X-Band 90-Deg Hybrid Coupler Phase Balance M. Stennes 2/21/ Measured Model Sij, Degrees Frequency, GHz 31

32 90-Degree Hybrid: Measured Performance Isolation 0 90 Degree Hybrid Coupler, Isolation, Measured Sij, db Ports 3 4 Ports GHz 32

33 90-Degree Hybrid: Measured Performance Reflection Coefficient 0 5 X Band 90 Degree Hybrid: Measured Return Loss, In Fixture M. Stennes 2/21/ s11 s22 s33 s

34 Microstrip Crossover, New Design s11 34

35 Microstrip Crossover Measured Results OMT Isolation, Linear Polarization Before and After Redesign of Microstrip Crossovers M. Stennes 03/06/ db Version 1 Microstrip Crossovers Version 2 Microstrip Crossovers GHz 35

36 Receiver Noise Temperature Prediction Comparison between Copper and YBCO Comparison of Copper and HTS Couplers in the X-Band Receiver Trx Trx (copper) Trx (HTS) GHz 36

37 Receiver Noise Temperature Predictions MMIC LNA Option Comparison of Copper and HTS Couplers in the X-Band Receiver Trx GHz Trx (copper) Trx (HTS) Turnstile Pre-amp 37

38 OMT Circuit Layout Inventor Model 38

39 Chip Mounting Inventor Model 39

40 50 K Waveguide Section Inventor Model 40

41 OMT with Sliding Backshort Inventor Model 41

42 Cryostat Inventor Model: Second Stage Cold Plate 42

43 Cryostat Inventor Model: First Stage Cold Plate 43

44 Vacuum Window, Thermal Transitions Input WG 44

45 WG Probe Interface to Microstrip Microstrip 45

46 MMIC Option MMIC LNA 46

47 MMIC Performance Measured Data from Sandy Weinreb 47

48 Receiver Noise Temperature Gold/Alumina OMT 48

49 Receiver Noise Temperature Gold/Alumina OMT 49

50 Receiver Noise Temperature Linear vs. Circular Polarization Thermal Gap Open, Closed Receiver Noise Temperature, Linear/Circular Pol, Open/Closed Thermal Gap Receiver Noise Temp, Kelvins first test linear pol, T=19K, May 28 circ pol, reduced gap width Sept 18, with absorber GHz 50

51 Receiver Noise Temperature YBCO/MgO OMT 51

52 Receiver Noise Temperature YBCO/MgO OMT X Band Receiver Noise HTS Planar OMT Trx RCP HTS 1 Trx RCP HTS 2 35 Kelvins GHz 52

53 Receiver Noise, HTS OMT 3 GHz IF This data was taken using a power meter, measuring 3GHz IF, filtered through a tunable microwave preselector. Receiver configuration is HTS OMT, old TRW cryo isolators. Thot Tcold f (GHz) Phot (dbm) Pcold(dB m) Y(dB) Y Trx (K) RCP

54 Receiver Noise Temperature Gold/Alumina OMT 250 Trx Au/Al, Reduced Gap Width Trx RCP May 21, no absorber Trx LCP Aug 21, with absorber 100 Trx Au/Al, Reduced Gap Width Sept 18, with absorber Note: Noise in GHz is higher, maybe due to degradation to circuits 54

55 Trx as a Function of OMT Loss Trx vs OMT Loss Trx (K) Trx (K) vs. OMT Loss OMT Loss (db) Trx (K) 55

56 Chip Resistor Return Loss Chip Resistor 0210, s11 Chip Resistor Termination s11, db GHz 56

57 OMT Input Return Loss Full OMT vs. Chip Resistor Terminated Probes OMT Return Loss s11 probes term'd in microstrip line and chip resistor s11 full Au OMT Chip Resistor Termination s11 OMT prototype, copper foil probes, with coax outputs

58 OMT Output Return Loss S22, S33 RCP & LCP Output Return Loss Au/alumina, Sept LCP output s11 with circ wg load RCP output s11 with circ wg load

59 YBCO OMT Loss SS Coax Loss, and 3 db Coupling Loss Removed from Measured Data 4 2 HTS Planar OMT s21, Minus SS Coax Loss, +3dB Input Probe Aligned with Y (X+90 deg), Output = LCP s21 corrected +3dB 0 db GHz 59

60 Closing the 15K/50K WG Thermal Gap Au/Alumina OMT, Room Temperature Measurements 60

61 HTS Wafer Artwork 3-Inch Diameter 61

62 Microstrip Line Loss Measurement Fixture 62

63 YBCO/MgO Au/alumina Cost Estimates Gold/Alumina YBCO/MgO Item Cost (for small quantities) USD Cost (for 30+) USD Microstrip circuits 325. Gold plating of chip carriers Done at NRAO CDL Done at NRAO CDL G10 fiberglass 50. Brass, aluminum blocks 45. Kovar sheet 25. Totals 445. Item Cost (for small quantities) USD Cost (for 30+) USD Microstrip circuits Gold plating of chip carriers 600. Done at NRAO CDL G10 fiberglass 50. Brass, aluminum blocks 45. Kovar sheet 25. Totals

64 Microstrip Line Loss, T= 15K YBCO/MgO, 4.7 cm Length 54% of the OMT s Path Length Insertion Loss of 4.7cm Length of YBCO 50 Ohm Microstrip Line 0 1 db s21, HTS plus fixturing s21, fixturing s21 HTS GHz 64

65 Microstrip Line Loss, T= 15K Removing effect of s11 Insertion Loss of 4.7cm Length of YBCO 50 Ohm Microstrip Line db GHz 65

66 Signal Loss Through Fixturing Warm and Cold 66

67 Loss Through Au/Alumina Microstrip Warm compared to Cold, Includes Fixture Losses 67

68 Microstrip Line Loss, Gold vs. YBCO Includes Fixture Losses 68

69 Earlier Loss Measurement: Au/Alumina T=15K Gold/Alumina Microstrip Line, 4.7cm Long, s21 db 0.1-6E s21 (db) Alumina T=21K, 11:30PM, Jan Frequency (GHz) 69

70 Microstrip Line Loss: Gold vs. YBCO December 2008 YBCO 50-Ohm Microstrip Line, Length = 4.7cm M. Stennes 12/10/08 s21 (db) Frequency (GHz) 16K 50K 70K 100K 110K 150K 200K 250K 300K 70

71 Microstrip Line Loss: Gold vs. YBCO December 2008 YBCO 50-Ohm Microstrip Line, Length = 4.7cm M. Stennes 12/10/08 s21 (db) Frequency (GHz) 16K 50K 70K 100K 110K 150K 200K 250K 300K 71

72 Conclusions OMT loss measurements are consistent with receiver noise (Trx) levels Receiver noise temperatures of 25K for Gold/Alumina were achieved. Cooled microstrip loss, and other data indicate that Trx = 15K may be possible YBCO/MgO OMT may offer lower loss for X-band. 8K to 9K demonstrated over narrow band. A significant design flaw was identified; waveguide thermal gap (15K/50K) must be redesigned. A lower-loss OMT may be realized, by implementing a single-ended probe design, and/or eliminating the 90-degree hybrid coupler. OMT input return loss of -15 db is predicted, but not demonstrated OMT polarization isolation is limited by the microstrip crossovers (-25 db) and 90-degree hybrid (-19 db) 72

73 Possible Improvements Reduce OMT loss by: elimination of wire bonds Full closure of 15/50K thermal gap Improve OMT isolation by optimizing microstrip crossover design, and by providing amplitude and phase predistortion to compensate for 90-degree hybrid s finite isolation (-19 db) Use single-ended waveguide probe, eliminate 180-degree hybrid Reduce receiver noise temperature with use of integrated MMIC LNA Improve OMT return loss through: Linear system modeling and fixed tuning Variable tuning with real-time s11 measurement Wafer probing and fixed tuning 73

74 Possible Improvements (continued) Total elimination of the 15K/50K thermal gap, having just one gap for 15K/300K. 74