Central Development Laboratory (Adapted from John Webber’s Viewgraphs, April 2002 Presented tonight by Skip Thacker) IEEE Tour April 2003

IEEE CDL Tour April Block Diagram

IEEE CDL Tour April CDL Activities Low-noise Amplifiers Low-noise Amplifiers Passive Electromagnetic Devices Passive Electromagnetic Devices ALMA SIS mixers for Bands 3 & 6 ALMA SIS mixers for Bands 3 & 6 ALMA Front End LO for All Bands ALMA Front End LO for All Bands ALMA Correlator ALMA Correlator Other Digital Projects Other Digital Projects L-band Array Receiver (with Green Bank) L-band Array Receiver (with Green Bank)

IEEE CDL Tour April Amplifier Goals Keep up with receiver builds Keep up with receiver builds Improve production efficiency Improve production efficiency Develop InP amplifiers for bands down to 1 GHz Develop InP amplifiers for bands down to 1 GHz Start replacement of antiquated test equipment Start replacement of antiquated test equipment

IEEE CDL Tour April Production Amplifiers Band (GHz) Noise (K) Comment Band (GHz) Noise (K) Comment balanced C balanced C balanced C/X InP balanced C/X InP balanced X/Ku InP balanced X/Ku InP balanced K InP balanced K InP balanced Ka InP balanced Ka InP Q InP Q InP V InP V InP W InP W InP

IEEE CDL Tour April Electromagnetics Feeds for GBT: and GHz Feeds for GBT: and GHz Feed for EVLA: GHz Feed for EVLA: GHz G/T slightly worse at zenith G/T slightly worse at zenith G/T much improved integrated over sky G/T much improved integrated over sky Scaled versions for 2-4 and 4-8 GHz Scaled versions for 2-4 and 4-8 GHz Optics for ALMA Band 6 ( GHz) Optics for ALMA Band 6 ( GHz)

IEEE CDL Tour April GBT GHz Feed Design

IEEE CDL Tour April SIS Mixer Objectives ALMA Band 6 ( ) GHz sideband- separating, balanced mixer ALMA Band 6 ( ) GHz sideband- separating, balanced mixer ALMA Band 3 ( GHz) elemental mixer for use by Herzberg Institute ALMA Band 3 ( GHz) elemental mixer for use by Herzberg Institute Internal IF amp for 8 GHz bandwidth Internal IF amp for 8 GHz bandwidth Band 6 cartridge development Band 6 cartridge development Automated mixer testing Automated mixer testing

IEEE CDL Tour April Band 6 Waveguide-Hybrid SIS Mixer Block

IEEE CDL Tour April Band 6 Waveguide-Hybrid SIS Mixer Block Detail

IEEE CDL Tour April New Band 3 Elemental SIS Mixer Wafer

IEEE CDL Tour April New Band 3 Elemental SIS Mixer Wafer Detail

IEEE CDL Tour April New Band 3 Elemental SIS Mixer Wafer Detail

IEEE CDL Tour April Band 6 Balanced Mixer-preamp Assembly

IEEE CDL Tour April SIS Mixer Test Facility With Two 4K Dewars

IEEE CDL Tour April ALMA Front End LO Tasks YIG-Tuned-Oscillator-based drivers YIG-Tuned-Oscillator-based drivers Low phase noise lock loops Low phase noise lock loops Final power amplifiers Final power amplifiers High-frequency multipliers High-frequency multipliers

IEEE CDL Tour April GHz Power-combining Balanced Power Amplifier

IEEE CDL Tour April ALMA Band 6 LO Prototype for SIS Mixer Test Facility

IEEE CDL Tour April Prototype Warm Multiplier Assembly

IEEE CDL Tour April Band 6 Cartridge LO components

IEEE CDL Tour April ALMA Correlator 64 antennas 8 IF bands per antenna 4 Gsamples/sec per IF band, 2 bits/sample correlated 1024 lead lag correlations per baseline 30 km maximum baseline delay range Full polarization capability plus autocorrelation Digital filter for bandwidths <2 GHz Switch modes in less than 1.5 seconds This requires 4,194,304 multiply-and-add correlators at 4 GHz rate Total computation rate is 1.7 X multiply-and-add operations/sec

IEEE CDL Tour April FIR Filter Card & Station Card FIR Filter CardStation Card

IEEE CDL Tour April Station Card in Test Fixture

IEEE CDL Tour April Correlator Card Back

IEEE CDL Tour April Front and Rear Views

IEEE CDL Tour April Station Bin

IEEE CDL Tour April Beam-Forming Array Receiver Objective: synthesize multiple beams for GHz, where conventional feed arrays are impractical on the GBT Objective: synthesize multiple beams for GHz, where conventional feed arrays are impractical on the GBT Approach: oversample e-m field at focal plane with closely spaced feeds Approach: oversample e-m field at focal plane with closely spaced feeds Challenges: Challenges: Achieve system noise temperature close to that of a conventional receiver Achieve system noise temperature close to that of a conventional receiver Achieve mechanical and electronic stability sufficient for reliable calibration Achieve mechanical and electronic stability sufficient for reliable calibration

IEEE CDL Tour April Beam Forming Array

IEEE CDL Tour April Beam-Forming Array Feeds Array of dipoles samples focal plane Array of dipoles samples focal plane Tuned for MHz Tuned for MHz 37-element prototype provides 7 beams on the sky 37-element prototype provides 7 beams on the sky

IEEE CDL Tour April Prototype Dipole