WVR workshop, Wettzell, Miroslav Pantaleev Development of the Dicke-switched WVR prototype for ALMA Magne Hagström, Lars Pettersson and Leif Helldner Collaboration with

WVR workshop, Wettzell, Miroslav Pantaleev

WVR workshop, Wettzell, Miroslav Pantaleev Development of the Dicke-switched prototype for the ALMA WVR  Radiometer design - Double Dicke  Critical components  Lab tests  SMA - tests  Single Dicke prototype

WVR workshop, Wettzell, Miroslav Pantaleev Optics layout - Double Dicke M5 C2 M4 C1 M3  Chopper wheel to select between sky - calibration  Measure all the time  Cryo cooler as cold load  Warm mixers and LNA

WVR workshop, Wettzell, Miroslav Pantaleev Calibration Hot and Cold Solenoid Vane Hot load

WVR workshop, Wettzell, Miroslav Pantaleev Chopper wheel function and design goals  Reliable > 10 years of continuous running  Small blade diameter – cut a small beam waist  Phase locked to external square wave

WVR workshop, Wettzell, Miroslav Pantaleev Chopper blade  Dynamically balanced chopper wheel  No holes to avoid turbulences

WVR workshop, Wettzell, Miroslav Pantaleev Chopper support  Bearings – SKF  Lifetime – more than 25 years (depending on the operational rpm)  Flexible coupling to dump vibrations

WVR workshop, Wettzell, Miroslav Pantaleev Chopper protective cover

WVR workshop, Wettzell, Miroslav Pantaleev Chopper blade positioning

WVR workshop, Wettzell, Miroslav Pantaleev Chopper timing

WVR workshop, Wettzell, Miroslav Pantaleev Measured chopper data Chopper blade jitter

WVR workshop, Wettzell, Miroslav Pantaleev Block diagram Double Dicke

WVR workshop, Wettzell, Miroslav Pantaleev Mixer

WVR workshop, Wettzell, Miroslav Pantaleev 3 dB, 91.6 GHz power divider  Waveguide branch type couplers – many section required to cover wide bandwidth  Double probe structure is coupled to the E-field in a waveguide By courtesy of V.Vassilev

WVR workshop, Wettzell, Miroslav Pantaleev DSB - Noise temperature Double Dicke

WVR workshop, Wettzell, Miroslav Pantaleev Sensitivity

WVR workshop, Wettzell, Miroslav Pantaleev Filter bands  The LO frequency is kept very close to line frequency.  Mixers are double sideband.  Four IF channels with larger bandwidth away from the centre of the line.

WVR workshop, Wettzell, Miroslav Pantaleev Filter and video assembly

WVR workshop, Wettzell, Miroslav Pantaleev Custom designed filters  Bandpass filter B (1.565GHz – 2.315GHz)  Ring resonators bandpass filter  Compact, low insertion-loss, sharp- rejection, and wide-band application

WVR workshop, Wettzell, Miroslav Pantaleev Calibration reference loads Two reference temperatures with a  T  150 K, one of them close to sky the temperature  Peltier element - not possible to get below – 50 ºC  Noise diode - only  4 dB ENR Sterling cooler  Cool a microwave absorber to below 150 K.  Stabilize the temperature of the absorber to < 0.05 K  Absorber reflectivity > 30 dB at 183 GHz.  Maintenance free time  10 years.

WVR workshop, Wettzell, Miroslav Pantaleev Cooling power

WVR workshop, Wettzell, Miroslav Pantaleev Cooled load mount

WVR workshop, Wettzell, Miroslav Pantaleev Thermal stabilization Insulation Frame with Peltier cooler IF temperature regulation

WVR workshop, Wettzell, Miroslav Pantaleev Single Dicke

WVR workshop, Wettzell, Miroslav Pantaleev Block diagram Single Dicke

WVR workshop, Wettzell, Miroslav Pantaleev Optics layout - Comparison

WVR workshop, Wettzell, Miroslav Pantaleev Physical size comparison: Double -Single Dicke Cost saving pre-production design work  Single Dicke Receiver  Replacement of the Hymatic Sterling cooler with a Peltier cooler  Replacement of the cold load with a cool/hot load combination

WVR workshop, Wettzell, Miroslav Pantaleev Cold load  Single Dicke Receiver  Replacement of the Hymatic Sterling cooler with a Peltier cooler  Replacement of the cold load with a cool/hot load combination

WVR workshop, Wettzell, Miroslav Pantaleev Current status

WVR workshop, Wettzell, Miroslav Pantaleev IF linearity