MILLIMETER WAVE
INSTRUMENTATION LAB


REDSHIFT tour page 1 2 3 4 5


Back to the Instrumentation Page


Back to the FCRAO Home Page


Back to the Astronomy Dept. Home Page


Send mail to the Webmaster


Last Modified: Monday, 19-Dec-05 1:05:31 PM EDT



This material is based on work supported by the National Science Foundation under Grant AST-0096854.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect those of the National Science Foundation.

REDSHIFT SEARCH RECEIVER

Optics

  • All HEMT based amplifiers have 1/f gain fluctuations requiring a ~1 KHz beam switch.
  • The receiver has two dual polarized beams with a beamswitch, therefore one beam is always on source.
  • Polarization ±45° rotator combined with an external wire grid forms a beamswitch
  • The beams are combined into dual polarized waveguide modes by the OMT.
  • The added noise is <10°K, with switching time <10 µsec (1 KHz practical)

Beamswitch schematic


    Faraday Rotator

  • The dual polarized beam is coupled into a ferrite rod with a switched magnetic bias,
    which rotates both modes by ±45°
  • Tapered square waveguides couple into dielectric rods, then into a ferrite rod with axial magnetic bias

Cross section through the Faraday rotator.
At the right and left sides the waveguide has a square cross section.



Optics as they will be configured for a high f ratio telescope.



Beams separated in azimuth with spacing of 3 HPBW



Previous Next
Continue the REDSHIFT tour...