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Subsections

Sideband separation mixer for ALMA Band 7

Following the design described in ALMA Memo 316 [1], and using two double side band (DSB) mixer units designed by Navarinni et al. [2], a sideband separation mixer for ALMA Band 7 has been built and tested at IRAM (Fig. 4,5).

An image rejection better than 10 dB has been obtained across the Band 7 (Fig. 6). The single side band (SSB) Trec was measured for two intermediate frequency (IF) bandwidths (Fig. 78. These tests were performed with a mixer IF impedance transformer that is not fully optimized for the 4-8 GHz ALMA required band. Further tests will include mixers with better noise temperature and a full 4-8 GHz IF.

It is interesting to note that the system proved to be quite simple to operate, i.e. not any more difficult than a DSB mixer.

References:

[1
] S. M. X. Claude, C. T. Cunningham, A. R. Kerr, and S.-K. Pan, Design of a Sideband-Separating Balanced SIS Mixer Based on Waveguide Hybrids, ALMA Memo No. 316
[2
] A. Navarrini, D. Billon-Pierron, I. Peron, B. Lazareff, "Design and characterization of a 225-370 GHz DSB and a 247-360 GHz SSB waveguide SSB mixers",Proceedings of the 26th. International Conferenceon Infrared and Millimeter Waves, Toulouse, FRANCE, 10/09/2001- 14/09/2001



Stephan CLAUDE


  
Figure 4: Assembled 2SB Mixer
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Figure 5: Open 2SB Mixer
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Figure 6: Sideband rejection for LSB and USB tuning
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Figure 7: SSB Trec, for an IF of 4-6 GHz
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Figure 8: SSB Trec, for an IF of 5 GHz
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