Open Access
Table 1
ALMA band 5 receiver specifications.
| RF bandwidth | 163 GHz to 211 GHz - the nominal RF input frequency range; 158 GHz to 211 GHz - the extended RF range |
| IF bandwidth | 4 GHz to 8 GHz both in upper and lower sidebands, in each polarisation |
| Receiver noise temperature | ≤55 K in 80% of the nominal RF frequency range, ≤75 K in the extended RF range |
| Image band rejection ratio | ≥10 dB in 90% of the IF band for any RF frequency within the nominal RF range, ≥7 dB for the entire IF band for any RF frequency within the extended RF range |
| Total in-band power | –32 to –22 dBm in 4–8 GHz |
| IF power variations | ≤7∕5∕1.35 dB p–p respectively full IF band/any 2 GHz/any 31 MHz sub-band |
| Gain compression | <5% for 373 K vs. 77 K |
| Amplitude stability | Allan variance σ2(2, T, T) < 4 × 10−7 for 0.05 ≤ T ≤ 100 s, <3 × 10−6 for T = 300 s |
| Signal path phase stability | Long term (delay drift) 20 s ≤ T < 300 s : ≤7.1 fs for all frequencies within the IF pass-band |
| Optical efficiencies | aperture;polarization;focus >80%;99.5%;98% |
| Nonoptical cross-talk between polarisation channels | <–63 dB |
| Beam squint between polarisation channels | ≤1/10 of FWHM on sky |
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