A cartridge-type side-band separating (2SB) mixer receiver for 350 GHz band, CATS345, is available for this semester.

Specifications (Feb. 10, 2012)

• Tunable LO frequency range: 330 GHz to 366 GHz
• IF frequency range: 4.5 GHz to 7.0 GHz (receiver IF range is 4.0 to 8.0 GHz, but it is limited by a filter at IF optical transmission section.)
• Observable frequency range (LO frequency range +/- IF center frequency): 324 GHz to 372 GHz. Please consult us in advance if you want to observe a line beyond the frequency range.
• Image rejection ratio (IRR): 15 dB typical.
• Polarization: single linear polarization only. Upgrade for dual-polarization is in progress.
• Expected system noise temperature (Tsys): Assume a SSB system noise temperature of T_sys = 250 K at 345 GHz at EL ~ 60. Note that this is for an averaged atmospheric condition in winter (i.e., for zenith opacity at 220 GHz of ~0.05 or precepitable water vapor, PWV, of ~1 mm). It can be highly variable depending on the atmospheric conditions and observing frequency. See Fig. 1 for atmospheric transparency as a function of frequency.

Table 1. Specification of CATS345.

Mixer	Npolar	Npix	fLO (GHz)	fobs (GHz)	IF (GHz)	typical IRR	TRX (2SB)	Tsys (SSB) #1
sideband-separating SIS mixer	1	1	330-366	324-372	4.5-7.0	15 dB	100-120 K	250 K

• Note #1: This is a value expected at 345 GHz at EL ~ 60 deg under a typical condition (zenith opacity at 220 GHz = 0.05).

Receiver tuning

It requires about 10 minutes for receiver tuning when you start observations or change your observing frequency. Attenuators for LO and IF powers and room temperature absorber will be adjusted remotely by observers.

Figure 1: Atmospheric transparency as a function of frequency, for PWV = 1 mm.