Receivers

Since December 2006 all antennas are equipped with a new generation of dual polarization receivers for the 3mm and 1.3mm atmospheric windows. The frequency range is 81GHz to 116GHz for the 3mm band, and 201 to 256GHz for the 1.3mm band.

Each band of the new receivers is dual-polarization (two RF and IF channels) with the two RF channels of one band observing at the same frequency (common LO). The different bands are not co-aligned in the focal plane (and therefore on the sky). The mixers are single-sideband, backshort-tuned; they can be tuned USB or LSB, both choices being available in the central part of the RF band. The typical image rejection is 10dB. Each IF channel is 4 GHz wide (4-8 GHz). Only one frequency band can be connected to the IF transmission lines at any time. Because of this reason and due to the pointing offsets between different frequency bands, only one band can be observed at any time. The other band is in stand-by (power on and local oscillator phase-locked) and is available, e.g., for pointing. Time-shared observations between two frequency bands can not be offered for the summer (this mode is currently being tested).

The two IF-channels (one per polarization), each 4 GHz wide (total 8 GHz) are transmitted by optical fibers to the central building. At present, the 4GHz bandwidth can be processed only partially by the existing correlator, through a dedicated IF processor that converts selected 1 GHz wide slices of the 4-8 GHz first IFs down to 0.1-1.1 GHz, the input range of the existing correlator. Further details are given in the section describing the correlator setup and the IF processor.

PdBI Receiver Specifications
	Band 1	Band 3
RF coverage	81-116	201-256
$\rm T_{rec}$	40-55	40-60 (LSB)
$\rm T_{rec}$		50-70 (USB)
$\rm G_{im}$	$\rm -10$ dB	$\rm -12 -8$ dB
RF range in LSB	81-104	201-244
RF range in USB	104-116	244-256