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Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the E-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity(More)
The Microwave Anisotropy Probe (MAP) satellite, launched June 30, 2001, will produce full sky maps of the cosmic microwave background radiation in 5 frequency bands spanning 20-106 GHz. MAP contains 20 differential radiometers built with High Electron Mobility Transistor (HEMT) amplifiers with passively cooled input stages. The design and test techniques(More)
Initial results are presented for a 200-300 GHz SIS mixer/preamplifier with an IF bandwidth of 8 GHz. The mixer uses Nb/Al-oxide/Nb tunnel junctions in a circuit with low IF capacitance and inductance. The mixer block mounts directly on the body of a three-stage 4-12 GHz preamplifier which uses discrete InP HFET devices. Mixer bias is provided through the(More)
Differential pseudo-correlation radiometers covering 20-25 GHz , 28-37 GHz, 35-46 GHz, 53-69 GHz and 82-106 GHz are used in the Microwave Anisotropy Probe (MAP) mission to be launched in late 2000. This paper describes the design, performance and manufacturing of 140 InP HFET amplifiers suitable for cryogenic cooling which exhibit low noise performance and(More)
The ALMA Band 6 (211-275 GHz) receivers use sideband-separating SIS mixer-preamplifiers with dual 4-12 GHz IF outputs. The sideband-separating mixers are of the phasing type, with the LO driving two component mixers in-phase and the RF signal connected to the mixers through a quadrature hybrid. The IF outputs of the mixers are amplified, then combined in a(More)
Quarter-micrometer gate-length HEMT's for cryogenic low-noise application with very low light sensitivity have been developed. At room temperature, these exhibit a noise figure of 0.4 dB with associated gain of 15 dB at 8 GHz. At a temperature of 12.5 K the minimum noise temperature of 5.3 f 1.5 K has been measured at 8.5 GHz, which is the best noise(More)
— Cryogenic cooling of receivers to reduce their noise temperature is especially important in radio astronomy, as the antenna noise temperature is determined by the cosmic microwave background radiation (2.725 K) modified by the presence of atmosphere. For frequencies up to 120 GHz direct amplification at cryogenic temperatures is typically employed using(More)
This paper describes an 84-116 GHz Nb/Al-oxide/Nb SIS mixer with multi-octave IF bandwidth and quantum-limited sensitivity. The mixer can be integrated with a three-stage 4-12 GHz HFET preamplifier or fitted with a coaxial connector for operation with an external isolator and IF amplifier. An 84-116 GHz receiver using the mixer with an integrated 4-12 GHz(More)
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