468,727 research outputs found
A 1.2 V and 69 mW 60 GHz Multi-channel Tunable CMOS Receiver Design
A multi-channel receiver operating between 56 GHz and 70 GHz for coverage of different 60 GHz bands worldwide is implemented with a 90 nm Complementary Metal-Oxide Semiconductor (CMOS) process. The receiver containing an LNA, a frequency down-conversion mixer and a variable gain amplifier incorporating a band-pass filter is designed and implemented. This integrated receiver is tested at four channels of centre frequencies 58.3 GHz, 60.5 GHz, 62.6 GHz and 64.8 GHz, employing a frequency plan of an 8 GHz-intermediate frequency (IF). The achieved conversion gain by coarse gain control is between 4.8 dB–54.9 dB. The millimeter-wave receiver circuit is biased with a 1.2V supply voltage. The measured power consumption is 69 mW
Statistical properties of 12.2 GHz methanol masers associated with a complete sample of 6.7 GHz methanol masers
We present definitive detection statistics for 12.2 GHz methanol masers
towards a complete sample of 6.7 GHz methanol masers detected in the Methanol
Multibeam survey south of declination -20 degrees. In total, we detect 250 12.2
GHz methanol masers towards 580 6.7 GHz methanol masers. This equates to a
detection rate of 43.1%, which is lower than that of previous significant
searches of comparable sensitivity. Both the velocity ranges and the flux
densities of the target 6.7 GHz sources surpass that of their 12.2 GHz
companion in almost all cases. 80 % of the detected 12.2 GHz methanol maser
peaks are coincident in velocity with the 6.7 GHz maser peak. Our data support
an evolutionary scenario whereby the 12.2 GHz sources are associated with a
somewhat later evolutionary stage than the 6.7 GHz sources devoid of this
transition. Furthermore, we find that the 6.7 GHz and 12.2 GHz methanol sources
increase in luminosity as they evolve. In addition to this, evidence for an
increase in velocity range with evolution is presented. This implies that it is
not only the luminosity, but also the volume of gas conducive to the different
maser transitions, that increases as the sources evolve. Comparison with
GLIMPSE mid-infrared sources has revealed a coincidence rate between the
locations of the 6.7 GHz methanol masers and GLIMPSE point sources similar to
that achieved in previous studies. Overall, the properties of the GLIMPSE
sources with and without 12.2 GHz counterparts are similar. There is a higher
12.2 GHz detection rate towards those 6.7 GHz methanol masers that are
coincident with extended green objects.Comment: Accepted to ApJ March 2011. 28 pages, 9 figure
Spectral Properties of the Core and the VLBI-Jets of Cygnus A
We present a detailed VLBI study of the spectral properties of the inner core
region of the radio galaxy Cygnus A at 5 GHz, 15 GHz, 22 GHz, 43 GHz and 86
GHz. Our observations include an epoch using phase-referencing at 15 GHz and 22
GHz and the first successful VLBI observations of Cygnus A at 86 GHz. We find a
pronounced two-sided jet structure, with a steep spectrum along the jet and an
inverted spectrum towards the counter-jet. The inverted spectrum and the
frequency-dependent jet-to-counter-jet ratio suggest that the inner counter-jet
is covered by a circum-nuclear absorber as it is proposed by the unified
scheme.Comment: 2 pages, 2 figures, Proceedings of the 7th EVN Symposium held in
Toledo, Spain in October 2004, needs evn2004.cl
NMR GHZ
We describe the creation of a Greenberger-Horne-Zeilinger (GHZ) state of the
form |000>+|111> (three maximally entangled quantum bits) using Nuclear
Magnetic Resonance (NMR). We have successfully carried out the experiment using
the proton and carbon spins of trichloroethylene, and confirmed the result
using state tomography. We have thus extended the space of entangled quantum
states explored systematically to three quantum bits, an essential step for
quantum computation.Comment: 4 pages in RevTex, 3 figures, the paper is also avalaible at
http://qso.lanl.gov/qc
The first high-resolution observations of 37.7-, 38.3- and 38.5-GHz methanol masers
We have used the Australia Telescope Compact Array (ATCA) to undertake the
first high angular resolution observations of 37.7-GHz ()
methanol masers towards a sample of eleven high-mass star formation regions
which host strong 6.7-GHz methanol masers. The 37.7-GHz methanol sites are
coincident to within the astrometric uncertainty (0.4 arcseconds) with the
6.7-GHz methanol masers associated with the same star formation region.
However, spatial and spectral comparison of the 6.7- and 37.7-GHz maser
emission within individual sources shows that the 37.7-GHz masers are less
often, or to a lesser degree co-spatial than are the 12.2-GHz and 6.7-GHz
masers. We also made sensitive, high angular resolution observations of the
38.3- and 38.5-GHz class II methanol transitions ( and
, respectively) and the 36.2-GHz () class
I methanol transition towards the same sample of eleven sources. The 37.7-,
38.3- and 38.5-GHz methanol masers are unresolved in the current observations,
which implies a lower limit on the brightness temperature of the strongest
masers of more than K. We detected the 38.3-GHz methanol transition
towards 7 sources, 5 of which are new detections and detected the 38.5-GHz
transition towards 6 sources, 4 of which are new detections. We detected
36.2-GHz class I methanol masers towards all eleven sources, 6 of these are new
detections for this transition, of which 4 sources do not have previously
reported class I methanol masers from any transition.Comment: Accepted for publication in MNRAS, 34 pages, 20 figure
Electromagnetic Bandgap Structure For Isolation In Mixed-signal Systems
Electromagnetic bandgap (EBG) structures, systems incorporating EBG structures, and methods of making EBG structures, are disclosed. An embodiment of the structure, among others, includes a plurality of first elements disposed on a first plane of a device; and a second element connecting each first element to an adjacent first element, the second element being disposed on the first plane of the device. The structure is configured to substantially filter electromagnetic waves to a stopband floor of about -40 dB to about -120 dB in a bandgap of about 100 MHz to about 50 GHz having a width selected from about 1 GHz, 2 GHz, 3 GHz, 5 GHz, 10 GHz, 20 GHz, and 30 GHz. In addition, the structure has a center frequency positioned at a frequency from about 1 GHz to 37 GHz.Georgia Tech Research Corporatio
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