Transcript 天線工程期末報告

微波電路期中報告
論文研討:
John C. Webber、Marian W. Pospieszalski,
“Microwave Instrumentation for Radio
Astronomy”,IEEE TRANSACTIONS ON MICROWAVE THEORY AND
TECHNIQUES, VOL. 50, NO. 3, MARCH 2002
報告人:
碩研電子一甲 MA030217
Southern Taiwan University
陳力源
Department of Electronic Engineering
摘要
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Radio astronomy is a branch of science that allows
observation of natural radio signals from cosmic sources.

Microwave techniques are employed in large radio
telescope systems.
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Index Terms—Amplifiers, radio astronomy, radio receivers,
superconductor–insulator–superconductor mixers.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 3,
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Radiometers
(a) Resistor at temperature T. (b) Antenna in an absorbing box at
temperature T. (c) Antenna observing sky at temperature T (after [2]).
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Simplified block diagram of a total power receiver.


from antenna theory that Upon substitution of (3) into (2), (1)
is obtained, i.n., the available noise power at the ideal
antenna terminals of Fig 2.
---(3)

---(2)
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---(1)
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Geometry of a simple two-element interferometer
Geometry of a simple two-element interferometer
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LOW-NOISE DEVICES
A.General Remarks
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The quest for ultra-low-noise reception is especially
important for radio astronomy
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as the receiver noise is usually a significant part of
the system noise
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LOW-NOISE DEVICES
B.HFET Amplifiers
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the technology of InP devices has matured and
allowed practical use.
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Hybrid “chip and wire” amplifiers have been
demonstrated up to frequencies of 118 GHz
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Comparison of noise temperature
of NRAO cryogenic receivers
using InP HFET amplifiers cooled
to approximately 20 K and SIS
mixer receivers cooled to 4 K.
Fig. 4.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 3,
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C. SIS Mixers
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An SIS mixer employs a superconducting tunnel junction as the nonlinear
mixing element.
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A high-quality SIS mixer can have a noise temperature ( 5 K at 100 GHz)
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Modern SIS mixers normally use Nb junctions, which give good results
when cooled to 4.0-K physical temperature
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Junction sizes are typically a few square micrometers, and critical current
densities are typically a few thousand A/cm .
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an IF bandwidth of 1 GHz, with the exception of an approximately 3GHz
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a balanced SIS mixer has the same
advantages as a balanced conventional
mixer: reduction of the required LO
power and canceling of the LO sideband
noise downconverted into the IF band.
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A balanced SIS mixer using niobium
MMIC technology has been demonstrated
at 200–300 GHz
Example of noise performance of a fixed-tuned SIS
mixer (discrete points) and the entire receiver (solid line)
for 200–290 GHz
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EXAMPLES OF RADIO ASTRONOMY RECEIVERS
A.HFET Receiver
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A critical area in very low-noise receiver design is a
low-loss coupling between an ambient temperature feed
horn and a cryogenic amplifier.
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The VLBA front-ends use a gapped circular waveguide
transition from the feed to a cooled polarizer located
within the vacuum Dewar.
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B. SIS Receiver
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SIS mixer receivers are typically employed above
frequencies of about 100 GHz.
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The radiation into the mixer are the same as for HFET
receivers,made even more difficult by smaller
dimensions and tolerances as the frequency is increased.
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Double-sideband receiver noise temperatures of
approximately 20 K have been reported near 100 GHz for
Nb SIS mixer receivers
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C. MAP Radiometer
Simplified block diagram of a MAP satellite pseudocorrelation radiometer
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Inner portion of the VLA in its most
compact configuration
100-meter Robert C. Byrd GBT
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結論
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本文內容對我自己幫助也很大 ，Microwave
Instrumentation for Radio Astronomy， 運作方法需要
電子學知識, 電磁波傳遞與接收, 需要使用微波工程內
容,,所以是一個十足有趣的領域。
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參考文獻
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 3,
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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 3,
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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 3,
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