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| Author |
Edward Tong, C.-Y.; Loudkov, Denis N.; Paine, Scott N.; Marrone, Dan P.; Blundell, Raymond |
| Title |
Vector measurement of the beam pattern of a 1.5 THz superconducting HEB receiver |
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Conference Article |
Year  |
2005 |
Publication |
Proc. 16th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 16th Int. Symp. Space Terahertz Technol. |
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453-456 |
| Keywords |
NbTiN HEB mixers |
| Abstract |
Near-field vector beam pattern of the 1.5 THz superconducting Hot Electron Bolometer (HEB) receiver currently in operation in Northern Chile has been performed in our laboratory. Using an open waveguide probe, we have mapped both the amplitude and phase of the beam emerging from our 1.5 THz HEB receiver package, across a number of planes along the line of propagation of the radio-beam. With an integration time of about 100 ms per point, a signal-to-noise ratio of about 25 dB was achieved for a beam waist of 3.5 mm. These measurements have proved to be invaluable in achieving good alignment between the cryostat housing the HEB mixer and the remainder of the receiver and telescope optics. The accuracy of our beam measurement is estimated to be ±0.2 mm in position and ±5 arc minutes in angular displacement. |
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1474 |
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Semenov, Alexei; Richter, Heiko; Smirnov, Konstantin; Voronov, Boris; Gol'tsman, Gregory; Hübers, Heinz-Wilhelm |
| Title |
The development of terahertz superconducting hot-electron bolometric mixers |
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Journal Article |
| Year |
2004 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
| Volume |
17 |
Issue |
5 |
Pages |
436-439 |
| Keywords |
NbN HEB mixers |
| Abstract |
We present recent advances in the development of NbN hot-electron bolometric (HEB) mixers for flying terahertz heterodyne receivers. Three important issues have been addressed: the quality of the source NbN films, the effect of the bolometer size on the spectral properties of different planar feed antennas, and the local oscillator (LO) power required for optimal operation of the mixer. Studies of the NbN films with an atomic force microscope indicated a surface structure that may affect the performance of the smallest mixers. Measured spectral gain and noise temperature suggest that at frequencies above 2.5 THz the spiral feed provides better overall performance than the double-slot feed. Direct measurements of the optimal LO power support earlier estimates made in the framework of the uniform mixer model. |
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357 |
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Kramer, B.; Chen, C-C.; Volakis, J.D. |
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The development of a mini-UWB antenna |
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Journal Article |
| Year |
2004 |
Publication |
Measurement and Techniques Association Symposium |
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AMTA |
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6 |
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optical antennas; Ultra Wide Band; Spiral Antenna, Dielectric Loading |
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There is a great interest in the automotive and military sectors for small and broadband antennas that meet modern communication needs. These needs require ultra-wide bandwidth (>10:1) UWB antennas, such as the spiral antenna. However, the physical size at the low-frequency end typically becomes too large for practical applications. To reduce the size of the antenna, miniaturization techniques must be employed such as the use of high-contrast dielectric materials. Size reduction using high-contrast materials has been demonstrated for narrowband antennas, such as patch antennas, but not for broadband antennas to our knowledge. Therefore, the concept of miniaturizing a broadband spiral antenna using dielectric materials will be investigated experimentally and numerically.Issues that arise from dielectric loading such as impedance reduction will also be addressed. It will be shown using the results from these studies that there are practical limitations to the amount of miniaturization which can be achieved. |
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RPLAB @ gujma @ |
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751 |
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Hubers, H.-W.; Semenov, A.; Richter, H.; Schwarz, M.; Gunther, B.; Smirnov, K.; Gol’tsman, G.; Voronov, B. |
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Heterodyne receiver for 3-5 THz with hot-electron bolometer mixer |
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Conference Article |
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2004 |
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Proc. SPIE |
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Proc. SPIE |
| Volume |
5498 |
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579-586 |
| Keywords |
NbN HEB mixers |
| Abstract |
Heterodyne receivers for applications in astronomy and planetary research need quantum limited sensitivity. In instruments which are currently build for SOFIA and Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. The local oscillator and the mixer are the most critical components for a heterodyne receiver operating at 3-5 THz. The design and performance of an optically pumped THz gas laser optimized for this frequency band will be presented. In order to optimize the performance for this frequency hot electron bolometer mixers with different in-plane dimensions and logarithmic-spiral feed antennas have been investigated. Their noise temperatures and beam patterns were measured. Above 3 THz the best performance was achieved with a superconducting bridge of 2.0 x 0.2 μm2 incorporated in a logarithmic spiral antenna. The DSB noise temperatures were 2700 K, 4700 K and 6400 K at 3.1 THz, 4.3 THz and 5.2 THz, respectively. The results demonstrate that the NbN HEB is very well suited as a mixer for THz heterodyne receivers up to at least 5 THz. |
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SPIE |
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Zmuidzinas, J.; Holland, W.S.; Withington, S. |
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Millimeter and Submillimeter Detectors for Astronomy II |
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1483 |
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Meledin, D. V.; Marrone, D. P.; Tong, C.-Y. E.; Gibson, H.; Blundell, R.; Paine, S. N.; Papa, D.C.; Smith, M.; Hunter, T. R.; Battat, J.; Voronov, B.; Gol'tsman, G. |
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A 1-THz superconducting hot-electron-bolometer receiver for astronomical observations |
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Journal Article |
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2004 |
Publication |
IEEE Trans. Microwave Theory Techn. |
Abbreviated Journal |
IEEE Trans. Microwave Theory Techn. |
| Volume |
52 |
Issue |
10 |
Pages |
2338-2343 |
| Keywords |
NbN HEB mixer, applications |
| Abstract |
In this paper, we describe a superconducting hot-electron-bolometer mixer receiver developed to operate in atmospheric windows between 800-1300 GHz. The receiver uses a waveguide mixer element made of 3-4-nm-thick NbN film deposited over crystalline quartz. This mixer yields double-sideband receiver noise temperatures of 1000 K at around 1.0 THz, and 1600 K at 1.26 THz, at an IF of 3.0 GHz. The receiver was successfully tested in the laboratory using a gas cell as a spectral line test source. It is now in use on the Smithsonian Astrophysical Observatory terahertz test telescope in northern Chile. |
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0018-9480 |
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1484 |
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