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Korneev, A., Kouminov, P., Matvienko, V., Chulkova, G., Smirnov, K., Voronov, B., et al. (2004). Sensitivity and gigahertz counting performance of NbN superconducting single-photon detectors. Appl. Phys. Lett., 84(26), 5338–5340.
Abstract: We have measured the quantum efficiencysQEd, GHz counting rate, jitter, and noise-equivalentpowersNEPdof nanostructured NbN superconducting single-photon detectorssSSPDsdin thevisible to infrared radiation range. Our 3.5-nm-thick and 100- to 200-nm-wide meander-typedevices(total area 10310mm2), operating at 4.2 K, exhibit an experimental QE of up to 20% inthe visible range and,10% at 1.3 to 1.55mm wavelength and are potentially sensitive up tomidinfrareds,10mmdradiation. The SSPD counting rate was measured to be above 2 GHz withjitter,18 ps, independent of the wavelength. The devices’ NEP varies from,10−17W/Hz1/2for1.55mm photons to,10−20W/Hz1/2for visible radiation. Lowering the SSPD operatingtemperature to 2.3 K significantly enhanced its performance, by increasing the QE to,20% andlowering the NEP level to,3310−22W/Hz1/2, both measured at 1.26mm wavelength.
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Koshelets, V. P. (2004). Integrated superconducting submm receivers.
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Koshelets, V. P., Dmitriev, P. N., Ermakov, A. B., Filippenko, L. V., Khudchenko, A. V., Koryukin, O. V., et al. (2004). SIR for TELIS (post-critical) review.
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Koshelets, V. P., Shitov, S. V., Dmitriev, P. N., Ermakov, A. B., Filippenko, L. V., Koryukin, O. V., Sobolev, A. S., et al. (2004). Integrated submillimeter and terahertz receivers with superconducting local oscillator. In Presanted at 8th International Workshop “From Andreev Reflection to the International Space Station”.
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Kramer, B., Chen, C. - C., & Volakis, J. D. (2004). The development of a mini-UWB antenna. AMTA, , 6.
Abstract: 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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Krasnopolsky, V. A., Maillard, J. P., & C. Owen, T. (2004). Detection of methane in the martian atmosphere: evidence for life? Icarus, 172(2), 537–547.
Abstract: Using the Fourier Transform Spectrometer at the Canada–France–Hawaii Telescope, we observed a spectrum of Mars at the P-branch of the strongest CH4 band at 3.3 μm with resolving power of 180,000 for the apodized spectrum. Summing up the spectral intervals at the expected positions of the 15 strongest Doppler-shifted martian lines, we detected the absorption by martian methane at a 3.7 sigma level which is exactly centered in the summed spectrum. The observed CH4 mixing ratio is 10±3 ppb. Total photochemical loss of CH4 in the martian atmosphere is equal to View the MathML source, the CH4 lifetime is 340 years and methane should be uniformly mixed in the atmosphere. Heterogeneous loss of atmospheric methane is probably negligible, while the sink of CH4 during its diffusion through the regolith may be significant. There are no processes of CH4 formation in the atmosphere, so the photochemical loss must therefore be balanced by abiogenic and biogenic sources. Outgassing from Mars is weak, the latest volcanism is at least 10 million years old, and thermal emission imaging from the Mars Odyssey orbiter does not reveal any hot spots on Mars. Hydrothermal systems can hardly be warmer than the room temperature at which production of methane is very low in terrestrial waters. Therefore a significant production of hydrothermal and magmatic methane is not very likely on Mars. The calculated average production of CH4 by cometary impacts is 2% of the methane loss. Production of methane by meteorites and interplanetary dust does not exceed 4% of the methane loss. Methane cannot originate from an extinct biosphere, as in the case of “natural gas†on Earth, given the exceedingly low limits on organic matter set by the Viking landers and the dry recent history which has been extremely hostile to the macroscopic life needed to generate the gas. Therefore, methanogenesis by living subterranean organisms is a plausible explanation for this discovery. Our estimates of the biomass and its production using the measured CH4 abundance show that the martian biota may be extremely scarce and Mars may be generally sterile except for some oases.
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Martin슠Harwit. (2004). The Herschel mission. Advances in Space Research, 34(3), 568–572.
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Maslennikov, S. N., Morozov, D. V., Ozhegov, R. V., Smirnov, K. V., Okunev, O. V., & Gol’tsman, G. N. (2004). Imaging system for submillimeter wave range based on AlGaAs/GaAs hot electron bolometer mixers. In Proc. 5-th MSMW (Vol. 2, pp. 558–560).
Abstract: Electromagnetic radiation of the submillimeter (SMM) range is dispersed and absorbed significantly less than infrared (IR) radiation when passing through different objects. That is the reason for the development of an SMM imaging system. In this paper, we discuss the design of an SMM heterodyne imager, based on a matrix of AlGaAs/GaAs heterostructure hot electron bolometer mixers (HEB) with relatively high (about 77 K) operating temperature. The predicted double side band (DSB) noise temperature is about 1000 K and optimal local oscillator (LO) power is about 1 /spl mu/W for such mixers, which seems to be quite prospective for an SMM heterodyne imager.
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Maslennikov, S., Vachtomin, Y., Antipov, S., Smirnov, K., Kaurova, N., Grishina, E., et al. (2004). NbN HEB mixers for frequencies of 2.5 and 3.8 THz. In Proc. Tenth All-Russian sceintific conference of student-physicists and young sceintists (VNKSF-10). Moscow.
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Meledin D., Pantaleev M., Pavolotsky A., Risacher C., Robles V.A.P., Belitsky V., et al. (2004). Design of a balanced waveguide HEB mixer for APEX 1.32 THz receiver. In Proc. 15th Int. Symp. Space Terahertz Technol. (pp. 211–217).
Abstract: The prototype of a waveguide balanced Hot Electron Bolometer (HEB) Terahertz mixer is designed as a part of development for the APEX Project of Band T2 receiver for 1250-1390 GHz. The proposed mixer employs balanced scheme with two identical HEB devices. These individual mixers would be placed on two separate crystalline quartz substrates with dimensions of 1000μm x67μm x17 μm each with integrated RF choke filters, DC-bias and IF circuitry. A 3 dB quadrature waveguide directional coupler is needed to provide local oscillator (LO) injection and RF signal distribution between the two HEB mixers. We have designed the coupler to achieve the required frequency band, low insertion loss and symmetrical division of the RF and LO power within the band of interest. Initial design of HEB mixer layout is developed based on a previous development for a 345 GHz sideband separation mixer. We present also results of development of microfabrication technology of the waveguide hybrid employing micromachining approach combined with electroplating technique.
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