TST, Vol. 11, No. 2, PP. 34-42
(Invited paper) Near-field measurements of the terahertz superconducting spectrometer for atmospheric observation
Jie Hu 1*, 2, 3, Sheng Li 1, 2, Chuan Su 1, 2, 3, Dong Liu 1, 2, Qi-Jun Yao 1, 2, Xiao-ling Zhang 1, 2, 4, Zheng Lou 1, 2, and Sheng-Cai Shi 1, 2
1 Purple Mountain Observatory, CAS, 2nd West Beijing Road, Nanjing, China
2 Key Lab of Radio Astronomy, CAS, China.
3 University of Chinese Academy of Science.
4 University of Science and Technology of China.
* Email: jiehu@pmo.ac.cn
(Received December 10，2017)
Abstract: The optical verification of a terahertz superconducting spectrometer (TSR) featured with superconducting-insulator-superconducting (SIS) receivers developed at Purple Mountain Observatory (PMO) for atmospheric profiling synthetic observation system project (APSOS) has been presented. Near-fields of TSR at 230 GHz and 280 GHz have been measured and far-fields are derived. The misalignment of the optics at 280 GHz is analysed in detail by physical optics (PO).
Keywords: Superconducting receiver, Near-field, Physical optics, SIS
doi: 10.11906/TST.034-042.2018.06.04
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TST, Vol. 11, No. 2, PP. 43-56
(Invited paper) Human sweat ducts as helical antennas in the sub-THz frequency range-an overview
Anna Kochnev 1, Noa Betzalel 1, Paul Ben Ishai 2, 1, and Yuri Feldman 1*
1 The Hebrew University of Jerusalem, The Rachel and Selim Benin School of Engineering and Computer Science, Department of Applied Physics, The Edmond J. Safra Campus – Givat Ram, Jerusalem, 9190401, Israel
2 The Department of Physics, University of Ariel, Ariel, Israel
* Email: yurif@mail.huji.ac.il
(Received January 17, 2018)
Abstract: Detailed anatomical studies of the human skin using optical coherence tomography (OCT) have revealed that the morphological structure of our eccrine sweat ducts is remarkably helical. These findings have raised the hypothesis that human sweat ducts can be the biological equivalent of helical antennas and hence resemble their electromagnetic (EM) behavior by receiving signals in the sub-THz frequency range. Here we show how this hypothesis evolved and was experimentally tested over the recent years, driven by the prospect of developing remote sensors for obtaining information about our physiological and mental state, as well as better understanding the consequences of using this frequency band for communications in the very near future.
Keywords: sub-THz frequency, Helical antennas, Sweat ducts
doi: 10.11906/TST.043-056.2018.06.05
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TST, Vol. 11, No. 2, PP. 57-64
(Invited paper) Low-noise high-electron-mobility-transistor terahertz detector integrated with bow-tie antenna
Safumi Suzuki * and Satoshi Shibuya
Tokyo Institute of Technology, Graduate School of Science and Engineering, 2-12-1-S9-3 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
* Email: suzuki.s.av@m.titech.ac.jp
(Received May 28, 2018)
Abstract: An increase in current responsivity of a terahertz (THz) detector using a broadband bow-tie antenna and an InAlAs/InGaAs high-electron-mobility transistor (HEMT) measurements was developed. We fabricated a HEMT THz detector with a reduced series resistance via etching control of the recess width. A high current responsivity of ≈13 A/W was obtained using an HEMT detector with a 45-nm-long gate. The transconductance was 2.35 S/mm, and the subthreshold slope was 89 mV/dec. The noise characteristics of the HEMT detector was also investigated. We measured the frequency dependence of the noise voltage, and a noise voltage of 5 nV/Hz1/2 was obtained above a 1/f corner frequency of ≈500 Hz, which well agreed with the theoretical thermal noise of 4.5 nV/Hz1/2 generated by drain conductance. We also measured the dependence of the noise voltage on the irradiated power of THz signal, and the noise equivalent power of 0.5 pW/Hz1/2 was estimated from these measurements.
Keywords: Terahertz detector, Noise measurement, Noise equivalent power.
doi: 10.11906/TST.057-064.2018.06.06
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