Monostatic Reflectivity and Transmittance of Radar Absorbing Materials at 650 GHz
ABSTRACT Transmittance and monostatic reflectivity of different radar absorbing materials at 650 GHz are presented. The reflectivity was measured in plane-wave conditions in a radar cross-section (RCS) range with vertical polarization. The lowest reflectivity level (-70 dB) was achieved with commercial absorbers TK THz RAM and Firam-500 with oblique incidence angles. Floor carpets were also studied, and the reflectivity level of those was found to be sufficiently low (from -50 to -60 dB) for use in antenna test ranges. Results agree with earlier studies and indicate the applicability of the RCS method in reflectivity measurements also at 650 GHz.
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ABSTRACT: We report on the detection of electromagnetic radiation at 0.65 THz by silicon field-effect transistors operated in heterodyne mode. Aiming at terahertz imaging with numerous pixels in a focal-plane array, we explore the improvement of the dynamic range achieved over power detection when the local-oscillator (LO) power is distributed quasioptically onto all detectors. These consist of resonantly antenna-coupled complementary metal-oxide-semiconductor transistors with a gate length of 0.25 μm, and each has an integrated voltage amplifier. With a LO power of 2 μW per detector, the noise-equivalent power amounts to 8 fW/Hz, leading to an estimated improvement of the dynamic range by 29 dB.Applied Physics Letters 01/2010; 96(4):042106-042106-3. DOI:10.1063/1.3292016 · 3.52 Impact Factor
Article: THz Metrology and Instrumentation[Show abstract] [Hide abstract]
ABSTRACT: This paper gives an overview of measurement techniques used in the THz region of the electromagnetic spectrum, from about 100 GHz to several THz. Currently available components necessary for THz metrology, such as sources, detectors and passives, are briefly described. A discussion of power measurements, vector network analysis and antenna measurements as well as the limitations of these measurements at THz frequencies is given. The paper concludes with a summary of available components and instrumentation for THz metrology at the time of writing.IEEE Transactions on Terahertz Science and Technology 09/2011; 1(1):133-144. DOI:10.1109/TTHZ.2011.2159553 · 4.34 Impact Factor
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ABSTRACT: The Submillimeter-Wave Technology Laboratory (STL) at the University of Massachusetts Lowell has investigated the electromagnetic scattering behavior of various broadband absorbers. Several absorbing materials were tested in a compact radar range operating at a center frequency of 160 GHz. The polarimetric radar cross section was measured at elevation angles from 15 to 75 . In addition to the backscattering behavior, the normal incidence transmittance of the materials was evaluated.Proceedings of SPIE - The International Society for Optical Engineering DOI:10.1117/12.822189 · 0.20 Impact Factor