Technology of remote sensing in the terahertz range (frequency interval arbitrarily set between 0.1-30 THz) is the object of considerable development efforts addressed to a number of new civilian and military applications. Technical challenges appear in the THz sensing of temperature differences above an existing hot surface target, such as radiation patterns produced by high energy electrons in laboratory accelerators, and thermal differentiated structures in the solar disk in space. The efficient suppression of radiation in the visible and near infrared (set arbitrarily for wavelengths < 10 μm) is an essential requirement. An experimental setup has been prepared for testing at room temperature THz materials and detectors, aiming the detection of solar radiation. A custom-made detector consisted in a room-temperature micro-bolometer INO camera with HRFZ-Si window. The THz transmission of two "low-pass" membranes were tested for black body temperatures ranging 300-1000 K: Zitex G110G and TydexBlack. It has been demonstrated that both are effective suppressors of radiation at wavelengths < 15 μm, with the first one exhibiting a small radiation excess, that may be attributed to small visible and NIR allowance. We describe optical setups prepared to detect solar radiation, consisting in a microbolometer camera preceded by a photon pipe, low-pass membrane and band-pass resonant metal mesh, placed at the focus of the 1.5 m reflector for submillimeter waves (SST) at El Leoncito, Argentina Andes. ©2009IEEE. 262266Harris, D.C., (1999) Materials for Infrared Windows and Domes, , SPIE Optical Engineering Press, Washington, USA, CSiegel, P.H., THz Technology: An Overview (2003) International Journal of High Speed Electronics and Systems, 13 (2), pp. 1-44Mlynczak, M., Johnson, D., Bingham, G., Far-Infrared Spectroscopy of the Troposphere (FIRST) project (2003) Proceedings of Geoscience and Remote Sensing Symposium, 1, p. 512Sherwin, M.S., Schmuttenmaer, C.A., Bucksbaum, P.H., Proceedings of DOE-NSF-NIH Workshop on Opportunities in THz Science, Arlington, VA, 2004Kinch, M.A., Infrared detector materials (2007) SPIE Optical Engineering Press, TT76. , Washington, USA, DCStrabala, K.I., Ackerman, S.A., Menzel, W.P., Cloud Properties inferred from 8-12-μm Data (1994) Journal of Applied Meteorology, 33 (2), p. 212Williams, G.P., FAR-IR/THz radiation from the Jefferson Laboratory, energy recovered linac, free electron laser (2002) Rev. Sci. Instrum., 73, pp. 1461-1463Kaufmann, P., Raulin, J.-P., Can microbunch instability on solar flare accelerated electron beams account for bright broadband coherent synchrotronmicrowaves? (2006) Phys. Plasmas, 13. , 070701-070701-70704Klopf, J.M., 1st SMESE Workshop, 10-12 March, Paris, France, 2008Benford, D.J., Gaidis, M.C., Kooi, J.W., Optical properties of Zitex in the infrared to submillimeter (2003) Applied Optics, 42, pp. 5118-5122(2008) Technical Note on THz Materials and Components, , www.tydex.ruBlackbody Radiance, , http://spectralcalc.com/blackbody_calculator/blackbody.php, GATS, IncKaufmann, P., New telescopes for ground-based solar observations at submillimeter and mid-infrared (2008) Proc. SPIE, 7012, pp. 70120L-1-8Kornberg, M., Rough Mirrors for the THz frequency range (2008) Proc. MOMAG 2008 - 13th SBMO and 8th CBMAG, Florianópolis, SC, Brazil, pp. 365-367(2008), ESSCO, West Concord, MA, USA, private communicationMelo, A.M., Submillimeter-wave Atmospheric Transmission at El Leoncito, Argentina Andes (2005) IEEE Trans Ant. Propagat., 53, p. 1528Gezari, D.Y., Joyce, R.R., Simon, M., Measurement of the Solar Brightness Temperature at 345, 450 and 1000 micrometers (1973) Astron.Astrophys., 26, pp. 409-411Melo, A.M., Metal mesh resonant filters for terahertz frequencies (2008) Applied Optics, 47, pp. 6064-6069Ruze, J., The effect of aperture errors on the antenna radiation pattern (1953) Nuovo Cimento Suppl., 9, pp. 364-380