Advances in Radio Science www.adv-radio-sci.net 1684-9965 1684-9973 5 Kleinheubacher Berichte 2006 2007 10.5194/ars-5-49-2007 http://www.adv-radio-sci.net/5/49/2007/ http://www.adv-radio-sci.net/5/49/2007/ars-5-49-2007.html http://www.adv-radio-sci.net/5/49/2007/ars-5-49-2007.pdf 49 55 2007-06-12 Airborne field strength monitoring J. Bredemeyer brd@flightcalibration.de T. Kleine-Ostmann T. Schrader K. Münter J. Ritter FCS Flight Calibration Services GmbH, Braunschweig, Germany Physikalisch-Technische Bundesanstalt, Braunschweig, Germany EADS Deutschland GmbH, Military Aircraft, Bremen, Germany In civil and military aviation, ground based navigation aids (NAVAIDS) are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS) increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR) is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000) by the International Civil Aviation Organization (ICAO). One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz), the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA) accelerated method of moments (MoM) using a complex geometric model of the aircraft. First results will be presented in this paper. Balanis, C. A.: Antenna Theory Analysis and Design, Wiley, New York, 1997. Bredemeyer, J., Battermann, S., Garbe, H., and Ritter, J.: Antenna Installed Performance of a Flight Inspection Aircraft, Proceedings of International Symposium on Precision Approach and Automatic Landing (ISPA 2004), Munich, Germany, 2004. Chew, W C., Jin, J.-M., Michielssen, E., and Song, J M.: Fast and efficient algorithms in computational electromagnetics, Artech House, Boston, London, 2000. DIN EN 45003 (Akkreditierungssysteme für Kalibrier- und Prüflaboratorien; allgemeine Anforderungen für Betrieb und Anerkennung), 1995. International Civil Aviation Organization: DOC 8071, Manual on Testing of Radio Navigation Aids, Volume I: Testing of Ground-based Radio Navigation Systems, Montreal, 2000. European cooperation for Accreditation of Laboratories, Publication Reference EAL-P7, EAL Interlaboratory Comparisons, Edition 1, March, 1996. Harrington, R. F.: Field Computation by Moment Methods, Cazenovia, N.Y., USA, 1968. Kraus, J. D.: Antennas, Mc-Graw-Hill, Boston, 1988. Unger, H.-G.: Elektromagnetische Wellen auf Leitungen, 4. Aufl., Heidelberg, 1996.