E.M. Iungaitis – Post-graduate Student,

South Ural State University (National Research University)

E-mail: jungaitis92@gmail.com

N.I. Voytovich – Dr.Sc. (Eng.), Professor, Head of Department, 

South Ural State University (National Research University)

E-mail: voytovichni@mail.ru

A.V. Ershov – Ph.D. (Eng.), Associate Professor,

South Ural State University (National Research University)

E-mail: eav@list.ru

B.V. Zhdanov – Ph.D. (Eng.), Associate Professor,

South Ural State University (National Research University)

E-mail: boris.z@inbox.ru

A.V. Zotov – Ph.D. (Eng.), Associate Professor,

South Ural State University (National Research University)

E-mail: tnt1000@mail.ru

The main means of providing instrumental approach of aircraft for landing are beacon landing systems. It forms in space a trajectory (glide path), located, as a rule, at an angle of 3º in respect to the horizontal plane. We showed in the paper the dependence of the glide path angle on the height of the snow cover on the underlying surface when using previously known antenna arrays in the glide slope. We proposed in this work a new class of glide slope antenna arrays. The requirements for the amplitude-phase distribution of currents along the antenna array of the glide slope, at which the glide path angle does not depend on the reflective properties of the underlying surface and the level of snow cover on it, are determined. We propose a procedure for constructing an antenna array with two subarrays, one of which radiate the so-called «Carrier plus sideband» (CSB) signal, and the second emits the «Suppressed carrier sideband only» (SBO) signal. In order to ensure the independence of the glide path parameters from the height of the antenna array (glide path angle and slope of the glide path), five conditions must be met as specified in the article.

A special case of the proposed antenna array is an equidistant antenna array, in which the radiating elements of the subarray of the CSB signal and the subarray of the SBO signal partially combine. We performed experimental studies with a 4-element equidistant antenna array as part of a glide slope prototype. We carried out flight measurements of the glide path angle at the airfield in the foothill with a difficult terrain for about two years: in summer, winter, next summer and next winter. The snow depth at the airport was 35…40 cm in the first winter, and 30…35 cm in the second winter. The experimental results showed that the changes in the glide path angle for the stated period of time do not exceed one angle minute. This value is commensurate with the error of the flight experiment.

In order to simulate the influence of a higher level of snow cover on the position of the glide path, we conducted a special experiment. When snow cover of 18 cm high established on the airfield surface, we lowered all four antennas by one meter and measured the glide path zone. The glide path angle remained the same.

Flight tests of a prototype landing system with the proposed glide path beacon showed that this landing system provides parameters for the III-rd category. It means that approaching the aircraft for landing and landing are possible at zero visibility.

1. Annex 10 to the Convention on International Civil Aviation. Radio Navigation Aids. V. 1. Monreal (Canada). ICAO. 2006.
2. Annex 10 to the Convention on International Civil Aviation. Aeronautical Telecommunications. V. 1. Radio Navigation Aids. 7th ed., Montreal (Canada). ICAO. 2018.
3. NII-33 / VNIIRA. Istoriya stanovleniya i razvitiya Vsesoyuznogo NII radioapparatury. SPb.: 2007. [in Russian]
4. Watts Jr. C.B. Instrument Landing Scrapbook. Trafford Publishing. 2005.
5. Walton E.K. Effect of wet snow on the null-reference ILS system». IEEE Transactions on Aerospace and Electronic Systems. July 1993. V. 29. № 3. P. 1030–1035.
6. Lopez A.R. Comments on Effect of wet snow an the null-reference ILS system. IEEE Transactions on Aerospace and Electronic  Systems. Oct. 1994. V. 30. № 4. P. 1086–1090.
7. Lopez A.R. Suppressed-Image ILS Glide Slope Antenna. Proceedings of the 51st Annual Meeting of The Institute of Navigation (1995). Colorado Springs, CO. June 1995. P. 253–259.
8. Marcum F. Evaluation of image-type glide slope performance in the presence of snow cover. IEEE Transactions on Aerospace and Electronic Systems. Jan. 1998. V. 34. № 1. P. 71–83.
9. Marcum F. Design of an image radiation monitor for ILS glide slope. IEEE Transactions on Aerospace and Electronic Systems. July 1998. V. 34. № 3. P. 836–843.
10. Oikawa Y., Yokoyama H. The investigation of the influence of snow upon Glide Slope. 16th International Flight Inspection Symposium (IFIS). Beijing. 2010, P. 29–38.
11. Patent RF № 2429499. GO1S 1/16. Glissadnyy radiomayak (varianty) / Voytovich N.I., Zhdanov B.V., Sokolov A.N. Zayavl. 28.04.2009. Opubl. 20.09.2011. Byul. № 26. [in Russian]
12. Patent RF № 2624263 C1. GO1S 1/16. Dvukhchastotnyy glissadnyy radiomayak / Voytovich N.I., Zhdanov B.V. Zayavl. 08.06.2016. Opubl. 03.07.2017. Byul. № 19. [in Russian]
13. Voytovich N.I., Ershov A.V., Repin N.N., Sokolov A.N. Cavity antenna with partly transparent aperture for wireless communications. PIERS 2006-Tokyo. Progress In Electromagnetics Research Symposium. 2006. The Electromagnetics Academy. P. 338.
14. Voytovich N.I., Ershov A.V., Repin N.N., Sokolov A.N. Cavity antenna with partly transparent aperture for wireless communications. Progress in Electromagnetics Research Symposium. 2006. P. 363–366.
15. Voytovich N.I., Ershov A.V., Bukharin V.A., Repin N.N. Temperature effect on cavity antenna parameters. 2011 XXXth URSI General Assembly and Scientific Symposium. Istanbul. 2011. P. 1–4.
16. Voytovich N.I., Ershov A.V., Bukharin V.A., Repin N.N. Flat cavity antenna. 6th European Conference on Antennas and Propagation (EUCAP). Prague. 2012. P. 2900–2903.