At the ultra-high frequencies (UHF) common to portable radios, the mine tunnel acts as a dielectric waveguide, directing and absorbing energy as a radio signal propagates. Understanding radio propagation behavior in a dielectric waveguide is critical for designing reliable, optimized communication systems in an underground mine. One of the major parameters used to predict the power attenuation in lossy waveguides is the attenuation constant. In this paper, we theoretically and experimentally investigate the attenuation constants for a rectangular waveguide with dielectric walls. We provide a new derivation of the attenuation constant based on the classic Fresnel reflection coefficients. The new derivation takes advantage of ray representation of plane waves and provides more insight into understanding radio attenuation in tunnels. We also investigate the impact of different parameters on the attenuation constant, including the tunnel transverse dimensions, permittivity, conductivity, frequency, and polarization, with an aim to find their theoretical optimal values that result in the minimum power loss. Additionally, measurements of the attenuation constants of the dominant mode at different frequencies (455, 915, 2450, and 5800 MHz) for a straight concrete tunnel are presented and compared to theoretical predictions. It is shown that the analytical results match the measured results very well at all four frequencies.
2. Porrat, D., "Radio propagation in hallways and streets for UHF communications,", Ph.D. Dissertation, Stanford University, 2002.
3. Kyritsi, P. and D. C. Cox, "Propagation characteristics of horizontally and vertically polarized electric fields in an indoor environment: Simple model and results," IEEE 54th Vehicular Technology Conference, VTC Fall, 1422-1426, 2001.
4. Didascalou, D., R. Maurer, and W. Wiesbeck, "Subway tunnel guided electromagnetic wave propagation at mobile communications frequencies," IEEE Transactions on Antennas and Propagation, Vol. 49, 1590-1596, Nov. 2001.
5. Masson, E., et al., "Radio wave propagation in curved rectangular tunnels at 5.8 GHz for metro applications, simulations and measurements," Eurasip Journal on Wireless Communications and Networking, Dec. 2011.
6. Zhang, Y. P., Z. R. Jiang, T. S. Ng, and J. H. Sheng, "Measurements of the propagation of UHF radio waves on an underground railway train," IEEE Transactions on Vehicular Technology, Vol. 49, 1342-1347, Jul. 2000.
7. Han, G. R., W. M. Zhang, and Y. P. Zhang, "An experiment study of the propagation of radio waves in a scaled model of long-wall coal mining tunnels," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 502-504, 2009.
8. Lienard, M. and P. Degauque, "Natural wave propagation in mine environments," IEEE Transactions on Antennas and Propagation, Vol. 48, 1326-1339, Sep. 2000.
9. Shanklin, J. P., "VHF railroad communications in tunnels," Communications, Vol. 27, 16-19, Jun. 1947.
10. Emslie, A., R. Lagace, and P. Strong, "Theory of the propagation of UHF radio waves in coal mine tunnels," IEEE Transactions on Antennas and Propagation,, Vol. 23, 192-205, 1975.
11. Mahmoud, S. F. and J. R.Wait, "Geometrical optical approach for electromagnetic wave propagation in rectangular mine tunnels," Radio Science, Vol. 9, 1147-1158, 1974.
12. United States Public Laws, PL 109-236, Mine Improvement and New Emergency Response Act of 2006 (MINER Act), 2006.
13. Zhou, C., J. Waynert, T. Plass, and R. Jacksha, "Modeling RF propagation in tunnels," IEEE International Symposium on Antennas and Propagation (APS2013), 1917-1918, Orlando, FL, 2013.
14. Plass, T., R. Jacksha, J. Waynert, and C. Zhou, "Measurement of RF propagation in tunnels," IEEE International Symposium on Antennas and Propagation (APS 2013), 1604-1605, Orlando, FL, 2013.
15. Marcatili, E. A. J. and R. A. Schemeltzer, "Hollow metallic and dielectric waveguides for long distance optical transmission and lasers," Bell Syst. Tech. J., Vol. 43, 1783-1809, Jul. 1964.
16. Laakmann, K. D. and W. H. Steier, "Waveguides: Characteristic models of hollow rectangular dielectric waveguides," Applied Optics, 1334-1340, May 1976.
17. Dudley, D. G., M. Lienard, S. F. Mahmoud, and P. Degauque, "Wireless propagation in tunnels," IEEE Antennas and Propagation Magazine, Vol. 49, No. 11-26, Apr. 2007.
18. Didascalou, D., T. M. Schafer, F. Weinmann, and W. Wiesbeck, "Ray-density normalization for ray-optical wave propagation modeling in arbitrarily shaped tunnels," IEEE Transactions on Antennas and Propagation, Vol. 48, 1316-1325, Sep. 2000.
19. Mahmoud, S. F., "Modal propagation of high frequency electromagnetic waves in straight and curved tunnels within the earth," Journal of Electromagnetic Waves and Applications, Vol. 19, No. 12, 1611-1627, 2005.
20. Yamaguchi, Y., T. Abe, T. Sekiguchi, and J. Chiba, "Attenuation constants of UHF radio-waves in arched tunnels," IEEE Transactions on Microwave Theory and Techniques, Vol. 33, 714-718, 1985.
21. Kermani, M. H. and M. Kamarei, "A ray-tracing method for predicting delay spread in tunnel environments," IEEE International Conference on Personal Wireless Communications, 538-542, 2000.
22. Uchida, K., C. K. Lee, T. Matsunaga, T. Imai, and T. Fujii, "A ray tracing method for evaluating field distribution in tunnels," Electronics and Communications in Japan (Part I: Communications), Vol. 83, 11-18, 2000.
23. Sun, Z. and I. F. Akyildiz, "Channel modeling and analysis for wireless networks in underground mines and road tunnels," IEEE Transactions on Communications, Vol. 58, 1758-1768, Jun. 2010.
24. Fuschini, F. and G. Falciasecca, "A mixed rays-modes approach to the propagation in real road and railway tunnels," IEEE Transactions on Antennas and Propagation, Vol. 60, 1095-1105, Feb. 2012.
25. Emslie, A., R. Lagace, and P. Strong, "Theory of the propagation of UHF radio waves in coal mine tunnels," IEEE Transactions on Antennas and Propagation, Vol. 23, 192-205, 1975.
26. Loyka, S., "Multiantenna capacities of waveguide and cavity channels," IEEE Transactions on Vehicular Technology, Vol. 54, 863-872, May 2005.
27. Collin, R. E., Field Theory of Guided Waves, McGraw-Hill, New York, 1960.
28. Balanis, C. A., Advanced Engineering Electromagnetics, Wiley, New York, 1989.
29. Schaubach, K. R., N. J. Davis, and T. S. Rappaport, "A ray tracing method for predicting path loss and delay spread in microcellular environments," IEEE 42nd Vehicular Technology Conference, 932-935, May 1992.
30. Chen, S. H. and S. K. Jeng, "SBR image approach for radio wave propagation in tunnels with and without traffic," IEEE Transactions on Vehicular Technology, Vol. 45, 570-578, Aug. 1996.
31. Mahmoud, S. F., "On modal propagation of high frequency electromagnetic waves in straight and curved tunnels," IEEE Antennas and Propagation Society Symposium, 2963-2966, 2004.
32. Alonso, J., B. Izquierdo, and J. Romeu, "Break point analysis and modelling in subway tunnels," 3rd European Conference on Antennas and Propagation (EuCAP 2009), 3254-3258, 2009.
33. Dudley, D. G. and H. Y. Pao, "System identification for wireless propagation channels in tunnels," IEEE Transactions on Antennas and Propagation, Vol. 53, 2400-2405, Aug. 2005.
34. Guan, K., Z. D. Zhong, B. Ai, and C. Briso-Rodriguez, "Propagation mechanism analysis before the break point inside tunnels," IEEE Vehicular Technology Conference (VTC2011 Fall), 1-5, Sep. 5-8, 2011.
35. Klemenschits, T. and E. Bonek, "Radio coverage of road tunnels at 900 and 1800MHz by discrete antennas," Wireless Networks - Catching the Mobile Future, Proceedings, Vol. I-Iv, 411-415, 1994.