3Stuntebeck E P, Pompili D, Melodia T. Wireless under-ground sensor networks using commodity terrestrial motes[C]// Wireless Mesh Networks, 2006. WiMesh 2006. 2nd IEEE Workshop on. IEEE, 2006:112-114.
4Silva A R, Vuran M C. Empirical Evaluation of Wireless Underground-to-Underground Communication in Wireless Underground Sensor Networks[M]// Distributed Computing in Sensor Systems. Springer Berlin Heidelberg, 2009:231-244.
5T. A. Milligan. Modern Antenna Design, 2nd Edition.IEEE Press, 2005.
6Akyildiz I F, Stuntebeck E P. Wireless underground sensor networks: Research challenges[J]. Ad Hoc Networks, 2006, 4(6):669–686.
7Ian F. Akyildiz, Zhi Sun, Mehmet C. Vuran. Signal propa-gation techniques for wireless underground commu-nication networks[J]. Physical Communication, 2009, 2(3):167-183.
8Bansal R. Near-field magnetic communication[J]. IEEE Antennas & Propagation Magazine, 2004, 46(2):114-115.
9Sun Z, Akyildiz I F. Underground Wireless Communication Using Magnetic Induction[C]// Communications, 2009. ICC ’09. IEEE International Conference on. IEEE, 2009:1-5.