Research on antenna model of underground magnetic induction communication and its signal transmission characteristics

In view of problem that magnetic signal propagation had significant directionality, but effect of antenna position and angle on transmission performance in magnetic communication had not been fully considered by current researches, magnetic signal transmission characteristics of three kinds of antenna models of underground magnetic induction communication were researched including double-coil array and four-coil array in 2D antenna array and 3D coil model. Firstly, expressions of corresponding magnetic induction intensity and mutual inductance between sending coil and receiving coil were given according to mathematical models of the three antennas. Secondly, magnetic induction intensity was simulated and analyzed. Position and angle of receiving antenna were optimized according to magnetic field distribution. Finally, transmission performances of the three antenna models were compared, and influences of offset of each sending coil and vertical distance between sending coil plane and receiving coil plane on magnetic induction intensity were given. The research results are as follows: ① Magnetic induction intensity of 2D antenna array model and 3D coil model has symmetry and directionality. ② Transmission direction of 2D antenna array model changes from multiple directions to one direction as the vertical distance increases. ③ When parameters of sending coils are as the same, transmission distance of 2D antenna array model is greater than that of point-to-point communication system and 3D coil model. The more the number of sending coils, the farther transmission distance of 2D antenna array model is. But magnetic induction intensity rapidly decreases as the vertical distance increases. ④ 3D coil model has the same distribution of magnetic induction intensity in three coordinate axes. Magnetic field of 3D coil model is the most widely distributed, but norm of magnetic induction intensity is less than the one of 2D antenna array model.