To accurately describe propagation characteristics of electromagnetic wave in trapezoid tunnel

the Fresnel zone theory and geometry vector are employed to deduce the calculation formulas of the division point in trapezium-shaped roadway

combined with software simulation

the relationship between the division point of the near-region and height of the antenna in trapezium-shaped roadway is analyzed intuitively. The results show that the distance of the point is larger when the transmitting antenna is located at the vertical middle of the tunnel comparing to the top of the tunnel. And the division point distance is related to the signal frequency

the point distance gradually increases with the carrier frequency.