Transmission apparatus, transmission method and a transmission system,

A possible improved safety transmission device, to provide a transmission method and transmission system. A transmission apparatus 100 includes a communication unit 110 including input and output terminals for inputting and outputting electrical signals of a predetermined frequency, while being coupled respectively to the input and output terminals, arranged in the longitudinal direction of one transmission medium 200 in the two coupling electrodes 120a and 120b are coupled to the transmission medium 200, includes a longitudinal direction of the up end 210a length La of the electrical signal (2n · 90 ± 45 of the transmission medium 200 from one coupling electrode 120a ) degrees (n is the electrical length in the range of 0 or more integers), from the other coupling electrode 120b to the other 210b in the longitudinal direction of the transmission medium 200 length Lb of the electric signal ((2n + 1) · 90 ± 45) and the electrical length of the range of the communication unit 110 transmits and receives the transmission device 300 and the electrical signal other combined with part of the region of the transmission medium 200. .FIELD 8