Starting from a single resonant rf cavity, disk-loaded travelling(forward or backward) wave accelerating structures'properties, such as the coupling coefficient K in the dispersion relation, group velocity vg, shunt impedance R, wake potential W (longitudinal and transverse), the coupling coefficient β of the coupler cavity and the coupler cavity axis shift δr which is introduced to compensate the asymmetry caused by the coupling apeerture, can be determined by rather simple analytical formulae