Coupler and radio frequency front end module

The utility model discloses a coupler and a radio frequency front-end module, and relates to the technical field of radio frequency. The coupler comprises a plurality of metal layers in different planes; comprising a signal input port, a signal output port and a plurality of signal connecting lines, and each signal connecting line is arranged on the corresponding metal layer; comprising a signal coupling port, a signal isolation port and a plurality of coupling connecting lines, and each coupling connecting line is arranged on the corresponding metal layer; wherein the signal connecting lines and the coupling connecting lines located on the same metal layer are coupled on the same layer in a narrow side mode. Coupling lines and signal transmission lines are arranged on a plurality of metal layers, and a coupling connecting line on each metal layer is coupled with a signal connecting line on the metal layer on the same layer in a narrow side manner, so that the influence of medium fluctuation on the performanc