Miniaturized multilayer broadband 3-dB coupler

The invention discloses a miniaturized multilayer broadband 3-dB coupler. The coupler comprises multiple dielectric layers, two metal layers, four port feeder lines and two coupling transmission lines, wherein the four port feeder lines are located on the topmost layer surface and bottommost layer surface of the multi-layer structure of the coupler and are connected through metallized through holes, the four port feeder lines and the two coupling transmission lines are located on the upper surface and the lower surface of the middle dielectric layer. The multi-layer structure adopts a broadside coupling mode, so that strong coupling of 3-dB is easily achieved, and broadband performance can be achieved. Two capacitors are loaded in the middles of the coupling transmission lines, so that theminiaturization of the device is realized. Port capacitors are introduced into the coupling of the adjacent ports, so that the odd-even mode phase velocities of the transmission lines are equal, andtherefore, the matching an