Dual-frequency small-frequency ratio coupler with adjustable frequency ratio

The invention discloses a dual-frequency small-frequency ratio coupler with an adjustable frequency ratio. The dual-frequency small-frequency ratio coupler comprises a round sheet and four segments of stubs, wherein the round sheet is provided with four input and output ports which are in central symmetry; and a coupling port is arranged between two adjacent input and output ports on the round sheet and is used for power coupling between the round sheet and the stubs. A double-frequency function and frequency ratio adjustment are simultaneously achieved by using a coupling structure of the four segments of stubs and the round sheet, and furthermore, two important parameters are adjusted in real time through the structure of the stubs disclosed by the invention, so that the small-frequency ratio application requirement of common microwave and millimeter wave communication can be met; and meanwhile, a controllable power division ratio can be achieved by changing the radius ratio of the round sheet structure and