In this article, an effective approach is proposed to design of compact single and dual-band patch filtering 180° hybrid couplers based on circular patch resonator. Without an additional circuit, the prescribed in-phase and out-of-phase specifications of the coupler are achieved by elaborately studying and utilizing the electric field distributions of the degenerate resonant modes in the unslotted/slotted patch resonators. Meanwhile, the desired single-/dual-band filtering responses are attained by virtue of the coupling extent between the two designed patch resonators in the back-To-back form. In our design, a pair of TM11-modes at first makeup a single passband for single-band operation, and a pair of TM11-like modes and a pair of TM12-like modes then construct the two separate passbands for dual-band operation, respectively. After the working principle is explained, the design procedure based on the coupling matrix is provided. For demonstration, two prototypes for single-and dual-band patch filtering 180° hybrid couplers are implemented, respectively. Measured results coincide well with simulated ones, verifying the proposed design concept.