This letter presents a simple and effective self-decoupling method for dielectric patch (DP) antenna (DPA) by choosing proper structural parameters, without adding extra components. By theoretical analysis, the attenuation constant of the employed fundamental TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode outside the DP is controlled by the structural parameters of the DP resonator, which is crucial for the decoupling between the two adjacent DPAs. It is found that the larger the attenuation constant of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode, the better the port-to-port isolation in broadband, and then the radiation pattern can be stabilized. Under the premise of satisfactory isolation, the operational bandwidth and boresight gain of the DPA are studied for ensuring good antenna performance, exhibiting high design freedom and flexibility of the DPA. For demonstration, 1 × 2 closely spaced DPAs with optimal parameters are fabricated and measured. The simulated and measured results show good agreement.