An isolated dual-mode converter includes a TE01 mode converter including a circular waveguide, and a plurality of rectangular waveguides connected to the circumference of the circular waveguide; and a TM01 mode converter including a coaxial waveguide, formed by coaxial outer and inner conductors, and the circular waveguide connected and aligned axially with the coaxial waveguide, wherein a symmetrical axis of an opening at the end of the rectangular waveguides connected to the circular waveguide is parallel to the axis of the circular waveguide, thereby avoiding interfering with the propagation of TM01 mode. In an application, the isolated dual-mode converter outputs TE01 mode and TM01 mode at the same port, thereby achieving more uniform microwave heating. In another application, two isolated dual-mode converters are aligned face-to-face, forming a dual-channel joint with high channel isolation and low transmission loss, which may be used for a rotary joint of a radar system.