Line transition device, high-frequency module, and communication apparatus

摘要

A line transition device that includes a waveguide and a microstrip line. The microstrip line is substantially orthogonal to an electromagnetic wave propagation direction in the waveguide. A choke groove crosses the microstrip line. A coupling conductor provided at a tip of the microstrip line is positioned at a terminal end of and inside the waveguide. A slit-like region where a ground conductor is not formed is substantially orthogonal to the electromagnetic wave propagation direction in the waveguide. A longitudinal length of the slit-like region is substantially equal to a quarter of the wavelength of electromagnetic waves. The slit-like region is provided such that it extends from an end of a ground conductor near a boundary between the coupling conductor and the microstrip line to reach the choke groove.