Patent ID: 7535314

Claim:
A line transition device comprising: a conductor block; a waveguide provided in the conductor block; a microstrip line including: a dielectric substrate having a first and a second surface; a line conductor disposed on the first surface of the dielectric substrate; a ground conductor disposed on the second surface of the dielectric substrate, the second surface including a region where the ground conductor is not provided; and a coupling conductor formed at an end of the line conductor and opposite the region where the ground conductor is not provided, the coupling conductor being positioned at a terminal end of the waveguide and inside the waveguide, the conductor block having a choke groove located at a position facing the ground conductor and surrounding the terminal end of the waveguide at a predetermined distance therefrom; and a slit-like no-ground-conductor-formed part extending from the region where the ground conductor is not provided and near a boundary between the coupling conductor and the microstrip line.