Elastically configured waveguide connecting structure usable in a waveguide connector, a waveguide unit, a mode converter, an imaging device and an endoscope

A waveguide connecting structure configured to connect a first waveguide to a second waveguide which is different from the first waveguide, or to connect the first waveguide to a transmitting and receiving device which is configured to transmit and receive radio waves, the waveguide connecting structure comprising:

• the first waveguide, which is configured to transmit the radio waves having a frequency of millimeter waves or higher, and which comprises a dielectric body and an external conductor, the external conductor covering an outer periphery of the dielectric body;
• an elastic body configured to cause the external conductor to closely contact the dielectric body;
• and
• a three-dimensional body configured to hold the dielectric body of the first waveguide, and the second waveguide or the transmitting and receiving device,
• wherein the three-dimensional body has electric conductivity inside an insertion hole for holding the first waveguide, and
• wherein the external conductor of the first waveguide includes a radially spread portion where the external conductor has been radially spread away from the outer periphery of the dielectric body, the radially spread portion being where the first waveguide and the three-dimensional body are connected to each other.