A transmission line includes connecting portions connected to the outside and a main body located between the connecting portions. Each of the connecting portions includes a terminal electrode connected to an external electrode, a signal conductor, and ground conductors. The main body includes the signal conductor and the ground conductors, and at least one of the plurality of connecting portions includes a first region including the terminal electrode, a second region adjacent to the first region along a signal propagation path, and a third region located between the second region and the main body. The first region, the second region, and the third region provide impedance matching at the connecting portion.

A circuit board is a circuit board on which a predetermined circuit unit that causes heat and electromagnetic noise is disposed, and which is to be fixed to a conductive housing with a conductive screw. The circuit board includes: an insulator layer including an insulating plate-shaped base material; a conductor layer having a circuit pattern including a ground portion, which is disposed on at least one surface of the insulator layer; and a screw insertion hole that penetrates the insulator layer and the ground portion, and through which the conductive screw is to be inserted. The ground portion has a slit disposed between the screw insertion hole and the predetermined circuit unit. The ground portion has a ground bridge that electrically connects a portion of the ground portion between the slit and the screw insertion hole and a portion of the ground portion between the slit and the predetermined circuit unit.

A transmission line (12) includes a multilayer substrate (20), a signal pattern line (30), a ground pattern conductor (50), and an intermediate ground pattern conductor (40) that is arranged between the signal pattern line (30) and the ground pattern conductor (50) and that is electrically connected to the ground pattern conductor (50). The signal pattern line (30) has a first connection point (30c) to which a signal conductor extending in a laminating direction of the multilayer substrate (20) is connected. A first cavity portion (41h) is formed in the intermediate ground pattern conductor (40) at a position overlapped with a first end portion (30a) of the signal pattern line (30) in a plan view of the multilayer substrate (20). A first end edge (41e) of the first cavity portion (41h) has a first overlapping portion (41a) overlapped with the signal pattern line (30).

An antenna device includes an antenna, a first ground conductor, and an artificial magnetic conductor. The artificial magnetic conductor is sandwiched between the antenna and the first ground conductor, and separated from the antenna and the first ground conductor. The first ground conductor includes a first cutaway part on one end side, the first cutaway part having a substantially rectangular shape.

An optical module, including: a first laser and a first laser chip for driving the first laser; a second laser and a second laser chip for driving the second laser; and a multi-layer circuit board, including a surface layer, a reference layer, and an intermediate layer provided between the surface layer and the reference layer, where a first row of edge connector pins and a second row of edge connector pins are disposed in at least one surface layer; the first row of edge connector pins are disposed to be closer than the second row of edge connector pins to a side edge, of the multi-layer circuit board, that is provided with an edge connector; and a region, of the intermediate layer, that corresponds to a data signal line pin in the second row of edge connector pins is a hollow region.

Techniques and mechanisms for mitigating the effect of signal noise on communication via an interconnect. In an embodiment, a substrate includes an interconnect and a conductor which has a hole formed therein. Portions of the interconnect variously extend over a side of the conductor, wherein another recess portion of the interconnect extends from a plane which includes the side, and further extends at least partially into the hole. The configuration of the recess portion extending within the hole may contribute to an impedance which dampens a transmitter slew rate of the communication. In an embodiment, a total distance along a path formed by the interconnect is equal to or less than 5.5 inches.

An electronic apparatus which achieves ease of incorporating flexible boards into the electronic apparatus and ease of impedance control at the same time. A first flexible board and a second flexible board are placed along a structure having a bent portion and a flat portion. Differential signal wires are wired on one surface of the first flexible board placed between the structure and the second flexible board, and first ground wires for impedance control of the differential signal wires are wired on the other surface and on a rear side of the differential signal wires. Second ground wires for impedance control of the differential signal wires are wired on one surface of the second flexible board the one surface of the first flexible board faces. A wiring density of the first and second ground wires differs between an area along the bent portion and an area along the flat portion.

A flexible substrate (1) is bent at a bending part (2). A dielectric plate (3) has first and second main surfaces opposite to each other. A high-frequency signal line (4) is provided on the first main surface of the dielectric plate (3). A ground conductor (5) is provided on the second main surface of the dielectric plate (3). The high-frequency signal line (4) and the ground conductor (5) form a micro strip line. A local absent part (6) facing the high-frequency signal line (4) is provided on the ground conductor (5) only at the bending part (2).

Lossy members, which are disposed to overlap with a part of branch conductors in a signal conductor, respectively, and cause a loss of the power of signals flowing in the branch conductors, and via holes connecting each of the output terminals of the signal conductor and the ground conductor are included. The branch conductor includes a delay circuit having an electrical length of 90 degrees.

A multilayer substrate includes a dielectric substrate, a pair of capacitor electrodes, and an input/output electrode that is an electrode for input, an electrode for output, or an electrode for input and output. The dielectric substrate has a first main surface and a second main surface that are opposite to each other in a thickness direction of the dielectric substrate. The pair of capacitor electrodes is disposed in the dielectric substrate. Electrodes of the pair of capacitor electrodes face each other in the thickness direction. The input/output electrode is disposed on the second main surface of the dielectric substrate. A capacitor that includes the pair of capacitor electrodes and a portion being part of the dielectric substrate and located between the electrodes of the pair of capacitor electrodes at least partially overlaps the input/output electrode electrically connected to the capacitor.