A pseudo coaxial line is connected to a first coplanar line at a first connecting portion and connected to a second coplanar line at a second connecting portion. The first coplanar line and the second coplanar line are, for example, differential coplanar lines. Also, a back surface concave portion in which the second connecting portion of the pseudo coaxial line is exposed is provided. The back surface concave portion is formed into an almost semicircular shape, an almost semielliptical shape, or a rectangular shape in a planar view.

A cable includes a first shield portion that includes at least one or more lines for transmitting a signal or electric power and that is provided on the outer side of the lines, a first layer that is provided in such a manner as to cover an outer circumference of the first shield portion and that includes a member that absorbs radio waves, a second shield portion that is provided on an outer side of the first layer, a second layer that is provided in such a manner as to cover an outer circumference of the second shield portion and that includes a member that absorbs radio waves, and insulating resin that covers an outer side of the second layer.

A transmission circuit includes a first semiconductor device, a second semiconductor device, a first signal line, a second signal line, a third signal line, and a ground line. A differential signal is composed of a first signal and a second signal. The first signal line is configured to connect the first semiconductor device and the second semiconductor device and used to transmit the first signal. The second signal line is configured to connect the first semiconductor device and the second semiconductor device and used to transmit the second signal. The second signal line, the first signal line, the ground line, and the third signal line are disposed in this order. A distance between the first signal line and the ground line is larger than a distance between the first signal line and the second signal line.

A transmission circuit includes a first semiconductor device, a second semiconductor device, a first signal line, a second signal line, a third signal line, and a ground line. A differential signal is composed of a first signal and a second signal. The first signal line is configured to connect the first semiconductor device and the second semiconductor device and used to transmit the first signal. The second signal line is configured to connect the first semiconductor device and the second semiconductor device and used to transmit the second signal. The second signal line, the first signal line, the ground line, and the third signal line are disposed in this order. A distance between the first signal line and the ground line is larger than a distance between the first signal line and the second signal line.

Electrical cables and optical waveguides are disclosed as including an electrically insulative foam. The electrically insulative foam can coat at least one electrical conductor of the electrical cable. The electrically insulative foam can coat the optical fiber of the waveguide. The electrically insulative foam can also define a waveguide.

A wiring substrate includes a first insulating layer with a first opening, a second insulating layer with a second opening, a high-frequency wiring layer, a first wiring layer, a second wiring layer, and a plurality of conductive pillars. The high-frequency wiring layer including a high-frequency trace is sandwiched between the first insulating layer and the second insulating layer. The first opening and the second opening expose two sides of the high-frequency trace respectively. The high-frequency trace has a smooth surface which is not covered by the first insulating layer and the second insulating layer and has the roughness ranging between 0.1 and 2 μm. The first insulating layer and the second insulating layer are all located between the first wiring layer and the second wiring layer. The conductive pillars are disposed in the second insulating layer and connected to the high-frequency trace.

One example includes an antenna-on-package (AoP) system. The system includes a first transmission line patterned on a first metal layer. The first metal layer can be arranged to be coupled on a printed circuit board (PCB). The system also includes an antenna portion patterned on a second metal layer. The first and second metal layers can be separated by at least one dielectric layer. The system further includes a coaxial transition portion comprising a via configured to communicatively couple the first transmission line on the first metal layer to a second transmission line on the second metal layer. The second transmission line can be coupled to the antenna portion.

One example includes an antenna-on-package (AoP) system. The system includes a first transmission line patterned on a first metal layer. The first metal layer can be arranged to be coupled on a printed circuit board (PCB). The system also includes an antenna portion patterned on a second metal layer. The first and second metal layers can be separated by at least one dielectric layer. The system further includes a coaxial transition portion comprising a via configured to communicatively couple the first transmission line on the first metal layer to a second transmission line on the second metal layer. The second transmission line can be coupled to the antenna portion.

A method for controlling gain of a line amplifier on a cable, the method comprising selecting an unused carrier frequency; transmitting a pulsed pilot signal on the unused carrier frequency into the cable; determining a pilot signal output strength by measuring signal strength of the pilot signal after amplification by the line amplifier; comparing the pilot signal output strength with a target signal strength to determine a difference; and adjusting the gain of the line amplifier corresponding to the difference.

A method for controlling gain of a line amplifier on a cable, the method comprising selecting an unused carrier frequency; transmitting a pulsed pilot signal on the unused carrier frequency into the cable; determining a pilot signal output strength by measuring signal strength of the pilot signal after amplification by the line amplifier; comparing the pilot signal output strength with a target signal strength to determine a difference; and adjusting the gain of the line amplifier corresponding to the difference.