A directional coupler includes a conductor serving as a primary line disposed in a multilayer body and conductors serving as a plurality of secondary lines that are disposed in the multilayer body and each of which is capable of being electromagnetically coupled to the conductor serving as the primary line. A facing area where the conductor serving as the secondary line and the conductor serving as the secondary line face each other is smaller than a facing area where the conductor serving as the secondary line and the conductor serving as the primary line face each other. A distance between the conductor serving as the secondary line and the conductor serving as the secondary line is longer than a distance between the conductor serving as the secondary line and the conductor serving as the primary line.

To provide a directional coupler in which a coupling characteristic is made even flatter. There are included an input terminal, an output terminal, a coupling terminal, a termination terminal, ground terminals, a main line, a first sub line, and a second sub line. The main line is electromagnetically coupled to sub lines (first sub line, second sub line). A phase conversion unit (low pass filter) is connected between the first sub line and the second sub line. Between a point between the coupling terminal and the termination terminal, and the ground terminals, a resonant circuit is connected in which an inductor, a capacitor, and a resistor are connected in series.

A directional coupler includes: a hollow coaxial line including a central conductor forming a main line and an outer conductor surrounding the central conductor and having an opening formed therein; a dielectric substrate covering the opening and provided with film-shaped ground conductors, wherein a film-shaped ground conductor covers a rear surface of the dielectric substrate facing the central conductor via the opening and a film-shaped ground conductor covers a front surface of the dielectric substrate, respectively, and are grounded; and a coupling line provided on the rear surface of the dielectric substrate in a region surrounded by the ground conductor formed on the rear surface and serving as an auxiliary line, wherein the ground conductor formed on the front surface is provided with a conductor-removed portion in which a portion of a conductor film in a region facing the coupling line via the dielectric substrate is removed.

A directional coupler includes a primary transmission line electrically coupled in series between an input port and an output port of the coupler, and an asymmetric, meander-shaped, secondary transmission line, which is electrically coupled in series between a coupling port and an isolation port of the coupler. The secondary transmission line includes a first coupling segment, which is reactively coupled to a first portion of the primary transmission line, and a second coupling segment, which is reactively coupled to a second portion of the primary transmission line, and is spaced closer to, or farther from, the primary transmission line relative to the first coupling segment, such that an asymmetry in reactive coupling is present between the first and second portions of the primary transmission line and the secondary transmission line. An intermediate segment is provided, which is electrically coupled in series between the first and second coupling segments. A coupling port segment is provided, which is electrically connected in series between the first coupling segment and the coupling port. And, an isolation port segment is provided, which is electrically connected in series between the second coupling segment and the isolation port.

A directional coupler includes a primary transmission line electrically coupled in series between an input port and an output port of the coupler, and an asymmetric, meander-shaped, secondary transmission line, which is electrically coupled in series between a coupling port and an isolation port of the coupler. The secondary transmission line includes a first coupling segment, which is reactively coupled to a first portion of the primary transmission line, and a second coupling segment, which is reactively coupled to a second portion of the primary transmission line, and is spaced closer to, or farther from, the primary transmission line relative to the first coupling segment, such that an asymmetry in reactive coupling is present between the first and second portions of the primary transmission line and the secondary transmission line. An intermediate segment is provided, which is electrically coupled in series between the first and second coupling segments. A coupling port segment is provided, which is electrically connected in series between the first coupling segment and the coupling port. And, an isolation port segment is provided, which is electrically connected in series between the second coupling segment and the isolation port.

A communication system according to an embodiment of the present disclosure is a communication system that transmits a signal from a plurality of transmission devices to one reception device via a transmission path. In the communication system, the transmission path includes a branch point at a midpoint, includes a plurality of first signal lines that couples the transmission devices and the branch point to each other, and further includes a second signal line that couples the branch point and the reception device to each other. Of the plurality of first signal lines or the second signal line, at least the plurality of first signal lines has a resistor element in proximity to the branch point.

A communication system according to an embodiment of the present disclosure is a communication system that transmits a signal from a plurality of transmission devices to one reception device via a transmission path. In the communication system, the transmission path includes a branch point at a midpoint, includes a plurality of first signal lines that couples the transmission devices and the branch point to each other, and further includes a second signal line that couples the branch point and the reception device to each other. Of the plurality of first signal lines or the second signal line, at least the plurality of first signal lines has a resistor element in proximity to the branch point.

A 90-degree, 3 dB coupler has an input port, an isolated port, a first output port, and a second output port. A plurality of solenoid structures are arranged in a parallel, spaced relationship. A first group of the interconnects bridge the solenoid structures of a first set that define a first contiguous connection from the input port to the first output port. A second group of interconnects bridge the solenoid structures of a second set that define a second contiguous connection from the isolated port to the second output port. A third group of interconnects bridge the solenoid structures of a third set that define a third contiguous connection from the isolated port to the second output port. The solenoid structures are each unique to a respective one of the first set, second set, and the third set.

The invention proposes a four-port coupler using micro-strip line in combination with ultra-wide-band compensation circuits. It can be applied for communication systems or information machine systems. The main feature of the invention is the structure and the distribution of the components in the compensation circuit to reduce the size of the coupler. The proposed coupler includes: microstrip directional coupler and compensation circuits, in which the microstrip directional coupler consists of one main line and two secondary transmission lines; the main transmission line has two ports: input and output ports; each secondary is connected to a load and a compensation circuit. The compensation circuit is composed of a low-pass filter and two parallel attenuation regulator circuits.

The invention proposes a four-port coupler using micro-strip line in combination with ultra-wide-band compensation circuits. It can be applied for communication systems or information machine systems. The main feature of the invention is the structure and the distribution of the components in the compensation circuit to reduce the size of the coupler. The proposed coupler includes: microstrip directional coupler and compensation circuits, in which the microstrip directional coupler consists of one main line and two secondary transmission lines; the main transmission line has two ports: input and output ports; each secondary is connected to a load and a compensation circuit. The compensation circuit is composed of a low-pass filter and two parallel attenuation regulator circuits.