A branch-line coupler of reduced size but comparable performance includes a first transmission line, a second transmission line, a first bent transmission line, and a second bent transmission line. The first transmission line includes a first strip transmission line, a first branch transmission line, and a second branch transmission line. The first strip transmission line extends along a predetermined direction, the first and second branch transmission lines being slotted. The first and second branch transmission lines are symmetrical around a first axis and around a second orthogonally-disposed axis. The first bent transmission line is electrically connected to the terminals of the first and second transmission lines on one side, and the second bent transmission line is electrically connected to the terminals of the first and second transmission lines on the other side.

A third coupler (3c) outputs a signal outputted from a first coupler (3a) to an input terminal (8-1) of a second septum polarizer (8b), and outputs a signal outputted from a second coupler (3b) to an input terminal (8-2) of a first septum polarizer (8a).

A hybrid coupler is disclosed. The hybrid coupler includes a printed circuit board. The printed circuit board includes at least two input ports, at least two output ports, and a plurality of couplers, each coupler of the plurality of couplers comprising first and second transmission traces and a coupling junction connecting the first and second transmission traces. The plurality of couplers are electrically coupled in series between the input ports and the output ports. The hybrid coupler further includes a defective ground structure below the coupling junction of at least one of the plurality of couplers.

A passive component comprising a first port and a second port, wherein the first and second ports are provided on a first axis, a third port and a fourth port, wherein the third and fourth ports are provided on a second axis perpendicular to the first axis, and a transmission line arrangement comprising four transmission lines, wherein the first port and the second port are each coupled to both the third port and the fourth port by respective transmission lines of the transmission line arrangement, wherein each transmission line follows a meandering path and each transmission line has the same length, such that the transmission line arrangement is symmetrical about at least one axis of symmetry.

A hybrid coupler for transmitting equally splitted amplitude and quadrature phase electro-magnetic waves, the hybrid coupler includes a dielectric substrate having a first main surface and a second main surface opposing the first main surface and a stripline placed at the first main surface of the dielectric substrate. The stripline comprising an input port and two output ports. The stripline is formed to provide an equally splitted amplitude and quadrature phase electro-magnetic wave at the output ports based on an input signal received at the input port. The hybrid coupler further includes a rectangular waveguide transition attached to both of the main surfaces of the substrate. The waveguide transition is configured to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave to an antenna.

A hybrid coupler includes a 90? hybrid coupler and a first quarter wavelength conductive stub. The 90? hybrid coupler includes a coupling section, a first input transmission line that is coupled to the coupling section, a second input transmission line that is coupled to the coupling section, a first output transmission line that is coupled to the coupling section and a second output transmission line that is coupled to the coupling section. The first quarter wavelength conductive stub is coupled to the second output transmission line.

Provided is a microwave filter system having a feedback structure. The microwave filter system may include an input hybrid coupler configured to output first output signals having a phase difference with respect to an input signal; filters disposed to be in parallel with an output end of the input hybrid coupler, and configured to filter the first output signals; and an output hybrid coupler configured to output second output signals having a phase difference with respect to each of signals filtered through the filters. An output signal of the output hybrid coupler is applied to an input end of the input hybrid coupler along a feedback path.

A coupling structure for crossing three transmission lines millimeter-wave or centimeter-wave signals a signal conductor layer of a circuit substrate, the coupling structure comprising three planar cross-couplers, and from each of the three cross-couplers two input/output points of the cross-coupler being connected clockwise in succession in the plane of the cross-coupler, to respectively one input/output point of a respective other of the three cross-couplers.

A demultiplexer/multiplexer includes an input terminal, which receives input signals from respective phases of a quadrifilar helix antenna; phase shifter/separator/mixers, which alternately phase-shift right-handed and left-handed circularly polarized waves of the input signals, respectively, by 90/90 to produce phase-shifted waves to be combined in an inphase combination; phase shifter/mixers, which receive the left-handed or right-handed circularly polarized waves from the phase shifter/separator/mixers, and phase-shift one of the left-handed and right-handed circularly polarized waves by 180/180 to produce a phase-shifted wave to be combined with the other of the left-handed and right-handed circularly polarized waves in an antiphase combination; a variable phase shifter, which adjusts an output signal from the phase shifter/mixers by a phase-shift amount that is received in advance; and an output terminal, which outputs an output signal from the variable phase shifter and the other output signal that is not input to the variable phase shifter.

A radio frequency module includes a carrier amplifier and a peak amplifier. A 90? hybrid circuit is connected to an input end of the carrier amplifier and an input end of the peak amplifier. A coupler is connected to an output end of the carrier amplifier and an output end of the peak amplifier. A control circuit varies a threshold value of a bias voltage of the peak amplifier based on a radio frequency signal input to the 90? hybrid circuit or the carrier amplifier, and a signal indicating a drive level of the carrier amplifier, in which the carrier amplifier and the peak amplifier are included in an integrated circuit. The control circuit is included in an integrated circuit, and the integrated circuit is disposed adjacent to the integrated circuit on a peak amplifier side.