According to various embodiments, a quadrature hybrid coupler included as part of a phase shifter is used to provide variable phase shift to an input signal. The quadrature hybrid coupler includes an input port, an output port, and two terminated ports. The phase shifter includes one or more static lumped elements connected to the QHC to reduce at least one electrical dimension of the QHC to substantially less than a quarter wavelength. The phase shifter also include one or more variable lumped elements connected to the QHC to provide a variable phase shift to the input signal between the input port and the output port of the QHC.

A small-scale branch-line coupler suitable for use in mobile devices includes a first, second, third, and fourth ports, respectively acting as input, transmission, coupled, and isolated ports. A first, second, third, and fourth connection parts are connected to the ports and transmission lines. First angular transmission lines are between first and second ports, third angular transmission lines are between third and fourth ports. A third long strip transmission line connects the first port and the fourth port. A fourth long strip transmission line connects the second port and the third port. The branch-line coupler occupies a small area and has high performance.

A small-scale branch-line coupler suitable for use in mobile devices includes a first, second, third, and fourth ports, respectively acting as input, transmission, coupled, and isolated ports. A first, second, third, and fourth connection parts are connected to the ports and transmission lines. First angular transmission lines are between first and second ports, third angular transmission lines are between third and fourth ports. A third long strip transmission line connects the first port and the fourth port. A fourth long strip transmission line connects the second port and the third port. The branch-line coupler occupies a small area and has high performance.

A multiport microwave device includes a first reactive three-port microwave device, a second reactive three-port microwave device, a third reactive three-port microwave device, and a matched four-port microwave device. The four-port microwave device includes first and second input ports and first and second output ports communicatively coupled to one another. A first port of each of the first, second and third three-port microwave devices is operative to receive a microwave signal, and a first output port and a second output port of the four-port microwave device are each operative to output a microwave signal. A second port of the first microwave device is communicatively coupled to a second port of the second microwave device, a second port of the third microwave device is communicatively coupled to a third port of the second microwave device, and a third port of the first microwave device is communicatively coupled to the first input port the four-port microwave device. A third port of the third microwave device is communicatively coupled to the second input port of the four-port microwave device.

The disclosed systems, structures, and methods are directed to an orbital angular momentum (OAM) receiver. The OAM receiver includes at least two receiver antenna elements to receive radiated OAM signal beams containing superposed order modes and to generate antenna element output signals based on the received OAM signal beams. The receiver antenna elements are positioned tangentially along a circular locus and spatially separated by a distance. A variable ratio combining unit operates to switch between the antenna output signals based on a high-rate periodic waveform that emulates unidirectional movement by the antenna elements to produce a pseudo-Doppler frequency shift. The variable ratio combining unit further modulates the antenna output signals based on the periodic waveform to impart a fractional pseudo-Doppler shift to each OAM mode and combines the modulated antenna element output signals in accordance with the fractional pseudo-Doppler shift to facilitate separation of the OAM modes.

A directional coupler includes: a first waffle-iron ridge waveguide extending from one end to other end; a second waffle-iron ridge waveguide extending from one end to the other end; a first bypass waveguide connecting a first site of the first waffle-iron ridge waveguide and a first site of the second waffle-iron ridge waveguide; and a second bypass waveguide connecting a second site of the first waffle-iron ridge waveguide and a second site of the second waffle-iron ridge waveguide.

A branch line coupler and active antenna system are provided. In an embodiment, the branch line coupler comprises four resonators. The four resonators are formed by a body and a grounded element. A resonator comprises a capacitor element and an inductor element. A first portion of the capacitor element comprises at least a portion of the body and a second portion comprises at least a portion of the grounded element. The inductor element is connected to the capacitor element in parallel. The inductor element comprises at least a portion of the body and extends to the grounded element. The first and second resonators are coupled by a first coupling, the second resonator and the third resonator are coupled by a second coupling, the third resonator and the fourth resonator are coupled by a second third coupling, and the fourth resonator and the first resonator are coupled by a fourth coupling.

In one aspect, a unit cell of a phased array antenna includes a metal plate having a hole, a first side and a second side opposite the first side, a first plurality of laminate layers disposed on the first side, a second plurality of layers disposed on the second side of the metal plate, a radiator disposed in the first plurality of layer on the first side, a feed circuit disposed in the second plurality of laminate layers on the second side and configured to provide excitation signals to the radiator and a first plurality of vias extending through the hole connecting the feed circuit to the radiator.

A branch line coupler and active antenna system are provided. In an embodiment, the branch line coupler comprises four resonators. The four resonators are formed by a body and a grounded element. A resonator comprises a capacitor element and an inductor element. A first portion of the capacitor element comprises at least a portion of the body and a second portion comprises at least a portion of the grounded element. The inductor element is connected to the capacitor element in parallel. The inductor element comprises at least a portion of the body and extends to the grounded element. The first and second resonators are coupled by a first coupling, the second resonator and the third resonator are coupled by a second coupling, the third resonator and the fourth resonator are coupled by a second third coupling, and the fourth resonator and the first resonator are coupled by a fourth coupling.

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.