A coupling circuit for power line communications includes a coupling transformer having first and second mutually coupled windings, with the first winding connectable to a power line. The second winding includes a pair of intermediate taps with one or more tuning inductor therebetween. The inductor or inductors are set between a first portion and a second portion of the second winding of the coupling transformer. A switch member is provided coupled with the inductor. The switch member is selectively actuatable to short-circuit the inductor.

Provided herein are methods of reconfiguring directional couplers in an RF transceiver. The methods can include designing and reconfiguring the directional couplers to provide high directivity and a desired coupling factor using configurable capacitors to effect a mutual coupling and using lumped components or delay lines to effect a phase shift. The reconfigurable directional couplers can be designed for multi-band operation with an adjustable coupling factor conducive to semiconductor process integration. The reconfigurable directional couplers can have variable phase shifters to achieve a desired level of directivity in the coupler. In various examples, the methods include monitoring the frequency of power signals received by the reconfigurable directional couplers, and adjusting the configurable capacitors and/or variable phase shifters to maintain desired directivity and coupling factors over multi-band operation of the reconfigurable directional couplers.

Provided herein are apparatus and methods for reconfigurable directional couplers in an RF transceiver. Reconfigurable directional couplers can be reconfigured and designed to provide high directivity using configurable capacitors to effect a mutual coupling and using lumped components or delay lines to effect a phase shift. Depending on the embodiment, the reconfigurable directional coupler can include capacitors, inductors, and switching components. The coupler can be designed for multi-band operation with an adjustable coupling factor conducive to semiconductor process integration. The coupler can have variable phase shifters to achieve a desired level of directivity in the coupler.

A technique relates to a microwave device. The microwave device includes a Josephson ring modulator, a first multimode resonator connected to the Josephson ring modulator, where the first multimode resonator is made of a first left-handed transmission line, and a second multimode resonator connected to the Josephson ring modulator, where the second multimode resonator is made of a second left-handed transmission line.

A discrete field coupled capacitor with a cross-connected capacitor-pair, such as for use as a discrete bypass capacitor. The FCC includes a first port with first and second terminals, and a second port with third and fourth terminals. A first capacitor structure is connected between the first and second terminals, and a second capacitor structure connected between the third and fourth terminals. A cross-connect structure includes a first cross-connection to connect the first terminal to the third terminal, and a second cross-connection to connect the second terminal to the fourth terminal, to cross-connect the first and second capacitor structures. The capacitor structures have respective parasitic ESL, and can be disposed in proximity to effect a pre-defined ESL field coupling with reverse phasing to reduce parasitic ESL. The FCC can be constructed as a PCB or monolithic device. In a PCB four-layer construction, the cross-connections can be formed on respective mid-layers.

A wide band radio frequency (RF) circulator is presented. The RF circulator includes at least one stage having four ports, a first end, and a second end, wherein a first port and a third port are connected at the first end of the at least one stage, wherein a second port and a fourth port are connected at the second end of the at least one stage, wherein each of the at least one stage includes a pair of couplers connected through a first delay line and a second delay line, thereby forming a network of couplers in the at least one stage.

An exponentially-scaling switched impedance circuit includes: two or more impedance scaling circuits, wherein each impedance scaling circuit comprises: an input port; an output port; and a switched impedance circuit connected in parallel to the output port. Each impedance scaling circuit is configured to provide an effective impedance at the input port corresponding to a scaled-down version of the exponentially-scaling switched impedance circuit. The two or more impedance scaling circuits are connected in a cascade such that an input of an impedance scaling circuit is connected to an output of a previous impedance scaling circuit and/or an output of the impedance scaling circuit is connected to an input of a next impedance scaling circuit.

Various examples are provided for enhanced guided surface waveguide probes, systems and methods. In one example, a guided surface waveguide probe includes a charge terminal comprising a upper terminal portion coupled to a lower terminal portion through a variable capacitance. In another example, a method includes positioning the charge terminal at a defined height over a lossy conducting medium; adjusting a phase delay () of a feed network connected to the charge a terminal to match a wave tilt angle () corresponding to a complex Brewster angle of incidence (.sub.i,B) associated with the lossy conducting medium; adjusting the variable capacitance based upon an image ground plane impedance (Z.sub.in) associated with the lossy conducting medium; and exciting the charge terminal with an excitation voltage via the feed network. The excitation voltage can establish an electric field that couples into a guided surface waveguide mode along a surface of the lossy conducting medium.

Data communication having improved electromagnetic interference (EMI) rejection when communicating through a coaxial cable is provided by using differential transmission and/or reception through a common-mode choke and a dissipative element resulting in extremely low radiated emissions and high immunity to external radiation interference in a low-cost way.

A signal transmission system includes: a first signal line and a second signal line each making up a differential line; a first capacitive load mechanism disposed in a first region connected to the first signal line, the first capacitive load mechanism having a first capacitance value; and a second capacitive load mechanism disposed in a second region connected to the second signal line and to the ground point line, the second capacitive load mechanism having a capacitance value asymmetric with the first capacitance value. This signal transmission system suppresses an increase in mode conversion loss caused by component characteristics variations.