According to one embodiment, there is provided a magnetic coupling device including a first coil, a second coil, a third coil, a fourth coil, a first constant-potential node and a second constant-potential node. The second coil is electrically connected with one end of the first coil and wound in a direction opposite to a direction in which the first coil is wound. The third coil faces the first coil. The fourth coil faces the second coil. The first constant-potential node is electrically connected with one end of the third coil. The second constant-potential node is electrically connected with one end of the fourth coil.

In accordance with some embodiments, non-reciprocal circulators are provided, the circulators comprising: a 3X/4-long ring section having a first end and a second end, wherein is an operating wavelength of the non-reciprocal circulator; and a N-path filter having a first port, a second port, and N-paths, each of the N-paths being connected to the first port and the second port. In some of these embodiments, the 3/4-long ring section includes a transmit port, an antenna port, and a receive port. In some of these embodiments, the transmit port is /4 away from the antenna port. In some of these embodiments, the antenna port is /4 away from the receive port. In some of these embodiments, the receive port is at the first port of the N-path filter.

In accordance with some embodiments, non-reciprocal circulators are provided, the circulators comprising: a 3X/4-long ring section having a first end and a second end, wherein is an operating wavelength of the non-reciprocal circulator; and a N-path filter having a first port, a second port, and N-paths, each of the N-paths being connected to the first port and the second port. In some of these embodiments, the 3/4-long ring section includes a transmit port, an antenna port, and a receive port. In some of these embodiments, the transmit port is /4 away from the antenna port. In some of these embodiments, the antenna port is /4 away from the receive port. In some of these embodiments, the receive port is at the first port of the N-path filter.

Systems, methods, and devices include a high-density analog multiplexer topology. Such topologies can be used, for example, in sensor device applications. An analog multiplexer circuit can include circuitry to receive N input signals; and circuitry to generate N selection signals for selecting one of said N data signals to be output from said analog multiplexer circuit. The analog multiplexer comprises one or more analog impedances.

Systems, methods, and devices include a high-density analog multiplexer topology. Such topologies can be used, for example, in sensor device applications. An analog multiplexer circuit can include circuitry to receive N input signals; and circuitry to generate N selection signals for selecting one of said N data signals to be output from said analog multiplexer circuit. The analog multiplexer comprises one or more analog impedances.

Disclosed are various embodiments for controlling the operation of a guided surface waveguide probe. A control system coupled to the guided surface waveguide probe can monitor and control the guided surface waveguide probe and one or more subsystems associated with the guided surface waveguide probe. Based on data collected from the guided surface waveguide probe and/or the various subsystems, the control system can adjust the operation of the guided surface waveguide probe. Human operators can interact with the control system at a location outside of a safety perimeter surrounding the guided surface waveguide probe.

An interface circuit, comprising: a signal line having signal, auxiliary and connection nodes defined therealong, the connection node for connection to a transmission line; signal-handling circuitry connected to the signal line at the signal node; an auxiliary circuit connected to the signal line at the auxiliary node; a signal pair of inductors connected in series along the signal line adjacent to and either side signal node; and an auxiliary pair of inductors connected in series along the signal line adjacent to and either side of the auxiliary node, wherein: the signal pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kS; the pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kA; and kS has a positive value and kA has a negative value.

An interface circuit, comprising: a signal line having signal, auxiliary and connection nodes defined therealong, the connection node for connection to a transmission line; signal-handling circuitry connected to the signal line at the signal node; an auxiliary circuit connected to the signal line at the auxiliary node; a signal pair of inductors connected in series along the signal line adjacent to and either side signal node; and an auxiliary pair of inductors connected in series along the signal line adjacent to and either side of the auxiliary node, wherein: the signal pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kS; the pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kA; and kS has a positive value and kA has a negative value.

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.

A balun includes a first winding which has a first terminal coupled to an input, and a second terminal coupled to a reference potential terminal. The balun includes a second winding magnetically coupled to the first winding. The second winding has a first terminal coupled to a first differential output, a second terminal coupled to a second differential output, and a tap coupled to the reference potential terminal. The balun includes a first capacitor which has a first terminal coupled to the first winding and a second terminal coupled to the second winding. The balun includes a third winding which has a first terminal coupled to the reference potential terminal and a floating second terminal. The balun includes a second capacitor which has a first terminal coupled to the third winding and a second terminal coupled to the second winding.