An electrical activity sensor attachable to a power cable of an electrical device for detecting an impulse generated in the power cable in response to a change in electrical power state of the electrical device is described. The electrical activity sensor has an antenna assembly including an antenna element operable to magnetically couple with an electrical pulse generated in the power cable, to induce an electrical signal, in response to a change in electrical power state of the electrical device and to wirelessly transmit data representative of the electrical power state change of the electrical device to a remote reader device. The antenna element is a helical shape dipole having at least one turn arranged, in use, around the power cable.

A three-dimensional compound loop antenna is provided, including a ground plane, a pair of horizontal conductive portions substantially horizontal relative to the ground plane, a feed line substantially vertical relative to the ground plane, and a vertical conductive portion coupling the pair of horizontal conductive portions to the ground plane.

An antenna module is described where uniform radiation pattern coverage is provided in the plane of a low profile antenna radiating element. A polarization that is orthogonal to the plane of the low profile antenna radiating element can be achieved for the radiated field. A ground plate aperture is implemented into the antenna ground plate to minimize frequency shift as the antenna is installed on metallic (conductive) and non-metallic (non-conductive) ground planes of varying sizes. This antenna system technique is applicable for use in communication systems such as a local Area network (LAN), cellular communication network, and Machine to Machine (M2M).

Methods, apparatuses, and embodiments related to estimating void fractions in real-time or substantially real-time without disrupting a production flow of, e.g., a geothermal power plant. Some embodiments describe methods and systems of determining void fraction of a two-phase mixture extracted from a geothermal well by measuring the attenuations of one or more radiofrequency signals in a fixed span of a transportation unit (e.g., a pipe). Depending on void fraction of the two-phase mixture in the transportation, the RF signals would attenuate differently across the fixed span. For example, a monitor system can utilize one or more transmitter antennas in the transportation unit to transmit one or more RF signals and utilize one or more receiver antennas to measure attenuations of these RF signals over the fixed span. In some embodiments, an antenna can be configured to serve as both a transmitter antenna and a receiver antenna.

Source radio frequency energy (RF) is coupled wirelessly, with no direct physical contact, between two compound loop (CPL) antennas across a variety of barriers such as plastic, human tissues, glass, and air. The compound coupling interface is highly efficient in transferring the RF energy from a source including one CPL antenna to a destination including a second CPL antenna. A re-radiating structure including a further CPL antenna or a different type of antenna may be connected on the destination side to completely physically isolate the source side from the destination side. When the destination coupling antenna is removed, the source coupling antenna may operate as an efficient radiator at the desired operating frequencies. Likewise, the destination coupling antenna may operate as an efficient radiator in the absence of the source coupling antenna.

An antenna of the present disclosure has a housing having a shallow cavity in a top of the housing and a shallow cavity in a bottom of the housing. The antenna further has a substantially circular radiating element disposed in the shallow cavity on the top of the housing, the radiating element having an are shape slot. In addition, the antenna has a substantially circular parasitic element disposed in the shallow cavity on the bottom of the housing.

The invention relates to an apparatus for transferring signals from an at least partially metallic housing with the aid of electromagnetic waves of a particular wavelength, comprising: a transmitter/receiver unit located in the housing for generating and receiving the electromagnetic waves; at least one primary antenna located in the housing for coupling out the generated electromagnetic waves from the transmitter/receiver unit and for coupling in and transferring received electromagnetic waves to the transmitter/receiver unit; at least one slot-shaped housing opening designed such that a length of the slot-shaped housing opening is an integer multiple of a quarter of the particular wavelength, preferably an integer multiple of a half of the particular wavelength, such that the slot-shaped housing opening, in cooperation with the primary antenna, transfers the signals with the aid of the electromagnetic waves into or out of the housing.

An instrument system for locating leakage at a subscriber's premises is disclosed.

An antenna module is described where uniform radiation pattern coverage is provided in the plane of a low profile antenna radiating element. A polarization that is orthogonal to the plane of the low profile antenna radiating element can be achieved for the radiated field. A ground plate aperture is implemented into the antenna ground plate to minimize frequency shift as the antenna is installed on metallic (conductive) and non-metallic (non-conductive) ground planes of varying sizes. This antenna system technique is applicable for use in communication systems such as a local Area network (LAN), cellular communication network, and Machine to Machine (M2M).

A voltage detecting device detects a differential voltage between two input nodes having a non-zero common mode voltage. A differential voltage detecting circuit 5 detects the differential voltage by sampling each voltage of the input nodes and outputs a detection voltage indicating a detection result. A leak canceling circuit generates a compensating current, which flows in opposition to a leak current flowing out from the input nodes in correspondence to an operation of the differential voltage detecting circuit. An operation control part controls the leak canceling circuit to perform or stop a canceling operation. A failure diagnosing part performs a failure diagnosis about the leak canceling circuit based on a first detection value and a second detection value of the detection voltages, which are detected during periods when the leak canceling circuit performs and stops the canceling operation.