The present disclosure includes an electromagnetic field detection and monitoring system. The system includes a single-ended amplifier and an impedance matching circuit which matches the impedance caused by an air gap between tissue and an electrode. The system includes passive detection, active detection, and signal processing capabilities. At least one embodiment includes a body worn system with sensing, processing, communications, and data storage capabilities. The system provides wearable antennas to transfer the EMF energy in its electrical or magnetic forms into the sensor efficiently. A specially designed processing algorithm can process the collected data and generated the results for medical professionals to read and make decisions. The processing can include machine learning technique which decompose an EMF signal into EEG bands to perform feature extraction. The features can then be used to train a machine learning model to classify other EMF signals.

The present disclosure includes an electromagnetic field detection and monitoring system. The system includes a single-ended amplifier and an impedance matching circuit which matches the impedance caused by an air gap between tissue and an electrode. The system includes passive detection, active detection, and signal processing capabilities. At least one embodiment includes a body worn system with sensing, processing, communications, and data storage capabilities. The system provides wearable antennas to transfer the EMF energy in its electrical or magnetic forms into the sensor efficiently. A specially designed processing algorithm can process the collected data and generated the results for medical professionals to read and make decisions. The processing can include machine learning technique which decompose an EMF signal into EEG bands to perform feature extraction. The features can then be used to train a machine learning model to classify other EMF signals.

An antenna device includes a body and at least one external antenna. The body includes a processor and a sensor electrically connected to the processor. The processor is configured to receive a sensing signal from the sensor. The external antenna is externally connected to the body at an adjustable angle, and includes a first antenna, a second antenna, and a switch. The switch is electrically connected to the processor, and is switchably electrically connected to the first antenna and the second antenna. When the sensor senses that the external antenna is at a first angle or a second angle relative to the body, the processor switches the switch electrically connected to the first antenna or the second antenna according to the sensing signal, so that the external antenna has a first radiation pattern or a second radiation pattern.

An antenna device includes a body and at least one external antenna. The body includes a processor and a sensor electrically connected to the processor. The processor is configured to receive a sensing signal from the sensor. The external antenna is externally connected to the body at an adjustable angle, and includes a first antenna, a second antenna, and a switch. The switch is electrically connected to the processor, and is switchably electrically connected to the first antenna and the second antenna. When the sensor senses that the external antenna is at a first angle or a second angle relative to the body, the processor switches the switch electrically connected to the first antenna or the second antenna according to the sensing signal, so that the external antenna has a first radiation pattern or a second radiation pattern.

A change in potential at a ground terminal is suppressed. A radio frequency module includes a mount board, a first circuit element, a second circuit element, a signal terminal (an antenna terminal, a signal input terminal, or a signal output terminal) for a radio frequency signal, and a block terminal. The mount board has a first principal surface and a second principal surface facing each other. The first circuit element is mounted on the first principal surface of the mount board. The second circuit element is mounted on the second principal surface of the mount board. The signal terminal (the antenna terminal, the signal input terminal, or the signal output terminal) is disposed on the second principal surface of the mount board. The block terminal is disposed on the second principal surface of the mount board. The block terminal includes a plurality of ground terminals.

A wireless device comprises a radiating system that comprises: an antenna system, a ground plane, and a matching network. The antenna system comprises an antenna component including a first multi-section antenna component comprising two sections, each comprising a conductive element. The matching network connected to the antenna system for impedance matching to a first frequency range. The radiating system operates in a frequency range of operation including the first frequency range, the first frequency range comprising a first highest frequency and a first lowest frequency. The first antenna component has a maximum size larger than 1/30 times and smaller than ? times a free-space wavelength corresponding to the lowest frequency of operation. The conductive elements in the different sections of the first antenna component are spaced apart from each other.

A wireless device comprises a radiating system that comprises: an antenna system, a ground plane, and a matching network. The antenna system comprises an antenna component including a first multi-section antenna component comprising two sections, each comprising a conductive element. The matching network connected to the antenna system for impedance matching to a first frequency range. The radiating system operates in a frequency range of operation including the first frequency range, the first frequency range comprising a first highest frequency and a first lowest frequency. The first antenna component has a maximum size larger than 1/30 times and smaller than ? times a free-space wavelength corresponding to the lowest frequency of operation. The conductive elements in the different sections of the first antenna component are spaced apart from each other.

There is provided a metal plate antenna transmitting and receiving wireless signals conforming to a prescribed communication standard, wherein an antenna width is designed to satisfy radiation resistance achieving a prescribed standing wave ratio in a resonant mode in which a loop length of the metal plate antenna is 1.5 wavelength of a wireless signal conforming to the prescribed communication standard.

A low-profile antenna device is provided for a vehicle. The low-profile antenna device includes a base plate, a circuit board, a base, a top-load element and a coil. The circuit board is disposed on the base plate, in parallel with the base plate. An amplifier circuit is placed on a front surface side of the circuit board, and a ground plate area having a ground plate and an empty area not having a ground plate are provided on a back, surface of the circuit board. The coil is disposed on the front surface side of the circuit board facing the empty area of the circuit board. The coil is disposed in a manner axially parallel with the circuit board, connected between the top-load element and the amplifier circuit, and adjusted to function as a resonance antenna.

A low-profile antenna device is provided for a vehicle. The low-profile antenna device includes a base plate, a circuit board, a base, a top-load element and a coil. The circuit board is disposed on the base plate, in parallel with the base plate. An amplifier circuit is placed on a front surface side of the circuit board, and a ground plate area having a ground plate and an empty area not having a ground plate are provided on a back, surface of the circuit board. The coil is disposed on the front surface side of the circuit board facing the empty area of the circuit board. The coil is disposed in a manner axially parallel with the circuit board, connected between the top-load element and the amplifier circuit, and adjusted to function as a resonance antenna.