A lighting device, such as a replacement lighting device, comprising a light source (LS), e.g. LEDs, for producing light along an optical axis (OA). A heat sink (HS) made of a material with an electrical resistivity being less than 0.01 Ωm, e.g. a metallic heat sink being a part of the housing, transports heat away from the light source (LS). A Radio Frequency (RF) communication circuit (CC) connected to an antenna (A) serves to enable RF signal communication, e.g. to control the device via a remote control. Metallic components, including the heat sink (HS), having an extension larger than 1/10 of a wavelength of the RF signal are arranged below a virtual plane (VP) drawn orthogonal to the optical axis (OA) and going through the antenna (A). Hereby a compact device can be obtained, and still a satisfying RF radiation pattern can be obtained. The antenna can be a wire antenna or a PCB antenna, e.g. a PIFA or a IFA type antenna. In a special embodiment the antenna is formed on a ring-shaped PCB with a central hole allowing passage of light from the light source. Preferably, the antenna is positioned at least 2 mm in front of the heat sink (HS).

A high-frequency power circuit includes a first antenna circuit and a second antenna circuit that are connected in parallel to a matching box connected to a high-frequency power supply. The first antenna circuit include a first antenna, a first distribution capacitor, and a first variable capacitor. The second antenna circuit includes a second antenna, a second distribution capacitor, and a second variable capacitor. A controller sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production to reduce this phase difference and sets a capacitance of the second variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the second antenna and the second variable capacitor during plasma production to reduce this phase difference.

A high-frequency power circuit includes a first antenna circuit and a second antenna circuit that are connected in parallel to a matching box connected to a high-frequency power supply. The first antenna circuit include a first antenna, a first distribution capacitor, and a first variable capacitor. The second antenna circuit includes a second antenna, a second distribution capacitor, and a second variable capacitor. A controller sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production to reduce this phase difference and sets a capacitance of the second variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the second antenna and the second variable capacitor during plasma production to reduce this phase difference.

A dipole antenna fed by a planar balun includes a first radiation element and a second radiation element respectively corresponding to poles of the dipole antenna, at least one dipole support column configured to connect the first radiation element and the second radiation element and to fix a gap between the first radiation element and the second radiation element, a planar balun connected to the first radiation element and the second radiation element and configured to feed the first radiation element and the second radiation element, and a balun housing coupled to the dipole support column and enclosing the planar balun.

A dipole antenna fed by a planar balun includes a first radiation element and a second radiation element respectively corresponding to poles of the dipole antenna, at least one dipole support column configured to connect the first radiation element and the second radiation element and to fix a gap between the first radiation element and the second radiation element, a planar balun connected to the first radiation element and the second radiation element and configured to feed the first radiation element and the second radiation element, and a balun housing coupled to the dipole support column and enclosing the planar balun.

A high-frequency power circuit includes a first antenna circuit and a second antenna circuit that are connected in parallel to a matching box connected to a high-frequency power supply. The first antenna circuit include a first antenna, a first distribution capacitor, and a first variable capacitor. The second antenna circuit includes a second antenna, a second distribution capacitor, and a second variable capacitor. A controller sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production to reduce this phase difference and sets a capacitance of the second variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the second antenna and the second variable capacitor during plasma production to reduce this phase difference.

A high-frequency power circuit includes a first antenna circuit and a second antenna circuit that are connected in parallel to a matching box connected to a high-frequency power supply. The first antenna circuit include a first antenna, a first distribution capacitor, and a first variable capacitor. The second antenna circuit includes a second antenna, a second distribution capacitor, and a second variable capacitor. A controller sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production to reduce this phase difference and sets a capacitance of the second variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the second antenna and the second variable capacitor during plasma production to reduce this phase difference.

This invention is an antenna structure inducing plasma in a chamber with applied alternative power, comprising: a first antenna segment and a second antenna segment arranged based on a virtual central axis to have a first curvature radius and a second curvature radius respectively, the central axis crossing a first plane, and a first capacitive load electrically connecting the first antenna segment and the second antenna segment, wherein the first antenna segment extends from one end of the first capacitive load with the first curvature radius having a first length and the second antenna segment extends from other end of the first capacitive load with the second curvature radius having a second length, and wherein a sum of the first length and the second length is shorter than a circumference of the first curvature radius or the second curvature radius.

This invention is an antenna structure inducing plasma in a chamber with applied alternative power, comprising: a first antenna segment and a second antenna segment arranged based on a virtual central axis to have a first curvature radius and a second curvature radius respectively, the central axis crossing a first plane, and a first capacitive load electrically connecting the first antenna segment and the second antenna segment, wherein the first antenna segment extends from one end of the first capacitive load with the first curvature radius having a first length and the second antenna segment extends from other end of the first capacitive load with the second curvature radius having a second length, and wherein a sum of the first length and the second length is shorter than a circumference of the first curvature radius or the second curvature radius.

According to the present invention, provided is an inductively coupled plasma reactor including: a reaction chamber configured to provide a plasma reaction space; a ferrite core arranged to surround the plasma reaction space; and an antenna coil formed by winding a strip-shaped wire structure on the ferrite core, wherein the wire structure includes a plurality of electrically conductive wires and a covering made of a flexible material and configured to surround the plurality of electrically conductive wires.