A device includes a first antenna arranged on a substrate, with the first antenna comprising a first semiconductor layer having terahertz-wave gain and a first conductor layer, a second antenna arranged on the substrate, with the second antenna comprising a second semiconductor layer having terahertz-wave gain and a second conductor layer, and a third conductor layer arranged on the substrate and electrically connecting the first antenna and the second antenna. A shunt device is arranged on the substrate and electrically connected to the third conductor layer. In planar view, the shunt device does not overlap with at least the first conductor layer.

An antenna system includes a first antenna, a second antenna, and a tuning stub, where the first antenna and the second antenna have a same first operating frequency band or similar first operating frequency bands. The tuning stub is electrically connected to the first antenna, and the tuning stub is configured to adjust an equivalent current path of the first antenna, so that a connection line between a projection point of a maximum equivalent current point of the first antenna and a projection point of a maximum equivalent current point of the second antenna on a first plane tends to be more perpendicular to a projection of the equivalent current path of the first antenna or of the second antenna on the first plane; or the equivalent current path of the first antenna and of the second antenna tend to be more perpendicular to each other.

An antenna system includes a first antenna, a second antenna, and a tuning stub, where the first antenna and the second antenna have a same first operating frequency band or similar first operating frequency bands. The tuning stub is electrically connected to the first antenna, and the tuning stub is configured to adjust an equivalent current path of the first antenna, so that a connection line between a projection point of a maximum equivalent current point of the first antenna and a projection point of a maximum equivalent current point of the second antenna on a first plane tends to be more perpendicular to a projection of the equivalent current path of the first antenna or of the second antenna on the first plane; or the equivalent current path of the first antenna and of the second antenna tend to be more perpendicular to each other.

A behind the ear hearing aid includes: a transceiver for wireless data communication interconnected with an antenna for electromagnetic field emission and electromagnetic field reception, the antenna extending on a first side of a hearing aid and a second side of the hearing aid, a first segment of the antenna extending from proximate the first side of the hearing aid to proximate the second side of the hearing aid; and a feed system configured for exciting the antenna to induce a current in at least the first segment, the current having a first local maxima proximate the first side of the hearing aid and a second local maxima proximate the second side of the hearing aid.

A behind the ear hearing aid includes: a transceiver for wireless data communication interconnected with an antenna for electromagnetic field emission and electromagnetic field reception, the antenna extending on a first side of a hearing aid and a second side of the hearing aid, a first segment of the antenna extending from proximate the first side of the hearing aid to proximate the second side of the hearing aid; and a feed system configured for exciting the antenna to induce a current in at least the first segment, the current having a first local maxima proximate the first side of the hearing aid and a second local maxima proximate the second side of the hearing aid.

An RF tag includes an inlay comprising an IC chip and an antenna, a planar auxiliary antenna laminated on the inlay in an insulating state to the inlay, and a substrate on which the inlay and the auxiliary antenna are laminated. The auxiliary antenna is formed into a rectangular planar shape including long sides each having a length of substantially of a wavelength of a radio wave frequency of the inlay, and has a cutout part which divides one of the long sides into two parts each having a length of substantially of the wavelength of the radio wave frequency of the inlay. The cutout part is formed into a concave shape which is opened in an edge portion of the one of the long sides and has a predetermined width and depth to allow the IC chip of the inlay to be disposed therein.

An RF tag includes an inlay comprising an IC chip and an antenna, a planar auxiliary antenna laminated on the inlay in an insulating state to the inlay, and a substrate on which the inlay and the auxiliary antenna are laminated. The auxiliary antenna is formed into a rectangular planar shape including long sides each having a length of substantially of a wavelength of a radio wave frequency of the inlay, and has a cutout part which divides one of the long sides into two parts each having a length of substantially of the wavelength of the radio wave frequency of the inlay. The cutout part is formed into a concave shape which is opened in an edge portion of the one of the long sides and has a predetermined width and depth to allow the IC chip of the inlay to be disposed therein.

A filter assembly operating at wider passband with an enhanced reflection coefficient is provided herein. In certain embodiments, the filter assembly comprises a first filter configured to allow signals received via an antenna node to pass at a first passband, the first filter including a plurality of resonators connected in series and parallel arms, the plurality of resonators of the first filter including a first type of resonator configured to broaden the first passband, at least a series resonator nearest to the antenna node or a shunt resonator nearest to the antenna node among the plurality of resonators of the first filter being a second type of resonator configured to improve reflection characteristics at a stopband of the first filter, and a second filter configured to allow the signals received via the antenna node to pass at a second passband using the second type of resonators.

A filter assembly operating at wider passband with an enhanced reflection coefficient is provided herein. In certain embodiments, the filter assembly comprises a first filter configured to allow signals received via an antenna node to pass at a first passband, the first filter including a plurality of resonators connected in series and parallel arms, the plurality of resonators of the first filter including a first type of resonator configured to broaden the first passband, at least a series resonator nearest to the antenna node or a shunt resonator nearest to the antenna node among the plurality of resonators of the first filter being a second type of resonator configured to improve reflection characteristics at a stopband of the first filter, and a second filter configured to allow the signals received via the antenna node to pass at a second passband using the second type of resonators.

An antenna system includes a first antenna, a second antenna, and a tuning stub, where the first antenna and the second antenna have a same first operating frequency band or similar first operating frequency bands. The tuning stub is electrically connected to the first antenna, and the tuning stub is configured to adjust an equivalent current path of the first antenna, so that a connection line between a projection point of a maximum equivalent current point of the first antenna and a projection point of a maximum equivalent current point of the second antenna on a first plane tends to be more perpendicular to a projection of the equivalent current path of the first antenna or of the second antenna on the first plane; or the equivalent current path of the first antenna and of the second antenna tend to be more perpendicular to each other.