A radio chain arrangement comprising at least two levels of radio chain entities. Each of the levels of radio chain entities is associated with a respective frequency range encompassing at least one radio frequency band each. At least two radio chain entities of a lower level of radio chains are comprised in a radio chain entity of a next higher level. Each radio chain entity of the at least two levels of radio chain entities comprises a respective radio transceiver arrangement that is connected to at least a respective one of a number of antenna multiplexers. For all radio chain entities except a lowest level, the respective radio transceiver arrangement is connected to the antenna multiplexers via a splitter arrangement. An active antenna system comprising such radio chain arrangements and a method for its operation is also disclosed.

A radio chain arrangement comprising at least two levels of radio chain entities. Each of the levels of radio chain entities is associated with a respective frequency range encompassing at least one radio frequency band each. At least two radio chain entities of a lower level of radio chains are comprised in a radio chain entity of a next higher level. Each radio chain entity of the at least two levels of radio chain entities comprises a respective radio transceiver arrangement that is connected to at least a respective one of a number of antenna multiplexers. For all radio chain entities except a lowest level, the respective radio transceiver arrangement is connected to the antenna multiplexers via a splitter arrangement. An active antenna system comprising such radio chain arrangements and a method for its operation is also disclosed.

An elastic wave device includes an LiNbO.sub.3 substrate, a first elastic wave resonator including a first IDT electrode and a first dielectric film, and a second elastic wave resonator including a second IDT electrode and a second dielectric film. A Rayleigh wave travels along at least one surface of the elastic wave device. A thickness of the first dielectric film differs from a thickness of the second dielectric film. A propagation direction of an elastic wave in the first elastic wave resonator coincides with a propagation direction of an elastic wave in the second elastic wave resonator. Euler angles of the LiNbO.sub.3 substrate fall within a range of (0°±5°, θ, 0°±10°).

An elastic wave device includes an LiNbO.sub.3 substrate, a first elastic wave resonator including a first IDT electrode and a first dielectric film, and a second elastic wave resonator including a second IDT electrode and a second dielectric film. A Rayleigh wave travels along at least one surface of the elastic wave device. A thickness of the first dielectric film differs from a thickness of the second dielectric film. A propagation direction of an elastic wave in the first elastic wave resonator coincides with a propagation direction of an elastic wave in the second elastic wave resonator. Euler angles of the LiNbO.sub.3 substrate fall within a range of (0°±5°, θ, 0°±10°).

A radio-frequency module includes a switch performing switching of the connection between a common terminal and a selection terminal, a reception filter having a reception band in a band A as a passband, a transmission filter that has a transmission band in a band B as a passband and has an output terminal connected to the selection terminal, a filter that has the transmission band in a band B as an attenuation band and has an input terminal connected to the selection terminal, a reception path which connects the selection terminal and an input terminal of the reception filter and on which the filter is disposed, a bypass path which connects the selection terminal and the input terminal of the reception filter and on which no filter is disposed, and a transmission path which connects the selection terminal and a transmission terminal and on which the transmission filter is disposed.

A radio-frequency module includes a switch performing switching of the connection between a common terminal and a selection terminal, a reception filter having a reception band in a band A as a passband, a transmission filter that has a transmission band in a band B as a passband and has an output terminal connected to the selection terminal, a filter that has the transmission band in a band B as an attenuation band and has an input terminal connected to the selection terminal, a reception path which connects the selection terminal and an input terminal of the reception filter and on which the filter is disposed, a bypass path which connects the selection terminal and the input terminal of the reception filter and on which no filter is disposed, and a transmission path which connects the selection terminal and a transmission terminal and on which the transmission filter is disposed.

An apparatus is disclosed for passive intermodulation distortion filtering. The apparatus includes a radio-frequency front-end circuit. The radio-frequency front-end circuit includes a transmit filter circuit and a receive filter circuit. The transmit filter circuit includes a passive circuit configured to combine at least two radio-frequency transmit signals associated with different transmit frequency bands. The transmit filter circuit also includes a filter coupled between the passive circuit and a first feed of an antenna. The filter is configured to attenuate frequencies associated with a receive frequency band. The receive filter circuit is coupled to a second feed of the antenna and is configured to pass the frequencies associated with the receive frequency band.

An apparatus is disclosed for passive intermodulation distortion filtering. The apparatus includes a radio-frequency front-end circuit. The radio-frequency front-end circuit includes a transmit filter circuit and a receive filter circuit. The transmit filter circuit includes a passive circuit configured to combine at least two radio-frequency transmit signals associated with different transmit frequency bands. The transmit filter circuit also includes a filter coupled between the passive circuit and a first feed of an antenna. The filter is configured to attenuate frequencies associated with a receive frequency band. The receive filter circuit is coupled to a second feed of the antenna and is configured to pass the frequencies associated with the receive frequency band.

A tunable antenna. includes a radio frequency integrated circuit, a first frequency modulation branch coupled to the radio frequency integrated circuit, a first antenna coupled to the radio frequency integrated circuit through the first frequency modulation branch, a second antenna coupled to the radio frequency integrated circuit through a second frequency modulation branch. The first antenna corresponds to a first frequency, the second antenna corresponds to a second frequency, and the first frequency and the second frequency are respectively a transmit frequency and a receive frequency in a specified frequency band. The first antenna and the second antenna are respectively connected to the radio frequency integrated circuit through the frequency modulation branches when the tunable antenna is being designed.

A tunable antenna. includes a radio frequency integrated circuit, a first frequency modulation branch coupled to the radio frequency integrated circuit, a first antenna coupled to the radio frequency integrated circuit through the first frequency modulation branch, a second antenna coupled to the radio frequency integrated circuit through a second frequency modulation branch. The first antenna corresponds to a first frequency, the second antenna corresponds to a second frequency, and the first frequency and the second frequency are respectively a transmit frequency and a receive frequency in a specified frequency band. The first antenna and the second antenna are respectively connected to the radio frequency integrated circuit through the frequency modulation branches when the tunable antenna is being designed.