Abstract: An antenna device includes a plurality of dipole antennas and a port. Each of the dipole antennas is connected to the port. The dipole antennas are arranged around the port. Each of the dipole antennas comprises two ends. The device further includes a plurality of passive elements. The ends of the dipole antennas and the passive elements are interchangeably arranged around the port such that each of the passive elements is situated between ends of two different antennas from the plurality of dipole antennas. One or more switches are configured to switch between an omnidirectional state, in which the ends of the dipole antennas are not connected to the plurality of passive elements, and a directional state, in which at least one end of one of the passive elements is connected to at least one end of one of the antennas.

Abstract: An antenna device includes a plurality of dipole antennas and a port. Each of the dipole antennas is connected to the port. The dipole antennas are arranged around the port. Each of the dipole antennas comprises two ends. The device further includes a plurality of passive elements. The ends of the dipole antennas and the passive elements are interchangeably arranged around the port such that each of the passive elements is situated between ends of two different antennas from the plurality of dipole antennas. One or more switches are configured to switch between an omnidirectional state, in which the ends of the dipole antennas are not connected to the plurality of passive elements, and a directional state, in which at least one end of one of the passive elements is connected to at least one end of one of the antennas.

Abstract: A directional antenna and a communication device are provided in this disclosure. The directional antenna includes a first element, a second element and a first reflector. An operating frequency band of the first element is a first frequency band, and an operating frequency band of the second element is a second frequency band. An equivalent electrical length of the first reflector is equal to or slightly greater than one half of the wavelength of the first frequency band. The first reflector includes a first resonant circuit, the first resonant circuit includes a first capacitive part and a first inductive part that are connected in parallel. A resonance frequency of the first resonant circuit is within the second frequency band, and an equivalent electrical length of any part other than the first resonant circuit in the first reflector is less than one half of the wavelength of the second frequency band.

Abstract: An antenna device includes a plurality of dipole antennas and a port. Each of the dipole antennas is connected to the port. The plurality of dipole antennas is arranged around the port. Each of the plurality of dipole antennas includes two ends. The ends of the dipole antennas are arranged in a plurality of pairs. Each pair includes one end of one of the dipole antennas and one end of another one of the dipole antennas. The two ends in each pair are arranged in proximity to each other. One or more switches are configured to switch between (1) an omnidirectional state, in which the ends of the dipole antennas are not connected to each other; and (2) a directional state, in which the two ends in each of one or more of the pairs are connected to each other.