Small cell beam-forming antennas
A small cell cellular base station includes an eight port radio and an eight-port base station antenna that has four linear arrays of dual-polarized radiating elements. Each of the linear arrays has a different azimuth boresight pointing direction and each dual-polarized radiating element includes first and second radiators that have respective directional radiation patterns. The radio is configured to determine and apply a first set of amplitude and phase weights to RF signals that are received through the eight ports of the antenna, and to apply a second set of amplitude and phase weights to RF signals that are output by the radio to the eight ports of the antenna.
1. A small cell base station, comprising:
a base station antenna comprising:
first through fourth linear arrays of dual-polarized radiating elements, where the first linear array points in a first direction, the third linear array points in a third direction that is substantially opposite the first direction, the second linear array points in a second direction, and the fourth linear array points in a fourth direction that is substantially opposite the second direction;
first through eighth phase shifters; and
first through eighth ports, where each of the first through fourth linear arrays is connected to a respective pair of the first through eighth ports through a respective pair of the first through eighth phase shifters; and
a time division duplex beamforming radio having first through eighth radio ports that are connected to the respective first through eighth ports of the base station antenna,
wherein the first direction is angularly offset from the second direction by about 90 degrees, and
where each of the first through eighth phase shifters is configured to split an RF signal output to the respective phase shifter from the beamforming radio into a plurality of sub-components and to apply a phase taper across the plurality of sub-components.
2. The base station of claim 1 , wherein an azimuth boresight pointing direction of the first linear array is offset from azimuth boresight pointing directions of the second through fourth linear arrays by about 90°, about 180° and about 270°, respectively.
3. A small cell base station, comprising:
a base station antenna comprising:
first through fourth linear arrays of dual-polarized radiating elements, where the first linear array points in a first direction, the third linear array points in a third direction that is substantially opposite the first direction, the second linear array points in a second direction, and the fourth linear array points in a fourth direction that is substantially opposite the second direction; and
first through eighth ports, where each of the first through fourth linear arrays is connected to a respective pair of the first through eighth ports; and
a time division duplex beamforming radio having first through eighth radio ports that are connected to the respective first through eighth ports of the base station antenna,
wherein the first direction is angularly offset from the second direction by about 90 degrees,
wherein the beamforming radio is configured to determine and apply a first set of amplitude and phase weights to radio frequency (“RF”) signals that are received from the respective first through eighth ports of the base station antenna, and to apply a second set of amplitude and phase weights to RF signals that are output by the radio to the first through eighth ports of the base station antenna, where the second set of amplitude and phase weights is different from the first set of amplitude and phase weights.
4. The base station of claim 3 , wherein the amplitude and phase weights of the first set of amplitude and phase weights and the amplitude and phase weights of the second set of amplitude and phase weights are each determined on a time slot-by-time slot basis.
5. The base station of claim 3 , wherein the amplitude and phase weights of the second set of amplitude and phase weights are the complex conjugates of the respective amplitude and phase weights of the first set of amplitude and phase weights.
6. The base station of claim 1 , wherein the base station antenna is configured to transmit as a multi-input-multi-output antenna using first radiators of the dual polarized radiating elements to transmit a first data stream and using the second radiators of the dual polarized radiating elements to simultaneously transmit a second data stream that is different than the first data stream.
7. The base station of claim 6 , wherein the first and second data streams are part of a composite data stream that is transmitted to a user.
8. The base station of claim 1 , wherein the base station antenna further includes first through fourth backplanes that together define a tubular reflector assembly.
9. The base station of claim 8 , wherein the tubular reflector assembly has a generally rectangular cross-section in the azimuth plane.
10. The base station of claim 1 , the base station antenna further comprising a ninth port and a calibration element that is connected to the ninth port and the radio further comprises a ninth radio port, wherein the ninth port of the base station antenna is connected to the ninth radio port.
11. The base station of claim 1 , wherein the base station antenna is configured to operate in an LTE Transmission Mode 8 beamforming mode.