Radiating elements having dipole arms with cloaked dielectric loading elements and base station antennas including such radiating elements
A base station antenna includes a reflector, a first radiating element that extends forwardly from the reflector and that is configured to operate in a first frequency band, and a second radiating element that extends forwardly from the reflector and that is configured to operate in a second frequency band that is different from the first frequency band. The first radiating element comprises a first dipole radiator that has first and second dipole arms, a second dipole radiator that has third and fourth dipole arms, a first dielectric block positioned adjacent the first dipole arm, and a first metal pattern positioned between the first dielectric block and the reflector.
1 . A base station antenna, comprising:
a reflector;
a first radiating element that extends forwardly from the reflector and that is configured to operate in a first frequency band, the first radiating element comprising:
a first dipole radiator that has first and second dipole arms;
a second dipole radiator that has third and fourth dipole arms;
a first dielectric block positioned adjacent the first dipole arm; and
a first metal pattern positioned between the first dielectric block and the reflector; and
a second radiating element that extends forwardly from the reflector and that is configured to operate in a second frequency band that is different from the first frequency band.
2 . The base station antenna of claim 1 , wherein the first metal pattern is configured to attenuate radio frequency (“RF”) energy emitted by the second radiating element that is incident on the first metal pattern.
3 . The base station antenna of claim 1 , wherein the first metal pattern comprises a metamaterial.
4 . The base station antenna of claim 1 , wherein the first metal pattern is printed on the first dielectric block.
5 . The base station antenna of claim 1 , wherein the first metal pattern has a negative refractive index.
6 . The base station antenna of claim 1 , wherein the first metal pattern has at least one of a negative permittivity and a negative permeability within at least a portion of the second frequency band.
7 . The base station antenna of claim 1 , wherein the first metal pattern comprises a plurality of unit cells.
8 . The base station antenna of claim 7 , wherein each unit cell includes a plurality of sub cells, and wherein at least some of the sub-cells in a first of the unit cells are oriented differently from other of the sub-cells in the first of the unit cells.
9 . The base station antenna of claim 7 , wherein a thickness of the first dielectric block in a forward direction is at least ten times a thickness of the first dipole arm.
10 . The base station antenna of claim 1 , wherein the first dielectric block is configured to dielectrically load the first dipole arm.
11 . A base station antenna, comprising:
a second radiating element that is configured to operate in a second frequency band;
a first radiating element that is configured to operate in a first frequency band that is different from the second frequency band, the first radiating element comprising a first radiator and a first dielectric loading element for the first radiator, the first dielectric loading element including a first metal pattern that is not part of the first radiator and that is configured to reduce the impact of the first dielectric loading element on radio frequency (“RF”) energy emitted by the second radiating element.
12 . The base station antenna of claim 11 , wherein the first radiator is a first dipole radiator has first and second dipole arms, the first radiating element further comprising a second dipole radiator that has third and fourth dipole arms, and the first dielectric loading element is positioned adjacent the first dipole arm.
13 . The base station antenna of claim 12 , wherein the first dipole arm is implemented using a first printed circuit board, and the first dielectric loading element is mounted rearwardly of the first printed circuit board.
14 . The base station antenna of claim 12 , wherein the first dipole arm is implemented as a sheet metal dipole arm.
15 . The base station antenna of claim 12 , wherein the first radiating element further comprises:
a second dielectric loading element positioned adjacent the second dipole arm;
a second metal pattern positioned between a second dielectric block and a reflector;
a third dielectric loading element positioned adjacent the third dipole arm;
a third metal pattern positioned between a third dielectric block and the reflector;
a fourth dielectric loading element positioned adjacent the fourth dipole arm; and
a fourth metal pattern positioned between a fourth dielectric block and the reflector.
16 . The base station antenna of claim 15 , wherein each of the first through fourth dielectric loading elements has a dielectric constant that is greater than 4.0.
17 . The base station antenna of claim 12 , wherein the first metal pattern has at least one of a negative permittivity and a negative permeability within at least a portion of the second frequency band.
18 . The base station antenna of claim 12 , wherein each of the first through fourth dipole arms has an end-to-end physical length that is less than 0.2 of a wavelength that corresponds to a center frequency of the first frequency band.
19 . The base station antenna of claim 11 , wherein the first metal pattern comprises a metamaterial.
20 . A radiating element that is configured to operate in a first frequency band, comprising:
a first dipole radiator that has a first dipole arm and a second dipole arm;
a second dipole radiator that has a third dipole arm and a fourth dipole arm wherein one or more dielectric blocks having dielectric constants of at least 4.0 are positioned adjacent the first through fourth dipole arms to dielectrically load the first through fourth dipole arms, and the dielectric blocks are cloaked with respect to radio frequency (“RF”) energy in a second frequency band that is different from the first frequency band.