High performance folded dipole for multiband antennas
Disclosed is a radiator assembly configured to operate in the range of 3.4-4.2 GHz. The radiator assembly comprises a folded dipole with four dipole arms that radiate in two orthogonal polarization planes, whereby the signal of each polarization orientation is radiated by two opposite radiator arms that radiate the signal 180 degrees out of phase from each other. The radiator assembly has a balun structure that includes a balun trace that conductively couples to a ground element on the same side of the balun stem plate. The combination of the shape of the folded dipole and the balun structure reduces cross polarization between the two polarization states and maintains strong phase control between the opposing radiator arms.
1. A multiband antenna, comprising:
a plurality of first radiator assemblies configured to radiate at a first frequency band; and
a plurality of second radiator assemblies configured to radiate at a second frequency band, wherein each of the plurality of second radiator assemblies is configured to radiate two orthogonally polarized radio frequency signals, wherein each second radiator assembly has a folded dipole, the folded dipole having a first pair of dipole arms configured to radiate in a first polarization orientation and a second pair of dipole arms configured to radiate in a second polarization orientation, wherein the folded dipole is formed of a single conductive plate that is disposed on a PCB (Printed Circuit Board).
2. The multiband antenna of claim 1 , wherein each folded dipole has a square shape.
3. The multiband antenna of claim 2 , wherein the plurality of second radiator assemblies are arranged in an array.
4. The multiband antenna of claim 3 , wherein the plurality of second radiator assemblies are spaced apart by 0.58λ.
5. The multiband antenna of claim 2 , wherein the second frequency band comprises a C-Band.
6. The multiband antenna of claim 2 , wherein the second frequency band comprises a CBRS (Citizens Broadband Radio Service) band.
7. The multiband antenna of claim 1 , wherein each of the plurality of second radiator assemblies comprises a balun stem that is mechanically coupled to its corresponding PCB, wherein the balun stem is configured to couple a first radio frequency signal to the first pair of dipole arms and a second balun stem plate configured to couple a second radio frequency signal to the second pair of dipole arms.
8. The multiband antenna of claim 7 , wherein each balun stem has a feed contact that electrically couples a ground element on the balun stem to its corresponding dipole arm.
9. The multiband antenna of claim 1 , wherein the first pair of dipole arms comprises a first dipole arm and a second dipole arm, wherein the first dipole arm and the second dipole arm are axially symmetric around a first axis that is parallel to the first polarization orientation, and wherein the second pair of dipole arms comprises a third dipole arm and a fourth dipole arm, wherein the third dipole arm and the fourth dipole arm are axially symmetric around a second axis that is parallel to the second polarization orientation.
10. The multiband antenna of claim 9 , wherein the first dipole arm, the second dipole arm, the third dipole arm, and the fourth dipole arm each comprise a current channel aperture.
11. The multiband antenna of claim 10 , wherein the first dipole arm, the second dipole arm, the third dipole arm, and the fourth dipole arm each comprise a current channel slot.