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 radiator assembly configured to radiate two orthogonally polarized radio frequency signals, comprising:
a folded dipole having 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; and
a balun stem mechanically couled to the folded dipole, the balun stem having a first balun stem plate 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.
2. The radiator assembly 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.
3. The radiator assembly of claim 2 , wherein the first dipole arm, the second dipole arm, the third dipole arm, and the fourth dipole arm each comprise a current channel aperture.
4. The radiator assembly of claim 3 , wherein the first dipole arm, the second dipole arm, the third dipole arm, and the fourth dipole arm each comprise a current channel slot.
5. The radiator assembly of claim 2 , wherein the first dipole arm is coupled to the third dipole arm by a first connecting trace, the first connecting trace defining a first gap between the first connecting trace and the first dipole arm and the third dipole arm, the first dipole arm is coupled to the fourth dipole arm by a second connecting trace, the second connecting trace defining a second gap between the second connecting trace and the first dipole arm and the fourth dipole arm, and wherein the second dipole arm is coupled to the third dipole arm by a third connecting trace, the third connecting trace defining a third gap between the third connecting trace and the first dipole arm and the third dipole arm, the second dipole arm is coupled to the fourth dipole arm by a fourth connecting trace, the fourth connecting trace defining a fourth gap between the fourth connecting trace and the first dipole arm and the fourth dipole arm.
6. The radiator assembly of claim 1 , wherein the first balun stem plate comprises a first balun trace and a first ground element disposed on a first side, and a second ground element disposed on a second side, wherein the balun trace is conductively coupled to the first ground element.
7. The radiator assembly of claim 6 wherein the first ground element is conductively coupled to the first dipole arm and the second ground element is conductively coupled to the second dipole arm.
8. The radiator assembly of claim 1 , wherein the first balun trace comprises a meander structure, wherein the meander structure is configured to maintain a 180 degree phase difference between the first radio frequency coupled to the first dipole arm and the first radio frequency coupled to the second dipole arm.