Base station antennas having radiating elements with sheet metal-on dielectric dipole radiators and related radiating elements
A radiating element for a base station antenna includes a feed stalk and a cross-dipole radiator mounted thereon. The cross-dipole radiator includes a dielectric mounting substrate, a first metal dipole that extends along a first axis on the dielectric mounting substrate, a second metal dipole that extends along a second axis on the dielectric mounting substrate that is generally perpendicular to the first axis, and an adhesive layer between the dielectric mounting substrate and the first and second metal dipoles.
1. A method of fabricating a radiating element for a base station antenna, the method comprising:
forming first through fourth metal dipole arms from one or more sheets of metal;
forming a dielectric mounting substrate via injection molding; and
mounting the first through fourth metal dipole arms to the dielectric mounting substrate via an attachment mechanism,
wherein each of the first through fourth metal dipole arms has spaced-apart first and second conductive segments that together form a generally oval shape, and
wherein each of the first and second conductive segments of the first through fourth metal dipole arms includes a first widened section that has a first average width, a second widened section that has a second average width and a narrowed section that has a third average width, the narrowed section being between the first widened section and the second widened section, wherein the third average width is less than half the first average width and less than half the second average width.
2. The method of claim 1 , wherein the dielectric mounting substrate includes a plurality of guides that extend from a first major surface thereof that are configured to mount the first through fourth metal dipole arms in pre-selected locations on the dielectric mounting substrate.
3. The method of claim 2 , wherein the dielectric mounting substrate further includes a plurality of ribs on a second major surface thereof that is opposite the first major surface.
4. The method of claim 1 , wherein distal ends of the first and second conductive segments of the first metal dipole arm are electrically connected to each other so that the first metal dipole arm has a closed loop structure.
5. The method of claim 1 , wherein the narrowed section comprises a meandered conductive trace.
6. The method of claim 1 , wherein the narrowed section creates a high impedance for currents that are at a frequency that is approximately twice the highest frequency in the operating frequency range of the radiating element.
7. The method of claim 1 , wherein the attachment mechanism comprises one or more mechanical fasteners.
8. The method of claim 1 , wherein each of the first through fourth dipole arms are non-planar dipole arms.
9. The method of claim 1 , wherein the dielectric mounting substrate comprises a monolithic structure that has a generally planar dipole support plate and a plurality of support arms that extend rearwardly from the dipole support plate.
10. The method of claim 1 , wherein a thickness of each of the first through fourth dipole arms is between 200 and 1800 microns.
11. The method of claim 1 , further comprising mounting the dielectric mounting substrate having the first through fourth metal dipole arms mounted thereon on a separate feed stalk.