Stacked patch antenna devices and methods
A stacked patch antenna comprises two or more patch antennas physically disposed in a stack to provide a multi-frequency or broad band antenna. However, independence of the resonant response frequencies of the lower and upper patches of each stacked patch antenna pair ground requires metallization dimensions for the upper patch's lower surface be contained within the perimeter of the lower patch's resonant metallization. Accordingly, composite stacked patch element dimensions are limited by the desired resonant frequency of the lower patch. The inventors have established an alternate physical structure where the resonant patch geometry of the lower patch element's upper metallization is not limited by the lower surface ground plane metallization of the first upper patch element. The inventors have also established design solutions allowing the lower frequency performance of the first, lower patch within a stacked patch antenna to be lowered without compromising the footprint of the resulting antenna.
1. An antenna comprising:
an upper antenna element comprising a first metallization layer and a first ground plane disposed below the first metallization layer where the upper patch antenna element has a first resonant frequency established in dependence upon a periphery of the first metallization layer;
a lower antenna element comprising a second metallization layer and a second ground plane disposed below the second metallization layer where the lower antenna element has a second resonant frequency established in dependence upon a periphery of the first metallization layer; and
a spacer disposed between the first ground plane of the upper antenna element and the second metallization layer of the lower antenna element; wherein
the electrical path of an electrical signal at the second resonant frequency traverses a path within the periphery of the second metallization layer that is longer than the periphery of the lower antenna element and comprises a portion within the footprint of the first ground plane.
2. The antenna according to claim 1 , wherein
the second resonant frequency is lower than the first resonant frequency.
3. The antenna according to claim 1 , wherein
a second predetermined portion of the periphery of the second metallization layer is outside the periphery of the first ground plane.
4. The antenna according to claim 1 , wherein
the periphery of the second metallization layer comprises a plurality of castellations each castellation defined by a notch within the second metallization layer;
each notch extends from the periphery of the second metallization layer towards the centre of the second metallization layer;
a first portion of each notch is outside the footprint of the first ground plane; and
a second portion of each notch is inside the footprint of the first ground plane.
5. A method comprising:
providing an upper antenna element comprising a first metallization layer and a first ground plane disposed below the first metallization layer where the upper patch antenna element has a first resonant frequency established in dependence upon a periphery of the first metallization layer;
providing a lower antenna element comprising a second metallization layer and a second ground plane disposed below the second metallization layer where the lower antenna element has a second resonant frequency established in dependence upon a periphery of the first metallization layer; and
providing a spacer disposed between the first ground plane of the upper antenna element and the second metallization layer of the lower antenna element; wherein
the electrical path of an electrical signal at the second resonant frequency traverses a path within the periphery of the second metallization layer that is longer than the periphery of the lower antenna element and comprises a portion within the footprint of the first ground plane.
6. The antenna according to claim 5 , wherein
the second resonant frequency is lower than the first resonant frequency.
7. The antenna according to claim 5 , wherein
a second predetermined portion of the periphery of the second metallization layer is outside the periphery of the first ground plane.
8. The antenna according to claim 5 , wherein
the periphery of the second metallization layer comprises a plurality of castellations each castellation defined by a notch within the second metallization layer;
each notch extends from the periphery of the second metallization layer towards the centre of the second metallization layer;
a first portion of each notch is outside the footprint of the first ground plane; and
a second portion of each notch is inside the footprint of the first ground plane.
9. An assembly to extend a single band antenna comprising a first antenna operating at a first resonant frequency to a dual band antenna operating at the first resonant frequency and a second resonant frequency comprising:
a second antenna comprising a first metallization layer and a first ground plane disposed below the first metallization layer where the second resonant frequency of the second antenna is established in dependence upon a periphery of the first metallization layer; and
a spacer disposed between a second metallization layer of the first antenna and the first ground plane of the second antenna; wherein
the electrical path of an electrical signal at the first resonant frequency traverses a path within the periphery of the second metallization layer that is longer than the periphery of the first antenna and comprises a portion within the footprint of the first ground plane.
10. The assembly according to claim 9 , wherein
the second resonant frequency is higher than the first resonant frequency.
11. The assembly according to claim 9 , wherein
a second predetermined portion of the periphery of the second metallization layer is outside the periphery of the first ground plane.
12. The assembly according to claim 9 , wherein
the periphery of the second metallization layer comprises a plurality of castellations each castellation defined by a notch within the second metallization layer;
each notch extends from the periphery of the second metallization layer towards the centre of the second metallization layer;
a first portion of each notch is outside the footprint of the first ground plane; and
a second portion of each notch is inside the footprint of the first ground plane.
13. The assembly according to claim 9 , wherein
the first resonant frequency of the first antenna assembled with the second antenna is lower than the operating frequency of the first antenna discretely.
14. The assembly according to claim 9 , wherein
the first resonant frequency of the first antenna assembled with the second antenna is lower than a third resonant frequency of the first antenna discretely; and
the reduction in operating frequency of the first antenna from the third resonant frequency of the discrete first antenna to the first resonant frequency of the first antenna assembled with the second antenna and spacer varies according to the thickness of the spacer.