Compact stacked quarter-wave circularly polarized SDS patch antenna
A miniaturized, circularly polarized SDS patch antenna. Generally, the inventive antenna includes a ground plane over which a first patch is disposed. A short is provided between a first edge of the first patch and ground plane. A second patch is disposed over said first patch. A second short is provided between a first edge of the second patch and the first patch. The patch antenna of the illustrative embodiment further includes a first volume of dielectric disposed between the ground plane and the first patch. A second volume of dielectric is disposed between the first patch and the second patch. In the illustrative embodiment, the edges are shorted orthogonally. In an alternative embodiment, the shorted edges are in substantially parallel alignment. In yet another alternative embodiment, the antenna is designed for dual frequency operation. In the best mode, the area of the first patch is greater than the area of the second patch. In the illustrative application, high dielectric substrates and vertical shorting walls are combined to implement a compact circularly polarized patch antenna for use in low frequency applications. Two different high dielectric substrates are utilized to achieve a compact footprint with a stacked structure. The use of vertical shorting walls affords a substantial reduction in size while providing quarter-wave operation in both orthogonal directions. The coaxial feed position on the diagonal effects a rotation of the fields in a circular manner from the upper layer to lower layer.
1. An antenna comprising:
a ground plane;
a first patch disposed over said ground plane;
a second patch disposed over said first patch; and
means for radiating a circularly polarized signal from said antenna, said means for radiating including:
a first shorting wall between an edge parallel to a radiating first edge of said first patch and said ground plane and
a second shorting wall between an edge parallel to a radiating first edge of said second patch and said first patch, said first edge of said first patch and said first edge of said second patch being disposed in substantially orthogonal relation.
2. The invention of claim 1 further including a first volume of dielectric disposed between said ground plane and said first patch.
3. The invention of claim 2 further including a second volume of dielectric disposed between said first patch and said second patch.
4. The invention of claim 1 further including means for feeding an input signal to said second patch.
5. The invention of claim 1 wherein the area of said first patch is greater than the area of said second patch.
6. The invention of claim 5 further including a first volume of dielectric disposed between said ground plane and said first patch.
7. The invention of claim 6 further including a second volume of dielectric disposed between said first patch and said second patch.
8. The invention of claim 7 wherein the dielectric constant of said second dielectric is greater than the dielectric constant of said first dielectric.
9. The invention of claim 1 wherein the length or width of said first patch is equal to one-quarter of the wavelength of a signal fed thereto.
10. The invention of claim 1 wherein the length or width of said second patch is equal to one-quarter of the wavelength of a signal fed thereto.
11. A quarter-wave antenna for circularly polarized signals comprising:
a ground plane;
a first patch disposed over said ground plane;
a first shorting wall connected between an edge parallel to a radiating first edge of said first patch and said ground plane;
a first layer of dielectric disposed between said ground plane and said first patch;
a second patch disposed over said first patch;
a second shorting wall connected between an edge parallel to a radiating first edge of said second patch and said first patch, said first edge of said first patch and said first edge of said second patch being disposed in substantially orthogonal relation; and
a second layer of dielectric disposed between said first patch and said second patch.
12. The invention of claim 11 further including means for feeding an input signal to said second patch.
13. The invention of claim 11 wherein the area of said first patch is greater than the area of said second patch.
14. The invention of claim 11 wherein the dielectric constant of said second layer of dielectric is greater than the dielectric constant of said first layer of dielectric.
15. The invention of claim 11 wherein the length or width of said first patch is equal to one-quarter of the wavelength of a signal fed thereto.
16. The invention of claim 11 wherein the length or width of said second patch is equal to one-quarter of the wavelength of a signal fed thereto.
17. A method for transmitting or receiving a circularly polarized signal including the steps of:
providing a ground plane;
providing a first patch disposed over said ground plane;
creating a short at least one frequency between an edge parallel to a radiating first edge of said first patch and said ground plane;
providing a second patch disposed over said first patch;
creating a short at least one frequency between an edge parallel to a radiating first edge of said second patch and said first patch, said first edge of said first patch and said first edge of said second patch being disposed in substantially orthogonal relation; and
feeding an input signal to or taking an output signal from said antenna.