Patch antenna for millimeter wave communications
An antenna has at least one resonant frequency within a millimeter wave frequency range. The antenna includes a ground plane disposed in a first plane, the ground plane having a first aperture at which the antenna is fed with an RF signal by a feed line; and a main patch disposed in a second plane parallel to the first plane, the first and second planes spaced apart to form a first cavity between the ground plane and the main patch, the main patch having a second aperture.
1. A patch antenna, comprising:
a ground plane disposed in a first plane, the ground plane having a first aperture at which the patch antenna is fed with an RF signal by a feed line;
a main patch disposed in a second plane parallel to the first plane, the first and second planes spaced apart to form a first antenna cavity between the ground plane and the main patch, the main patch having a second aperture, wherein the patch antenna has a first desired operating frequency within a millimeter wave frequency range over which wireless communications is supported and the first desired operating frequency is a function of a length of the second aperture, the length of the second aperture being set to achieve the first desired operating frequency of the patch antenna; and
a parasitic patch disposed in a third plane parallel to the first and second planes, the third plane spaced apart from the second plane to form a second antenna cavity between the main patch and the parasitic patch on a side of the main patch opposite the first antenna cavity, the parasitic patch adding a second desired operating frequency within the millimeter wave frequency range to the patch antenna over which wireless communications is supported, the second desired operating frequency higher than the first desired operating frequency; and
wherein the length of the second aperture is further set to achieve the second desired operating frequency of the patch antenna by establishing a hybrid mode where both the main patch and the parasitic patch radiate at the second desired operating frequency.
2. The patch antenna of claim 1 , wherein the first antenna cavity is an air gap.
3. The patch antenna of claim 1 , wherein geometric centers of the apertures are coaxially aligned.
4. The patch antenna of claim 1 , wherein the ground plane is disposed on a first substrate and the main patch is disposed on a second substrate.
5. The patch antenna of claim 4 , wherein the first and second substrates are layers of a multilayer printed circuit board.
6. The patch antenna of claim 5 , wherein the first antenna cavity is formed by removing a portion of the multilayer printed circuit board.
7. The patch antenna of claim 1 , wherein the first desired operating frequency of the patch antenna is at about 28 GHz and the second desired operating frequency is at about 39 GHz.
8. The patch antenna of claim 1 , wherein the geometric centers of the main patch and the parasitic patch are coaxially aligned.
9. The patch antenna of claim 8 , wherein the geometric centers of the main patch, the parasitic patch and the apertures are coaxially aligned.
10. The patch antenna of claim 1 , wherein:
the apertures have lengths of about 2.7 mm;
a height of the first antenna cavity is about 0.3 mm;
a height of the second antenna cavity is about 0.1 mm;
a length of the main patch is about 3.4 mm to about 3.6 mm;
a width of the main patch is about 3.4 mm to about 3.6 mm; and
a length of the parasitic patch is about 0.6 mm to about 0.9 mm.
11. An electronic device, comprising:
the patch antenna of claim 1 ; and
communication circuitry operatively coupled to the patch antenna, wherein the communication circuitry is configured to generate the radio frequency signal that is feed to the patch antenna for emission as part of wireless communication with another device.
12. The patch antenna of claim 10 , wherein the first aperture is linear and the second aperture is linear and parallel to the first aperture.
13. The patch antenna of claim 1 , wherein the first aperture is linear and the second aperture is linear and parallel to the first aperture.
14. The patch antenna of claim 1 , wherein the first antenna cavity extends an entire distance from the ground plane to the main patch.
15. The patch antenna of claim 1 , wherein the second aperture consists of a single slot in the main patch.
16. The patch antenna of claim 15 , wherein the geometric centers of the first aperture in the ground plane and the second aperture in the main patch are coaxially aligned.
17. The patch antenna of claim 16 , wherein the first aperture is linear and the second aperture is linear and parallel to the first aperture.
18. The patch antenna of claim 1 , wherein first desired operating frequency and a bandwidth of the patch antenna decrease with increases in physical length of the second aperture.