Dielectric covered planar antennas
An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.
1. An apparatus, comprising:
an extended spherical lens including a substantially spherical lens having a base at a radius of the substantially spherical lens disposed directly adjacent to a substantially planar lens extension; and
a substantially planar resonant cavity defined between a ground plane and a lower surface of the substantially planar lens extension;
wherein a feed for propagating a dominant TE 10 mode is coupled to the resonant cavity at the ground plane and the substantially spherical lens and the substantially planar lens extension each comprise a dielectric material and the feed is coupled to the resonant cavity by an iris through the ground plane, the iris substantially matching impedance to the dominant TE 10 mode.
2. The apparatus of claim 1 , wherein the substantially spherical lens comprises a hemispherical lens and the base comprises a great circle of the hemispherical lens.
3. The apparatus of claim 1 , wherein the cavity comprises a dielectric material having a dielectric constant less than that of the substantially spherical lens and that of the substantially planar lens extension.
4. The apparatus of claim 1 , wherein the substantially spherical lens comprises silicon.
5. The apparatus of claim 1 , wherein the substantially spherical lens and the substantially planar lens extension are contiguous and produced from a common dielectric material.
6. The apparatus of claim 1 , wherein the iris comprises a double arc slot through the ground plane.
7. The apparatus of claim 1 , wherein the feed is coupled to the resonant cavity at the ground plane along a normal axis through the substantially spherical lens.
8. The apparatus of claim 1 , wherein the feed is coupled to the resonant cavity at the ground plane substantially off a normal axis through the substantially spherical lens.
9. A method, comprising the steps of:
etching from a dielectric material at least one extended spherical lens each including a substantially spherical lens having a base at a radius of the substantially spherical lens disposed directly adjacent to a substantially planar lens extension;
forming a substantially planar resonant cavity between a lower surface of the substantially planar lens extension and a ground plane; and
coupling a feed for propagating a dominant TE 10 mode to the resonant cavity at the ground plane;
wherein the substantially spherical lens and the substantially planar lens extension each comprise a dielectric material and the feed is coupled to the resonant cavity by an iris through the ground plane, the iris substantially matching impedance to the dominant TE 10 mode.
10. The method of claim 9 , wherein the substantially spherical lens comprises a hemispherical lens and the base comprises a great circle of the hemispherical lens.
11. The method of claim 9 , wherein the cavity comprises a dielectric material having a dielectric constant less than that of the substantially spherical lens and that of the substantially planar lens extension.
12. The method of claim 9 , wherein the substantially spherical lens comprises silicon.
13. The method of claim 9 , wherein the substantially spherical lens and the substantially planar lens extension are contiguous and produced from a common dielectric material.
14. The method of claim 9 , wherein the iris comprises a double arc slot through the ground plane.
15. The method of claim 9 , wherein the feed is coupled to the resonant cavity at the ground plane along a normal axis through the substantially spherical lens.
16. The method of claim 9 , wherein the feed is coupled to the resonant cavity at the ground plane substantially off a normal axis through the substantially spherical lens.
17. An apparatus, comprising:
an array of extended spherical lenses each including a substantially spherical lens having a base at a radius of the substantially spherical lens and disposed directly adjacent to a substantially planar lens extension; and
a substantially planar resonant cavity defined between a ground plane and a lower surface of the substantially planar lens extension;
wherein a feed for each of the extended spherical lenses for propagating a dominant TE 10 mode is coupled to the resonant cavity at the ground plane and the substantially spherical lens and the substantially planar lens extension each comprise a dielectric material and the feed is coupled to the resonant cavity by an iris through the ground plane, the iris substantially matching impedance to the dominant TE 10 mode.
18. The apparatus of claim 17 , wherein the substantially planar lens extension comprises silicon.
19. The apparatus of claim 18 , wherein the substantially planar lens extension comprises silicon from a common wafer with the substantially spherical lenses.