Ground plane heater

1. An antenna, comprising:

an antenna aperture having a plurality of radio-frequency (RF) radiating antenna elements, the antenna aperture having a ground plane and a material for tuning permittivity or capacitance, the ground plane having a plurality of metal layers;

a heater structure in thermal contact with the material and is at least part integral with the plurality of metal layers, wherein the heater structure comprises a first metal layer on the ground plane distinct from a second metal layer of the ground plane used as a waveguide and part of an RF radiating antenna element; and

at least one heater bus bar connected to the heater structure with a gap between the second metal layer and each bus bar of the at least one heater bus bars to isolate the at least one heater bus bar from the second metal layer and block RF leakage as part of the waveguide through the gap.

2. The antenna of claim 1 , wherein the heater structure comprises a plurality of resistive elements.

3. The antenna of claim 1 , wherein the metal layer on the ground plane is distinct from an iris forming layer on the ground plane forming an iris.

4. The antenna of claim 1 , wherein the heater structure comprises a metal layer fabricated as a thin film transistor (TFT) array in the antenna.

5. The antenna of claim 1 , wherein the heater structure contacts a substrate layer, a passivation layer on the substrate layer, or an adhesion layer on the substrate layer.

6. The antenna of claim 1 , further comprising:

a substrate layer that comprises glass, printed circuit board, polyimide, polyester, flouropolymer, or fused silica, and

an iris forming layer comprising a first metal layer, and wherein the heater structure comprises a second metal layer separated from the first metal layer by a passivation layer, and wherein the second metal layer is between the substrate and the first metal layer.

7. The antenna of claim 1 , further comprising:

a substrate layer that comprises glass, printed circuit board, polyimide, polyester, fluoropolymer, or fused silica, and

an iris forming layer comprising a first metal layer, and wherein the heater structure comprises a second metal layer from the first metal layer by a passivation layer, and wherein the iris metal layer is between the substrate and the second metal layer.

8. The antenna of claim 1 , wherein the ground plane comprises a substrate layer comprising glass, printed circuit board, polyimide, polyester, fluoropolymer, or fused silica and having a first metal layer, wherein the heater structure comprises a second metal layer separated from the first metal layer and the substrate layer by a passivation layer.

9. The antenna of claim 1 , wherein the at least one heater bus bar comprises a plurality of bus bars connected to the heater structure, each of the plurality of bus bars being on a first metal layer with an iris forming layer and spaced apart from iris forming metal that forms irises for the antenna aperture.

10. The antenna of claim 9 wherein the heater structure is on a second metal layer that covers at least one gap in iris forming metal.

11. The antenna of claim 1 , further comprising a first plurality of bus bars interleaved with a second plurality of bus bars and having resistive heater elements of the heater structure therebetween.

12. The antenna of claim 1 , further comprising:

a first electrical connection point to the iris forming layer and a second electrical connection point to the iris forming layer, wherein the heater structure is integral with the iris forming layer, wherein the antenna is operable in a heating mode having the first electrical connection point and the second electrical connection point biased to differing voltage levels, and wherein the antenna is operable in an antenna mode having the first electrical connection point and the second electrical connection point biased to a same voltage level.

13. The antenna of claim 1 , wherein the material comprises liquid crystal (LC).

14. An antenna, comprising:

an antenna aperture having a plurality of radio-frequency (RF) antenna elements, the antenna aperture having a patch substrate, a ground plane having a plurality of metal layers, and a material for tuning permittivity or capacitance between the patch substrate and the ground plane, the ground plane substrate having a first layer comprising an iris forming layer for irises of a plurality of radio-frequency (RF) antenna elements;

a second layer on the ground plane comprising a heater structure for heating the material;

at least one heater bus bar connected to the heater structure with a gap between the first metal layer and each bus bar of the at least one bus bars to isolate the at least one heater bus bar from the second metal layer and block RF leakage as part of a waveguide through the gap.

15. The antenna of claim 14 , wherein:

the first layer comprises a first metal layer;

the second layer comprises a second metal layer; and

the material comprises liquid crystal.

16. The antenna of claim 15 wherein the second layer comprises a metal layer fabricated as metal in a thin film transistor (TFT) array in the antenna.

17. The antenna of claim 15 , wherein the ground plane comprises a substrate layer, wherein the second layer comprising the heater structure contacts the substrate layer, a passivation layer on the substrate layer, or an adhesion layer on the substrate layer.

18. The antenna of claim 15 wherein the heater structure is separated from the first metal layer by a passivation layer, and wherein the second metal layer is between the ground plane and the first metal layer.

19. The antenna of claim 15 wherein the heater structure is separated from the first metal layer by a passivation layer, and wherein the iris metal layer is between the substrate and the second metal layer.

20. The antenna of claim 14 , wherein the heater structure is separated from the first layer by a passivation layer.

21. The antenna of claim 14 , wherein the first layer is separated from the second layer and substrate layer of the ground plane by a passivation layer.

22. The antenna of claim 14 , wherein the at least one bus bar comprises a plurality of bus bars connected to the heater structure.

23. The antenna of claim 22 wherein each of the plurality of bus bars is on a same metal layer as the iris forming layer and spaced apart from iris forming metal that forms irises for the antenna aperture.

24. The antenna of claim 22 wherein each of the plurality of bus bars is spaced apart by a gap from iris metal of the iris forming layer and is coupled to the second layer through vias.

25. The antenna of claim 14 wherein the antenna is operable in a heating mode in which the heater structure is driven to bring the material up to a predefined temperature, and wherein the antenna is operable in an antenna mode in which the heater structure is not driven once the material is at least at the predefined temperature.