Scanning antenna
A scanning antenna provided with an array of a plurality of antenna units includes a TFT substrate, a slot substrate, and a liquid crystal layer disposed between the TFT substrate and the slot substrate. The slot substrate includes a second dielectric substrate, a slot electrode supported on a first main surface of the second dielectric substrate, and a first dielectric layer disposed between the second dielectric substrate and the slot electrode. The slot electrode has tensile stress. The first dielectric layer has compressive stress.
1. A scanning antenna provided with an array of a plurality of antenna units, the scanning antenna comprising:
a thin-film transistor (TFT) substrate including a first dielectric substrate, a plurality of TFTs supported on the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes;
a slot substrate including a second dielectric substrate, a slot electrode supported on a first main surface of the second dielectric substrate, and an insulating layer disposed between the second dielectric substrate and the slot electrode;
a liquid crystal layer provided between the TFT substrate and the slot substrate; and
a reflective conductive plate disposed to face via a dielectric layer a second main surface opposite the first main surface of the second dielectric substrate,
wherein the slot electrode comprises a plurality of slots disposed corresponding to the plurality of patch electrodes,
the plurality of patch electrodes are each connected to a drain of a corresponding TFT,
the slot electrode has tensile stress, and
the insulating layer has compressive stress.
2. The scanning antenna according to claim 1 ,
wherein the slot electrode comprises a Cu layer, and has a thickness of from approximately 2 μm to approximately 6 μm, inclusive.
3. The scanning antenna according to claim 1 ,
wherein the insulating layer comprises a silicon nitride layer, and has a thickness of from approximately 200 nm to approximately 900 nm, inclusive.
4. The scanning antenna according to claim 3 ,
wherein the silicon nitride layer has a hydrogen removal amount of approximately 3×10 16 /cm 2 or less.
5. The scanning antenna according to claim 3 ,
wherein the silicon nitride layer has a refractive index of approximately 1.805 or greater.
6. The scanning antenna according to claim 1 ,
wherein the insulating layer comprises a silicon oxide layer, and has a thickness of from approximately 200 nm to approximately 900 nm, inclusive.
7. The scanning antenna according to claim 6 ,
wherein the silicon oxide layer has a refractive index of from approximately 1.4 to approximately 1.6, inclusive.
8. The scanning antenna according to claim 1 ,
wherein the insulating layer comprises a silicon nitride layer and a silicon oxide layer,
the silicon nitride layer is closer to the slot electrode than the silicon oxide layer, and
the insulating layer has a thickness of from approximately 200 nm to approximately 900 nm, inclusive.
9. The scanning antenna according to claim 1 ,
wherein the insulating layer comprises a silicon nitride layer and a silicon oxide layer,
the silicon oxide layer is closer to the slot electrode than the silicon nitride layer, and
the insulating layer has a thickness of from approximately 200 nm to approximately 900 nm, inclusive.
10. The scanning antenna according to claim 1 ,
wherein the second dielectric substrate is a glass substrate, and has a thickness of from approximately 0.65 mm to approximately 0.74 mm, inclusive.
11. The scanning antenna according to claim 1 ,
wherein the slot substrate further comprises a conductive layer covering a surface of the slot electrode.