Antennas having substrate layers with compound curvature
A head-mounted device may have a head-mounted housing that is configured to be worn on a head of a user. While the head-mounted device is being worn, optical modules in the head-mounted device may provide images to eye boxes located rearward of the head-mounted device. A forward-facing display on a front portion of the head-mounted device may be covered with a transparent housing portion forming a display cover layer. An antenna may be mounted in the device. A curved portion of the display cover layer or other dielectric housing layer may overlap the antenna. The antenna and/or other components may be formed by contouring a flexible printed circuit into a shape characterized by a surface with compound curvature. The contoured flexible printed circuit may have polymer layers and a metal trace between the polymer layers. A neutral stress plane may be aligned with the metal trace.
1 . An electronic device, comprising:
a housing; and
an antenna mounted in the housing, wherein the antenna comprises a flexible printed circuit that has a flexible printed circuit substrate layer with a surface having compound curvature and that has an antenna resonator formed from a metal trace in the flexible printed circuit substrate layer, wherein the housing comprises a head-mounted housing having a portion with a curved cross-sectional profile, and wherein the antenna is overlapped by the portion.
2 . The electronic device defined in claim 1 further comprising:
a radio-frequency transceiver configured to transmit and receive wireless signals using the antenna, wherein the portion of the head-mounted housing comprises a dielectric layer overlapping the antenna, and wherein the metal trace is configured to form an inverted-F antenna resonator.
3 . The electronic device defined in claim 2 further comprising a display that is overlapped by the dielectric layer.
4 . The electronic device defined in claim 3 wherein the dielectric layer comprises a layer that is at least partly transparent.
5 . The electronic device defined in claim 4 wherein the dielectric layer has an area of compound curvature and wherein the antenna is overlapped by the area of compound curvature.
6 . The electronic device defined in claim 1 wherein the portion of the head-mounted housing comprises a dielectric layer with compound curvature adjacent to the antenna.
7 . The electronic device defined in claim 1 wherein the flexible printed circuit substrate layer has an upper polymer layer and a lower polymer layer and wherein the metal trace is between the upper polymer layer and the lower polymer layer.
8 . The electronic device defined in claim 7 wherein the flexible printed circuit substrate layer has a neutral stress plane aligned with the metal trace.
9 . A head-mounted device, comprising:
a head-mounted housing;
optical assemblies in the head-mounted housing that are configured to display images in eye boxes; and
an antenna in the housing that comprises a flexible printed circuit having a flexible printed circuit substrate layer with a surface of compound curvature and an antenna resonator formed from a metal trace in the flexible printed circuit substrate layer.
10 . The head-mounted device defined in claim 9 wherein the flexible printed circuit substrate layer comprises first and second polymer layers and wherein the metal trace is between the first and second polymer layers.
11 . The head-mounted device defined in claim 10 wherein the flexible printed circuit substrate layer has a neutral stress plane aligned with the metal trace.
12 . The head-mounted device defined in claim 9 further comprising a display that faces away from the eye boxes, wherein the head-mounted housing comprises a dielectric layer that overlaps the display.
13 . The head-mounted device defined in claim 12 wherein the dielectric layer has a portion that overlaps the antenna.
14 . The head-mounted device defined in claim 13 wherein the portion that overlaps the antenna has a curved cross-sectional profile.
15 . The head-mounted device defined in claim 9 further comprising:
a display, wherein the head-mounted housing comprises a dielectric layer overlapping the antenna and the display.
16 . An electronic device, comprising:
a housing; and
a flexible printed circuit in the housing, wherein the flexible printed circuit comprises polymer layers having surfaces with compound curvature and a metal trace between the polymer layers.
17 . The electronic device defined in claim 16 wherein the metal trace forms an antenna resonator.
18 . The electronic device defined in claim 16 wherein the metal trace is a capacitive sensor electrode.
19 . The electronic device defined in claim 16 wherein the housing comprises a head-mounted housing.
20 . The electronic device defined in claim 16 wherein the polymer layers are configured to place a neutral stress plane in alignment with the metal trace.