Antenna Systems for Wireless Sensor Devices
In a general aspect, an antenna array system includes an array of monopole antennas. In some implementations, the antenna array system includes a planar substrate having a substrate surface, a ground plane residing on the substrate surface, feeds residing on the substrate surface and elliptical patches. The ground plane has an outer boundary and slots extending inwardly from the outer boundary. Each of the slots includes slot sides that define an interior region of the slot. The feeds reside in the slots and are separated from the ground plane by a gap. Each of the feeds extends from a first end in the interior region of a respective one of the slots to a second end in an exterior area beyond the outer boundary of the ground plane. Each of the elliptical patches is coupled to a respective one of the plurality of feeds.
1 . An antenna array system comprising an array of monopole antennas, the antenna array system comprising:
a planar substrate comprising a substrate surface;
a ground plane residing on the substrate surface, the ground plane comprising an outer boundary and a plurality of slots extending inwardly from the outer boundary, each of the slots comprising slot sides that define an interior region of the slot;
a plurality of feeds residing on the substrate surface, the plurality of feeds residing in the plurality of slots and being separated from the ground plane by a gap, each of the feeds extending from a first end in the interior region of a respective one of the slots to a second end in an exterior area beyond the outer boundary of the ground plane; and
a plurality of elliptical patches, each of the elliptical patches coupled to a respective one of the plurality of feeds.
2 . The antenna array system of claim 1 , wherein each of the slots defines an opening between the interior region of the slot and the exterior area, and the openings of the plurality of slots are distributed uniformly about the outer boundary of the ground plane.
3 . The antenna array system of claim 1 , wherein each of the elliptical patches comprises a planar conductor residing on the substrate surface in the exterior area.
4 . The antenna array system of claim 1 , wherein each of the feeds comprises a planar conductor that has a width that is tapered from the first end to the second end.
5 . The antenna array system of claim 1 , configured to transmit and receive electromagnetic signals in the range of 600 MHz to 6 GHz.
6 . The antenna array system of claim 1 , comprising an array of two monopole antennas, each of the two monopole antennas comprising one of the feeds and one of the elliptical patches.
7 . The antenna array system of claim 1 , comprising an array of four monopole antennas, each of the four monopole antennas comprising one of the feeds and one of the elliptical patches.
8 . The antenna array system of claim 1 , comprising an array of eight monopole antennas, each of the eight monopole antennas comprising one of the feeds and one of the elliptical patches.
9 . A wireless sensor device comprising:
a housing;
a radio frequency signal processor system residing in the housing; and
an antenna array system residing in the housing, coupled to the radio frequency signal processor system, and configured to communicate wirelessly with a wireless communication network, the antenna array system comprising:
a planar substrate comprising a substrate surface;
a ground plane residing on the substrate surface, the ground plane comprising an outer boundary and a plurality of slots extending inwardly from the outer boundary, each of the slots comprising slot sides that define an interior region of the slot;
a plurality of feeds residing on the substrate surface, the plurality of feeds residing in the plurality of slots and being separated from the ground plane by a gap, each of the feeds extending from a first end in the interior region of a respective one of the slots to a second end in an exterior area beyond the outer boundary of the ground plane; and
a plurality of elliptical patches, each of the elliptical patches coupled to a respective one of the plurality of feeds.
10 . The wireless sensor device of claim 9 , wherein each of the slots defines an opening between the interior region of the slot and the exterior area, and the openings of the plurality of slots are distributed uniformly about the outer boundary of the ground plane.
11 . The wireless sensor device of claim 9 , wherein each of the elliptical patches comprises a planar conductor residing on the substrate surface in the exterior area.
12 . The wireless sensor device of claim 9 , wherein each of the feeds comprises a planar conductor that has a width that is tapered from the first end to the second end.
13 . The wireless sensor device of claim 9 , wherein the wireless communication network comprises a cellular network, and the antenna array system is configured to receive cellular network signals formatted according to any of multiple distinct cellular network standards.
14 . A method for constructing an antenna array system comprising an array of monopole antennas, the method comprising:
receiving a planar substrate comprising a substrate surface;
forming a ground plane on the substrate surface, the ground plane comprising an outer boundary and a plurality of slots extending inwardly from the outer boundary, each of the slots comprising slot sides that define an interior region of the slot;
forming a plurality of feeds on the substrate surface, the plurality of feeds residing in the plurality of slots and being separated from the ground plane by a gap, each of the feeds extending from a first end in the interior region of a respective one of the slots to a second end in an exterior area beyond the outer boundary of the ground plane; and
coupling a plurality of elliptical patches to the plurality of feeds, each of the elliptical patches being coupled to a respective one of the plurality of feeds.
15 . The method of claim 14 , wherein each of the slots defines an opening between the interior region of the slot and the exterior area, and the openings of the plurality of slots are distributed uniformly about the outer boundary of the ground plane.
16 . The method of claim 14 , wherein each of the elliptical patches comprises a planar conductor residing on the substrate surface in the exterior area.
17 . The method of claim 14 , wherein each of the feeds comprises a planar conductor that has a width that is tapered from the first end to the second end.
18 . The method of claim 14 , comprising forming an array of two monopole antennas, each of the two monopole antennas comprising one of the feeds and one of the elliptical patches.
19 . The method of claim 14 , comprising forming an array of four monopole antennas, each of the four monopole antennas comprising one of the feeds and one of the elliptical patches.
20 . The method of claim 14 , comprising forming an array of eight monopole antennas, each of the eight monopole antennas comprising one of the feeds and one of the elliptical patches.