PATCH ANTENNA TO REDUCE CROSS-POLARIZED RADIATION
A playback device is configured to transmit and receive signals via a patch antenna coupled to a wireless radio. The patch antenna is configured to reduce cross-polarized radiation and comprises an electrically conductive ground plane, a substrate disposed on the ground plane, and a radiator disposed on the substrate. The radiator comprises a first portion and a second portion, wherein the first portion of the radiator is coupled through an opening in an interior region of the patch antenna to a first leg of a differential feed. The differential feed is configured to provide a signal to drive the radiator. The patch antenna also comprises a delay element, wherein the second portion of the radiator is coupled via the delay element and further through the opening of the patch antenna to a second leg of the differential feed.
1 . A playback device comprising:
a patch antenna comprising:
an electrically conductive ground plane;
a substrate disposed on the ground plane;
a radiator disposed on the substrate, the radiator comprising a first portion and a second portion, wherein the first portion of the radiator is coupled through an opening in an interior region of the patch antenna to a first leg of a differential feed, the differential feed configured to provide a signal to drive the radiator; and
a delay element, wherein the second portion of the radiator is coupled via the delay element and further through the opening of the patch antenna to a second leg of the differential feed;
a wireless radio coupled to the patch antenna via the differential feed;
at least one processor;
at least one non-transitory computer-readable medium comprising program instructions that are executable by the at least one processor such that the playback device is configured to:
based on signals received via the patch antenna from another playback device, determine a relative location of the playback device to the other playback device; and
operate in a playback configuration where the playback device plays back one or more channels of multi-channel audio content, the playback configuration based on the determined relative location.
2 . The playback device of claim 1 , wherein the opening in the interior region of the patch antenna is centrally located within the radiator.
3 . The playback device of claim 1 , wherein the delay element is a lumped element circuit comprising one or more capacitive elements and/or inductive elements configured to introduce a phase shift to the signal.
4 . The playback device of claim 3 , wherein the delay element is configured to introduce a 180 degree phase shift to the signal.
5 . The playback device of claim 1 , wherein the delay element is a delay line of a length selected to introduce a 180 degree phase shift to the signal.
6 . The playback device of claim 5 , wherein the delay line is tunable to provide a variable delay based on a frequency band of the signal.
7 . The playback device of claim 1 , wherein the delay element is a radio frequency integrated circuit (RFIC) configured to introduce a 180 degree phase shift to the signal.
8 . The playback device of claim 7 , wherein the RFIC is located within the opening in the interior region of the patch antenna or beneath the opening in the interior region of the patch antenna.
9 . The playback device of claim 7 , wherein the RFIC comprises the wireless radio.
10 . The playback device of claim 1 , the patch antenna further comprises one or more parasitic elements located adjacent to opposite edges of the patch antenna.
11 . A patch antenna comprising:
an electrically conductive ground plane;
a substrate disposed on the ground plane;
a radiator disposed on the substrate, the radiator comprising a first portion and a second portion, wherein the first portion of the radiator is coupled through an opening in an interior region of the patch antenna to a first leg of a differential feed, the differential feed configured to provide a signal to drive the radiator; and
a delay element, wherein the second portion of the radiator is coupled via the delay element and further through the opening of the patch antenna to a second leg of the differential feed.
12 . The patch antenna of claim 11 , wherein the opening in the interior region of the patch antenna is centrally located within the radiator.
13 . The patch antenna of claim 11 , wherein the delay element is a lumped element circuit comprising one or more capacitive elements and/or inductive elements configured to introduce a phase shift to the signal and the delay element is configured to introduce a 180 degree phase shift to the signal.
14 . The patch antenna of claim 11 , wherein the delay element is a delay line of a length selected to introduce a 180 degree phase shift to the signal.
15 . The patch antenna of claim 11 , wherein the delay element is a radio frequency integrated circuit (RFIC) configured to introduce a 180 degree phase shift to the signal.
16 . The patch antenna of claim 15 , wherein the RFIC is located within the opening in the interior region of the patch antenna or beneath the opening in the interior region of the patch antenna.
17 . The patch antenna of claim 11 , further comprising one or more parasitic elements located adjacent to opposite edges of the patch antenna.
18 . The patch antenna of claim 11 , wherein the differential feed is a coaxial cable or a microstrip transmission line.
19 . The patch antenna of claim 11 , wherein the patch antenna is a printed circuit board (PCB) and the opening in the interior region of the patch antenna is a via through the ground plane and the substrate.
20 . A media playback system comprising:
a first playback device; and
a second playback device, wherein the first playback device comprises:
a patch antenna including:
an electrically conductive ground plane;
a substrate disposed on the ground plane;
a radiator disposed on the substrate, the radiator comprising a first portion and a second portion, wherein the first portion of the radiator is coupled through an opening in an interior region of the patch antenna to a first leg of a differential feed, the differential feed configured to provide a signal to drive the radiator; and
a delay element, wherein the second portion of the radiator is coupled via the delay element and further through the opening of the patch antenna to a second leg of the differential feed;
a wireless radio coupled to the patch antenna via the differential feed;
at least one processor;
at least one non-transitory computer-readable medium comprising program instructions that are executable by the at least one processor such that the first playback device is configured to:
based on signals received via the patch antenna from the second playback device, determine a relative location of the first playback device to the second playback device;
and operate in a playback configuration where the first playback device plays back one or more channels of multi-channel audio content, the playback configuration based on the determined relative location.