Patch antenna element with reactive areal loading
A patch antenna element has a plurality of patches that are coplanar, each having a length along a resonant dimension that is no greater than one-quarter of a wavelength of a maximum operating frequency of the patch antenna element. The antenna element also includes one or more discrete reactive elements. For each pair of neighboring patches of the plurality of patches, the pair forms an electrically insulating space therebetween. At least one discrete reactive element lies within the electrically insulating space and is electrically connected to both of the neighboring patches of the pair. A patch antenna combines the patch antenna element with a counterpoise that is parallel to, and displaced from, the patch antenna element. Each discrete reactive element may be an inductor or capacitor, either planar or non-planar. The patch antenna may be configured as a dual-polarization patch antenna or quarter-wave patch antenna.
1 . A patch antenna element, comprising:
a plurality of radiating patches that are coplanar, each of the plurality of radiating patches having a length along a resonant dimension of the patch antenna element, the length being no greater than one-half of a wavelength of a maximum operating frequency of the patch antenna element; and
one or more passive inductors;
wherein for each pair of neighboring patches of the plurality of radiating patches:
the pair of neighboring patches forms an electrically insulating space therebetween;
at least one passive inductor of the one or more passive inductors lies within the electrically insulating space; and
each passive inductor of the at least one passive inductor is directly electrically connected to both of the pair of neighboring patches such that no circuit element is electrically connected between the passive inductor and each of the pair of neighboring patches;
wherein the patch antenna element is disposed above a counterpoise and has a smaller footprint than a conventional single-patch half-wave air-loaded patch antenna sized to resonate at the maximum operating frequency.
2 . The patch antenna element of claim 1 , wherein for each pair of neighboring patches:
a first patch of the pair of neighboring patches has a first edge nearest a second patch of the pair of neighboring patches; and
the second patch has a second edge that is nearest the first patch, parallel to the first edge, and displaced from the first edge to create the electrically insulating space.
3 . The patch antenna element of claim 2 , wherein:
the first edge is parallel to a first radiating edge of the plurality of patches; and
the second edge is parallel to a second radiating edge of the plurality of patches.
4 . The patch antenna element of claim 2 , wherein for each pair of neighboring patches, the at least one passive inductor comprises a plurality of passive inductors that are uniformly spaced along a direction parallel to the first and second edges.
5 . The patch antenna element of claim 1 , each of the one or more passive inductors being a planar inductor that is coplanar with the plurality of radiating patches.
6 . The patch antenna element of claim 1 , the one or more passive inductors including a planar inductor.
7 . The patch antenna element of claim 1 , the plurality of radiating patches being identically shaped and regularly spaced along the resonant dimension.
8 . The patch antenna element of claim 1 , the plurality of radiating patches being identically shaped and regularly spaced along (i) the resonant dimension and (ii) a dimension that is perpendicular to the resonant dimension and parallel to a plane of the plurality of radiating patches.
9 . The patch antenna element of claim 1 , wherein:
the plurality of radiating patches includes a first patch and a second patch; and
the second patch fully surrounds the first patch in a plane of the plurality of radiating patches.
10 . A patch antenna comprising:
the patch antenna element of claim 1 ; and
the counterpoise of claim 1 , the counterpoise being parallel to the patch antenna element and at least partially underneath the patch antenna element.
11 . The patch antenna of claim 10 ,
further comprising a substrate between the patch antenna element and the counterpoise;
wherein the patch antenna element is located on a first side of the substrate and the counterpoise is located on a second side of the substrate that is opposite to the first side.
12 . The patch antenna of claim 11 , the substrate comprising one or more layers of a printed circuit board.
13 . The patch antenna of claim 10 , further comprising a feed that electrically connects to one of the plurality of radiating patches.
14 . The patch antenna of claim 10 , further comprising:
a first feed electrically connecting to a first patch of the plurality of radiating patches; and
a second feed electrically connecting to a second patch of the plurality of radiating patches, the second patch being different from the first patch;
wherein:
the patch antenna, when driven via the first feed, emits radiation polarized in a first direction; and
the patch antenna, when driven via the second feed, emits radiation polarized in a second direction that is perpendicular to the first direction.
15 . The patch antenna of claim 10 , further comprising a magnetodielectric material at least partially located between the patch antenna element and the counterpoise.
16 . The patch antenna of claim 10 , wherein a gap between the patch antenna element and the counterpoise is filled with air.
17 . The patch antenna of claim 10 , one of the plurality of radiating patches having a distal widthwise edge that is electrically shorted to the counterpoise.