Waveguide with radiation slots and parasitic elements for asymmetrical coverage
This document describes a waveguide with radiation slots and parasitic elements for asymmetrical coverage. An apparatus may include a waveguide for providing asymmetrical coverage in an azimuth plane. The waveguide includes a hollow channel containing a dielectric and an array of radiation slots through a surface that is operably connected with the dielectric. The waveguide includes an array of parasitic elements positioned on or in the surface and offset from a longitudinal side of the array of radiation slots. The radiation slots and parasitic elements configure the described waveguide to focus an antenna radiation pattern that provides an asymmetrical coverage to focus on a particular portion within the antenna field-of-view.
1 . An apparatus comprising:
a waveguide including a hollow channel for a dielectric, the waveguide including:
a plurality of radiation slots, each of the plurality of radiation slots comprising an opening through a first layer that defines a surface of the hollow channel, each of the plurality of radiation slots being operably connected with the dielectric; and
a plurality of parasitic cavity elements each being a recess or cavity forming a depression within the surface of the first layer, the plurality of parasitic cavity elements each being positioned adjacent to and offset along the surface from a same longitudinal side of each radiation slot of the plurality of radiation slots such that each of the plurality of parasitic cavity elements overlaps a different and single one of the plurality of radiation slots in a direction perpendicular to a longitudinal direction through the hollow channel, the longitudinal side being parallel with the longitudinal direction through the hollow channel, the plurality of parasitic cavity elements and the plurality of radiation slots being arranged to produce an asymmetrical radiation pattern.
2 . The apparatus of claim 1 , wherein:
the waveguide includes a printed circuit board (PCB) having the first layer, a second layer, and a third layer, the first layer being a first conductive layer, wherein
the plurality of radiation slots and the plurality of parasitic cavity elements are formed in the first conductive layer with a depth of the plurality of parasitic cavity elements being less than a depth of the plurality of radiation slots, and
the hollow channel is within the second layer below the first layer.
3 . The apparatus of claim 1 , wherein each of the plurality of parasitic cavity elements is offset a distance from the longitudinal side of each radiation slot of the plurality of radiation slots, the distance being selected to generate a particular band of coverage in the asymmetrical radiation pattern of an antenna element, the antenna element being electrically coupled to the dielectric from a floor of the hollow channel.
4 . The apparatus of claim 1 , wherein each of the plurality of parasitic cavity elements has a rectangular shape.
5 . The apparatus of claim 1 , wherein the hollow channel includes a second opening in the longitudinal direction at one end of the waveguide and a closed wall at an opposite end of the waveguide, the second opening being a rectangular shape and the hollow channel forming another rectangular shape along the longitudinal direction.
6 . The apparatus of claim 5 , wherein each of the plurality of radiation slots is offset a non-uniform distance from a centerline of the hollow channel, the centerline being parallel with the longitudinal direction.
7 . The apparatus of claim 5 , wherein the plurality of radiation slots is evenly distributed between the second opening and the closed wall along the longitudinal direction.
8 . The apparatus of claim 1 , wherein the hollow channel includes a second opening in the longitudinal direction at one end of the waveguide and a closed wall at an opposite end of the waveguide, the second opening being a rectangular shape and the hollow channel forming a zigzag shape along the longitudinal direction through the hollow channel.
9 . The apparatus of claim 8 , wherein the zigzag shape comprises multiple turns along the longitudinal direction, each of the multiple turns having a turning angle between 0 and 90 degrees.
10 . The apparatus of claim 8 , wherein the plurality of radiation slots is positioned along a centerline of the hollow channel, the centerline being parallel with the longitudinal direction through the hollow channel.
11 . The apparatus of claim 10 , wherein the plurality of parasitic cavity elements comprises a rectangular cavity element that extends along the longitudinal direction of the waveguide, the rectangular cavity element positioned adjacent to and offset from the longitudinal side of the plurality of radiation slots.
12 . The apparatus of claim 1 , wherein the hollow channel includes a second opening in the longitudinal direction at one end of the waveguide and a closed wall at an opposite end of the waveguide, the second opening comprises a square shape, oval shape, or circular shape.
13 . The apparatus of claim 1 , wherein the waveguide is formed of metal.
14 . The apparatus of claim 1 , wherein the waveguide is formed of plastic.
15 . The apparatus of claim 1 , wherein the dielectric comprises air and the waveguide is an air waveguide.
16 . A system comprising:
an antenna element;
a device configured to transmit or receive electromagnetic signals via the antenna element; and
a waveguide including a hollow channel for a dielectric, the waveguide including:
a plurality of radiation slots, each of the plurality of radiation slots comprising an opening through a first layer that defines a surface of the hollow channel, each of the plurality of radiation slots being operably connected with the dielectric; and
a plurality of parasitic cavity elements each being a recess or cavity forming a depression within the surface of the first layer, the plurality of parasitic cavity elements each being positioned adjacent to and offset along the surface from a same longitudinal side of each radiation slot of the plurality of radiation slots such that each of the plurality of parasitic cavity elements overlaps a different and single one of the plurality of radiation slots in a direction perpendicular to a longitudinal direction through the hollow channel, the longitudinal side being parallel with the longitudinal direction through the hollow channel, the plurality of parasitic cavity elements and the plurality of radiation slots being arranged to produce an asymmetrical radiation pattern.
17 . The system of claim 16 , wherein:
the device comprises a radar system; and
the system is a vehicle.
18 . The system of claim 16 , wherein:
the waveguide includes a printed circuit board (PCB) having the first layer, a second layer, and a third layer, the first layer being a first conductive layer, wherein
the plurality of radiation slots and the plurality of parasitic cavity elements are formed in the first conductive layer with a depth of the plurality of parasitic cavity elements being less than a depth of the plurality of radiation slots, and
the hollow channel is within the second layer below the first layer.
19 . The system of claim 16 , wherein each of the plurality of parasitic cavity elements is offset a distance from the longitudinal side of each radiation slot of the plurality of radiation slots, the distance being selected to generate a particular band of coverage in the asymmetrical radiation pattern of the antenna element, the antenna element being electrically coupled to the dielectric from a floor of the hollow channel.