Slot array antenna including parasitic features
An illustrative example antenna device includes a substrate. A plurality of conductive members in the substrate establish a substrate integrated waveguide. A plurality of first and second slots are on an exterior surface of a first portion of the substrate. Each of the second slots is associated with a respective one of the first slots. The first and second slots are configured to establish a radiation pattern that varies across a beam of radiation emitted by the antenna device. A plurality of parasitic interruptions include slots on the exterior surface of a second portion of the substrate. The parasitic interruptions reduce ripple effects otherwise introduced by adjacent antennas.
1. An antenna device, comprising:
a substrate;
a plurality of conductive members positioned at least partially within the substrate, the conductive members establishing a waveguide, a first portion of the substrate being within the waveguide and a second portion of the substrate being outside the waveguide;
a plurality of first slots positioned at least partially on an exterior surface of the first portion of the substrate;
a plurality of second slots positioned at least partially on the exterior surface of the first portion of the substrate, each of the second slots being associated with a respective one of the first slots, the first and second slots being configured to establish a radiation pattern that varies across a beam of radiation emitted by the antenna device; and
a plurality of parasitic interruptions, at least a first one of the parasitic interruptions being on a first side of the waveguide, the first one of the parasitic interruptions having a first set of one or more first parasitic-interruption slots, the first set comprising one or more of the following:
a different number of respective parasitic-interruption slots;
different lengths of respective parasitic-interruption slots; or
different respective continuities.
2. The antenna device of claim 1 , wherein the waveguide is a substrate integrated waveguide (SIW), the SIW integrated into the substrate.
3. The antenna device of claim 1 , wherein each of the plurality of the first slots on the exterior surface of the first portion of the substrate include spacings from the plurality of conductive members of the substrate, the spacings varying along the waveguide and effective to enable stronger radiation from smaller of the spacings relative to weaker radiation from larger of the spacings.
4. The antenna device of claim 3 , wherein the varying of the spacings is effective to achieve a tapering of the beam of radiation emitted by the antenna device.
5. The antenna device of claim 1 , wherein the parasitic interruptions respectively comprise:
at least one conductive connector establishing a conductive connection between an exterior surface of the second portion near two sides of the first parasitic-interruption slots and a conductive layer near an opposite side of the substrate.
6. The antenna device of claim 1 , wherein:
the first slots emit radiation having a first characteristic; and
the second slots emit radiation having a second characteristic that is different than the first characteristic, the first characteristic and the second characteristic biasing a gain of the beam of radiation toward one side of the radiation pattern.
7. The antenna device of claim 6 , wherein:
the first slots have a first length;
the second slots have a second length; and
the first and second characteristics are based on the first and second lengths, respectively.
8. The antenna device of claim 1 , wherein:
the substrate includes a plurality of waveguides;
at least a first one of the parasitic interruptions is on a first side of each waveguide; and
at least a second one of the parasitic interruptions is on a second, opposite side of each waveguide.
9. The antenna device of claim 8 , wherein:
each waveguide includes an input port between opposite ends of the waveguide;
at least some of the parasitic interruptions are on one side of a respective one of the input ports; and
at least some others of the parasitic interruptions are on a different side of the respective one of the input ports.
10. The antenna device of claim 8 , wherein:
the waveguides are aligned parallel to each other;
the parasitic interruptions are parallel to the waveguides;
an input port to at least one of the waveguides is situated between adjacent waveguides; and
at least some of the parasitic interruptions are situated between adjacent waveguides.
11. The antenna device of claim 1 , wherein each of the plurality of the first slots on the exterior surface of the first portion of the substrate are longer than each of the plurality of the second slots on the exterior surface of the first portion.
12. The antenna device of claim 1 , wherein each of the plurality of the first slots on the exterior surface of the first portion of the substrate has an associated one of the plurality of the second slots on the exterior surface of the first portion, each of the first slots having outer bounds along a length that extend past outer bounds along a length of the second slots relative to a plane perpendicular to the lengths of the first slots and the second slots.
13. The antenna device of claim 1 , wherein each of the plurality of the first slots on the exterior surface of the first portion of the substrate has an associated one of the plurality of the second slots on the exterior surface of the first portion, each of the first slots and the second slots having a spacing between each of the respective associated slots, the spacing varying between at least two of each of the spacings between the respective slots.
14. The antenna device of claim 13 , wherein the spacings are smaller at ends of the waveguide.
15. The antenna device of claim 1 , further comprising a second one of the parasitic interruptions positioned on a second side of the waveguide, the second side opposite the first side, the second one of the parasitic interruptions having a second set of one or more second parasitic-interruption slots, the second set comprising one or more of the following:
a different number of respective parasitic-interruption slots;
different lengths of respective parasitic-interruption slots; or
different respective continuities.
16. The antenna device of claim 15 , wherein:
the plurality of first slots include lengths that are substantially parallel;
the lengths of the first slots are substantially parallel to the first parasitic-interruption slots or the second parasitic-interruption slots;
the plurality of second slots include lengths that are substantially parallel; and
the lengths of the second slots are substantially parallel to the lengths of the first slots and the first parasitic-interruption slots or the second parasitic-interruption slots.
17. The antenna device of claim 15 , wherein the first or second parasitic-interruption slots have a depth corresponding to one-quarter of a guided wavelength.
18. The antenna device of claim 15 , wherein the first set and the second set have a different number of respective parasitic-interruption slots.
19. The antenna device of claim 15 , wherein the first set and the second set have the different lengths of the respective parasitic-interruption slots.
20. The antenna device of claim 15 , wherein the first set and the second set have different respective continuities, the one or more first parasitic-interruption slots of the first set being discontinuous along the first side of the waveguide and the one or more second parasitic-interruption slots of the second set being continuous along the second, opposite side of the waveguide.