Waveguide radiation structure

Abstract

Waveguide radiation structure (100, 200), comprising: a radiating element (208), comprising: an offset ribbed waveguide (205); and a first single-mode ribbed waveguide (203) which is functionally adjacent to the offset ribbed waveguide (205), wherein the offset ribbed waveguide (205) has an opening (213) with a long side (213L) and a short page (213S) contains wherein the offset ribbed waveguide (205) contains ribs (214) which are offset with respect to centerlines of both the short side (213S) and the long side (213L).

Description

[0001] This disclosure relates to high-resolution radio detection and tracking (radar) systems. Radar systems are increasingly used for object detection and tracking in a variety of applications. For example, vehicle radar systems can detect and track objects for a variety of situational awareness applications and autonomous and semi-autonomous vehicle control. In one type of radar system, traveling-wave imaging manifolds (TIMs) have been proposed for use with one-dimensional (i.e., linear) arrays of waveguide slot antennas to desirablely achieve E-field polarization along the array axis, with the individual slot antennas having slot orientations that are orthogonal to the array axis and spaced approximately half a wavelength or slightly more apart to achieve acceptable sidelobe levels and efficiency.Achieving E-field polarizations orthogonal to the array axis in one-dimensional arrays of waveguide slot antennas is significantly limited by the incompatible power and design parameters of such individual slot antennas. Simply reorienting individual slot antennas orthogonally within the array leads to a strong attenuation of the radiated power, unless the radiating slot is also shifted from the narrow waveguide wall to the wide waveguide wall. However, if the spacing of the individual slot antennas were maintained at or slightly greater than about half a wavelength, the waveguide width would have to be narrowed to the limit, which would also significantly attenuate the radiated power. Therefore, the parameters for the spacing of the individual slot antennas and the slot width are practically incompatible.Therefore, in certain applications it may be desirable to provide a one-dimensional array of waveguide slot antennas that have longitudinal E-field polarizations orthogonal to the array axis, maintaining the individual slot antenna spacing at or slightly greater than about half a wavelength and efficient radiated power.

[0002] CN 2 04 720 551 U1 discloses a ridge-waveguide-bias-slit-coupled microstrip oscillator dual-polarization antenna comprising two ridge-waveguide-bias-slit resonant array antenna units arranged side by side, two or more positive metal fields and two or more negative metal fields uniformly arranged on the outer surface of a microstrip plate, wherein the centers of the two or more positive metal fields correspond one-to-one with two or more radiation gaps in a first radiating waveguide and the centers of the two or more negative metal fields correspond one-to-one with two or more radiation gaps in a second radiating waveguide, wherein the positive metal fields and the negative metal fields are coupled to a second radiating waveguide.The positive metal fields and the negative metal fields are coupled with a second radiating waveguide, the centers of the two or more negative metal fields correspond one-to-one to the two or more radiation slots on the second radiating waveguide, and the positive metal fields and the negative metal fields are coupled with microstrip oscillators to achieve bipolarization of the antenna.

[0003] A waveguide radiation structure comprises a radiating element with an offset ribbed waveguide and a first single-mode ribbed waveguide functionally adjacent to the offset ribbed waveguide. The offset ribbed waveguide has an opening with a long side and a short side. The offset ribbed waveguide contains ribs that are offset with respect to the centerlines of both the short and long sides.

[0004] In addition to one or more of the features described here, the radiating element may contain a second ribbed waveguide that is functionally adjacent to the first single-mode ribbed waveguide opposite the offset ribbed waveguide.

[0005] In addition to one or more of the features described here, the structure may include a feed line coupled to the offset ribbed waveguide relative to the first single-mode ribbed waveguide.

[0006] In addition to one or more of the features described here, the structure may include a rectangular waveguide that is functionally adjacent to the offset ribbed waveguide opposite a feed line.

[0007] In addition to one or more of the features described here, the supply line may include one of several direction-changing, parallel supply lines that have a meandering supply path.

[0008] In another exemplary embodiment, a method for orthogonal rotation of a radiation E-field polarization may include guiding an RF signal moving through a feed guide, providing a rectangular waveguide coupled to the feed guide, providing an offset ribbed waveguide functionally adjacent to the rectangular waveguide opposite the feed guide, and providing a first single-mode ribbed waveguide functionally adjacent to the offset ribbed waveguide opposite the rectangular waveguide.

[0009] In addition to one or more of the features described here, the method may include the provision of a second ribbed waveguide that is functionally adjacent to the first single-mode ribbed waveguide opposite the offset ribbed waveguide.

[0010] In another exemplary embodiment, a waveguide radiation structure can include a meandering feed guide comprising a plurality of alternating, parallel feed guides for guiding an RF signal along respective feed line axes and a one-dimensional array of radiating elements orthogonal to the feed line axes. Each radiating element can include an offset ribbed waveguide functionally coupled to a respective feed line and a first single-mode ribbed waveguide functionally adjacent to the offset ribbed waveguide opposite the respective feed line.

[0011] In addition to one or more of the features described here, each radiating element may contain a second ribbed waveguide that is functionally adjacent to the first single-mode ribbed waveguide opposite the offset ribbed waveguide.

[0012] In addition to one or more of the features described here, the structure may include a rectangular waveguide that is functionally adjacent to and located between the offset ribbed waveguide and the respective feed line.

[0013] In addition to one or more of the features described here, at least two rectangular waveguides can have different heights.

[0014] In addition to one or more of the features described here, at least two supply lines have different lengths.

[0015] Further features, advantages and details are listed only as examples in the following detailed description, which refers to the drawings in which: Fig. 1 shows an exemplary waveguide radiation structure according to the present disclosure; Fig. 2 exemplary waveguides according to the present disclosure shows; Fig. 3 shows an exemplary waveguide radiation structure according to the present disclosure; and Fig. 4 shows an exemplary E-field polarization in an offset ribbed waveguide according to the present disclosure.

[0016] Fig. Figure 1 schematically shows a waveguide radiation structure 100, for example, for a radar system. The directions X and Y are labeled on two dimensions of a three-dimensional axis system. The third dimension, Z, is understood to lie outside the page. The structure 100 comprises a traveling wave imaging distributor (TIM) 101. In one embodiment, the distributor 101 can have the form of a meandering feed guide to carry a radio frequency signal (RF signal) through it. An RF signal can be a signal generated at or received at the input 102. The feed guide can comprise a plurality of feed lines 103 aligned along the Y-axis, which are substantially parallel and reverse direction (with respect to the guided RF signal) at end-limiting circuits 107.In one embodiment, the end boundary points along the Y-axis can vary, thereby changing the effective lengths 109 of the respective feed lines 103 defined between them. In one embodiment, all feed lines 103 can have the same length. In an alternative embodiment, at least two of the feed lines 103 have different lengths. In a further embodiment, no two feed lines 103 have the same length. In the latter embodiment, the feed guide can be characterized by a pseudorandom distribution of the lengths of the feed lines 103. The structure 100 further comprises a one-dimensional array 105 of individual radiating elements 108. The array 105 of individual radiating elements 108 is arranged along the X-axis orthogonally to the Y-axis of the feed line.

[0017] Referring to Fig. Figure 2 shows a disassembled isometric partial view of a waveguide radiation structure 200. The structure 200 can include a traveling wave imaging distributor 101 with a plurality of feed lines 103, as shown here in relation to Fig. As described in Figure 1, each feed line 103 can be connected to a corresponding radiating element 208. Each radiating element 208 comprises an offset finned waveguide 205 and a first single-mode finned waveguide 203. Each radiating element 208 can further comprise a rectangular waveguide 207 and a second finned waveguide 201. The second finned waveguide 201 can be a single-mode finned waveguide. Each waveguide 201-207 is characterized by an X-axis orthogonal to the feed lines 103, a Y-axis aligned with the feed lines 103, and a Z-axis aligned with the direction of radiation. Each radiating element 208 is signal-coupled to a corresponding feed line 103 through a corresponding feed opening 210 in the cover 212. All waveguides 201-207 are shown as separate components.It is understood that the waveguides 201-207 can be separate or integrated structures. The waveguides 201-207 are functionally adjacent in the relative positions shown. Waveguides are considered functionally adjacent when their Z-axes are aligned and they are signal-coupled. A person skilled in the art will recognize that the waveguides 201-207 can be directly adjacent or spaced apart by intermediate layers. For example, in one embodiment, an intermediate layer may contain an applied adhesive. In another embodiment, an intermediate layer may contain washers, spacers, or other transitions. In another embodiment, an intermediate layer may contain a dielectric. In yet another embodiment, an intermediate layer may contain another waveguide. The rectangular waveguide 207 may be separate from or integrated into the cover 212.An integrated rectangular waveguide 207 can eliminate the need for a separate feed port 210.

[0018] Fig. Figure 3 shows each of the different waveguides 201-207 in a top view along the Z-axis. The rectangular waveguide 207 contains an opening 211 with a long side 211L and a short side 211S with height (h). In one embodiment, the respective heights of the individual openings 211 are equal. In an alternative embodiment, at least two of the openings have different heights. In a further embodiment, no two openings 211 have the same height. In the latter embodiment, the one-dimensional arrangement 105 of the individual radiating elements 108 can be characterized by corresponding opening heights of the rectangular waveguide 207, resulting in substantially equivalent radiated power. The rectangular waveguide 207 transmits a signal with E-field polarization along the X-axis. The offset ribbed waveguide 205 contains an opening 213 with a long side 213L and a short side 213S.The offset ribbed waveguide 205 contains ribs 214 that are offset with respect to the centerlines of both the short side 213S and the long side 213L. Thus, each rib 214 occupies one of the opposite corners formed by an adjacent short side 213S and long side 213L. It is noted that each rib 214 has two surfaces, one extending orthogonally from the short side 213S and one extending orthogonally from the long side 213L. In one embodiment, the offset ribbed waveguide 205 is functionally adjacent to the rectangular waveguide 207 opposite the feed line 103. The offset ribbed waveguide 205 radiates a signal with a substantial E-field polarization lying between the X-axis and the Y-axis, as shown in [Figure]. Fig.Figure 4 shows the first single-mode ribbed waveguide 203, which includes an opening 215 with a long side 215L and a short side 215S. The first single-mode ribbed waveguide 203 includes ribs 216 projecting from the short sides 215S and parallel to the long sides 215L. Each rib 216 lies between the long sides 215L. It is estimated that each rib 216 has three surfaces: two parallel surfaces extending orthogonally from the short side 215S, and one extending orthogonally between the terminal ends of the two parallel surfaces. In one embodiment, the first single-mode ribbed waveguide 203 is functionally adjacent to the offset ribbed waveguide 205 opposite the rectangular waveguide 207. The second ribbed waveguide 201 includes an opening 217 with a long side 217L and a short side 217S.The second ribbed waveguide 201 contains ribs 218 projecting from the short sides 217S and parallel to the long sides 217L. Each rib 218 lies between the long sides 217L. It is estimated that each rib 218 has three surfaces: two parallel surfaces extending orthogonally from the short side 217S, and one extending orthogonally between the terminal ends of the two parallel surfaces. In one embodiment, the first single-mode ribbed waveguide 201 is functionally adjacent to the first single-mode ribbed waveguide 203 opposite the offset ribbed waveguide 205. The second ribbed waveguide 201 impedance-matches the low-impedance single-mode ribbed waveguide 203 to the high-impedance radiation field.

[0019] It is therefore estimated that the disclosed arrangements of finned waveguides 205, 207 can be designed to achieve cutoff frequencies low enough to support the desired polarization with dimensional widths (X-direction dimensions) at or slightly greater than about half a wavelength of the signals of interest. The finned waveguides 205, 207 are fed by the offset finned waveguide 203, which couples energy from the feed line 103 into the desired finned waveguide mode. The offset finned waveguide 203 is coupled to the feed line 103 via the rectangular waveguide 201, the height (h) of which controls the amount of energy radiated by the element. The disclosed structure achieves efficient radiation in both desired polarizations while avoiding cutoff frequencies.

[0020] The complexity of the disclosed radiating element 208, including the waveguides 201-207, may necessitate the fabrication and assembly of components. In one embodiment, the disclosed radiating element 208, including the waveguides 201-207, can be machined from one or more metal blocks, e.g., copper, bronze, brass, aluminum, iron-nickel, and other alloys. In other embodiments, the disclosed radiating element 208, including the waveguides 201-207, can be manufactured by metal casting or sintering. In other embodiments, plastic injection molding in conjunction with a metal coating or plating of the active waveguide surfaces can be used.In other embodiments, additive manufacturing processes, including plastic and metal deposits, can be used in the manufacture of the disclosed radiating element 208, including the waveguides 201-207.

Claims

[1] Waveguide radiation structure (100, 200), comprising: a radiating element (208), comprising: an offset ribbed waveguide (205); and a first single-mode ribbed waveguide (203) which is functionally adjacent to the offset ribbed waveguide (205), wherein the offset ribbed waveguide (205) has an opening (213) with a long side (213L) and a short page (213S) contains wherein the offset ribbed waveguide (205) contains ribs (214) which are offset with respect to centerlines of both the short side (213S) and the long side (213L). [2] Structure (100, 200) according to claim 1, wherein the radiating element (208) comprises a second ribbed waveguide (201) which is functionally adjacent to the first single-mode ribbed waveguide (203) opposite the offset ribbed waveguide (205). [3] Structure (100, 200) according to claim 1, comprising a feed line (103) coupled to the offset ribbed waveguide (205) relative to the first single-mode ribbed waveguide (203). [4] Structure (100, 200) according to claim 2, comprising a feed line (103) coupled to the offset ribbed waveguide (205) relative to the first single-mode ribbed waveguide (203). [5] Structure (100, 200) according to claim 1, comprising a rectangular waveguide (207) which is functionally adjacent to the offset ribbed waveguide (205) opposite a feed line (103). [6] Structure (100, 200) according to claim 5, wherein the supply line (103) comprises one of a plurality of direction-changing, parallel supply lines (103) with a meandering supply guide (101). [7] Waveguide radiation structure (100, 200), comprising: a meandering feed guide (101) with a plurality of direction-changing, parallel feed lines (103) for guiding an RF signal along respective feed line axes; a one-dimensional array (105) of radiating elements (208) orthogonal to the supply line axes; wherein each radiating element (208) comprises: an offset ribbed waveguide (205) which is functionally coupled to a respective feed line (103); and a first single-mode ribbed waveguide (203) which is functionally adjacent to the offset ribbed waveguide (205) opposite the respective feed line (103), wherein the offset ribbed waveguide (205) has an opening (213) with a long side (213L) and a short page (213S) contains wherein the offset ribbed waveguide (205) contains ribs (214) which are offset with respect to centerlines of both the short side (213S) and the long side (213L). [8] Structure (100, 200) according to claim 7, wherein each radiating element (208) comprises a second ribbed waveguide (201) which is functionally adjacent to the first single-mode ribbed waveguide (203) opposite the offset ribbed waveguide (205). [9] Structure (100, 200) according to claim 7, comprising a rectangular waveguide (207) which is functionally adjacent to and arranged between the offset ribbed waveguide (205) and the respective feed line (103). [10] Structure (100, 200) according to claim 8, comprising a rectangular waveguide (207) which is functionally adjacent to and arranged between the offset ribbed waveguide (205) and the respective feed line (103).

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