Waveguide slot antenna array

Abstract

The waveguide slot antenna array disclosed by the embodiments of the present disclosure comprises: an array unit, a rectangular compact waveguide with a top wall width greater than a side wall width, two radiation slots symmetrically designed in the top wall of the array unit, a waveguide side ridge arranged at the center position of the side wall of the array unit, and a coaxial line arranged at the azimuth center position of the bottom of the array unit for feeding, wherein the inner conductor of the coaxial line is connected to the waveguide side ridge and the impedance is adjusted by a stepped balun. The antenna array uses a compact ridge waveguide with a narrow side ridge and a wide side slot as an array unit, and is fed by a coaxial center. The waveguide slot antenna array disclosed by the present disclosure has a low profile, a narrow unit spacing, and a wide operating bandwidth.

Description

Technical Field

[0001] This disclosure relates to the field of radar technology, and specifically to a waveguide slot antenna array. Background Technology

[0002] Spaceborne synthetic aperture radar (SAR) possesses all-weather, all-day Earth observation capabilities, offering unique advantages over optical radar. The antenna subsystem, primarily responsible for transmitting radar signals and receiving scene echo signals, largely determines the overall performance of the radar. Waveguide slot array antennas offer high power transmission capacity, high efficiency, robust mechanical structure, and well-defined calculation methods. This type of antenna meets many requirements for spaceborne SAR applications and is widely used. However, constrained by the transmission characteristics of rectangular waveguides, traditional waveguide slot array antennas are large, thick in profile, and narrow in bandwidth, severely limiting antenna performance optimization. Their element structure, array configuration, and feeding scheme require further optimization and improvement.

[0003] Ridge waveguide slot array antennas have narrower element spacing, wider bandwidth, and are easier to optimize in terms of frequency band, scanning range, weight, and space occupation. Summary of the Invention

[0004] This disclosure provides a waveguide slot antenna array.

[0005] In a first aspect, this disclosure provides a waveguide slot antenna array, comprising: an array element, a rectangular compact waveguide with a top wall width greater than the side wall width, two symmetrically designed radiation slots at the central axis of the top wall of the array element, a waveguide side ridge at the center of the side wall of the array element, and a coaxial line for feeding connected from the bottom of the array element to the center, wherein the internal conductor of the coaxial line is connected to the waveguide side ridge and the impedance is adjusted by a stepped balun.

[0006] Furthermore, the waveguide slot antenna array includes multiple array elements, which are connected end to end in the azimuth direction, maintain a predetermined interval in the range direction, and are connected by a ground plane.

[0007] Furthermore, the predetermined interval of the array elements in the distance direction is calculated as follows:

[0008]

[0009] Where d is the predetermined interval, λ0 is the operating frequency of the waveguide slot antenna array, and θ is the preset maximum scanning angle of the waveguide slot antenna array.

[0010] The technical solutions provided in this disclosure can include the following beneficial effects:

[0011] This antenna array uses compact ridge waveguides with narrow sides and wide sides with slots as array elements, and is center-fed by a coaxial line. The waveguide slot antenna array proposed in this disclosure has a low profile, narrow element spacing, and a large operating bandwidth.

[0012] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0013] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0014] Figure 1 shows a schematic diagram of the structure of a waveguide slot antenna array according to an embodiment of the present disclosure.

[0015] Figure 2 shows a schematic diagram of the overall structure of a waveguide slot antenna array according to an embodiment of the present disclosure.

[0016] Figure 3 The normal far-field radiation pattern of a waveguide slot antenna array according to an embodiment of the present disclosure is shown.

[0017] Figure 4 A schematic diagram of the array standing wave characteristics of an array element of a waveguide slot antenna array according to an embodiment of the present disclosure at different scanning angles is shown.

[0018] Figure 5 A schematic diagram of the range pattern scan result of a waveguide slot antenna array according to an embodiment of the present disclosure is shown.

[0019] Figure 6 A schematic diagram of a wave slot antenna array formed by conventional wave generation according to an embodiment of the present disclosure is shown. Detailed Implementation

[0020] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings to enable those skilled in the art to readily implement them. Furthermore, for clarity, portions unrelated to the description of the exemplary embodiments have been omitted from the drawings.

[0021] In this disclosure, it should be understood that terms such as “comprising” or “having” are intended to indicate the presence of features, figures, steps, behaviors, components, parts or combinations thereof disclosed in this specification, and do not preclude the possibility of the presence or addition of one or more other features, figures, steps, behaviors, components, parts or combinations thereof.

[0022] It should also be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] This disclosure presents a compact waveguide slot antenna array. The array uses compact ridge waveguides with narrow sides and wide sides with slots as array elements, and is center-fed by a coaxial line. The waveguide slot antenna array proposed in this disclosure has a low profile, narrow element spacing, and a large operating bandwidth, giving it unique advantages over similar designs and demonstrating strong application potential.

[0024] Figure 1(a)-Figure 1(d) A schematic diagram of a waveguide slot antenna array according to an embodiment of the present disclosure is shown. As shown in Figure 1, the array element of the waveguide slot antenna array is a compact waveguide derived from a conventional rectangular waveguide. The width of the top wall of the array element is greater than the width of the side wall. Two symmetrically designed radiation slots are located at the central axis of the top wall of the waveguide. A ridge is provided at the center of the side wall of the array element. A coaxial line for feeding is connected from the bottom of the array element to the center. The internal conductor of the coaxial line is connected to the ridge and the impedance is adjusted by a stepped balun.

[0025] The array unit is a compact rectangular waveguide with a wide top wall and narrow side walls. Two symmetrical radiation slots are designed at the central axis of the top wall of the waveguide, and a waveguide side ridge is added at the center of the side wall to improve radiation characteristics. A coaxial line for power feeding is connected to the center of the bottom of the array unit. The internal conductor of the coaxial line is connected to the waveguide side ridge through a stepped balun for impedance matching.

[0026] Figure 2(a)-Figure 2(b) A schematic diagram of the overall structure of a waveguide slot antenna array according to an embodiment of the present disclosure is shown. Figures 2(a)-2(b) As shown, the waveguide slot antenna array consists of 9×9 array elements, each element having two radiating slots in the azimuth direction. The elements are connected end-to-end in the azimuth direction, and maintain a certain interval in the range direction, connected by a ground plane.

[0027] When discussing uniform linear arrays, there is another important conclusion regarding antenna scanning: to avoid pattern grating lobes appearing within the predetermined scanning range (-θ, θ), the element spacing d should satisfy the following relationship:

[0028]

[0029] Where λ0 is the operating frequency of the waveguide slot antenna array, and θ is the preset scanning angle of the waveguide slot antenna array. The above formula is also known as the grating lobe condition.

[0030] Based on the no-grating-lobe condition:

[0031]

[0032] The distance-oriented cell spacing is designed to be as narrow as possible to avoid the generation of grating lobes within the scan range.

[0033] The following is an implementation result of the proposed array design. Table 1 summarizes... Figure 1(a)-Figure 1(d) The values ​​of each parameter are as follows: a is the element height, b is the element width, and L is the element length. s w is the gap length. s w is the gap width. x p is the distance to the cell interval. r To increase ridge depth, p b1 p b2 The positions of the baron and the coaxial line were located, d s With d r The thicknesses of the floor and ridge are respectively, w b With w L These represent the height and length of Baron, respectively, p c The position of the coaxial line was located, r i With r o These are the inner and outer radii of the coaxial line, respectively.

[0034] Table 1 summarizes the antenna parameters mentioned.

[0035]

[0036]

[0037] The full-wave simulation results are shown below.

[0038] Figure 3 The normal far-field radiation pattern of a waveguide slot antenna array according to an embodiment of the present disclosure is shown. The array has a gain of 28.20 dB and a first sidelobe level of 15.00 dB. The E-plane 3 dB beamwidth is 11.46° and the H-plane 3 dB beamwidth is 4.22°.

[0039] Figure 4 A schematic diagram of the array element standing wave characteristics of a waveguide slot antenna array according to an embodiment of the present disclosure at different scanning angles is shown. The scanning angle range is selected from 0° to 45° and the sampling interval is 5°. Figure 4 It can be seen that the VSWR of the array elements in the selected frequency band of 5 to 5.9 GHz remains below 1.5, which reflects the array's good scanning and radiation characteristics.

[0040] Figure 5 A schematic diagram of the range pattern scan results of a waveguide slot antenna array according to an embodiment of the present disclosure is shown, with the scan range selected from -45° to 45° and intervals of 5°. From Figure 5 It can be seen that the waveguide slot antenna array did not exhibit any blind spots or grating lobes during the scanning process, demonstrating good scanning characteristics.

[0041] Figure 6A schematic diagram of a waveguide-formed wave slot antenna array according to an embodiment of the present disclosure is shown. Figure 6 As shown, the waveguide slot structure can be considered as a traditional waveguide shown in the upper left corner that has been reduced in height and folded. The field distribution inside the structure can be calculated by dividing the internal region into three regions. The theoretical radiation characteristics of the first two field modes of the structure are still the same as those of the traditional waveguide. Therefore, the waveguide structure used can replace the traditional waveguide design under the premise of being more compact.

[0042] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

Claims

1. A waveguide slot antenna array, characterized in that, include: The array unit is a rectangular compact waveguide with a top wall width greater than the side wall width. Two symmetrical radiation slots are designed at the central axis of the top wall of the array unit. A waveguide side ridge is set at the center of the side wall of the array unit. A coaxial line for feeding is connected to the center from the bottom of the array unit. The internal conductor of the coaxial line is connected to the waveguide side ridge and the impedance is adjusted by a stepped balun. The waveguide slot antenna array is formed by reducing the height of the rectangular waveguide and folding it. The waveguide slot antenna array includes multiple array elements, which are connected end to end in the azimuth direction, maintain a predetermined interval in the range direction, and are connected by a ground plane; The predetermined interval of the array elements in the distance direction is calculated as follows: in, For the predetermined interval, The operating frequency of the waveguide slot antenna array. The preset maximum scanning angle is the waveguide slot antenna array.

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