Slot antenna and high frequency module

Abstract

A thin slot antenna capable of wide-angle position detection and a high-frequency module are achieved. A slot antenna (1) is configured with a dielectric substrate (2) having a first face (2a), which is a radio wave emission face, and a second face (2b), which is a reverse face of the emission face. The dielectric substrate has a first conductor layer provided on the first face, one or a plurality of second conductor layers provided on an inner layer of the dielectric substrate (2), and a third conductor layer provided at a lower layer from the second conductor layers. The first conductor layer includes a first GND conductor in which a plurality of slots (3) having the same length (L) are formed side by side on a common center line (CL). The second conductor layer includes, for each of the plurality of slots (3), a second GND conductor provided with an opening that is wider than a region overlapping each slot (3) in a stacking direction. The third conductor layer includes a third GND conductor covering a region overlapping the plurality of openings provided in the second GND conductor in the stacking direction. The first GND conductor, the second GND conductor, and the third GND conductor are electrically connected by a plurality of vias that surround the openings provided in the second GND conductor in the stacking direction.

Description

Slot Antenna and High-Frequency Module

[0001] The present invention relates to a slot antenna and a high-frequency module.

[0002] For example, a foreign object detection system is disclosed in which a plurality of in-vehicle sensors are installed on the front, rear, left, and right of a vehicle to detect foreign objects located around the vehicle (for example, Patent Document 1). As sensors used in such a system, a wider-angle directivity is required. Patent Document 2 below discloses a slot antenna in which a plurality of feeding slot elements having a wide-angle directivity in the E-plane direction are arranged in the E-plane direction to enable wide-angle position detection.

[0003] Japanese Patent Application Laid-Open No. 2019-116773, Japanese Patent Application Laid-Open No. 2015-041995

[0004] In the slot antenna described in Patent Document 1, a reflector is provided behind the substrate provided with the feeding line, and a wall member is provided at a position corresponding to between the slot elements, so as to suppress the influence of the creeping wave between adjacent feeding slot elements. In such a configuration, a thickness in the height direction of the wall member occurs between the substrate and the reflector, raising concerns about thinning when mounted on a vehicle.

[0005] The present disclosure has been made in view of the above, and an object thereof is to realize a thin slot antenna and a high-frequency module capable of wide-angle position detection.

[0006] A slot antenna according to one aspect of the present disclosure is a slot antenna composed of a dielectric substrate having a first surface which is a radio wave radiating surface and a second surface which is the back surface of the radiating surface, wherein the dielectric substrate has a first conductor layer provided on the first surface, one or more second conductor layers provided in the inner layer of the dielectric substrate, and a third conductor layer provided below the second conductor layer, wherein the first conductor layer includes a first GND conductor in which a plurality of slots of the same length are arranged on a common center line, the second conductor layer includes a second GND conductor in which each of the plurality of slots has an opening wider than the region overlapping with each slot in the stacking direction, the third conductor layer includes a third GND conductor that covers the region overlapping with the plurality of openings provided in the second GND conductor in the stacking direction, and the first GND conductor, the second GND conductor, and the third GND conductor are electrically connected by a plurality of vias that surround the openings provided in the second GND conductor in the stacking direction.

[0007] One aspect of the present disclosure is a high-frequency module equipped with the above-mentioned slot antenna, wherein SMD components constituting the high-frequency module are mounted on the second surface.

[0008] According to this disclosure, a thin slot antenna and a high-frequency module capable of wide-angle position detection can be realized.

[0009] Figure 1 is a perspective view showing an example of a slot antenna according to the embodiment. Figure 2 is a conceptual diagram showing an example of a block configuration of a high-frequency module using the slot antenna according to the embodiment. Figure 3 is a diagram showing an example of a schematic cross-sectional structure of a high-frequency module using the slot antenna according to the embodiment. Figure 4 is a plan view of the first conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 5A is a plan view of the second conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 5B is a plan view of the second conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 5C is a plan view of the second conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 6 is a plan view of the third conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 7 is a plan view of the fourth conductor layer of the slot antenna according to the embodiment, viewed in the stacking direction. Figure 8A is a schematic cross-sectional view of the slot antenna according to the embodiment. Figure 8B is a schematic cross-sectional view of the slot antenna according to the embodiment. Figure 8C is a schematic cross-sectional view of the slot antenna according to the embodiment. Figure 9A is a diagram showing a first characteristic example of the slot antenna according to the embodiment. Figure 9B is a diagram showing a first characteristic example of the slot antenna according to the embodiment. Figure 10A is a diagram showing a second characteristic example of the slot antenna according to the embodiment. Figure 10B is a diagram showing a second characteristic example of the slot antenna according to the embodiment. Figure 10C is a diagram showing a second characteristic example of the slot antenna according to the embodiment. Figure 11A is a diagram showing a third characteristic example of the slot antenna according to the embodiment. Figure 11B is a diagram showing a third characteristic example of the slot antenna according to the embodiment. Figure 11C is a diagram showing a third characteristic example of the slot antenna according to the embodiment. Figure 12 is a plan view of the first conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction. Figure 13A is a plan view of the second conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction. Figure 13B is a plan view of the second conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction. Figure 13C is a plan view of the second conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction. Figure 14 is a plan view of the third conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction.Figure 15 is a plan view of the fourth conductor layer of a slot antenna according to a modified embodiment, viewed in the stacking direction. Figure 16A is a schematic cross-sectional view of a slot antenna according to a modified embodiment. Figure 16B is a schematic cross-sectional view of a slot antenna according to a modified embodiment. Figure 16C is a schematic cross-sectional view of a slot antenna according to a modified embodiment.

[0010] The slot antenna and high-frequency module according to the embodiment will be described in detail below with reference to the drawings. However, this embodiment is not limited to the present disclosure.

[0011] Figure 1 is a perspective view showing an example of a slot antenna according to the embodiment. Figure 2 is a conceptual diagram showing an example of a block configuration of a high-frequency module using the slot antenna according to the embodiment. Figure 3 is a diagram showing an example of a schematic cross-sectional structure of a high-frequency module using the slot antenna according to the embodiment.

[0012] The high-frequency module 100 is, for example, a radar module mounted on a vehicle such as an automobile to detect foreign objects located around the vehicle. The high-frequency module 100 is not limited to a radar module mounted on a vehicle. The high-frequency module 100 may also be a communication module mounted on a mobile device such as a mobile phone, smartphone or tablet, or a personal computer equipped with communication functions.

[0013] The high-frequency module 100 comprises a transmitting antenna 10, a receiving antenna 20, and a processing unit 30. The high-frequency module 100 is configured such that at least one of the transmitting antenna 10 and the receiving antenna 20 uses a slot antenna 1 as shown in Figure 1.

[0014] As shown in Figure 1, the slot antenna 1 according to this embodiment is composed of a dielectric substrate 2 having a first surface 2a which is a radio wave radiating surface and a second surface 2b which is the back surface of the radiating surface. Multiple slots 3 of the same length L (three in the example shown in Figure 1) are formed in the GND conductor of the radiating surface of the dielectric substrate 2 (the first GND conductor G1 provided in the first conductor layer WL1 in Figure 4). Each of the multiple slots 3 is aligned on a center line CL connecting the ends of each slot 3 in the longitudinal direction (X direction in the figure) at positions L / 2. The length L and width W of each slot 3 can be appropriately changed depending on the frequency and bandwidth of the transmission and reception signals of the high-frequency module 100.

[0015] The YZ plane shown in Figure 1 corresponds to the E-plane parallel to the electric field vector E of each slot 3. The XZ plane shown in Figure 1 corresponds to the H-plane of the slot antenna 1 according to this embodiment.

[0016] The high-frequency module 100 is constructed by mounting surface mount components (SMDs: Surface Mount Devices, hereinafter also referred to as "SMD components") that constitute the processing unit 30 of the high-frequency module 100 on the second surface 2b of the dielectric substrate 2. SMD components include, for example, integrated circuits 301 such as radar ICs and communication ICs, and various discrete components 302a, 302b, 302c, etc.

[0017] In this disclosure, the dielectric substrate 2 constituting the slot antenna 1 according to the embodiment is formed by laminating a plurality of conductive layers with a dielectric layer in between. Examples of the dielectric substrate 2 include low-temperature co-fired ceramic multilayer substrates (LTCC (Low Temperature Co-fired Ceramics) multilayer substrates), multilayer resin substrates formed by laminating a plurality of resin layers made of resins such as epoxy and polyimide, multilayer resin substrates formed by laminating a plurality of resin layers made of liquid crystal polymer (LCP) having a lower dielectric constant, multilayer resin substrates formed by laminating a plurality of resin layers made of fluororesin, and ceramic multilayer substrates (excluding low-temperature co-fired ceramic multilayer substrates).

[0018] The specific configuration of the slot antenna 1 according to this embodiment will be described below. Figure 4 is a plan view of the first conductor layer of the slot antenna according to this embodiment, viewed in the stacking direction. Figures 5A, 5B, and 5C are plan views of the second conductor layer of the slot antenna according to this embodiment, viewed in the stacking direction. Figure 6 is a plan view of the third conductor layer of the slot antenna according to this embodiment, viewed in the stacking direction. Figure 7 is a plan view of the fourth conductor layer of the slot antenna according to this embodiment, viewed in the stacking direction. Figures 8A, 8B, and 8C are schematic cross-sectional views of the slot antenna according to this embodiment.

[0019] The slot antenna 1 according to this embodiment includes a first conductor layer WL1 provided on the first surface 2a (see Figure 1) of the dielectric substrate 2, second conductor layers WL2A, WL2B, and WL2C provided in the inner layer of the dielectric substrate 2, and a third conductor layer WL3 provided below the second conductor layers WL2A, WL2B, and WL2C. Dielectric layers DL are provided between the first conductor layer WL1 and the second conductor layer WL2A, between the second conductor layer WL2A and the second conductor layer WL2B, between the second conductor layer WL2B and the second conductor layer WL2C, and between the second conductor layer WL2C and the third conductor layer WL3.

[0020] The first conductor layer WL1 includes a first GND conductor G1 in which a plurality of slots 3 of the same length L (see Figure 1) are formed side by side on a common center line. In this embodiment, an example is shown in which three slots 31, 32, and 33 are formed side by side on a common center line CL.

[0021] The second conductor layers WL2A, WL2B, and WL2C include second GND conductors G2A, G2B, and G2C, each of which has an opening 41, 42, and 43 that is wider than the area overlapping with each slot 31, 32, and 33 in the stacking direction (Z direction) for each slot 31, 32, and 33 formed in the first GND conductor G1.

[0022] The third conductor layer WL3 includes a third GND conductor G3 that covers a region overlapping with the stacking direction (Z direction) with a plurality of openings 41, 42, 43 provided in the second GND conductors G2A, G2B, and G2C.

[0023] The first GND conductor G1, the second GND conductors G2A, G2B, G2C, and the third GND conductor G3 are electrically connected by multiple vias that surround the openings 41, 42, and 43 provided in the second GND conductors G2A, G2B, and G2C in the stacking direction. These multiple vias are arranged at intervals of less than 1 / 4 of the signal wavelength within the substrate dielectric.

[0024] With the above configuration, coupling between each slot 31, 32, and 33 due to electromagnetic waves propagating within the dielectric substrate 2 can be suppressed.

[0025] The second conductor layer WL2B is provided with power supply lines FL that are coupled to each of the slots 31, 32, and 33, respectively. At one end of the power supply line FL, a signal supplied from the processing unit 30 of the high-frequency module 100 is supplied from the fourth conductor layer WL4 (see Figure 7) via via VI. The other end of the power supply line FL is open and overlaps each of the slots 31, 32, and 33 at a position 1 / 4 of the signal wavelength within the substrate dielectric from the open end.

[0026] In this embodiment, an offset power supply method is employed in which the power supply point FP, where each power supply line FL and each slot 31, 32, and 33 overlap, is offset with respect to the center line CL of each slot 31, 32, and 33.

[0027] Figures 9A and 9B show a first characteristic example of the slot antenna according to the embodiment. The dashed lines in Figures 9A and 9B show the reflection characteristics at the feed point FP of each slot 31, 32, and 33 in a central feeding system, where the feed point FP where each feed line FL and each slot 31, 32, and 33 overlap is superimposed on the center line CL of each slot 31, 32, and 33. The solid lines in Figures 9A and 9B show the reflection characteristics at the feed point FP of each slot 31, 32, and 33 in an offset feeding system. In the following description, the target bandwidth of the slot antenna according to the embodiment is denoted as f1 to f2.

[0028] In the central power supply system shown by the dashed lines in Figures 9A and 9B, a separate matching circuit is required to achieve impedance matching. In this case, there are concerns about increased losses and reduced bandwidth due to the addition of the matching circuit.

[0029] In this embodiment, as described above, an offset power supply method is employed in which the power supply points FP for each slot 31, 32, and 33 are offset with respect to the center line CL of each slot 31, 32, and 33. By appropriately setting the offset amount OA1 of the power supply points FP of each slot 31, 32, and 33 with respect to the center line CL of each slot 31, 32, and 33, impedance matching can be achieved without adding a matching circuit, as shown by the solid lines in Figures 9A and 9B.

[0030] Furthermore, the second conductor layer WL2B is provided with decoupling lines DCL1 and DCL2, which reduce electromagnetic mutual coupling between slot 31 and slot 32, and between slot 32 and slot 33.

[0031] In this embodiment, one end of the decoupling line DCL1 is connected via VI to the first GND conductor G1 of the first conductor layer WL1 near slot 31, and the other end of the decoupling line DCL1 is connected via VI to the first GND conductor G1 of the first conductor layer WL1 near slot 32.

[0032] Furthermore, in this embodiment, one end of the decoupling line DCL2 is connected via VI to the first GND conductor G1 of the first conductor layer WL1 near slot 32, and the other end of the decoupling line DCL2 is connected via VI to the first GND conductor G1 of the first conductor layer WL1 near slot 33.

[0033] Figures 10A, 10B, and 10C show a second characteristic example of the slot antenna according to the embodiment. Figures 11A, 11B, and 11C show a third characteristic example of the slot antenna according to the embodiment. The second characteristic example shown in Figures 10A, 10B, and 10C shows a characteristic example when decoupling lines DCL1 and DCL2 are not provided. The third characteristic example shown in Figures 11A, 11B, and 11C shows a characteristic example when decoupling lines DCL1 and DCL2 are provided.

[0034] The solid lines in Figures 10A and 11A show the reflection characteristics at the feed point of slot 31. The dashed lines in Figures 10A and 11A show the isolation characteristics of slot 32 as viewed from the feed point of slot 31. The dashed lines in Figures 10A and 11A show the isolation characteristics of slot 33 as viewed from the feed point of slot 31.

[0035] In Figures 10B and 11B, the dashed lines represent the gain in slot 31, the solid lines represent the gain in slot 32, and the dashed-dotted lines represent the gain in slot 33. In addition, in Figures 10C and 11C, the solid lines represent the shift in the radial phase difference of slot 32 relative to slot 31, and the dashed lines represent the shift in the radial phase difference of slot 33 relative to slot 31.

[0036] In this embodiment, decoupling lines DCL1 and DCL2 are provided between adjacent slots 31 and 32, and between slot 32 and 33, respectively, to cancel out electromagnetic coupling. The coupling point DCP where the line connecting the connection points of the decoupling lines DCL1 and DCL2 to the first GND conductor G1 overlaps with each of the slots 31, 32, and 33 is offset with respect to the center line CL of each of the slots 31, 32, and 33. By appropriately setting the line length and line width of the decoupling lines DCL1 and DCL2, and the offset amount OA2 of the coupling point DCP between the decoupling lines DCL1 and DCL2 and each of the slots 31, 32, and 33 with respect to the center line CL of each of the slots 31, 32, and 33, the mutual isolation, gain difference, and radiation phase difference between each of the slots 31, 32, and 33 can be reduced, as shown in Figures 11A, 11B, and 11C.

[0037] Furthermore, by offsetting the power supply points FP of each slot 31, 32, and 33, and the coupling points DCP between the decoupling lines DCL1 and DCL2 and each slot 31, 32, and 33 in opposite directions with respect to the center line CL of each slot 31, 32, and 33, respectively, the power supply lines FL and the decoupling lines DCL1 and DCL2 can not interfere with each other, and the offset amount OA1 of the power supply points FP of each slot 31, 32, and 33 with respect to the center line CL of each slot 31, 32, and 33, and the offset amount OA2 of the coupling points DCP between the decoupling lines DCL1 and DCL2 and each slot 31, 32, and 33 with respect to the center line CL of each slot 31, 32, and 33 can be appropriately set.

[0038] With the above-described configuration, in a slot antenna 1 composed of a dielectric substrate 2 in which multiple conductor layers (first conductor layer WL1, second conductor layers WL2A, WL2B, WL2C, and third conductor layer WL3) are stacked with a dielectric layer DL in between, it is possible to suppress directivity disturbances caused by electromagnetic coupling between each slot 31, 32, and 33. As a result, for example, a thin radar module capable of wide-angle and high-precision position detection can be realized.

[0039] In the configuration of the slot antenna 1 according to the embodiment described above, an example was given in which three layers of the second conductor layers WL2A, WL2B, and WL2C are provided, but the invention is not limited thereto. For example, the antenna may not have either or both of the second conductor layers WL2A and WL2C, but may only have the second conductor layer WL2B, or it may have multiple layers of the second conductor layer WL2A, or it may have multiple layers of the second conductor layer WL2C.

[0040] Furthermore, in the configuration of the slot antenna 1 according to the embodiment described above, an example was given in which each feed line FL and the decoupling lines DCL1 and DCL2 are provided in the same layer (second conductor layer WL2B). However, it is also possible to provide each feed line FL and the decoupling lines DCL1 and DCL2 in different layers among the second conductor layers WL2A, WL2B, and WL2C, respectively.

[0041] (Modified Example) FIG. 12 is a plan view of the first conductor layer of the slot antenna according to a modified example of the embodiment, as viewed in the stacking direction. FIGS. 13A, 13B, and 13C are plan views of the second conductor layer of the slot antenna according to a modified example of the embodiment, as viewed in the stacking direction. FIG. 14 is a plan view of the third conductor layer of the slot antenna according to a modified example of the embodiment, as viewed in the stacking direction. FIG. 15 is a plan view of the fourth conductor layer of the slot antenna according to a modified example of the embodiment, as viewed in the stacking direction. FIGS. 16A, 16B, and 16C are schematic cross-sectional views of the slot antenna according to a modified example of the embodiment.

[0042] The slot antenna 1a according to the modified example of the embodiment has, similarly to the slot antenna 1 according to the embodiment, a first conductor layer WL1 provided on the first surface 2a (see FIG. 1) of the dielectric substrate 2, second conductor layers WL2A, WL2B, WL2C provided in the inner layer of the dielectric substrate 2, and a third conductor layer WL3 provided in a layer lower than the second conductor layers WL2A, WL2B, WL2C. Dielectric layers DL are provided between the first conductor layer WL1 and the second conductor layer WL2A, between the second conductor layer WL2A and the second conductor layer WL2B, between the second conductor layer WL2B and the second conductor layer WL2C, and between the second conductor layer WL2C and the third conductor layer WL3, respectively.

[0043] The first conductor layer WL1 includes a first GND conductor G1 in which a plurality of slots 3 having the same length L (see FIG. 1) are formed side by side on a common center line. In the modified example, an aspect in which two slots 31 and 32 are formed side by side on a common center line CL is illustrated.

[0044] The second conductor layers WL2A, WL2B, WL2C each include second GND conductors G2A, G2B, G2C provided with openings 41, 42 wider than regions overlapping the slots 31, 32 in the stacking direction (Z direction) for each of the slots 31, 32 formed in the first GND conductor G1.

[0045] The third conductor layer WL3 includes a third GND conductor G3 that covers regions overlapping the plurality of openings 41, 42 provided in the second GND conductors G2A, G2B, G2C in the stacking direction (Z direction).

[0046] The first GND conductor G1, the second GND conductors G2A, G2B, G2C, and the third GND conductor G3 are electrically connected by a plurality of vias surrounding the openings 41 and 42 provided in the second GND conductors G2A, G2B, G2C in the stacking direction.

[0047] With the above-described configuration, coupling between the slots 31 and 32 due to electromagnetic waves propagating in the dielectric substrate 2 can be suppressed.

[0048] The second conductor layer WL2B is provided with feeding lines FL respectively coupled to the slots 31 and 32. A signal supplied from the processing unit 30 of the high-frequency module 100 is supplied to one end of the feeding line FL from the fourth conductor layer WL4 (see FIG. 15) via a via VI. The other end of the feeding line FL is open, and overlaps the slots 31 and 32 at a position of 1 / 4 of the signal wavelength in the substrate dielectric from the open end.

[0049] In the modified example, similar to the embodiment, an offset feeding method is adopted in which the feeding points FP where the respective feeding lines FL and the slots 31 and 32 overlap are offset with respect to the center lines CL of the slots 31 and 32. By appropriately setting the offset amount OA1 of the feeding point FP of each of the slots 31 and 32 with respect to the center line CL of each of the slots 31 and 32, impedance matching can be achieved without adding a matching circuit.

[0050] Further, the second conductor layer WL2B is provided with a decoupling line DCL for reducing electromagnetic mutual coupling between the slot 31 and the slot 32.

[0051] In the modified example, one end of the decoupling line DCL overlaps the slot 31 in the stacking direction, and the other end of the decoupling line DCL overlaps the slot 32 in the stacking direction.

[0052] In the modified configuration, a decoupling line DCL is provided that acts to cancel out the electromagnetic coupling between adjacent slots 31 and 32, and the coupling point DCP where the decoupling line DCL overlaps with each slot 31 and 32 is offset with respect to the center line CL of each slot 31 and 32. By appropriately setting the line length and line width of the decoupling line DCL, and the offset amount OA2 of the coupling point DCP between the decoupling line DCL and each slot 31 and 32 with respect to the center line CL of each slot 31 and 32, the mutual isolation, gain difference, and radiation phase difference between each slot 31 and 32 can be reduced.

[0053] Furthermore, by offsetting the power supply points FP of each slot 31 and 32 and the coupling points DCP between the decoupling line DCL and each slot 31 and 32 in opposite directions with respect to the center line CL of each slot 31 and 32, the power supply lines FL and the decoupling line DCL can not interfere with each other, and the offset amount OA1 of the power supply points FP of each slot 31 and 32 with respect to the center line CL of each slot 31 and 32, and the offset amount OA2 of the coupling points DCP between the decoupling line DCL and each slot 31 and 32 with respect to the center line CL of each slot 31 and 32 can be appropriately set.

[0054] With the above-described configuration, similar to the slot antenna 1 according to the embodiment, in a slot antenna 1a composed of a dielectric substrate 2 in which multiple conductor layers (first conductor layer WL1, second conductor layers WL2A, WL2B, WL2C, and third conductor layer WL3) are stacked with a dielectric layer DL in between, it is possible to suppress directivity disturbances due to electromagnetic coupling between each slot 31, 32. As a result, for example, a thin radar module capable of wide-angle and high-precision position detection can be realized.

[0055] In the configuration of the slot antenna 1a according to the modified embodiment described above, an example was given in which three layers of the second conductor layers WL2A, WL2B, and WL2C are provided, but the invention is not limited thereto. For example, the antenna may not have either or both of the second conductor layers WL2A and WL2C, but may only have the second conductor layer WL2B, or it may have multiple layers of the second conductor layer WL2A, or it may have multiple layers of the second conductor layer WL2C.

[0056] Furthermore, in the configuration of the slot antenna 1a according to the modified embodiment described above, an example was given in which each feed line FL and the decoupling line DCL are provided in the same layer (second conductor layer WL2B). However, it is also possible to provide each feed line FL and the decoupling line DCL in different layers among the second conductor layers WL2A, WL2B, and WL2C.

[0057] The embodiments described above are provided to facilitate understanding of this disclosure and are not intended to limit the invention. This disclosure may be modified or improved without departing from its spirit, and equivalents thereof are included.

[0058] 1, 1a Slot antenna 2 Dielectric substrate 2a First surface 2b Second surface 3, 31, 32, 33 Slots 10 Transmitting antenna 20 Receiving antenna 30 Processing unit 41, 42, 43 Aperture 100 High-frequency module CL Centerline DCL, DCL1, DCL2 Decoupling line DCP Coupling point FL Feed line FP Feed point G1 First GND conductor G2A, G2B, G2C Second GND conductor G3 Third GND conductor OA1 First offset amount OA2 Second offset amount VI Via WL1 First conductor layer WL2A, WL2B, WL2C Second conductor layer WL3 Third conductor layer WL4 Fourth conductor layer

Claims

1. A slot antenna comprising a dielectric substrate having a first surface which is a radio wave radiating surface and a second surface which is the back surface of the radiating surface, wherein the dielectric substrate comprises: a first conductor layer provided on the first surface; one or more second conductor layers provided in the inner layer of the dielectric substrate; and a third conductor layer provided below the second conductor layer, wherein the first conductor layer includes a first GND conductor in which a plurality of slots of the same length are arranged on a common center line; the second conductor layer includes a second GND conductor in which each of the plurality of slots has an opening wider than the area overlapping with each slot in the stacking direction; the third conductor layer includes a third GND conductor that covers the area overlapping with the plurality of openings provided in the second GND conductor in the stacking direction; and the first GND conductor, the second GND conductor, and the third GND conductor are electrically connected by a plurality of vias that surround the openings provided in the second GND conductor in the stacking direction.

2. A slot antenna according to claim 1, wherein it has a feed line connected to each of the plurality of slots, and the feed line is provided in the second conductor layer.

3. A slot antenna according to claim 2, wherein the feed point of the slot is offset with respect to the center line of the slot.

4. A slot antenna according to claim 3, comprising a decoupling line that acts to cancel out electromagnetic mutual coupling between adjacent slots, wherein the decoupling line is provided in the second conductor layer.

5. A slot antenna according to claim 4, wherein the coupling point between the slot and the decoupling line is offset with respect to the center line of the slot.

6. A slot antenna according to claim 5, wherein both ends of the decoupling line are connected by vias to the first GND conductor near adjacent slots.

7. A slot antenna according to claim 5, wherein both ends of the decoupling line overlap with adjacent slots in the stacking direction.

8. A slot antenna according to any one of claims 5 to 7, wherein the feed point of the slot and the coupling point between the slot and the decoupling line are offset in opposite directions with respect to the center line of the slot.

9. A slot antenna according to claim 8, wherein the feed line and the decoupling line are provided in the same layer.

10. A high-frequency module comprising a slot antenna according to any one of claims 1 to 9, wherein SMD components constituting the high-frequency module are mounted on the second surface.

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