Antenna equipment

Abstract

This technology provides an improvement in antenna characteristics over a wide frequency range without increasing the size of the reflector. [Solution] The antenna device comprises a radiator and a reflector. The radiator is configured to transmit or receive linearly polarized waves. The reflector is made of a plate-shaped member using an electrical conductor and is positioned opposite the radiator at a distance from it. The reflector also has a plurality of slots on its plate surface. A plurality of slots arranged along a specific direction are called a slot group, and the plurality of slots belonging to the slot group are arranged such that at least one of the slot size and the spacing between adjacent slots changes.

Description

Technical Field

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[0001] The present disclosure relates to an antenna device including a radiator and a reflector, wherein the reflector is a plate-shaped member using an electrical conductor having a plurality of openings in a plate surface.

Background Art

[0002] As an antenna device for receiving television broadcasts used in ordinary households, there is known one in which a radiator and a reflector are formed of plate-shaped members using an electrical conductor, and these are housed in a case in a facing state. Patent Document 1 describes a technique in which, as a reflector, a plate-shaped member using an electrical conductor having a large number of diamond-shaped openings is used, and by expanding the frequency bandwidth of radio waves that can be reflected by the reflector to the lower frequency side, a broadband radio wave such as a television broadcast wave can be received by one antenna device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional technology has a structure in which openings of the same size are arranged, and can only correspond to a specific one frequency according to the size of the opening. For this reason, there is a problem that it is difficult to improve the characteristics on the mid- and high-frequency sides while maintaining the characteristics on the low-frequency side improved by the conventional technology.

[0005] One aspect of the present disclosure provides a technique for improving antenna characteristics in a wide frequency range without increasing the size of the reflector.

Means for Solving the Problems

[0006] One aspect of the present disclosure is an antenna device comprising a radiator and a reflector. The radiator is configured to transmit or receive linearly polarized waves. The reflector is made of a plate-shaped member using an electrical conductor and is positioned opposite the radiator at a distance from it. The reflector also has a plurality of slots on its plate surface. A plurality of slots arranged along a specific direction are called a slot group, and the plurality of slots belonging to the slot group are arranged such that at least one of the size of the slots and the spacing between adjacent slots changes.

[0007] With this configuration, by appropriately selecting the size of multiple slots belonging to the slot group and the spacing between slots, the reflector can reflect radio waves of various wavelengths. As a result, without increasing the size of the reflector, the characteristics of the reflector, and consequently the characteristics of the antenna device, can be varied in a wide frequency range, not just in the low frequency range of use.

[0008] In one aspect of this disclosure, the specific direction may be parallel to the polarization plane of the radio waves transmitted or received by the radiator. With such a configuration, the antenna characteristics can be changed efficiently.

[0009] In one aspect of this disclosure, the particular direction may be any direction passing through the center of the reflector and along the plate surface of the reflector. That is, the size of the slots and the spacing between the slots may be set to vary radially with respect to the center of the reflector. Such a configuration makes it possible to achieve symmetrical antenna characteristics with respect to the center of the reflector.

[0010] In one aspect of this disclosure, a plurality of slots belonging to a slot group may be configured such that the size of the slots or the way in which the spacing between adjacent slots changes is symmetrical with respect to a center in a particular direction within the slot group. Such a configuration makes it possible to achieve antenna characteristics that are symmetrical with respect to the center of the slot group.

[0011] In one aspect of this disclosure, a plurality of slots belonging to a slot group may be configured such that the size of the slots or the spacing between adjacent slots increases or decreases monotonically in one direction in a particular direction. With such a configuration, the gain and VSWR can be adjusted in any bandwidth.

[0012] In one aspect of this disclosure, a plurality of slots belonging to a group of slots may be configured such that the size of the slots or the spacing between adjacent slots changes randomly. In one aspect of this disclosure, a plurality of slot groups may be arranged on the plate surface of the reflector along a specific orthogonal direction perpendicular to a particular direction. Any two adjacent slot groups in the specific orthogonal direction may be configured such that the way in which the size of the slots changes is in opposite directions. [Brief explanation of the drawing]

[0013] [Figure 1] This is a side view of an antenna device fixed to a wall, seen from the side. [Figure 2] This is a plan view of an antenna device fixed to a wall, seen from above. [Figure 3] This is a perspective view showing the configuration of the radiator and reflector that make up the antenna device. [Figure 4] This is an explanatory diagram illustrating comparative patterns 1 and 2, which are conventional patterns for slots formed in a reflector, and patterns 1 to 3 according to the present disclosure. [Figure 5] This table shows the directional gain and VSWR values ​​calculated by simulation for antenna devices employing comparison patterns 1 and 2, and patterns 1 through 3. [Figure 6] This graph shows the results of simulations calculating the directional gain and VSWR for antenna devices employing comparison patterns 1 and 2, and patterns 1 through 3. [Figure 7] This is an explanatory diagram illustrating other patterns 4-8 of slots to be formed in the reflector. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present disclosure will be described while referring to the drawings. [1. Configuration] As shown in FIGS. 1 and 2, the antenna device 2 of the present embodiment has a synthetic resin case 10.

[0015] The case 10 is fixed to the wall surface 100 by using a support piece 14 protruding from the bottom 12 of the case 10 and a fixing piece 16 fixed to the wall surface 100 to be attached. Specifically, the support piece 14 is fitted into the fixing piece 16, and the fitting portion is fixed using a fixture 18 composed of a bolt and a nut so as to be rotatable around the central axis in the vertical direction.

[0016] Inside the case 10, a pair of radiators 20A and 20B and a pair of reflectors 50A and 50B are arranged. The pair of radiators 20A and 20B constitute a stacked radiator. The reflector 50A is arranged to face the radiator 20A, and the reflector 50B is arranged corresponding to the radiator 20B.

[0017] Since the radiators 20A and 20B have the same configuration, they are denoted as the radiator 20 when there is no need to particularly distinguish between the two. Also, since the reflectors 50A and 50B have the same configuration, they are denoted as the reflector 50 when there is no need to particularly distinguish between the two.

[0018] As shown in FIG. 3, the radiator 20 is configured by forming, in a rectangular metal plate which is an electrical conductor, opening holes 26 and 28 for forming a pair of loops 22 and 24, and a connecting hole 30 connecting the opening holes 26 and 28.

[0019] In the radiator 20, power supply points 32 and 34 for connecting connection members 42 and 44 using an electrical conductor are formed on both sides sandwiching the connecting hole 30, respectively. The radiators 20A and 20B are arranged such that the plate surfaces of the respective metal plates are located in the same plane and the loop 24 (that is, the opening hole 28) side ends of the respective metal plates face each other with a gap therebetween.

[0020] The radiators 20A and 20B are electrically connected via connection members 42 and 44. The connection member 42 connects the power supply points 32 of the radiators 20A and 20B to each other, and the connection member 44 connects the power supply points 34 of the radiators 20A and 20B to each other. The midpoints of the respective connection members 42 and 44 are used as common power supply points 46 and 48 for the respective radiators 20A and 20B, to which a power supply cable (not shown) is connected.

[0021] Hereinafter, the direction in which the radiators 20A and 20B are arranged is referred to as the Y-axis direction. The direction orthogonal to the Y-axis and along the plate surface of the radiator 20 is referred to as the X-axis direction. The direction orthogonal to the X-axis direction and the Y-axis direction is referred to as the Z-axis direction.

[0022] The radiator 20B is arranged in a state where the radiator 20A is inverted in the Y-axis direction. The radiator 20 irradiates a linearly polarized wave having a polarization plane parallel to the X-axis direction. The radiator 20 and the reflector 50 are arranged at intervals in the Z-axis direction.

[0023] The reflector 50 is manufactured, for example, by bending a rectangular metal plate, which is an electrical conductor, into a U-shape. The reflector 50 includes a reflector body 52 and side wall portions 54 and 56. The reflector body 52 is a portion arranged such that the plate surface is along the X-Y plane. The reflector body 52 has a size that covers the entire plate surface of the opposed radiators 20. The side wall portions 54 and 56 are portions that protrude in the Z-axis direction by bending both ends of the reflector body 52 in the X-axis direction.

[0024] The reflectors 50A and 50B are arranged side by side in the Y-axis direction in the same manner as the radiators 20A and 20B, and the reflector 50B is arranged in a state where the reflector 50A is inverted in the Y-axis direction. Hereinafter, the side of the reflector 50B as viewed from the reflector 50A, and the central side of the reflector 50A as viewed from the reflector 50B are referred to.

[0025] The reflector body 52 includes a plurality of openings (hereinafter, slots) SL having different rectangular sizes. Hereinafter, a group of slots SL arranged in a line along the X-axis will be referred to as the X-axis slot group, and a group of slots SL arranged in a line along the Y-axis will be referred to as the Y-axis slot group. In this case, the X-axis direction corresponds to the specific direction of this disclosure. Furthermore, the three types of slots SL with different sizes will be referred to as the large slot LSL, the medium slot MSL, and the small slot SSL. The large slot LSL is set to have, for example, approximately twice the area of ​​the medium slot MSL, and the medium slot MSL is set to have, for example, approximately twice the area of ​​the small slot SSL.

[0026] Figure 4 illustrates three different patterns with varying arrangements and numbers of slot SLs. Pattern 1 has a structure in which four X-axis slot groups SX1-4 are arranged along the Y-axis. The X-axis slot group SXi (i=1~4) of Pattern 1 is all configured similarly, having two large slots LSL, two medium slots MSL, and two small slots SSL. The six slots SL that make up the X-axis slot group SXi of Pattern 1 are arranged in a single row along the X-axis direction such that the spacing between adjacent slots SL is constant.

[0027] In the X-axis slot group SXi of Pattern 1, two large slots LSL are positioned on either side of the center of the X-axis direction in the reflector body 52. ​​Two medium slots MSL are positioned on the outer sides of the two large slots LSL in the X-axis direction. Two small slots SSL are positioned further outwards from the two medium slots MSL. In other words, in the X-axis slot group SXi of Pattern 1, the slot size SL increases in stages as it approaches the center of the X-axis direction in the reflector body 52.

[0028] Pattern 1 can also be described as having a structure in which six Y-axis slot groups SY1 to SY6 are arranged along the X-axis. In this case, the Y-axis direction corresponds to the specific direction of this disclosure. The Y-axis slot groups SY1 and SY6, located at both ends of the X-axis direction, each have a structure in which four small slots SSL are arranged in a row along the Y-axis. The Y-axis slot groups SY3 and SY4, located at the center of the X-axis direction, each have a structure in which four large slots LSL are arranged in a row along the Y-axis. The Y-axis slot groups SY2 and SY5, located between the center and both ends of the X-axis direction, each have a structure in which four medium slots MSL are arranged in a row along the Y-axis. Each slot SL constituting the Y-axis slot group SYj (j=1 to 6) is arranged such that the distance between the center points of the slots SL is constant. Therefore, in the Y-axis slot groups SY1 and SY6, where small slots SSL are used, the distance between adjacent slots SL is the largest, and in the Y-axis slot groups SY3 and SY4, where large slots LSL are used, the distance between adjacent slots is the smallest.

[0029] Pattern 2, like Pattern 1, has a structure in which four X-axis slot groups SX1-4 are arranged along the Y-axis. In Pattern 2, the six slots SL that make up the X-axis slot group SXi are arranged so that the spacing between each slot SL is constant. However, in Pattern 2, the arrangement of the slots SL of different sizes in the X-axis slot group SXi differs from that in Pattern 1.

[0030] In the X-axis slot group SXi of pattern 2, two small slots SS are arranged on either side of the center of the reflector body 52 in the X-axis direction. Two medium slots MSL are arranged on the outer sides of the two small slots SSL in the X-axis direction. Two large slots LSL are arranged further outwards from the two medium slots MSL. In other words, in the X-axis slot group SXi of pattern 2, the slot size SL decreases in stages as it approaches the center of the reflector body 52 in the X-axis direction.

[0031] Pattern 2 can also be described as having a structure in which six Y-axis slot groups SY1 to SY6 are arranged along the X-axis. In this case, Y-axis slot groups SY1 and SY6, located at both ends in the X-axis direction, each have a structure in which four large slots LSL are arranged in a row along the Y-axis. Y-axis slot groups SY3 and SY4, located at the center of the X-axis, each have a structure in which four small slots SSL are arranged in a row along the Y-axis. Y-axis slot groups SY2 and SY5, located between the center and both ends in the X-axis direction, each have a structure in which four medium slots MSL are arranged in a row along the Y-axis. Each slot SL constituting the Y-axis slot group SYj (j=1 to 6) is arranged such that the distance between the center points of the slots SL is constant. Therefore, in Y-axis slot groups SY1 and SY6, where large slots LSL are used, the distance between adjacent slots SL is smallest, and in Y-axis slot groups SY3 and SY4, where small slots SSL are used, the distance between adjacent slots SL is largest.

[0032] Pattern 3 has a structure in which six Y-axis slot groups SY1 to SY6 are arranged along the X-axis. The Y-axis slot groups SY1 and SY6, located at both ends in the X-axis direction, each have a structure in which multiple (e.g., 10) small slots SSL are arranged in a line at regular intervals along the Y-axis. The Y-axis slot groups SY3 and SY4, located in the center in the X-axis direction, each have a structure in which multiple (e.g., 4) large slots LSL are arranged in a line at regular intervals along the Y-axis. The Y-axis slot groups SY2 and SY5, located between the center and both ends in the X-axis direction, both have a structure in which multiple (for example, 6) intermediate slots MSL are arranged in a line at regular intervals along the Y-axis. The regular intervals in each Y-axis slot group SYj are set to be the same.

[0033] In other words, in Pattern 2, each slot SL is arranged such that the size of the slot SL gradually increases as it approaches the center of the reflector body 52 in the X-axis direction. Note that the center points of each slot SL are aligned on the same axis in the Y-axis direction, but are not aligned in the X-axis direction.

[0034] With reference point F being the point on the plate surface of reflectors 50A and 50B opposite the center points of radiators 20A and 20B, each slot SL in patterns 1 to 3 is set to be point-symmetric with respect to reference point F, line-symmetric with respect to the Y-axis passing through reference point F, or line-symmetric with respect to the X-axis passing through reference point F.

[0035] [2. Operation] Here, the basic path is defined as the electromagnetic wave propagation path whose path length is the dimension of the reflector body 52 along the X-axis. In addition, the bypass path is defined as the path through which the electromagnetic wave propagates along the contour of the slot SL between two points located at both ends of the reflector body 52 along the X-axis.

[0036] In other words, the detour route has a longer path length than the basic route. Furthermore, there are many different path patterns for the detour route, each with a different path length. The reflector 50 reflects radio waves of wavelengths corresponding to the path lengths of the basic route and the detour route. The wavelength corresponding to the path length is a wavelength that is twice the path length or slightly longer.

[0037] The path length of the basic path is set to a length suitable for reflecting the upper frequency limit of electromagnetic waves transmitted or received by the antenna device 2. By appropriately selecting the shape and size of slot SL and the arrangement of slot SL, the reflector 50 can be designed to change the characteristics of the reflector 50, and consequently the characteristics of the antenna device 2.

[0038] [3. Measurement] By placing experimental radiators 20A and 20B in front of each of the reflectors 50A and 50B shown in patterns 1 to 3 in Figure 4, an antenna device 2 for receiving television broadcasts (UHF band, frequency: 470MHz to 770MHz) was constructed, and a simulation was performed.

[0039] In the reflector 50, the length of slot SL in the X-axis direction is 60 mm, and the length in the Y-axis direction is 80 mm. The dimensions of the reflector body 52 are 290 mm in the X-axis direction and 230 mm in the Y-axis direction. The height of the side wall portions 54 and 56 from the plate surface of the reflector body 52 is 15 mm.

[0040] For comparison, similar simulations were performed for comparison patterns 1 and 2, which are typical examples of conventional reflectors 50. Comparison pattern 1 has a simple structure without slot SL. Comparison pattern 2 has a structure in which rectangular slots of the same size are arranged regularly.

[0041] Figures 5 and 6 are a table and graph showing the antenna characteristics of antenna device 2, specifically the directional gain, VSWR (i.e., standing wave ratio), and the results calculated by simulation. When using reflector 50 of pattern 1, the directional gain is improved (i.e., increased) across the mid-to-high frequency range of the operating frequency band compared to when using reflectors 50 of comparison patterns 1 and 2 (hereinafter referred to as the conventional device). Furthermore, when using reflectors 50 of patterns 2 and 3, compared to the conventional device... This improves the directional gain in the mid-range to low-range frequencies within the operating frequency band. However, Pattern 2 shows a relatively greater improvement in the low-range frequencies, while Pattern 3 shows a relatively greater improvement in the mid-range frequencies.

[0042] The VSWR for patterns 1-3 is improved across the entire operating frequency band compared to comparison pattern 1, but is about the same or slightly worse compared to comparison pattern 2. Thus, by changing the arrangement of multiple types of slots SL of different sizes, it can be seen that the frequency characteristics of directional gain and VSWR change in various patterns.

[0043] [4. Effects] The embodiments described in detail above produce the following effects. In antenna device 2, multiple types of slots LSL, MSL, and SSL of different sizes are used as slot SL for reflector 50. Therefore, compared to conventional devices where all slot SL are the same size, the number of resonant frequencies in the reflector 50 can be increased in the polarization direction of the radio waves transmitted or received by the radiator 20. As a result, by appropriately selecting the arrangement of multiple types of slots LSL, MSL, and SSL of different sizes, the characteristics of the reflector 50, and consequently the antenna characteristics of antenna device 2 (for example, the frequency characteristics of directional gain and VSWR), can be adjusted in various ways. In other words, the characteristics of a specific frequency range in the operating frequency band can be improved.

[0044] [5. Other Embodiments] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0045] (5a) In patterns 1 and 2 above, the X-axis slot groups SX1 to SX4 all have the same structure, but this is not the only option. For example, as shown in pattern 4 in Figure 7, the odd-numbered X-axis slot groups SX1 and SX3 may have a structure in which the slot size decreases towards the center in the X-axis direction, while the even-numbered X-axis slot groups SX2 and SX4 may have a structure in which the slot size increases towards the center in the X-axis direction.

[0046] (5b) In patterns 1 to 3 above, slots SL are arranged so that the slot size changes along the X-axis, but this is not the only way. For example, as shown in pattern 5 in Figure 7, slots SL may be arranged so that the slot size changes along the Y-axis. That is, pattern 5 has a structure in which Y-axis slot groups SY1 to SY4 are arranged along the X-axis. The odd-numbered Y-axis slot groups SY1 and SY3 have a structure in which the slot size becomes smaller towards the center in the Y-axis direction, while the even-numbered Y-axis slot groups SY2 and SY4 have a structure in which the slot size becomes larger towards the center in the Y-axis direction.

[0047] Furthermore, as shown in pattern 6 in Figure 7, for example, the slots SL may be arranged concentrically or radially with respect to the center of each reflector 50, and the slot size may increase (or decrease) as the slots SL are located further out. The slots SL may also be arranged concentrically or radially with respect to the center of the pair of reflectors 50A and 50B (i.e., the reference point F).

[0048] (5c) In patterns 1 and 2 above, the multiple types of slots SL of different sizes that constitute the X-axis slot group SXi are arranged to form a symmetrical structure with respect to the center in the X-axis direction, but this is not limited to this. For example, as shown in pattern 7 in Figure 7, the multiple types of slots SL of different sizes that constitute the X-axis slot group SXi may be arranged so that their size increases or decreases monotonically in one direction from one end to the other. Here, the size of the slots SL is changed, but the spacing between adjacent slots SL may also be changed. Also, for example, as shown in pattern 8 in Figure 7, multiple types of different sizes Slot SL may be arranged randomly without any particular pattern.

[0049] (5d) In patterns 1 and 2 above, the X-axis slot group SXi is set so that the way the slot size changes in the X-axis direction is the same. In contrast, as in the X-axis slot group SXi shown in patterns 4 and 7, or the Y-axis slot group SYj shown in pattern 5, the way the slot size changes between adjacent X-axis slot groups SXi or Y-axis slot groups SYi may be set to be opposite or complementary. In this case, in patterns 4 and 7, the X-axis direction corresponds to a specific direction of this disclosure, and the Y-axis direction corresponds to a specific orthogonal direction of this disclosure, while in pattern 5, the Y-axis direction corresponds to a specific direction of this disclosure, and the X-axis direction corresponds to a specific orthogonal direction of this disclosure.

[0050] (5e) In the above embodiment, the shape of the slot SL provided in the reflectors 50A and 50B does not necessarily have to be rectangular, and any shape such as a polygon or ellipse can be used.

[0051] (5f) In the above embodiment, the radiators 20A and 20B were described as being made of a double-loop type radiator (so-called skeleton slot radiator) which is made by forming two openings 26 and 28 in a metal plate that is an electrical conductor. However, the radiator may be a dipole type or a planar antenna of another type.

[0052] (5g) In the above embodiment, the reflectors 50A and 50B were described as having slots SL provided in a metal plate which is an electrical conductor. However, they may also be constructed by providing slots SL in a plate-shaped member made of a non-electrical conductor such as synthetic resin, and providing an electrical conductor (paint, metal foil, etc.) on its surface.

[0053] (5h) Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configuration of the above embodiment may be omitted. Also, at least some of the configuration of the above embodiment may be added to or replaced with the configuration of other above embodiments.

[0054] (5i) In addition to the antenna device described above, this disclosure can also be implemented in various forms, such as a system that uses the antenna device as a component, or a method for adjusting antenna characteristics. [Explanation of Symbols]

[0055] 2...Antenna device, 10...Case, 12...Bottom, 14...Support piece, 16...Fixing piece, 18...Fixing device, 20...Radiator, 22,24...Loop, 26,28...Opening hole, 30...Connecting hole, 32,34...Feed point, 42,44...Connecting member, 46,48...Feed point, 50...Reflector, 52...Reflector body, 54,56...Side wall, F...Reference point, SL...Slot, SXi...X-axis slot group, SYj...Y-axis slot group.

Claims

1. A radiator configured to transmit or receive linearly polarized waves, A reflector is made of a plate-shaped member using an electrical conductor and is positioned opposite the radiator at a distance from it, Equipped with, The reflector has a plurality of slots on its plate surface, Multiple slots arranged along a specific direction are considered as a group of slots, The plurality of slots belonging to the slot group are arranged such that at least one of the size of the slots and the spacing between adjacent slots changes. Antenna device.

2. The antenna device according to claim 1, The aforementioned specific direction is a direction parallel to the polarization plane of the radio waves transmitted or received by the radiator. Antenna device.

3. The antenna device according to claim 1, The aforementioned specific direction is any direction that passes through the center of the reflector and along the plate surface of the reflector. Antenna device.

4. An antenna device according to any one of claims 1 to 3, The plurality of slots belonging to the slot group are set such that the size of the slot or the way in which the spacing between adjacent slots changes is symmetrical with respect to the center of the specific direction in the slot group. Antenna device.

5. An antenna device according to any one of claims 1 to 3, The plurality of slots belonging to the slot group are set such that the size of the slot or the spacing between adjacent slots increases or decreases monotonically in one direction of the specific direction. Antenna device.

6. An antenna device according to any one of claims 1 to 3, The plurality of slots belonging to the aforementioned slot group are set such that the size of the slot or the spacing between adjacent slots changes randomly. Antenna device.

7. An antenna device according to any one of claims 1 to 3, On the plate surface of the reflector, a plurality of the slot groups are arranged along a specific orthogonal direction perpendicular to the specific direction. Any two adjacent groups of slots in the specified orthogonal direction are set such that the way in which the size of the slots changes is in opposite directions. Antenna device.

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