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 constructed using an electrical conductor and is positioned opposite the radiator at a distance from it. The radiator is powered via a feed line. The antenna characteristics are adjusted by making the structure of the adjustment section, which is the part of the reflector opposite the feed line, different from the structure of the area surrounding the adjustment section.

Description

Technical Field

[0001] The present disclosure relates to an antenna device including a radiator and a reflector, the reflector being formed of a plate-like 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-like members using an electrical conductor, and these are housed in a case in a facing state. Patent Document 1 describes a technique for using a plate-like member using an electrical conductor having a large number of diamond-shaped openings as a reflector, and widening the frequency bandwidth of radio waves that can be reflected by the reflector to the lower frequency side, so that broadband radio waves such as television broadcast waves can be received by a single 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 prior art has a structure in which openings of the same size are arranged, and can only correspond to a specific single frequency according to the size of the openings. For this reason, there is a problem that it is difficult to improve the characteristics on the middle and high frequency sides while maintaining the characteristics on the low frequency side improved by the prior art.

[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 constructed using an electrical conductor and is positioned opposite the radiator at a distance from it. The radiator is fed via a feed line. The antenna characteristics are adjusted by making the structure of the adjustment section, which is the part of the reflector facing the feed line, different from the structure of the area surrounding the adjustment section.

[0007] With this configuration, the characteristics of the reflector, and consequently the characteristics of the antenna device, can be varied in various ways by appropriately selecting the structure of the adjustment section. In one aspect of this disclosure, the adjustment unit may have a removal unit obtained by removing at least a portion of the member forming the reflector. With such a configuration, the gain decreases as the area of ​​the electrically conductive part in the reflector decreases, but the VSWR is improved.

[0008] In one aspect of this disclosure, the adjustment unit may include one or more transverse members made of electrical conductors arranged to traverse the removal unit. With such a configuration, the VSWR deteriorates, but the gain can be improved compared to the case without transverse members.

[0009] In one aspect of this disclosure, the antenna characteristics may be adjusted by adjusting at least one of the width and number of the transverse members. With such a configuration, increasing the width of the transverse members or increasing the number of transverse members degrades the VSWR, but improves the gain.

[0010] In one aspect of this disclosure, the reflector may be constructed by arranging linear members made of an electrical conductor in a grid pattern. The antenna characteristics may be adjusted by adjusting at least one of the width and number of the linear members located in the adjustment section.

[0011] In one aspect of this disclosure, the reflector may have a plate-shaped member made of a non-electrical conductor and a conductive layer made of an electrical conductor covering the surface of the plate-shaped member. In this case, the adjustment unit may be configured by removing a portion of the conductive layer. [Brief explanation of the drawing]

[0012] [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, reflector, and feed line that make up the antenna device. [Figure 4] This is an explanatory diagram showing the relative positions of the radiator, reflector, and power supply line. [Figure 5] This is an explanatory diagram illustrating comparative pattern 1, which is a conventional pattern of slots formed in a reflector, and patterns 1 to 3 according to this disclosure. [Figure 6] This is an explanatory diagram illustrating other patterns 4-7 of slots to be formed in the reflector. [Figure 7] This table shows the directional gain and VSWR values ​​calculated by simulation for antenna devices employing comparison pattern 1 and patterns 1-7. [Figure 8] This graph shows the simulation results for comparison pattern 1 and the antenna device using pattern 1. [Figure 9] This graph shows the simulation results of antenna devices using comparison patterns 1 and 2-5. [Figure 10] This graph shows the simulation results of antenna devices using comparison patterns 1 and 2, 3, 6, and 7. [Figure 11] This is an explanatory diagram illustrating pattern 8, which is a slot formed in the reflector of the second embodiment, and comparative pattern 2 of a conventional device in which no slot is formed. [Figure 12]This is a table showing the values of the directivity gain and VSWR calculated by simulation for the antenna device adopting comparison pattern 2 and pattern 8. [Figure 13] This is a graph showing the simulation results of the antenna device adopting comparison pattern 2 and pattern 8. [Embodiments for Carrying Out the Invention]

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. [1. First Embodiment] [1-1. Configuration] As shown in FIGS. 1 and 2, the antenna device 2 of this embodiment has a synthetic resin case 10.

[0014] 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.

[0015] Inside the case 10, a pair of radiators 20A, 20B and a pair of reflectors 50A, 50B are arranged. The pair of radiators 20A, 20B constitutes a stacked radiator. The reflector 50A is arranged opposite to the radiator 20A, and the reflector 50B is arranged corresponding to the radiator 20B.

[0016] Since the radiators 20A, 20B have the same configuration, when there is no need to particularly distinguish between the two, they are denoted as the radiator 20. Also, since the reflectors 50A, 50B have the same configuration, when there is no need to particularly distinguish between the two, they are denoted as the reflector 50.

[0017] 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, 28 for forming a pair of loops 22, 24, and a connecting hole 30 connecting the opening holes 26, 28.

[0018] In the radiator 20, on both sides of the connecting hole 30, there are feed points 32 and 34 for connecting elongated plate-shaped feed lines 42 and 44, which are made of an electrical conductor.

[0019] The radiators 20A and 20B are arranged with the surfaces of their respective metal plates on the same plane, and the loop 24 (i.e., opening 28) sides of each metal plate facing each other, spaced apart. Radiators 20A and 20B are electrically connected via feed lines 42 and 44. Feed line 42 connects the feed points 32 of radiators 20A and 20B to each other, and feed line 44 connects the feed points 34 of radiators 20A and 20B to each other. The midpoints of each feed line 42 and 44 are used as common feed points 46 and 48 for each radiator 20A and 20B, to which power supply cables (not shown) are connected.

[0020] In the following, the direction in which radiators 20A and 20B are aligned is referred to as the Y-axis direction. The direction perpendicular to the Y-axis and along the plate surface of radiator 20 is referred to as the X-axis direction. The direction perpendicular to the X-axis direction and the Y-axis direction is referred to as the Z-axis direction.

[0021] Radiator 20B is positioned in the same orientation as radiator 20A, but inverted along the Y-axis. Radiator 20 emits linearly polarized waves with a polarization plane parallel to the X-axis. Radiator 20 and reflector 50 are positioned with a gap between them along the Z-axis.

[0022] 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 comprises a reflector body 52 and side wall portions 54 and 56. The reflector body 52 is the portion whose plate surface is arranged along the X-Y plane. The reflector body 52 is large enough to cover the entire plate surface of the opposing 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.

[0023] Reflectors 50A and 50B are arranged in the same way as radiators 20A and 20B, aligned along the Y-axis, with reflector 50B being positioned as an inverted version of reflector 50A along the Y-axis. In the following, the side of reflector 50B from the perspective of reflector 50A, and the side of reflector 50A from the perspective of reflector 50B, will be referred to as the center side.

[0024] The reflector body 52 comprises an outer frame 521 that forms the outer circumference of the reflector body 52, and an inner frame 522 that is arranged in a grid pattern inside the outer frame 521 so that multiple rhombus-shaped openings (hereinafter referred to as slots) SL of the same size and shape are formed.

[0025] In the following, multiple slots SL arranged in a line along the X-axis will be called the X-axis slot group, and multiple slots SL arranged along the Y-axis will be called the Y-axis slot group. Here, as shown in Comparison Pattern 1 in Figure 5 (i.e., the conventional reflector), we assume that there are six rows of X-axis slot groups SX1 to SX6 and five rows of Y-axis slot groups SY1 to SY5. Furthermore, a slot belonging to both the X-axis slot group SXi (i=1 to 6) and the Y-axis slot group SYj (j=1 to 5) will be denoted as SLij.

[0026] The reflector 50 of the antenna device 2 according to this disclosure is provided with an adjustment section 58 in the portion facing the feed lines 42 and 44, as shown in pattern 1 of Figures 3, 4 and 5. The adjustment section 58 is formed between slots SL22 and SL24 and is formed by removing the X-shaped inner frame 522 located in the portion corresponding to the adjustment section 58 in comparison pattern 1. However, in slot SL22, the two ends of the inner frame 522 located at the boundary with the adjustment section 58 are connected using a frame similar to the inner frame 522. The same applies to the slot SL24 side. Frames arranged along the Y axis at both ends of the adjustment section 58 in the X-axis direction and formed integrally with the inner frame 522 are hereinafter referred to as adjustment section frame 523.

[0027] Because the adjustment section 58 is formed, slots SL13 and SL33 have a structure in which they are connected as one. In the X-axis slot group SX5, linear partitions 524 are placed inside slots SL51 and SL55 located at both ends in the Y-axis direction, and slots SL51 and SL55 are each divided into three sub-slots. In addition, the non-rhomboid slot formed by the inner frame 522 and outer frame 521 of slot SL13 located in the center of the X-axis slot group SX1 has a linear partition 524 placed inside and is divided into two sub-slots. Furthermore, in comparison pattern 1, the inner frame 522 at the boundary between slots SL31 and SL35 located at both ends of the X-axis slot group SX3 and the triangular slots located at both ends of the X-axis slot group SX2 is omitted in the reflector 50 of this disclosure.

[0028] The antenna characteristics of the antenna device 2 are adjusted by appropriately selecting the structure of the adjustment unit 58. Figures 5 and 6 illustrate seven different patterns of the structure of the adjustment unit 58. Pattern 1 is a basic structure in which nothing is provided in the adjustment section 58.

[0029] Pattern 2 has a structure in which a pair of adjustment frame bodies 523 in the adjustment section 58 are connected by a single transverse member 525 having the same width as the inner frame body 522. Pattern 3 has a structure in which a pair of adjustment frame bodies 523 in the adjustment section 58 are connected by two transverse members 525 having the same width as the inner frame body 522.

[0030] Pattern 4 has a structure in which a pair of adjustment frame bodies 523 in the adjustment section 58 are connected by three transverse members 525 having the same width as the inner frame body 522. Pattern 5 has a structure in which the entire space between the pair of adjustment frame bodies 523 in the adjustment section 58 is covered with a plate-shaped transverse member 526 made of an electrical conductor.

[0031] Pattern 6 has a structure in which a pair of adjustment frame bodies 523 in the adjustment section 58 are connected by a single transverse member 527 that is thinner than the transverse member 525. Pattern 7 has a structure in which a pair of adjustment frame bodies 523 in the adjustment section 58 are connected by two transverse members 527 that are narrower than the transverse member 525.

[0032] [1-2. Operation] The basic path is the electromagnetic wave propagation path whose path length is the dimension of the reflector body 52 along the X-axis. In addition, a bypass path is defined as the path through which electromagnetic waves propagate between two points located at both ends of the reflector body 52 along the X-axis, along the inner frame 522, adjustment frame 523, partition 524, and transverse members 525-527.

[0033] 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 path length of the basic route is set to a length suitable for reflecting the upper frequency limit of electromagnetic waves transmitted or received by the antenna device 2.

[0034] The characteristics of the feed lines 42 and 44 vary depending on the structure of the adjustment unit 58, that is, the area of ​​the electrically conductive portion of the reflector 50 facing the feed lines 42 and 44. Similarly, the characteristics of the reflector 50 also vary depending on the structure of the adjustment unit 58, as this changes the path length of the detour path formed. In other words, by appropriately selecting the structure of the adjustment unit 58 and changing the characteristics of the feed lines 42 and 44 and the reflector 50, the antenna characteristics of the antenna device 2 can be changed.

[0035] [1-3. Measurement] By placing experimental radiators 20A and 20B in front of each reflector 50A and 50B in patterns 1 to 7 shown in Figures 5 and 6, an antenna device 2 for receiving television broadcasts (UHF band, frequency: 470MHz to 770MHz) was constructed and simulations were performed.

[0036] 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 sections 54 and 56 from the plate surface of the reflector body 52 is 15 mm. The width of the transverse member 525 is 5 mm, and the width of the transverse member 527 is 1 mm.

[0037] For comparison, a similar simulation was performed on comparison pattern 1, which is a typical example of a conventional reflector 50. Comparison pattern 1 has a structure in which rectangular slots of the same size are arranged regularly, that is, a structure without the adjustment section 58.

[0038] Figure 7 is a table showing the antenna characteristics of antenna device 2, including directional gain, VSWR (i.e., standing wave ratio), and values ​​calculated by simulation. Figures 8 to 10 are graphs based on the calculated values ​​from the simulation.

[0039] As shown in Figure 8, when using the reflector 50 of pattern 1, the directivity gain decreases across the entire operating frequency band compared to when using the reflector 50 of comparison pattern 1 (hereinafter referred to as the conventional device), but the characteristics become flat across the entire band, and a wide bandwidth can be obtained. The VSWR is improved across the entire operating frequency band.

[0040] As shown in Figure 9, when reflectors 50 of patterns 2 and 3 are used, the directional gain deviates more from the characteristics of pattern 1 as the number of transverse members 525 increases, and approaches the characteristics of comparison pattern 1 (i.e., the conventional device). When reflectors 50 of patterns 4 and 5 are used, the directional gain is greater than that of comparison pattern 1 across the entire operating frequency range. For patterns 2 and 3, the VSWR is improved compared to the characteristics of comparison pattern 1 across almost the entire operating frequency range, and for pattern 2 in particular, the low-frequency side is improved compared to pattern 1. For patterns 4 and 5, characteristics similar to those of comparison pattern 1 are obtained in the mid-frequency range, and are increased compared to comparison pattern 1 at both the high and low frequency ends.

[0041] As shown in Figure 10, when using reflectors 50 with patterns 6 and 7, which have narrower partition line widths than patterns 2 and 3, the characteristics are closer to those of pattern 1 when the partition line width is narrower. The VSWR is improved in both patterns 6 and 7 over almost the entire operating frequency range compared to the characteristics of comparison pattern 1, and is particularly improved at low frequencies.

[0042] Thus, it can be seen that by changing the structure of the adjustment unit 58, the frequency characteristics of the directivity gain and VSWR change in various patterns. As a general trend, in the adjustment unit 58, reducing the number of partition pieces that cross the feed lines 42 and 44, or narrowing the width of the partition pieces, the directivity gain decreases, but the VSWR improves. Conversely, in the adjustment unit 58, increasing the number of partition pieces that cross the feed lines 42 and 44, or widening the width of the partition pieces, the VSWR deteriorates, but the directivity gain improves.

[0043] [1-4. Correspondence of Terms] In this embodiment, the inner frame 522 corresponds to the linear member of the present disclosure, and the space between the pair of adjustment frame 523 that form the adjustment section 58 corresponds to the removal section of the present disclosure.

[0044] [1-5. Effects] The embodiments described in detail above produce the following effects. (1a) In the antenna device 2, an adjustment section 58 is provided on the reflector 50 facing the feed lines 42 and 44, with the inner frame 522 that crosses the feed lines 42 and 44 removed. In other words, the adjustment section 58 has a different structure from the surrounding area. By appropriately selecting the structure of the adjustment section 58 which is deformed by the transverse members 525 to 527, the characteristics of the feed lines 42 and 44 and the characteristics of the reflector 50 can be changed, and consequently the antenna characteristics of the 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.

[0045] [2. Second Embodiment] [2-1. Differences from the First Embodiment] The second embodiment has the same basic configuration as the first embodiment, so the differences will be explained below. Note that the same reference numerals as in the first embodiment indicate the same components, and refer to the preceding description.

[0046] In the first embodiment described above, the case in which the adjustment section 58 is formed based on a reflector 50 constructed using an inner frame 522 that forms a diamond-shaped slot SL, as shown in comparison pattern 1. In contrast, the second embodiment differs from the first embodiment in that, as shown in comparison pattern 2 of Figure 11, the adjustment section 58 is formed based on a reflector 50 in which the reflector body 52 is constructed of a plate-shaped member using an electrical conductor.

[0047] In this embodiment, as shown in pattern 8 of Figure 11, the reflector 50 has a rectangular slot SL, which serves as an adjustment section 58, formed in the part of the reflector body 52 facing the power supply lines 42 and 44, which are made of plate-shaped members using an electrical conductor.

[0048] Figure 11 shows a reflector 50 as comparison pattern 2, which has a reflector body 52 made of a plate-shaped member using an electrical conductor and does not have an adjustment section 58, i.e., no slot SL is formed.

[0049] [2-2. Measurement] A simulation was performed using the same conditions as in the first embodiment, with comparison pattern 2 (which removes the adjustment unit 58 from pattern 8) and the reflectors 50A and 50B of pattern 8. In the simulation, the directional gain and VSWR were calculated as antenna characteristics of antenna device 2. Figure 12 is a table showing the calculated values ​​from the simulation. Figure 13 is a graph based on the calculated values ​​from the simulation.

[0050] When using the reflector 50 of pattern 8, the directivity gain decreases across the entire operating frequency band compared to when using the reflector 50 of comparison pattern 2 (hereinafter referred to as the conventional device), but the characteristics become flat across the entire band, and a wide bandwidth can be obtained. In addition, the VSWR is improved across the entire operating frequency band, and is particularly significantly improved in the low and mid frequencies.

[0051] [2-3. Effects] The second embodiment described in detail above provides the following effects. (2a) Even if the reflector 50 is of a different type than that of the first embodiment, by providing the adjustment unit 58, the antenna characteristics can be improved compared to a conventional device that uses a reflector 50 without the adjustment unit 58.

[0052] Furthermore, similar to the first embodiment, by providing various transverse members 525 to 527, etc., in the adjustment section 58 and appropriately selecting the structure of the adjustment section 58, finer adjustment of the antenna characteristics can be achieved.

[0053] [3. Other Embodiments] Although embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0054] (3a) In the first embodiment, the shape of the slot SL provided in the reflectors 50A and 50B is rhombic, but it is not necessary to make it rhombic, and any shape such as any polygon or ellipse can be used.

[0055] (3b) 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) made by forming two openings 26 and 28 in a metal plate which is an electrical conductor. However, the radiator may be a dipole type or a planar antenna of another type.

[0056] (3c) 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.

[0057] (3d) In the above embodiment, the reflector body 52 is formed of a metal plate, and the adjustment portion 58 is formed by removing the portion of the reflector body 52 that faces the power supply lines 42 and 44. If the reflector body 52 is formed of a plate-shaped member made of a non-electrically conductive material and a conductive layer covering the surface of the plate-shaped member, the adjustment portion 58 may be formed by removing only the conductive layer in the facing portion.

[0058] (3e) 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 configurations of the above embodiment may be omitted. Also, at least some of the configurations of the above embodiment may be added to or replaced with the configurations of other above embodiments.

[0059] (3f) In addition to the antenna device 2 described above, this disclosure can also be realized in various forms, such as a system that uses the antenna device 2 as a component, or an antenna characteristic adjustment method. [Explanation of symbols]

[0060] 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, 32,34,46,48...Feed point, 42,44...Feed line, 50...Reflector, 52...Reflector body, 54,56...Side wall, 58...Adjustment section, 521...Outer frame, 522...Inner frame, 523...Adjustment section frame, 524...Partition, 525~527...Transverse members, 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 constructed using an electrical conductor and positioned opposite the radiator at a distance from it, Equipped with, The aforementioned radiator is powered via a power line, By making the structure of the adjustment section, which is the part of the reflector facing the feed line, different from the structure of the area surrounding the adjustment section, the antenna characteristics are adjusted. Antenna device.

2. The antenna device according to claim 1, The adjustment section has a removal section obtained by removing at least a portion of the member forming the reflector. Antenna device.

3. The antenna device according to claim 2, The adjustment section comprises one or more transverse members made of an electrical conductor, arranged to traverse the removal section. Antenna device.

4. The antenna device according to claim 3, The antenna characteristics are adjusted by adjusting at least one of the width and number of the aforementioned cross-sectional members. Antenna device.

5. An antenna device according to any one of claims 1 to 4, The reflector is constructed by arranging linear members made of electrical conductors in a grid pattern. The antenna characteristics are adjusted by adjusting at least one of the width and number of the linear members located in the adjustment section. Antenna device.

6. An antenna device according to any one of claims 1 to 4, The reflector comprises a plate-shaped member made of a non-electrical conductor and a conductive layer made of an electrical conductor covering the surface of the plate-shaped member. The adjustment section is formed by removing a portion of the conductive layer. Antenna device.

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