Antenna

Abstract

This antenna comprises: a substrate; a first conductor part that is formed on the substrate and to which a signal line is connected; a second conductor part that is formed on the substrate and to which a ground line is connected; a third conductor part that is formed on the substrate and that operates as a sleeve dipole antenna together with the first conductor part and the second conductor part; and a power supply part that is positioned between the first conductor part and the second conductor part. The second conductor part has two extension parts that extend from the power supply part, and a line part that extends from the power supply part and is positioned between the two extension parts. The third conductor part is positioned between the power supply part and an end part of one of the extension parts, and connects the one extension part and the line part.

Description

Antenna

[0001] The present invention relates to an antenna.

[0002] Patent Document 1 discloses an antenna formed on a flat substrate.

[0003] Japanese Patent Application Laid-Open No. 2012-244347

[0004] By the way, for an antenna formed on a flat substrate such as in Patent Document 1, it may be required to have good voltage standing wave ratio characteristics in a wide frequency band.

[0005] An example of the object of the present invention is to provide an antenna having good voltage standing wave ratio characteristics in a wide frequency band. Other objects of the present invention will become apparent from the description herein.

[0006] One aspect of the present invention includes a substrate, a first conductor portion formed on the substrate to which a signal line is connected, a second conductor portion formed on the substrate to which a ground line is connected, a third conductor portion formed on the substrate that operates as a sleeve dipole antenna together with the first conductor portion and the second conductor portion, and a feeding portion located between the first conductor portion and the second conductor portion. The second conductor portion has two extending portions extending from the feeding portion and a line portion extending from the feeding portion and located between the two extending portions. The third conductor portion is located between the feeding portion and an end of one of the extending portions and connects the one extending portion and the line portion. It is an antenna.

[0007] According to one aspect of the present invention, an antenna having good voltage standing wave ratio characteristics in a wide frequency band can be provided.

[0008] This is an exploded perspective view of the first example antenna 10 of this embodiment. This is a view of the antenna 10 from the front. This is a view of the antenna 10 from the back. This is a cross-sectional view of the line portion of the antenna 10. This is a schematic diagram of the cross-section of the line portion of the antenna 10. This is a diagram showing the measurement results of the voltage standing wave ratio characteristics of the antenna 10 in the 2.4 GHz band, 5 GHz band, and 6 GHz band. This is a diagram showing the measurement results of the voltage standing wave ratio characteristics of the antenna 10 in the 2.4 GHz band. This is a diagram showing the measurement results of the voltage standing wave ratio characteristics of the antenna 10 in the 5 GHz band and 6 GHz band. This is a view of the comparative example antenna 100 from the front. This is a view of the antenna 100 from the back. This is a diagram showing the measurement results of the voltage standing wave ratio characteristics of the antenna 100 in the 2.4 GHz band, 5 GHz band, and 6 GHz band. This is a diagram showing the measurement results of the voltage standing wave ratio characteristics of the antenna 100 in the 2.4 GHz band. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 100 in the 5GHz and 6GHz bands. This is a view of the second example antenna 80 from the front. This is a view of antenna 80 from the back. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 80 in the 2.4GHz, 5GHz, and 6GHz bands. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 80 in the 2.4GHz band. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 80 in the 5GHz and 6GHz bands. This is a view of the third example antenna 90 from the front. This is a view of antenna 90 from the back. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 90 in the 2.4GHz, 5GHz, and 6GHz bands. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 90 in the 2.4GHz band. This figure shows the measurement results of the voltage standing wave ratio characteristics of antenna 90 in the 5 GHz and 6 GHz bands.

[0009] The following matters will become clear from this specification and the accompanying drawings. Preferred embodiments of the present invention will be described below with reference to the drawings.

[0010] In the following, identical or equivalent components, members, etc., shown in each drawing will be denoted by the same reference numeral, and redundant explanations will be omitted as appropriate.

[0011] Furthermore, when it is necessary to distinguish between individual elements of a cohesive overall structure, identifiers may be attached to the code indicating the cohesive structure to distinguish each element.

[0012] Furthermore, when it is necessary to distinguish between similar configurations, identifiers may be assigned to a code that collectively refers to each configuration to differentiate them individually.

[0013] In the following, "to connect" is not limited to physical connection, but also includes "to connect electrically." Furthermore, "to connect electrically" includes, for example, connecting objects with a conductor, or connecting them with electronic circuits, electronic components, etc. In addition, "to connect electrically" includes electrical coupling such as capacitive coupling and electrostatic coupling, as well as electromagnetic coupling such as electromagnetic induction.

[0014] In the following, the "length" of the components (elements) that make up the antenna refers to the "electrical length".

[0015] ==Antenna of the First Example== Figure 1 shows an exploded perspective view of the antenna 10 shown as the first example of this embodiment. Figure 2A shows the antenna 10 viewed from the front side. Figure 2B shows the antenna 10 viewed from the back side.

[0016] As shown in Figures 1, 2A, and 2B, the antenna 10 has a configuration in which various components are mounted on a substrate 11.

[0017] <Definition of Direction, etc.> First, the direction, plane, shape, etc. of the antenna 10 are defined with reference to Figures 1, 2A, and 2B.

[0018] In the following, the side of the substrate 11 on which the cable connection portion 12 is provided will be referred to as the "front side," and the side opposite the front side will be referred to as the "back side." The direction perpendicular to the surface of the substrate 11 (the direction perpendicular to the surface) will be defined as the X direction. The direction from the front side of the substrate 11 toward the back side will be defined as the +X direction, and the direction from the back side of the substrate 11 toward the front side will be defined as the -X direction.

[0019] The direction in which the pair of front-side second track sections 31A are aligned is defined as the Y direction, and the direction in which the first track section 21 extends is defined as the Z direction. The +Y and +Z directions are determined so that, together with the +X direction mentioned above, they form a right-handed triaxial system. The -Y and -Z directions are determined as the opposite directions of the +Y and +Z directions, respectively.

[0020] In Figures 1, 2A, and 2B, the +X, +Y, and +Z directions are represented by line segments with arrows to facilitate understanding of the antenna 10's direction. The intersection of these line segments with arrows does not represent the coordinate origin.

[0021] The outer shape of the substrate 11 of the antenna 10 is roughly rectangular. Here, the Y direction is sometimes referred to as the "width direction" and the Z direction as the "length direction". The Y direction is the direction along the shorter side of the substrate 11, and the Z direction is the direction along the longer side of the substrate 11.

[0022] The "approximately rectangular" shape described above is included in the "approximately quadrilateral" shape. An "approximately quadrilateral" shape is, for example, a shape consisting of four sides, and for example, at least some of the corners may be cut diagonally relative to the sides. In the shape of an "approximately quadrilateral," some of the sides may have notches (recesses) or protrusions (convex parts). Furthermore, a coaxial cable 1 is connected to the antenna 10 in a direction along the longitudinal direction of the substrate 11. The characteristics of the shape of the substrate 11 and the direction in which the coaxial cable 1 extends help in understanding the direction of the antenna 10.

[0023] Unless otherwise specified, the definitions of directions, etc., described above are common throughout this embodiment.

[0024] <Overview of the First Example Antenna> The overview of the first example antenna 10 of this embodiment will be described with reference to Figures 1, 2A, and 2B.

[0025] Antenna 10 is, for example, a broadband antenna for mobile communications. Antenna 10 is compatible with radio waves in frequency bands used for Wi-Fi®, Bluetooth®, etc. (for example, the 2.4 GHz band, 5 GHz band, and 6 GHz band).

[0026] Antenna 10 is compatible with linear polarization. Linear polarization is sometimes called vertical polarization when the polarization plane is perpendicular to the ground, and horizontal polarization when the polarization plane is horizontal to the ground.

[0027] The communication standards and frequency bands that antenna 10 supports are not limited to those described above, and antenna 10 may support other communication standards and frequency bands. Antenna 10 may support radio waves in at least some of the frequency bands used for telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, vehicle-to-infrastructure communication), GSM (Global System for Mobile Communications), UMTS (Universal Mobile Telecommunications System), LTE (Long Term Evolution), and 5G.

[0028] Antenna 10 may also support MIMO (Multiple-Input Multiple-Output) communication. In MIMO communication, data is transmitted from each of the multiple antennas 10, and the data is received simultaneously by the multiple antennas 10.

[0029] Antenna 10 may also be compatible with antennas for keyless entry or smart entry.

[0030] As shown in Figures 1, 2A, and 2B, a coaxial cable 1, which is a feed line, is connected to the antenna 10. The coaxial cable 1 has an internal conductor, which is a signal line 2, and an external conductor, which is a ground line. In this embodiment, the ground line 3 is covered with a sheath.

[0031] In Figures 1 and 2A, the ground line 3 is shown as a dashed line. The signal line 2 is connected to the first conductor portion 20 formed on the substrate 11. The ground line 3 is connected to the second conductor portion 30 formed on the substrate 11.

[0032] The antenna 10 includes a circuit board 11, a cable connection section 12, a first conductor section 20, a second conductor section 30, a third conductor section 35, and a power supply section 40.

[0033] The first conductor section 20, the second conductor section 30, and the third conductor section 35 constitute a sleeve dipole antenna. This enables the antenna 10 to be made smaller and thinner, and also suppresses leakage current.

[0034] The substrate 11 is a plate-shaped member on which the conductor patterns constituting the first conductor portion 20, the second conductor portion 30, and the third conductor portion 35 are formed. In this embodiment, the substrate 11 is a rigid substrate, which is a printed circuit board (PCB). The substrate 11 may be other types of substrates, such as a flexible substrate. In addition to the conductor patterns constituting the first conductor portion 20, the second conductor portion 30, and the third conductor portion 35, the substrate 11 may also be provided with circuit elements such as filters.

[0035] The substrate 11 has a dielectric layer 16. The dielectric layer 16 is formed of a dielectric material. In this embodiment, the dielectric layer 16 is formed of a dielectric material such as glass epoxy resin used in printed circuit boards. The dielectric layer 16 may also be formed of a dielectric material other than glass epoxy resin, such as phenolic resin.

[0036] The substrate 11 is a double-sided substrate (two-layer substrate) in which a conductive pattern is formed on both sides of a single dielectric layer 16. The substrate 11 may also be a single-sided substrate (one-layer substrate) in which a conductive pattern is formed on one side of a single dielectric layer 16. Furthermore, the substrate 11 may be configured as a three-layer substrate by having a dielectric layer other than the dielectric layer 16, or it may be configured as a multilayer substrate with four or more layers.

[0037] As shown in Figure 1, in the following, the layer on the front side of the substrate 11 on which the conductor pattern, etc., is formed will be referred to as the "first layer 13". The layer on the back side of the substrate 11 on which the conductor pattern, etc., is formed will be referred to as the "second layer 14".

[0038] The cable connection section 12 is a component for connecting the coaxial cable 1 to the antenna 10. As shown in Figure 1, the cable connection section 12 is composed of a ring-shaped retaining member that holds the end of the coaxial cable 1. The retaining member is joined to the substrate 11 by soldering. The cable connection section 12 is not limited to the exemplary embodiment, and may be composed of, for example, a connector. The cable connection section 12 is provided at the -Z direction end of the substrate 11. As a result, the coaxial cable 1 is connected to the end of the substrate 11.

[0039] As shown in Figures 1 and 2B, the substrate 11 has a notch 11A. The notch 11A is a region formed by cutting out the edge of the substrate 11. The cable connection portion 12 is located in the notch 11A. A part of the retaining member that holds the end of the coaxial cable 1 is positioned inside the notch 11A. Both sides of the retaining member in the Y direction are joined to the edge of the notch in the substrate 11 by soldering. As a result, the coaxial cable 1 is positioned inside the notch 11A, and the thickness (size in the X direction) of the antenna 10 to which the coaxial cable 1 is connected can be reduced, making it possible to miniaturize and thin the antenna 10. In addition, since the retaining member that holds the end of the coaxial cable 1 can be positioned to straddle the notch, soldering the retaining member to the substrate 11 can be made easier.

[0040] Thus, by having the substrate 11 have a notch 11A and the cable connection portion 12 located in the notch 11A, it becomes easier to connect the coaxial cable 1 to the antenna 10. Furthermore, it becomes possible to miniaturize and thin the antenna 10 to which the coaxial cable 1 is connected.

[0041] The first conductor section 20 is connected to the signal line 2 of the coaxial cable 1. The first conductor section 20 includes a first line section 21 provided on the first layer 13 (the front-facing layer of the substrate 11), a first extension section 22 (including a bent section 23) provided on the second layer 14 (the back-facing layer of the substrate 11), and a through-hole 24.

[0042] The second conductor part 30 is connected to the ground wire 3 of the coaxial cable 1. The second conductor part 30 has a second line part 31, a second extension part 32, and a third conductor part 35.

[0043] The second line part 31 has a front-side second line part 31A, a back-side second line part 31B, and a through hole 31C that connects the front-side second line part 31A and the back-side second line part 31B.

[0044] The second extension part 32 has a main body part 32A, an additional part 32B, and a through hole 32C that connects the main body part 32A and the additional part 32B.

[0045] The third conductor part 35 is located between the power supply part 40 and the end of the second extension part 32, and connects the second extension part 32 and the second line part 31.

[0046] Both the first conductor part 20 and the second conductor part 30 are conductor patterns formed on the substrate 11, and function as elements that resonate in the corresponding radio wave frequency band of the antenna 10. Thus, by forming the elements of the antenna 10 as conductor patterns on the substrate 11, the thickness of the entire antenna 10 is reduced, and the antenna 10 can be made thinner. Furthermore, the degree of freedom in arranging the antenna 10 can be improved. Also, by forming the elements of the antenna 10 as conductor patterns on the substrate 11, it becomes easier to hold the elements.

[0047] The power supply part 40 is an area including the power supply part in the antenna 10. As shown in FIG. 2B, the power supply part 40 is located between the first conductor part 20 and the second conductor part 30.

[0048] The first line part 21 of the first conductor part 20 is a part where a configuration corresponding to the signal line 2 of the coaxial cable 1 is mounted on the substrate 11. As shown in FIGS. 1 and 2A, the first line part 21 is formed on the first layer 13 of the substrate 11. The end on the -Z direction side of the first line part 21 is connected to the signal line 2 of the coaxial cable 1. Also, the end on the +Z direction side of the first line part 21 is connected to the first extension part 22 via the through hole 24.

[0049] The first extended portion 22 (including the bent portion 23), together with the second extended portion 32 described later, is a part mounted on the substrate 11 that functions as an element that resonates in the corresponding frequency band of the radio waves of the antenna 10. For this reason, the first extended portion 22 is formed to have a length and width corresponding to the wavelength used in the corresponding frequency band of the radio waves of the antenna 10.

[0050] In this embodiment, the length of the first extension portion 22 from the power supply portion 40 is formed to resonate with signals in the 2.4 GHz band, and is formed to a length equivalent to one-quarter of the wavelength of radio waves in the 2.4 GHz band.

[0051] However, the wavelength of the antenna 10 in the corresponding frequency band of radio waves is not necessarily expressed as an even integer. Also, the actual length of the first extension section 22 from the feed section 40 changes due to various factors. For this reason, in this embodiment, if we describe the wavelength of the antenna 10 in the corresponding frequency band of radio waves as "one-quarter" or "one-half," the specific length does not necessarily have to be exactly "one-quarter" or "one-half" of the wavelength, but any value that resonates with the radio waves in the desired frequency band is sufficient.

[0052] As shown in Figure 2B, the first extensions 22 are formed to extend from the power supply unit 40 to both sides in the Y direction (+Y direction side and -Y direction side). The length of each of the first extensions 22 extending from the power supply unit 40 to both sides in the Y direction is formed to correspond to one-quarter of the wavelength in the frequency band of the corresponding radio waves of the antenna 10.

[0053] As shown in Figures 1 and 2B, the first extension portion 22 is formed in the second layer 14 of the substrate 11. The end of the first extension portion 22 on the -Z direction side is connected to the first line portion 21 via a through-hole 24.

[0054] The first extended portion 22 has a bent portion 23 that bends and extends further from the end of the first extended portion 22 on the +Z direction side. In this way, by having the bent portion 23 in the first extended portion 22, even when the substrate 11 is small, it is possible to secure the length necessary to resonate the antenna 10 in the corresponding radio wave frequency band. The bent portion 23 may be any shape that further extends the first extended portion 22, and is not limited to the example shape. For example, the bent portion 23 may have a curved shape, a bent shape, or a meandering shape. The bent portion 23 may also be called a bent portion, a meandering portion, etc.

[0055] The illustrated bent portion 23 is formed to bend inward from the first extended portion 22, but it may also be formed to bend outward. Furthermore, the bent portion 23 may be formed to extend from an end other than the +Z direction end of the first extended portion 22. In addition, in this example, the bent portion 23 is formed in a similar shape on each of the first extended portions 22 extending on both sides in the Y direction, but the bent portion 23 may be formed on only one of the first extended portions 22.

[0056] Furthermore, each of the first extended portions 22 extending in the Y direction may have a different shape of bent portion 23 formed on it. For example, the end of the first extended portion 22 extending in the +Y direction may have a bent portion 23 that bends inward, and the end of the first extended portion 22 extending in the -Y direction may have a bent portion 23 that bends outward.

[0057] The through-hole 24 connects the first line portion 21 formed in the first layer 13 of the substrate 11 and the first extension portion 22 formed in the second layer 14 of the substrate 11.

[0058] The second line section 31 of the second conductor section 30 is a part on the substrate 11 in which a configuration corresponding to the ground wire 3 of the coaxial cable 1 is mounted. As shown in Figures 1 and 2A, the second line section 31 has a front-side second line section 31A formed on the first layer 13 of the substrate 11 and a back-side second line section 31B formed on the second layer 14 of the substrate 11.

[0059] Of these, the front-facing second line section 31A is formed extending in the Z direction along the first line section 21 of the first conductor section 20. The front-facing second line section 31A is formed in pairs on both sides of the first line section 21 in the Y direction. Each of the ends of this pair of front-facing second line sections 31A on the -Z direction side is connected to the ground wire 3.

[0060] On the other hand, the second track section 31B on the reverse side is formed to extend in the Z direction, similar to the second track section 31A on the front side. The end of the second track section 31B on the reverse side in the +Z direction is connected to the main body section 32A of the second extension section 32.

[0061] As shown in Figure 2B, the second line section 31B on the back side is provided between the cable connection section 12 and the power supply section 40. In this embodiment, the second line section 31 is arranged parallel to the first line section 21. However, as long as the first line section 21 and the second line section 31 are not connected to each other, the first line section 21 and the second line section 31 may not be parallel, or at least one of them may be curved or meandering.

[0062] The second line section 31 has a through-hole 31C. The through-hole 31C connects the front-side second line section 31A, which is formed in the first layer 13 of the substrate 11, and the back-side second line section 31B, which is formed in the second layer 14 of the substrate 11.

[0063] As shown in Figures 1 and 2A, multiple through-holes 31C are arranged in a line in the Z direction along the second line section 31A on the front side. Each through-hole 31C connects the second line section 31A on the front side to the second line section 31B on the back side. The numerous through-holes 31C function as if a wall formed of conductors were provided.

[0064] The second extension portion 32, together with the first extension portion 22, is a part mounted on the substrate 11 that functions as an element that resonates in the corresponding frequency band of the radio waves of the antenna 10. For this reason, the second extension portion 32 is formed to have a length and width corresponding to the wavelength used in the corresponding frequency band of the radio waves of the antenna 10.

[0065] As shown in Figures 1 and 2B, the second extension 32 is formed to extend from the power supply section 40 to both sides in the Y direction (+Y direction and -Y direction). In other words, the second extension 32 is formed to start from the power supply section 40 and sandwich the second line section 31B on the back side.

[0066] In the following, of the parts of the second extension 32 that extend from the power supply unit 40 in the Y direction, the part on the +Y direction side will be referred to as the second extension 321. The part on the -Y direction side will be referred to as the second extension 322.

[0067] The main body portion 32A of the second extension portion 321 is referred to as the main body portion 321A. Similarly, the main body portion 32A of the second extension portion 322 is referred to as the main body portion 322A.

[0068] The added portion 32B of the second extension portion 321 is referred to as the added portion 321B. Similarly, the added portion 32B of the second extension portion 322 is referred to as the added portion 322B.

[0069] The through-hole 32C of the second extension 321 is referred to as through-hole 321C. Similarly, the through-hole 32C of the second extension 322 is referred to as through-hole 322C.

[0070] The length of the second extension 32 from the power supply section 40, that is, the length from the power supply section 40 to the end of the extension section 321B (the end in the +Z direction) via the main body section 321A, the through-hole 321C, and the extension section 321B (hereinafter referred to as "first length L1"), is formed to resonate with 2.4 GHz band radio waves. Specifically, the first length L1 is formed to a length corresponding to one-quarter of the wavelength of 2.4 GHz band radio waves.

[0071] As shown in Figures 1 and 2B, the main body portion 32A (main body portion 321A, main body portion 322A), which is part of the second extension portion 32, is formed in the second layer 14 of the substrate 11.

[0072] On the other hand, the additional portion 32B (additional portion 321B, additional portion 322B), which is part of the second extension portion 32, is formed on the first layer 13 of the substrate 11. Here, the additional portion 32B is a part that is additionally provided to the main body portion 32A in order to secure the length necessary for the antenna 10 to resonate in the corresponding radio wave frequency band. In this example, both the additional portion 321B and the additional portion 322B are substantially rectangular in shape, extending parallel to the longitudinal direction of the first line portion 21 of the first layer 1.

[0073] The additional portion 32B (additional portion 321B, additional portion 322B) may be formed on the second layer 14 of the substrate 11, rather than on the first layer 13 of the substrate 11. For example, the additional portion 32B may be formed on the same layer as the main body portion 32A, such as the bent portion 23 of the first extension portion 22. However, in this case, the additional portion 32B would be formed to bend inward from the end of the main body portion 32A, and the additional portion 32B would couple with the back side second line portion 31B, potentially affecting the characteristics of the antenna 10. In contrast, in the example antenna 10, the additional portion 32B is provided on a different layer from the layer on which the main body portion 32A is formed, thereby minimizing the impact on the characteristics of the antenna 10 while ensuring the necessary length for resonance in the corresponding radio wave frequency band.

[0074] The through-holes 32C (through-holes 321C and 322C) are the parts that connect the addition portion 32B formed in the first layer 13 of the substrate 11 and the main body portion 32A formed in the second layer 14 of the substrate 11. The addition portion 321B and the main body portion 321A are electrically connected by the through-hole 321C. The addition portion 322B and the main body portion 322A are electrically connected by the through-hole 322C.

[0075] In the antenna 10 of this embodiment, as shown in Figure 1, the first extension portion 22 of the first conductor portion 20 and the second extension portion 32 of the second conductor portion 30 are located in the second layer 14 of the substrate 11. Within the region where the first conductor portion 20 and the second conductor portion 30, located in the second layer 14, face each other, the first conductor portion 20 and the second conductor portion 30 have a self-similar shape portion 41. This makes it possible to realize an antenna 10 that can handle a wide bandwidth.

[0076] Here, "self-similar shape" refers to a shape that remains similar even when the scale (size ratio) is changed. However, the first conductor portion 20 and the second conductor portion 30 do not necessarily have a self-similar shape portion 41.

[0077] In this embodiment, in the main body 321A, the width of the conductor pattern from part 45 to the end of the main body 321A (the end in the -Z direction) is wider than the width of the conductor pattern from the power supply part 40 to part 45. Similarly, in the main body 322A, the width of the conductor pattern from part 45 to the end of the main body 322A (the end in the -Z direction) is wider than the width of the conductor pattern from the power supply part 40 to part 45. This makes it possible to realize an antenna 10 that can handle a wide bandwidth.

[0078] In the following text, at least one of the first track section 21 and the second track section 31 may be simply referred to as the "track section." Also, at least one of the first extension section 22 and the second extension section 32 may be simply referred to as the "extension section."

[0079] Figures 3A and 3B illustrate the configuration of the transmission line section of the antenna 10. Figure 3A is a cross-sectional view of the transmission line section of the antenna 10, and Figure 3B is a schematic diagram of the cross-section of the transmission line section of the antenna 10.

[0080] As shown in Figure 3A, the line portion of the antenna 10 has a structure similar to a microstrip line, consisting of a second line portion 31B on the back side connected to the ground line 3 and a first line portion 21 connected to the signal line 2. Furthermore, the line portion of the antenna 10 has through-holes 31C on its side that function as conductors for grounding. Thus, as shown in Figure 3B, the antenna 10 of this embodiment has a shape in which half of the coaxial structure, consisting of the first line portion 21 connected to the signal line 2 and the second line portion 31 connected to the ground line 3, is formed.

[0081] <<Third Conductor Section>> Next, the third conductor section 35 will be described in detail.

[0082] As shown in Figures 1 and 2B, the third conductor section 35 is provided in the second layer 14 between the power supply section 40 and the end (the -Z direction end) of the main body section 322A of the second extension section 322. More specifically, the third conductor section 35 is provided in the second layer 14 parallel to the Y direction so as to bridge the gap between the main body section 322A of the second extension section 322 and the second line section 31B on the back side. As a result, the third conductor section 35 functions as a so-called short stub to connect the second extension section 322 and the second line section 31.

[0083] The length from the power supply unit 40, through the point where the third conductor unit 35 of the main body 322A is connected, to the point where the third conductor unit 35 is connected to the second line unit 31B on the back side (hereinafter referred to as "second length L2") is formed to be a length equivalent to half the wavelength of the 6 GHz band. The second length L2 can also be described as the length of the main body 322A from the power supply unit 40 to the point where the main body 322A and the third conductor unit 35 are connected, and the length of the third conductor unit 35.

[0084] As mentioned above, the first length L1 is formed to a length equivalent to one-quarter of the wavelength of the 2.4 GHz band radio waves. Therefore, the impedance of the antenna 10 to the 2.4 GHz band radio waves as seen from the feed point 40 is reduced, and leakage current is also suppressed.

[0085] The second length L2 is equivalent to half the wavelength of a 6GHz band radio wave. As a result, the impedance of the antenna 10 to the 6GHz band radio wave as seen from the feed point 40 is reduced, and leakage current is also suppressed.

[0086] As described above, in the first example, the antenna 10 has a low impedance as seen from the feed point 40 in all frequency bands, including the 2.4 GHz band, the 5 GHz band, and the 6 GHz band, and leakage current is suppressed in all frequency bands.

[0087] The inventors also conducted tests in the case where a third conductor portion 35 is provided on both the second extension portion 321 and the second extension portion 322. In this case, an increase in the impedance of the antenna 10 as seen from the feed portion 40 was confirmed in the 2.4 GHz band and the 5 GHz band.

[0088] <Verification of the first example antenna> Figures 4A to 4C all show the measurement results of the voltage standing wave ratio characteristics of the first example antenna 10.

[0089] Figure 4A shows the measurement results of the voltage standing wave ratio (VSWR) of antenna 10 in the frequency range (2.0 to 8.0 GHz) which includes the entire 2.4 GHz, 5 GHz, and 6 GHz bands. Figure 4B is a graph that shows an enlarged view of the frequency range of Figure 4A, specifically the 2.36 to 2.52 GHz range which includes the 2.4 GHz band. Figure 4C is a graph that shows an enlarged view of the frequency range of Figure 4A, specifically the 4.9 to 7.4 GHz range which includes the 5 GHz and 6 GHz bands.

[0090] In the graphs shown in each figure, the horizontal axis represents frequency (GHz), and the vertical axis represents the voltage standing wave ratio (VSWR). The graphs in each figure show the measurement results obtained by changing the length of the coaxial cable 1 connected via the cable connection part 12, and by changing the type of cable.

[0091] As shown in Figure 4B, the voltage standing wave ratio (VSWR) of the first example antenna 10 in the frequency range of 2.36 to 2.52 GHz, including the 2.4 GHz band, is at most 2.5 or less. Therefore, the antenna 10 has good voltage standing wave ratio characteristics in this frequency range.

[0092] As shown in Figure 4C, the voltage standing wave ratio (VSWR) of the first example antenna 10 in the frequency range of 4.9 to 7.4 GHz, including the 5 GHz and 6 GHz bands, is at most 2.5 or less. Therefore, the antenna 10 has good voltage standing wave ratio characteristics in this frequency range.

[0093] As described above, it was confirmed that the first example antenna 10 has good voltage standing wave ratio characteristics in all three bands: 2.4 GHz, 5 GHz, and 6 GHz.

[0094] <Verification by Comparison> Figures 5A and 5B show a comparative antenna 100, which was created for comparison with the first example antenna 10 of this embodiment, and the second example antenna 80 and the third example antenna 90 described later.

[0095] Figure 5A is a view of the antenna 100 from the front side, and Figure 5B is a view of the antenna 100 from the back side. The configuration of the comparative example antenna 100 is the same as that of the first example antenna 10, except that the third conductor portion 35 is not provided.

[0096] Figures 6A to 6C are graphs showing the measurement results of the voltage standing wave ratio characteristics of the comparative example antenna 100. In all graphs, the horizontal axis represents frequency (GHz), and the vertical axis represents the voltage standing wave ratio (VSWR). Each graph shows the measurement results obtained by changing the length of the coaxial cable 1 connected via the cable connection part 12, and also shows the results for different types of cable.

[0097] Comparing the graphs in Figure 4B and Figure 6B, we can see that in both graphs, the voltage standing wave ratio (VSWR) in the 2.4 GHz band shows little change (variation) with respect to frequency changes, indicating stability.

[0098] Comparing the graph in Figure 4C with the graph in Figure 6C, the graph in Figure 4C shows less variation (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes in the 5 GHz and 6 GHz bands compared to the graph in Figure 6C, indicating greater stability.

[0099] Thus, it was confirmed that even when a third conductor section 35 is provided, as in the first example antenna 10, it has almost no effect on the voltage standing wave ratio characteristics in the 2.4 GHz band and the 5 GHz band.

[0100] Furthermore, it was confirmed that the first example antenna 10, compared to the comparative example antenna 100, suppressed the change (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes in the 5 GHz and 6 GHz bands, and that the voltage standing wave ratio characteristics were improved.

[0101] Based on the above, it was confirmed that the antenna 10 of the first example has good voltage standing wave ratio characteristics over a wide frequency range.

[0102] <Antenna of the Second Example> Figures 7A and 7B show an antenna (hereinafter referred to as "antenna 80") as a second example of this embodiment. Figure 7A is a view of antenna 80 from the front side, and Figure 7B is a view of antenna 80 from the back side. The basic configuration of antenna 80 of the second example is the same as that of antenna 10 of the first example, so the following explanation will focus on the differences from antenna 10 of the first example.

[0103] As shown in Figure 7B, the substrate of the second example antenna 80 (hereinafter referred to as "substrate 111") has a shape that is an extension of the substrate 11 of the first example antenna 10 in a substantially rectangular shape toward the -Y direction. Furthermore, a passive element 36 is provided in the extended area on the back side of the substrate 111.

[0104] As shown in Figure 7B, the passive element 36 is roughly rectangular in shape, extending in the Z direction, and the length of its longest side is slightly shorter than half the wavelength of the radio waves in the 6 GHz band. Furthermore, the passive element 36 is positioned at a distance of approximately one-quarter of the wavelength of the radio waves in the 6 GHz band in the -Y direction from the first conductor portion 20 or the second conductor portion 30.

[0105] As described above, by providing the passive element 36 on the back surface of the substrate 111, the passive element 36 capacitively couples with at least one of the first conductor portion 20 and the second conductor portion 30. This lowers the impedance of the antenna 80 for the 6 GHz band as seen from the power supply portion 40, and also suppresses leakage current.

[0106] Furthermore, the length of the longer side of the passive element 36 is made slightly shorter than half the wavelength of the 6 GHz band. As a result, the passive element 36 functions as a director relative to the first conductor section 20, which functions as a radiator, and can give directionality to the radio waves radiated from the first conductor section 20.

[0107] Furthermore, by positioning the unpowered element 36 closer to the first conductor portion 20 along the +Z direction, the directivity of the antenna 80 can be improved.

[0108] Furthermore, the higher the frequency of the signal supplied to the power supply unit 40, the greater the apparent area of ​​the second conductor unit 30, which functions as ground, and the beam pattern shifts towards the ground side (closer to the second conductor unit 30). Therefore, by positioning the passive element 36 closer to the first conductor unit 20, the bias of the beam pattern can be adjusted to an optimal state.

[0109] The placement position of the passive element 36 on the substrate 111 and the shape of the passive element 36 are not necessarily limited, and the beam pattern of the antenna 80 may be set to a beam pattern that conforms to the required specifications.

[0110] The second example antenna 80 shown in Figures 7A and 7B has only one (single) parasitic element 36. However, in order to improve the directivity of the antenna 80, for example, the area of ​​the substrate 111 may be further expanded, and multiple parasitic elements 36 may be arranged in the -Y direction parallel to each other in the Z direction, with a spacing of 1 / 4 the wavelength of the 6 GHz band.

[0111] <Verification of Antenna 80 in the Second Example> Figures 8A to 8C show the measurement results of the voltage standing wave ratio characteristics of Antenna 80 in the second example. In the graphs shown in each figure, the horizontal axis is frequency (GHz) and the vertical axis is voltage standing wave ratio (VSWR).

[0112] Figure 8A shows the measured voltage standing wave ratio (VSWR) of antenna 80 in a frequency range (2.0 to 8.0 GHz) that includes the entire 2.4 GHz, 5 GHz, and 6 GHz bands. Figure 8B is a graph showing an enlarged view of the frequency range from 2.36 to 2.52 GHz, which includes the 2.4 GHz band, from Figure 8A. Figure 8C is a graph showing an enlarged view of the frequency range from 4.9 to 7.4 GHz, which includes the 5 GHz and 6 GHz bands, from Figure 8A.

[0113] The graph in Figure 8A shows the measurement results for the second example antenna 80, with different lengths of coaxial cable 1 connected via the cable connection part 12, and with different wire types. The graphs in Figures 8B and 8C show the results for the second example antenna 80, with and without the coaxial cable 1 connected to the cable connection part 12, and with different wire types.

[0114] As shown in Figure 8B, the voltage standing wave ratio (VSWR) of antenna 80 in the frequency range of 2.36 to 2.52 GHz, including the 2.4 GHz band, is at most 2.0 or less. Therefore, antenna 80 has good voltage standing wave ratio characteristics in this frequency range.

[0115] As shown in Figure 8C, the voltage standing wave ratio (VSWR) of antenna 80 in the frequency range of 4.9 to 7.4 GHz, including the 5 GHz and 6 GHz bands, is at most 2.2 or less. Therefore, antenna 80 has good voltage standing wave ratio characteristics in this frequency range.

[0116] As described above, it was confirmed that the second example antenna 80 has good voltage standing wave ratio characteristics in all three bands: 2.4 GHz, 5 GHz, and 6 GHz.

[0117] Comparing the graph in Figure 8B with the graph in Figure 6B, in both graphs, the change (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes is small and stable in the 2.4 GHz band.

[0118] Comparing the graph in Figure 8C with the graph in Figure 6C, the graph in Figure 8C shows less variation (variation) in the voltage standing wave ratio (VSWR) in response to frequency changes in the 5 GHz and 6 GHz bands compared to the graph in Figure 6C, indicating greater stability.

[0119] Thus, it was confirmed that even when a parasitic element 36 is added to the configuration of the antenna 10 in the first example, as in the antenna 80 of the second example, it has almost no effect on the voltage standing wave ratio characteristics in the 2.4 GHz band.

[0120] Furthermore, it was confirmed that the second example antenna 80, compared to the comparative example antenna 100, suppressed the change (variation) in voltage standing wave ratio (VSWR) with respect to frequency changes in the 5 GHz and 6 GHz bands, and that the voltage standing wave ratio characteristics were improved.

[0121] Based on the above, it was confirmed that the second example antenna 10 has good voltage standing wave ratio characteristics over a wide frequency range.

[0122] <Third Example Antenna> Figures 9A and 9B show an antenna (hereinafter referred to as "antenna 90") as the third example of this embodiment. Figure 9A is a view of antenna 90 from the front side, and Figure 9B is a view of antenna 90 from the back side. The basic configuration of antenna 90 of the third example is the same as that of antenna 10 of the first example, so the following explanation will focus on the differences from antenna 10 of the first example.

[0123] As shown in Figure 9B, the third example of the antenna 90 has a fourth conductor portion 37 on the back surface of the substrate 11, at a point near the feed point 40 of the second conductor portion 30 which functions as ground, with one end connected to the second conductor portion 30. The fourth conductor portion 37 has a predetermined width (approximately the same width as the main body portion 32A of the second conductor portion 30) and extends in the -Y direction while curving in an arc in the +Z direction from the connection point with the second conductor portion 30.

[0124] The arc length of the fourth conductor section 37 is slightly shorter than one-quarter of the wavelength of a 6 GHz band radio wave. The shape of the second conductor section 30 is not limited to the example shown. For example, the shape of the second conductor section 30 may be a roughly rectangular shape with a longitudinal length slightly shorter than one-quarter of the wavelength of a 6 GHz band radio wave.

[0125] In this way, by providing the fourth conductor portion 37 on the back surface of the substrate 11, the fourth conductor portion 37 is capacitively coupled to at least one of the first conductor portion 20 or the second conductor portion 30. As a result, the impedance of the antenna 90 to the 6GHz band radio waves as seen from the power supply portion 40 is reduced, and leakage current is also suppressed.

[0126] <Verification of Antenna 90 in Example 3> Figures 10A to 10C all show the measurement results of the voltage standing wave ratio characteristics of Antenna 90 in Example 3. In the graphs shown in each figure, the horizontal axis is frequency (GHz) and the vertical axis is voltage standing wave ratio (VSWR).

[0127] Figure 10A shows the measured voltage standing wave ratio (VSWR) of antenna 90 in a frequency range (2.0 to 8.0 GHz) that includes the entire 2.4 GHz, 5 GHz, and 6 GHz bands. Figure 10B is a graph showing an enlarged view of the frequency range of Figure 10A, specifically the 2.36 to 2.52 GHz range, which includes the 2.4 GHz band. Figure 10C is a graph showing an enlarged view of the frequency range of Figure 10A, specifically the 4.9 to 7.4 GHz range, which includes the 5 GHz and 6 GHz bands.

[0128] The graph in Figure 10A shows the measurement results of the third example antenna 90, which was performed by connecting the coaxial cable 1 to the cable connection part 12. The graphs in Figures 10B and 10C show the measurement results of the first example antenna 10 (without the fourth conductor part 37) and the third example antenna 90, with different wire types.

[0129] As shown in Figure 10B, the voltage standing wave ratio (VSWR) of antenna 90 in the frequency range of 2.36 to 2.52 GHz, including the 2.4 GHz band, is at most 2.0 or less. Therefore, antenna 90 has good voltage standing wave ratio characteristics in this frequency range.

[0130] As shown in Figure 10C, in the frequency range of 4.9 to 7.4 GHz, including the 5 GHz and 6 GHz bands, the voltage standing wave ratio (VSWR) of antenna 90 is at most 2.2 or less. Therefore, antenna 90 has good voltage standing wave ratio characteristics in this frequency range.

[0131] As described above, it was confirmed that the third example antenna 90 has good voltage standing wave ratio characteristics in all three bands: 2.4 GHz, 5 GHz, and 6 GHz.

[0132] Furthermore, comparing the graphs in Figure 10B and Figure 6B, it can be seen that in both graphs, the change (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes is small and stable in the 2.4 GHz band.

[0133] Comparing the graphs in Figure 10C and Figure 6C, the graph in Figure 10C shows less variation (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes in the 5 GHz and 6 GHz bands compared to the graph in Figure 6C, indicating greater stability.

[0134] Thus, it was confirmed that even when a fourth conductor section 37 is added to the configuration of the antenna 10 in the first example, as in the antenna 90 of the third example, it has almost no effect on the voltage standing wave ratio characteristics in the 2.4 GHz band.

[0135] Furthermore, it was confirmed that the third example antenna 90, compared to the comparative example antenna 100, suppressed the change (variation) in the voltage standing wave ratio (VSWR) with respect to frequency changes in the 5 GHz and 6 GHz bands, and that the voltage standing wave ratio characteristics were improved.

[0136] Based on the above, it was confirmed that the antenna 90 of the third example has good voltage standing wave ratio characteristics over a wide frequency range.

[0137] ==

[0138] (Aspect 1) Aspect 1 is an antenna comprising: a substrate; a first conductor portion formed on the substrate and to which a signal line is connected; a second conductor portion formed on the substrate and to which a ground line is connected; a third conductor portion formed on the substrate and to which together with the first and second conductor portions operate as a sleeve dipole antenna; and a feed portion located between the first and second conductor portions, wherein the second conductor portion has two extension portions extending from the feed portion and a line portion extending from the feed portion and located between the two extension portions, and the third conductor portion is located between the feed portion and the end of one of the extension portions and connects the one extension portion and the line portion.

[0139] According to the above-described embodiment, antennas 10, 80, and 90 having good voltage standing wave ratio characteristics over a wide frequency band can be realized.

[0140] Here, the two extensions correspond to the second extension 321 and the second extension 322, respectively, and one of the extensions mentioned above corresponds to the second extension 322.

[0141] (Aspect 2) Aspect 2 is an antenna in which the first length of each of the two extensions is a length corresponding to 1 / 4 of the wavelength of the first frequency band, and the second length from the feed point to the line section via the one extension and the third conductor is a length corresponding to 1 / 2 of the wavelength of the second frequency band which is higher than the first frequency band.

[0142] By setting the first length L1 and the second length L2 to such lengths, it is possible to realize an antenna with good voltage standing wave ratio characteristics over a wide frequency band including the first frequency band (e.g., the 2.4 GHz band) and the second frequency band (e.g., the 6 GHz band).

[0143] (Aspect 3) Aspect 3 is an antenna comprising a passive element that capacitively couples with at least one of the first and second conductor portions.

[0144] By providing such a powerless element 36, an antenna 80 with good voltage standing wave ratio characteristics over a wide frequency band can be realized.

[0145] (Aspect 4) Aspect 4 is an antenna in which the parasitic element has a length corresponding to half the wavelength of the second frequency band.

[0146] By making the unpowered element 36 of this length, an antenna with good voltage standing wave ratio characteristics can be realized in a wide frequency band including the first and second frequency bands.

[0147] (Aspect 5) Aspect 5 is an antenna comprising a fourth conductor portion connected to the second conductor portion, wherein the fourth conductor portion has a length corresponding to one-quarter of the wavelength of the second frequency band.

[0148] By providing such a fourth conductor section 37, an antenna 90 having good voltage standing wave ratio characteristics in a wide frequency band including the first and second frequency bands can be realized.

[0149] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that equivalents thereof are included.

[0150] 1 Coaxial cable 2 Signal line 3 Ground line 10, 80, 90, 100 Antenna 11 Circuit board 11A Notch 12 Cable connection part 13 First layer 14 Second layer 16 Dielectric layer 20 First conductor part 21 First line part 22 First extension part 23 Bent part 24, 31C, 32C Through hole 30 Second conductor part 31 Second line part 31A Front side second line part 31B Back side second line part 32 Second extension part 41 Self-similar shape part 45 Part 321 Second extension part 322 Second extension part 321A Main body part 322A Main body part 321B Additional part 322B Additional part 321C Through hole 322C Through hole 35 Third conductor section 36 Powerless element 37 Fourth conductor section 40 Power supply section

Claims

1. An antenna comprising: a substrate; a first conductor portion formed on the substrate and to which a signal line is connected; a second conductor portion formed on the substrate and to which a ground line is connected; a third conductor portion formed on the substrate and together with the first and second conductor portions to function as a sleeve dipole antenna; and a feed portion located between the first and second conductor portions, wherein the second conductor portion has two extension portions extending from the feed portion and a line portion extending from the feed portion and located between the two extension portions, and the third conductor portion is located between the feed portion and the end of one of the extension portions and connects the one extension portion and the line portion.

2. The antenna according to claim 1, wherein the first length of each of the two extensions is a length corresponding to one-quarter of the wavelength of the first frequency band, and the second length from the feed point to the line section via one of the extensions and the third conductor section is a length corresponding to one-half of the wavelength of the second frequency band which is higher than the first frequency band.

3. The antenna according to claim 2, comprising a passive element that capacitively couples with at least one of the first and second conductor portions.

4. The antenna according to claim 3, wherein the unpowered element has a length corresponding to half the wavelength of the second frequency band.

5. The antenna according to claim 2, comprising a fourth conductor portion connected to the second conductor portion, wherein the fourth conductor portion has a length corresponding to one-quarter of the wavelength of the second frequency band.

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