Mantle Cloak embedded radome

Abstract

To provide a radome that is easy to implement and can effectively suppress interference due to mutual coupling between antennas.SOLUTION: A radome with a built-in mantle cloak (10) that covers an antenna (101) and protects it from the surrounding environment includes a radome body (101), and a mantle cloak layer consisting of a plurality of conductor strips (103) provided on the radome body. The return loss characteristics of the antenna (101) can be changed by adjusting at least one of the dielectric constant and thickness of the radome body (101) and the width (w) of the conductor strip (103).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for suppressing interference caused by mutual coupling between antennas. [Background technology]

[0002] In recent years, as wireless terminals have become smaller, it has become common for multiple antennas to be placed in close proximity. In particular, when the frequencies used by multiple antennas are close to each other, interference due to mutual coupling can significantly distort the radiation patterns of both antennas, causing the antennas to lose their original performance. Many methods have been proposed to suppress such interference.

[0003] For example, Patent Document 1 discloses a method of suppressing antenna interference by providing a mechanism for adjusting the relative positions of multiple antennas in a mobile phone, while Patent Document 2 discloses a method of suppressing gain degradation of closely-located antennas by providing an LC parallel resonant circuit in the high-frequency circuit within the mobile phone.

[0004] As another method, Non-Patent Document 1 proposes a method of reducing mutual coupling between antennas by covering the antennas with a mantle cloke that controls electromagnetic waves. Note that cloaking is a technology that hides objects that cause interference and provides a field (such as an electric field) around them that makes them appear as if they do not exist, and a mantle cloke is a simple cloaking method that controls electromagnetic waves by covering an antenna like a mantle with an appropriately designed reactance layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-063523 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-110473 [Non-patent literature]

[0006] [Non-Patent Document 1] Nguyen Thanh Binh, Naofumi Michishita, Hisashi Morishita, Terunori Miyazaki, and Masato Tadokoro, "Mutual Coupling Reduction between Dipole Antennas Using Mantle Cloaks," IEICE Technical Report, vol. 121, no. 34, AP2021-10, pp. 7-11, May 2021. Summary of the Invention [Problem to be solved by the invention]

[0007] However, the interference suppression methods disclosed in Patent Documents 1 and 2 require the installation of special mechanisms or circuits within the mobile phone, which hinders miniaturization and results in inefficient use of space for antenna installation.

[0008] Furthermore, the method of covering the antenna with a mantle clook disclosed in the above-mentioned non-patent document 1 is difficult to implement because a dielectric of a predetermined thickness is laminated on the antenna itself, and it is also difficult to obtain sufficient environmental resistance.

[0009] To improve environmental resistance, antennas are protected by being covered with a radome. However, the purpose of a radome is usually to provide good transmission characteristics in the transmission frequency band, and not to suppress interference caused by mutual coupling between antennas.

[0010] The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide an easily mounted radome that can effectively suppress interference due to mutual coupling between antennas. [Means for solving the problem]

[0011] In order to achieve the above object, one embodiment of the present invention provides a mantle cloke-embedded radome, which is a radome that covers an antenna and protects it from the surrounding environment, and is characterized by comprising a radome body and a mantle cloke layer consisting of a plurality of conductive strips provided on the radome body. Furthermore, according to one embodiment of the present invention, the return loss characteristics of the antenna can be changed by adjusting at least one of the dielectric constant and thickness of the radome body and the width of the conductor strip. Furthermore, according to one embodiment of the present invention, by adjusting at least one of the dielectric constant and thickness of the radome body and the width of the conductive strip, it is possible to minimize the return loss at the operating frequency of the antenna and maximize the return loss at the operating frequency of another antenna close to the antenna. Furthermore, according to one embodiment of the present invention, the plurality of conductive strips can be formed on the radome body by any method including sputtering, vapor deposition, attaching a conductive foil, etching a conductive layer, and applying a conductive paint. [Effects of the Invention]

[0012] As described above, according to one embodiment of the present invention, interference due to mutual coupling between antennas can be easily suppressed simply by mounting a radome on the antenna. Furthermore, according to one embodiment of the present invention, the reflection loss characteristics of the antenna can be changed by adjusting at least one of the dielectric constant, thickness, and width of the conductor strip of the radome body, thereby easily suppressing interference due to mutual coupling between antennas. Furthermore, according to one embodiment of the present invention, by adjusting at least one of the dielectric constant, thickness, and width of the conductor strip of the radome body, it is possible to reduce the reflection loss of the antenna itself and increase the reflection loss of other antennas, making it possible to arrange antennas operating at similar frequencies in close proximity, and enabling antennas to be arranged more densely than before, thereby making more efficient use of space. Furthermore, according to one embodiment of the present invention, a conductive strip can be formed on the radome body by any method including sputtering, vapor deposition, attaching a conductive foil, etching a conductive layer, and applying a conductive paint, so that the characteristics of the mantle cloke layer can be easily adjusted. In addition, antenna performance can be easily changed by simply replacing the appropriately designed Mantle Cloak embedded radome. Furthermore, by installing a Mantle Cloak embedded radome on an antenna, not only can the antenna's performance be changed, but the entire antenna can also be made more environmentally resistant. [Brief explanation of the drawings]

[0013] [Figure 1] 1A is a schematic plan view of a mantle cloke-integrated radome according to one embodiment of the present invention, FIG. 1B is a cross-sectional view taken along line II, and FIG. 1C is a cross-sectional view taken along line II-II. [Figure 2] FIG. 1 is a perspective view showing a schematic configuration of a mantle cloke antenna without a radome. [Figure 3] 3 is a diagram for explaining the difference in configuration between the dipole antenna covered with the mantle cloke-embedded radome according to this embodiment and the mantle cloke antenna shown in FIG. 2. FIG. [Figure 4] 3 is a graph showing the return loss versus frequency of the mantle clook antenna shown in FIG. 2 and the dipole antenna covered with the mantle clook-embedded radome according to this embodiment, with the antenna length L as a parameter. [Figure 5] 1 is a graph showing the reflection loss versus frequency of a dipole antenna covered with a mantle clook-embedded radome according to this embodiment, with the conductor split width w as a parameter. [Figure 6] 1 is a graph showing the reflection loss versus frequency of a dipole antenna covered with a mantle clook-embedded radome according to this embodiment, with the relative dielectric constant ε as a parameter. [Figure 7] 1 is a graph showing return loss versus frequency for a dipole antenna enclosed in a mantle clook embedded radome according to an embodiment of the present invention when set to predetermined parameters. [Figure 8] 1 is a schematic diagram for explaining the interference suppression effect when a dipole antenna covered with a mantle clook-embedded radome according to this embodiment is placed close to another antenna. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a dipole antenna will be illustrated, but the present invention is not limited thereto. The components of the illustrated mantle cloke-integrated radome, their dimensions, and the size ratios between the illustrated components are merely examples for the sake of convenience, and are not intended to limit the technical scope of the present invention to these.

[0015] 1. Mantle Cloak Composition 1, a mantle cloke-embedded radome 10 according to one embodiment of the present invention comprises a radome body (hereinafter referred to as the shell) 102 that covers a dipole antenna 101, and a plurality of conductor strips 103 provided as a mantle cloke layer on the shell 102. The dipole antenna 101 comprises two dipole antenna elements, and a feed section 104 of the dipole antenna 101 is provided in the feed point space between them.

[0016] Shell 102 covers dipole antenna 101 to protect it from the surrounding environment, and is made of a dielectric material with a dielectric constant in accordance with the Mantle Cloak design described below. Dipole antenna 101 is detachably housed in the hollow space of shell 102, and may be in contact with the inner wall of shell 102 or may be separated by a predetermined distance. In this example, shell 102 covers the entire dipole antenna 101, but it may also be a split type that covers each antenna element separately.

[0017] Each of the multiple conductive strips 103 constituting the mantle clook layer has a rectangular shape of a predetermined width extending in the longitudinal direction of the dipole antenna 101. If n is an integer greater than or equal to 2, n conductive strips 103 are provided at equal intervals on the periphery of the shell 102 surrounding the two dipole antenna elements. The number n of conductive strips 103 is determined by the periphery length of the shell 102 (the length determined by the radius of the dipole antenna elements and the thickness of the shell 102), the width of the conductive strips 103, and the spacing between the conductive strips. Note that the thickness of the conductive strips 103 is exaggerated in FIG. 1(C) for clarity and does not represent the actual thickness of the conductive strips 103.

[0018] The plurality of conductive strips 103 can be formed by sputtering or vapor deposition of a conductive material, attaching a conductive foil, etching a conductive layer on the shell 102, applying a conductive paint, etc. Furthermore, the outer surface of the shell 102 on which the plurality of conductive strips 103 are provided may be painted to improve environmental resistance.

[0019] Hereinafter, the antenna length of dipole antenna 101 is L, its radius is r, the feed point space of dipole antenna 101 (the spacing between antenna elements) is g, the thickness of shell 102 is t, the width of each conductive strip 103 is w, the spacing between the conductive strips is d, and the relative dielectric constant of the dielectric of shell 102 is ε. It is also assumed that dipole antenna 101 is housed in the hollow portion of cylindrical shell 102.

[0020] 2. Mantle Cloak Design Hereinafter, a method for designing the mantle clook of the radome 10 will be described using a dipole antenna as an example.

[0021] In a configuration in which a mantle clook is applied to dipole antenna 101, desired characteristics can be obtained by adjusting various parameters. These parameters include antenna length L, antenna radius r, antenna element spacing g, relative permittivity ε of the dielectric covering the antenna elements, shell dielectric thickness t, number of conductive strips n, conductive strip width w, and ratio of conductive strip width w to spacing d (w / d). By adjusting these parameters, as described below, it is possible to design a system in which the return loss S11 is minimized at the operating frequency of the antenna itself, maximizing radiation efficiency, and S11 is maximized at the operating frequency of a nearby antenna, minimizing sensitivity.

[0022] The frequency characteristics of the return loss S11 when the antenna length L and the strip width w of the conductive strip 102 are changed will be exemplified below.

[0023] As shown in Fig. 2, a mantle cloke antenna 20 having a length L is provided with a mantle cloke in which a dielectric layer having a thickness t is laminated on the side of each dipole antenna element 201, and multiple conductive strips 202 having a width w are formed on top of the dielectric layer. In addition, a feed point space g between the antenna elements 201 of the mantle cloke antenna 20 is provided with a feed portion 203 of the mantle cloke antenna 20. Hereinafter, as shown in Fig. 3, a case will be considered in which such a mantle cloke antenna 20 is made into a radome to form a dipole antenna 101 covered by the radome 10 shown in Fig. 1.

[0024] In FIG. 3, the mantle cloke antenna 20 shown in FIG. 2 and the dipole antenna 101 formed by converting it into a radome can achieve equivalent performance by adjusting the parameters as shown below.

[0025] The graph in Figure 4 shows the frequency characteristics of return loss (S11) for the following parameters: dipole antenna radius r = 10 mm, shell 102 thickness t = 2 mm, relative permittivity ε = 8, antenna element spacing g = 46 mm, and conductor strip width w = 4.19 mm. The analysis was performed using the electromagnetic field analysis software "Feko" (registered trademark). As shown in Figure 4, the S11 frequency characteristics of the mantle cloke antenna 20 with a length L = 195 mm are slightly different from those of the radome-equipped dipole antenna 101 with the same length. However, it can be seen that nearly equivalent performance can be achieved by adjusting the length L of the radome-equipped dipole antenna 101 from 195 mm to 192 mm.

[0026] Furthermore, when the length L of the radome-shaped dipole antenna 101 is changed to 192, 195, and 198 mm, it can be seen that the frequency 301 showing the minimum value of S11 and the frequency 302 showing the maximum value shift with approximately the same frequency difference.

[0027] The graph in Fig. 5 shows the frequency characteristics of the return loss (S11) with the conductive strip width w as a parameter. In this case, the radius of the dipole antenna is r = 10 mm, the antenna length L = 211 mm, the thickness t of the shell 102 is t = 2 mm, the relative dielectric constant ε = 10, the antenna element spacing g = 46 mm, and the number of conductive strips n are all fixed constants.

[0028] As shown in Figure 5, when the conductor strip width w is changed to 3.14, 4.19, and 5.24 mm, the frequency 303 where S11 shows its minimum value and the frequency 304 where it shows its maximum value shift by approximately the same frequency difference. In this way, simply by adjusting the conductor strip width w, it is possible to match the frequency 303 where S11 shows its minimum value with the frequency used by the antenna itself, and the frequency 304 where S11 shows its maximum with the frequency used by a nearby antenna. This reduces the reflection loss of the radio waves from the antenna itself and increases the reflection loss of the radio waves from other antennas, thereby suppressing interference due to mutual coupling between antennas.

[0029] In particular, the mantle cloke-integrated radome 10 according to this embodiment has a plurality of conductive strips 103 on the shell 102, which makes it easy to adjust the width w of the conductive strips 103. This makes it extremely easy to align the frequency 303 where S11 is the minimum value and the frequency 304 where S11 is the maximum value with the frequencies used by the antenna itself and the other antennas, respectively. Furthermore, performance can be easily changed by replacing the radome 10 with an appropriately designed conductive strip width w.

[0030] Figure 5 shows an example in which the conductive strip width w is adjusted, but the mantle cloke-embedded radome 10 of this embodiment can easily change the antenna performance by adjusting at least one of the relative dielectric constant ε of the dielectric of the shell 102, the dielectric thickness t of the shell, the number n of conductive strips, and the ratio (w / d) of the conductive strip width w to the spacing d.

[0031] 6 shows the frequency characteristics of the return loss (S11) with the relative permittivity ε of the dielectric of the shell 102 as a parameter. In this case, the radius of the dipole antenna is r=10 mm, the antenna length L=211 mm, the thickness of the shell 102 is t=2 mm, the conductive strip width w=4.19 mm, the antenna element spacing g=46 mm, and the number of conductive strips n are all fixed constants.

[0032] As shown in FIG. 6, the relative dielectric constant ε r In the case of ε = 6, the frequencies at which S11 exhibits a minimum and a maximum are 305 and 306, respectively, and the pair of frequencies at which this minimum and maximum value is exhibited is r For =8, frequencies 307 and 308, ε r When ε = 10, the frequencies change to 309 and 310. In this way, simply by determining the relative permittivity ε of shell 102, the frequency at which S11 is at its minimum can be made to match the frequency used by the antenna itself, and the frequency at which S11 is at its maximum can be made to match the frequency used by a nearby antenna. This makes it possible to reduce the reflection loss of the radio waves from the antenna itself and increase the reflection loss of the radio waves from other antennas, thereby suppressing interference due to mutual coupling between antennas.

[0033] 3. Application Examples As shown in FIG. 7, assuming that the dipole antenna 101 has a radius r of 10 mm, an antenna length L of 192 mm, a shell 102 with a thickness t of 2 mm, a relative dielectric constant ε of 8, an antenna element spacing g of 46 mm, and a conductor strip width w of 4.19 mm, the frequency 305 at which S11 is minimized is the operating frequency f1 of the antenna itself, and the frequency 306 at which S11 is maximized is the operating frequency f2 of the other antenna. Here, the operating frequency f1 of the antenna itself is 750 MHz, and the operating frequency f2 of the other antenna is 720 MHz. The mantle cloke-embedded radome 10 according to this embodiment minimizes the reflection loss of the radio wave from the antenna itself and maximizes the reflection loss of the radio wave from the other antenna, thereby suppressing interference due to mutual coupling between the antennas even with a frequency difference of 30 MHz. Below, we will explain an example in which the mantle cloke-embedded radome 10 according to this embodiment is applied to a case in which the operating frequency of one antenna is f1 and the operating frequency of the other antenna is f2.

[0034] 8, the mantle cloke-integrated radome 10a is a mantle cloke-integrated radome 10 that is set so that the operating frequency of its own antenna is f1 and the operating frequency of the other antenna is f2. Similarly, the mantle cloke-integrated radome 10b is a mantle cloke-integrated radome 10 that is set so that the operating frequency of its own antenna is f2 and the operating frequency of the other antenna is f1.

[0035] When the distance D between the mantle cloke-integrated radomes 10a and 10b was changed and the radiation patterns of both antennas were analyzed, it was found that the radiation pattern was not significantly distorted and the initial antenna performance could be maintained even when the distance was reduced to D = 40 mm. By using the mantle cloke-integrated radome 10 of this embodiment, multiple antennas can be arranged closely together, allowing for efficient use of space.

[0036] 4.Effects As described above, by mounting the mantle cloke-integrated radome 10 according to this embodiment, interference due to mutual coupling between antennas can be suppressed, and antennas operating at nearby frequencies can be arranged closely together. Therefore, antennas can be arranged more densely than before, allowing for more efficient use of space.

[0037] Furthermore, the desired return loss characteristics can be set simply by attaching the Mantle Cloak integrated radome 10 to the antenna. Therefore, the performance of the antenna can be easily changed by replacing the appropriately designed Mantle Cloak integrated radome 10. Another advantage of installing the Mantle Cloak integrated radome 10 on the antenna is that it not only changes the performance of the antenna but also gives the entire antenna excellent environmental resistance.

[0038] In the above-described embodiment and application example, a cylindrical dipole antenna is exemplified, but the present invention is not limited to a cylindrical shape, and similar effects can be obtained with, for example, a square pillar-shaped dipole antenna. [Explanation of symbols]

[0039] 10, 10a, 10b Mantle Cloak Integrated Radome 20 Mantle Cloak Antenna without radome 101 Dipole Antenna 102 Shell (Radome body) 103 Conductor Strip 104 Power supply unit 201 Dipole Antenna 202 Conductor Strip 203 Power Supply Unit

Claims

1. A radome that covers an antenna and protects it from the surrounding environment, The radome body, a mantle cloke layer formed of a plurality of conductive strips provided on the radome body; It consists of A mantle cloke-embedded radome characterized in that at least one of the dielectric constant and thickness of the radome body and the width of the conductive strip is adjusted to minimize the reflection loss at the frequency of the radio waves radiated from the antenna and maximize the reflection loss at the frequency of the radio waves radiated from another antenna close to the antenna.

2. 2. The mantle cloke-integrated radome according to claim 1, wherein the plurality of conductive strips are formed on the radome body by any method including sputtering, vapor deposition, attaching a conductive foil, etching a conductive layer, or applying a conductive paint.

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