Heat sinks and wireless devices

Abstract

To provide a heat sink that can improve the design flexibility of heat sinks. [Solution] A heat sink according to one embodiment of the present disclosure includes a heat sink supporting a heat source, a first heat sink fin provided on the heat sink and extending in a first direction in the plane of the heat sink, and a second heat sink fin provided on the heat sink and extending in a first direction. The heat sink, the first heat sink fin and the second heat sink fin are made of a solid material having thermal conductivity and electrical conductivity. The first heat sink fin and the second heat sink fin form a heat sink fin structure in which they are arranged in a predetermined order in a second direction in the plane of the heat sink. The fin length of the second heat sink fin in the first direction is shorter than the fin length of the first heat sink fin in the first direction. The fin height of the first heat sink fin is lower than the fin height of the second heat sink fin.

Description

Technical Field

[0001] The present disclosure relates to a radiator and a wireless device.

Background Art

[0002] In recent years, the sophistication of mobile communication systems, such as the increase in capacity and speed of wireless communication represented by the fifth-generation mobile communication system (5G), has advanced, and higher functionality of mobile base stations, such as beamforming, has been demanded.

[0003] With such a demand for higher functionality, high heat dissipation performance has been demanded for wireless devices. For example, Patent Document 1 discloses a wireless device in which a heat radiator is constituted by a metal base plate disposed on the same surface as an antenna surface and a metal wall provided on the metal base plate so as to surround an antenna element.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a heat dissipation part (heat sink) is provided on the same surface as the antenna surface as disclosed in Patent Document 1, it is necessary to provide a wall surrounding the antenna element in order to reduce the influence on the antenna characteristics, and there is a problem that the degree of freedom in the design of the radiator decreases.

[0006] An object of the present disclosure is to provide a radiator and a wireless device for solving such problems.

Means for Solving the Problems

[0007] A radiator according to one aspect of the present disclosure is A heat sink that supports the heat source, The heat sink is provided with a first heat sink fin that extends in a first direction within the plane of the heat sink, A second heat dissipation fin is provided on the heat sink and extends in the first direction, It has, The heat sink, the first heat sink fin, and the second heat sink fin are made of a solid material having thermal conductivity and electrical conductivity. The first heat dissipation fin and the second heat dissipation fin are arranged in a predetermined order in a second direction within the plane of the heat dissipation plate, forming a heat dissipation fin structure. The fin length of the second heat dissipation fin in the first direction is shorter than the fin length of the first heat dissipation fin in the first direction. The fin height of the first heat dissipation fin is lower than the fin height of the second heat dissipation fin.

[0008] A wireless device relating to one form of this disclosure is: The heat sink mentioned above, A radiating element or a reflective element is arranged inside the heat dissipation fin structure of the heat sink. It is equipped with. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a heat sink that can improve the design flexibility of the heat sink, and a wireless device. [Brief explanation of the drawing]

[0010] [Figure 1A] This is a perspective view showing an example configuration of a heat sink in this disclosure. [Figure 1B] This is a side view showing an example configuration of a heat sink in this disclosure. [Figure 2] This is a schematic diagram for calculating the heat dissipation fin area of ​​a heat sink in the configuration example of this disclosure. [Figure 3] This figure shows a perspective view of example heat dissipation structure 1, and a definition of the direction of radio wave propagation. [Figure 4A] This figure shows the electromagnetic field simulation results for the frequency dispersion characteristics of heat dissipation structure example 1. [Figure 4B] It is a schematic diagram of each symmetry point (K point) in the Brillouin zone of the reciprocal lattice space. [Figure 4C] It is a diagram excerpting the low frequency band including EBG of the electromagnetic field simulation result of the frequency dispersion characteristic of Heat dissipation structure example 1. [Figure 5A] It is a diagram showing the electromagnetic field simulation result of the S parameter S21 (transmission intensity) when radio waves propagate in the direction perpendicular to the straight fin (y-axis) in Heat dissipation structure example 1. [Figure 5B] It is a diagram showing the electromagnetic field simulation result of the S parameter S21 (transmission intensity) when radio waves propagate in the longitudinal direction of the straight fin (x-axis) in Heat dissipation structure example 1. [Figure 6] It is a perspective view of Heat dissipation structure example 2 and a diagram showing the definition of the radio wave propagation direction. [Figure 7] It is a diagram showing the electromagnetic field simulation result of the surface wave propagation in the fin longitudinal direction in the heat dissipation fin structure of Heat dissipation structure example 2. [Figure 8] It is a perspective view of Heat dissipation structure example 3 and a diagram showing the definition of the radio wave propagation direction. [Figure 9] It is a diagram showing the electromagnetic field simulation result of the surface wave propagation in the fin longitudinal direction in the heat dissipation fin structure of Heat dissipation structure example 3. [Figure 10] In the configuration example of the radiator of the present disclosure, it is a diagram showing the electromagnetic field simulation result of the frequency dispersion characteristic when the fin height of the first heat dissipation fin is changed and the fin height of the second heat dissipation fin is fixed. [Figure 11] It is a perspective view showing the configuration example of the radiator of the present disclosure and a diagram showing the definition of the radio wave propagation direction. [Figure 12] It is a diagram showing the electromagnetic field simulation result of the surface wave propagation in the fin longitudinal direction in the heat dissipation fin structure exemplified in the present disclosure. [Figure 13A] In the configuration example of the radiator of the present disclosure, it is a diagram showing the electromagnetic field simulation result of the S parameter S21 (transmission intensity) when radio waves propagate in the direction perpendicular to the heat dissipation fin (y-axis). [Figure 13B]This is a diagram showing the electromagnetic field simulation result of the S parameter S21 (transmission intensity) when radio waves propagate in the longitudinal direction (x-axis) of the heat dissipation fins in the configuration example of the radiator of the present disclosure. [Figure 14] This is a diagram showing the simulation result of the electric field vector when the fin heights of the straight fins and the rectangular fins are equal. [Figure 15] This is a diagram showing the simulation result of the electric field vector when the fin height of the straight fin is lower than the fin height of the rectangular fin. [Figure 16A] This is an analytical model diagram of a general straight fin in a thermal fluid simulation. [Figure 16B] This is an analytical model diagram of a general rectangular fin in a thermal fluid simulation. [Figure 16C] This is an analytical model diagram of the heat dissipation fin structure exemplified in the present disclosure in a thermal fluid simulation. [Figure 17A] This is a diagram of the steady-state temperature distribution on the surface of the heat dissipation structure with a general straight fin under natural convection conditions obtained from a thermal fluid simulation. [Figure 17B] This is a diagram of the steady-state temperature distribution on the surface of the heat dissipation structure with a general rectangular fin under natural convection conditions obtained from a thermal fluid simulation. [Figure 17C] This is a diagram of the steady-state temperature distribution on the surface of the heat dissipation structure with the heat dissipation fin structure exemplified in the present disclosure under natural convection conditions obtained from a thermal fluid simulation. [Figure 18A] This is a graph comparing the steady-state maximum temperatures of internal heat sources with each heat dissipation fin shape under natural convection conditions obtained from a thermal fluid simulation. [Figure 18B] This is a graph comparing the steady-state maximum temperatures on the surface of the heat dissipation structure with each heat dissipation fin shape under natural convection conditions obtained from a thermal fluid simulation. [Figure 19] This is a configuration diagram showing a Vivaldi antenna element. [Figure 20] This is a diagram showing an overview of the surface impedance at the fin end face of a heat dissipation fin structure having EBG characteristics. [Figure 21A] This is a perspective view showing an example configuration of an array antenna device according to the present disclosure. [Figure 21B] This is a side view showing an example configuration of an array antenna device according to the present disclosure. [Figure 21C] This is a different side view showing an example configuration of an array antenna device in this disclosure. [Figure 21D] This is a plan view showing an example configuration of an array antenna device according to the present disclosure. [Figure 22A] This figure shows the radiation pattern at 3.4 GHz when a 3x2 element antenna is operating in an array antenna device equipped with a typical heat sink. [Figure 22B] This figure shows the radiation pattern at 3.7 GHz when a 3x2 element antenna is operating in an array antenna device equipped with a typical heat sink. [Figure 22C] This figure shows the radiation pattern at 4.0 GHz when a 3x2 element antenna is operating in an array antenna device equipped with a typical heat sink. [Figure 23A] This figure shows the radiation pattern at 3.4 GHz during operation of a 3x2 element antenna in an array antenna device equipped with the heat dissipation fin structure illustrated in this disclosure. [Figure 23B] This figure shows the radiation pattern at 3.7 GHz during operation of a 3x2 element antenna in an array antenna device equipped with the heat dissipation fin structure illustrated in this disclosure. [Figure 23C] This figure shows the radiation pattern at 4.0 GHz during the operation of a 3x2 element antenna in an array antenna device equipped with the heat dissipation fin structure illustrated in this disclosure. [Figure 24] This diagram schematically shows the flow of refrigerant inside a typical rectangular fin. [Figure 25] This diagram schematically shows the flow of refrigerant inside the heat dissipation fins of an example configuration of the present disclosure. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings. Note that the drawings are simplified, and the technical scope of the embodiments should not be narrowly interpreted based on their depiction. Furthermore, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0012] In the following embodiments, the description will be divided into multiple sections or embodiments where necessary for convenience. However, unless otherwise specified, these are not unrelated, and one may be a modification, application, detailed explanation, or supplementary explanation of part or all of the other.

[0013] Furthermore, in the following embodiments, when referring to the number of elements, etc. (including the number of elements, numerical values, quantities, ranges, etc.), unless specifically stated, or when it is clearly limited in principle to a particular number, the number is not limited to that particular number, and may be greater than or less than that particular number.

[0014] Furthermore, in the following embodiments, the components are not necessarily essential unless specifically stated otherwise, or unless they are clearly essential in principle.

[0015] Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, unless otherwise specifically stated, or when it is clearly not the case in principle, etc., it shall include those that substantially approximate or resemble such shapes, etc. The same applies to the numbers, etc. (including the number of items, numerical values, quantities, ranges, etc.).

[0016] <Embodiment 1> This embodiment will be described using Figures 1 to 18. Figure 1A is a perspective view showing an example configuration of the heat sink of this disclosure, and Figure 1B is a side view showing an example configuration of the heat sink of this disclosure. As shown in Figures 1A and 1B, the heat sink 1 of this embodiment comprises a heat sink plate 2, a first heat sink fin 3, and a second heat sink fin 4.

[0017] As shown in Figures 1A and 1B, the heat sink 2 is flat. The heat sink 2 supports the heat source, as will be described later. The first heat fin 3 is made of a solid material having high thermal conductivity and electrical conductivity. The first heat fin 3 is provided on the heat sink 2.

[0018] As shown in Figures 1A and 1B, the first heat dissipation fin 3 extends in a first direction within the plane of the heat sink 2 and has a continuous shape in the first direction. Here, in this disclosure, fins that are continuous in the first direction, such as the first heat dissipation fin 3, may be collectively referred to as straight fins. Here, it is preferable that the first direction and the second direction are orthogonal.

[0019] The second heat dissipation fin 4 is made of a solid material having high thermal conductivity and electrical conductivity. As shown in Figures 1A and 1B, the second heat dissipation fin 4 is provided on the heat sink 2 and extends in a first direction. The fin length L2 (fin width a2 in Figure 2) of the second heat dissipation fin 4 in the first direction is shorter than the fin length L1 (fin width a1 in Figure 2) of the first heat dissipation fin 3 in the first direction.

[0020] The second heat dissipation fin 4 is substantially rectangular when viewed from a second direction, as shown in Figures 1A and 1B. The fin height h2 of the second heat dissipation fin 4 is higher than the fin height h1 of the first heat dissipation fin 3, as shown in Figure 1B.

[0021] As shown in Figure 1A, the second heat dissipation fin 4 constitutes a heat dissipation fin row 5 in which the second heat dissipation fins 4 are discretely and periodically arranged on the heat sink 2 in a first direction with a pitch p (= a² + d, d: fin spacing).

[0022] The first heat dissipation fin 3 and the second heat dissipation fin 4 constitute a heat dissipation fin structure 6 arranged alternately in the second direction. Here, in this disclosure, rectangular fins that are discretely arranged in the first direction, such as the second heat dissipation fin 4, may be collectively referred to as rectangular fins.

[0023] At this time, the fin height h1 of the first heat dissipation fin 3 and the fin height h2 of the second heat dissipation fin 4 are adjusted so that the entire heat dissipation fin structure 6 exhibits an electromagnetic band gap (EBG) for a predetermined operating frequency f.

[0024] Here, as a numerical example of the fin heights of the first heat dissipation fin 3 and the second heat dissipation fin 4, if the fin height h1 of the first heat dissipation fin 3 is approximately λ / 6 to λ / 5 in length, where λ (=c / f, c: speed of light) is the wavelength corresponding to a predetermined operating frequency f, and the fin height h2 of the second heat dissipation fin 4 is in the vicinity of approximately λ / 4 in length, then this is suitable for achieving both improved heat dissipation area and EBG (electroluminescent glow) generation.

[0025] Figure 2 is a schematic diagram for calculating the heat dissipation fin area of ​​a heat sink in an example configuration of the present disclosure. From Figure 2, the area ratio S1 / S2 of the area of ​​the first heat sink 3 in the portion with the same width as the pitch p of the second heat sink 4, S1 = h1 × (a2 + d) = λ / 5 × (a2 + d), and the area of ​​the second heat sink 4, S2 = h2 × a2 = λ / 4 × a2, is (4 / 5) × (1 + d / a2). As a condition for the area of ​​the first heat sink 3 to increase compared to the area of ​​the second heat sink 4, it is desirable that a2 < 4d, since S1 / S2 > 1.

[0026] In this case, increasing the heat dissipation area ratio is more preferable when the fin spacing d of the second heat dissipation fin 4 is large. That is, in addition to the rectangular heat dissipation fin shape shown in Figures 1A, B, and 2, if a pin-shaped second heat dissipation fin 4 such as a cylinder is used, the ratio of increase in heat dissipation area will be even higher.

[0027] Furthermore, the ratios of the fin height, fin width, and fin spacing of the first heat dissipation fin 3 and the second heat dissipation fin 4 should be appropriately selected considering both electromagnetic characteristics and heat dissipation performance, represented by the heat dissipation area.

[0028] Figure 3 is a perspective view of Example 1 of a heat dissipation structure consisting only of general straight fins, for comparison of the effects of the heat sink configuration examples of this disclosure, and is a schematic diagram showing the definition of the radio wave propagation direction in the fin longitudinal direction (x axis) P_x and the fin perpendicular direction (y axis) p_y.

[0029] Here, the fin height h3 of the straight fin 101 is set to 20 mm, which is equivalent to λ / 4 when λ is the wavelength corresponding to the main frequency of the sub6 band, 3.7 GHz, and the pitch p in the y-axis direction of the straight fin 101 is set to 9 mm.

[0030] Figure 4A shows the electromagnetic field simulation results of the frequency dispersion characteristic f(k) for wavenumber k (∝p: phase) of the heat dissipation structure example 1 in Figure 3, and Figure 4B is a schematic diagram showing each symmetry point (K point): Γ point, X_i point, M_i point (where i represents the x and y axes, respectively) in the Brillouin zone in reciprocal lattice space. Figure 4C is an excerpt of the low-frequency band including the electromagnetic bandgap (EBG) of the frequency dispersion characteristic in Figure 4A.

[0031] As shown in Figure 4C, for the +p_x direction (x-axis direction), a propagation mode exists for any wavenumber k, and radio wave propagation occurs in the longitudinal direction of the fin. On the other hand, for the +p_y direction (y-axis direction), a non-propagation region, i.e., an EGB, occurs in the frequency domain shown by the hatching, and radio wave propagation is blocked.

[0032] Figures 5A and 5B show the electromagnetic field simulation results for the frequency characteristics of the S-parameter S21 component (transmission intensity) in the y-axis and x-axis directions, respectively. Corresponding to the results in Figure 4C, Figure 5A (propagation in the y-axis direction) shows a high attenuation characteristic of approximately S21 = -60 dB near the EBG. On the other hand, Figure 5B (propagation in the X-axis direction) shows a transmission characteristic with S21 ~ 0 dB.

[0033] This characteristic means that it cannot prevent radio wave propagation in a specific direction, making it unsuitable for use in array antenna devices composed of polarization antenna elements such as orthogonal or circular polarization, which have a directional electromagnetic excitation, or for suppressing unwanted radiation in wireless devices.

[0034] Figure 6 is a perspective view of Example 2 of a heat dissipation structure consisting of straight fins and rectangular fins, for comparing the effects of the heat sink configuration examples of this disclosure, and is a schematic diagram showing the definition of the radio wave propagation direction in the fin longitudinal direction (x axis) p_x and the fin perpendicular direction (y axis) p_y.

[0035] Here, the fin height h4 of the straight fin 102 and the fin height h5 of the rectangular fin 103 are set to h4 = h5 = 20 mm, that is, both are equivalent to λ / 4 when λ is the wavelength corresponding to the main frequency of the sub6 band, 3.7 GHz. The distance in the y-axis direction between the straight fin 102 and the rectangular fin 103 is 9 mm, the fin width a of the rectangular fin 103 is 9 mm, and the fin spacing d is 9 mm (i.e., pitch p = 18 mm).

[0036] Figure 7 shows the electromagnetic field simulation results for surface wave propagation in the longitudinal direction of the fins within the heat dissipation fin structure of example 2 in Figure 6. It can be seen that radio wave propagation in the longitudinal direction of the fins occurs on the fin end faces of both the straight fin 102 and the rectangular fin 103.

[0037] Similar to the heat dissipation structure example 1, this characteristic does not prevent radio wave propagation in a specific direction, making it unsuitable for use in array antenna devices composed of polarization antenna elements such as orthogonal and circular polarization with directional electromagnetic excitation, or for suppressing unwanted radiation in wireless devices.

[0038] Figure 8 is a perspective view of example 3 of a heat dissipation structure consisting of straight fins 104 and rectangular fins 105, for comparison of the effects of the heat sink configuration examples of this disclosure, and is a schematic diagram showing the definition of the radio wave propagation direction in the fin longitudinal direction (x axis) p_x and the fin perpendicular direction (y axis) p_y.

[0039] Here, the fin height h6 of the straight fin 104 is 20 mm, and the fin height h7 of the rectangular fin 105 is 15 mm. That is, it is equivalent to λ / 4 when the wavelength corresponding to the main frequency of 3.7 GHz in the sub6 band is λ for the straight fin 104, and for the rectangular fin 105, it is equivalent to λ / 6 < h6 < λ / 5. The fin height h6 of the straight fin 104 is higher than the fin height h7 of the rectangular fin 105.

[0040] Also, the interval in the y-axis direction between the straight fin 104 and the rectangular fin 105 is 9 mm, the fin width a of the rectangular fin 105 is 9 mm, and the fin interval d is 9 mm (that is, the pitch p = 18 mm).

[0041] FIG. 9 is a diagram showing the electromagnetic field simulation result of surface wave propagation in the fin longitudinal direction in the heat radiation fin structure of the heat radiation structure example 3 in FIG. 8. It can be understood that radio wave propagation in the fin longitudinal direction occurs on the fin end surfaces of both the straight fin 104 and the rectangular fin 105.

[0042] In particular, radio wave propagation also occurs in the rectangular fin 105 with a low fin height. This characteristic, similar to the heat radiation structure examples 1 and 2, cannot prevent radio wave propagation in a specific direction, and is not suitable for use in, for example, an array antenna device composed of polarization antenna elements such as orthogonal and circularly polarized waves with a specific direction of electromagnetic excitation, or for suppressing unnecessary radiation in a wireless device.

[0043] The present disclosure was conceived to improve the heat radiation area while preventing radio wave propagation in any direction. FIG. 10 is a diagram showing the electromagnetic field simulation result of frequency dispersion characteristics when the fin height h1 of the first heat radiation fin is changed to 15, 16, 17, 20 mm and the fin height h2 of the second heat radiation fin is fixed at 20 mm in the heat radiator of the configuration example in FIG. 1.

[0044] As shown in Fig. 10, in the range where h1 > 16 mm, propagation modes exist in both the fin longitudinal direction (x-axis) px and the fin perpendicular direction (y-axis) py of the radio wave propagation direction. On the other hand, when the fin height h1 of the continuous first heat dissipation fin 3 is 15 mm, that is, corresponding to λ / 6 < h2 < λ / 5, an electromagnetic bandgap (EBG) occurs in the frequency region indicated by the hatching, and no propagation mode occurs, suppressing radio wave propagation.

[0045] Fig. 11 is a perspective view showing a configuration example of the radiator of the present disclosure conceived in the above analysis, and a diagram showing the definition of the radio wave propagation direction. That is, the fin height h1 of the first heat dissipation fin 3 is 15 mm, and the fin height h2 of the second heat dissipation fin 4 is 20 mm.

[0046] Fig. 12 is a diagram showing the electromagnetic field simulation result of surface wave propagation in the fin longitudinal direction in the fin structure of the radiator of the configuration example of the present disclosure in Fig. 11. It can be understood that radio wave propagation in the fin longitudinal direction is suppressed on the fin end faces of both the first heat dissipation fin 3 and the second heat dissipation fin 4.

[0047] This characteristic can prevent radio wave propagation in any direction in the plane, and is particularly suitable for use in array antenna devices composed of polarization antenna elements such as orthogonal and circularly polarized waves with electromagnetic excitation directionality, and for suppressing unnecessary radiation in wireless devices.

[0048] Also, when the fin width a of the second heat dissipation fin 4 is 9 mm and the fin interval d is 9 mm (that is, the pitch p is 18 mm) as in the above configuration example of the radiator, the heat dissipation area ratio S1 / S2 increases by 4 / 3 times, contributing to the improvement of the heat dissipation characteristics.

[0049] Figs. 13A and 13B are diagrams showing the electromagnetic field simulation results of the frequency characteristics of the S-parameter S21 component (transmission component) in the y-axis direction and the x-axis direction of the radiator of the configuration example of the present disclosure in Fig. 11.

[0050] The EBG characteristics at a fin height h1 = 15 mm for the first heat dissipation fin 3 in Figure 10 correspond to the attenuation of radio wave propagation in Figure 12. In both directions, Figure 13A (propagation in the y-axis direction) and Figure 13B (propagation in the x-axis direction), S21 shows high attenuation characteristics near the EBG.

[0051] Here, Figure 14 shows the simulation results of the electric field vector when the fin heights of the straight fin and the rectangular fin are equal. Figure 15 shows the simulation results of the electric field vector when the fin height of the rectangular fin is higher than that of the straight fin.

[0052] Observing the behavior of the electric field around the fins in electric field vector simulations, as shown in Figure 15, when the straight fins are low, strong capacitive coupling occurs between adjacent rectangular fins, particularly between the fin tips, resulting in a situation where the electric field is concentrated at the tip of the straight fin.

[0053] From these results, as shown in Figures 14 and 15, it is inferred that electromagnetic energy is absorbed once by the rectangular fins that exhibit an EBG / radio wave propagation suppression effect in a single heat dissipation fin array via capacitive coupling, and that the EBG / radio wave propagation suppression effect of the rectangular fins becomes dominant.

[0054] Therefore, as in this embodiment, when the fin height h2 of the second heat dissipation fin 4 is higher than the fin height h1 of the first heat dissipation fin 3, the electric field can be confined by the adjacent second heat dissipation fin 4 in the y-axis direction, and it is presumed that the EBG and radio wave propagation suppression effect is high.

[0055] Furthermore, the fin spacing in the y-axis direction between the first heat dissipation fin 3 and the second heat dissipation fin 4 should be smaller than the fin height h1 of the first heat dissipation fin 3, in order to facilitate coupling between the first heat dissipation fin 3 and the second heat dissipation fin 4.

[0056] To verify the heat dissipation characteristics of the heat sink configuration example of this disclosure, Figures 16A, 16B, and 16C show, respectively, analysis models for thermal fluid analysis simulations of a heat dissipation structure consisting of only a typical continuous straight fin (fin height 20 mm), only a typical discrete rectangular fin (fin height 20 mm), and a heat dissipation structure in which the first heat dissipation fin 3, which is a straight fin (fin height 15 mm), and the second heat dissipation fin 4, which is a rectangular fin (fin height 20 mm), are arranged alternately.

[0057] Here, the surface area of ​​the heat sink base plate (heat sink), heat source, and rear insulation plate is set to 400mm x 600mm, the base plate thickness is 20mm, the heat source thickness is 10mm, and the insulation plate thickness is 50mm. The thermal conductivity of each is set to 140W / (m·K) for the base plate and fins, and 0.3W / (m·K) for the insulation plate. The heat output of the heat source is set to 500W, and the ambient temperature is set to 50℃.

[0058] Figures 17A, 17B, and 17C are steady-state temperature distribution diagrams of the heat dissipation structure surface obtained from thermal fluid simulations under natural convection (windless) conditions in the analysis models of Figures 16A, 16B, and 16C.

[0059] In detail, Figure 17A shows the results of a heat dissipation structure example using only typical continuous straight fins (fin height 20 mm), Figure 17B shows the results of a heat dissipation structure using only typical discrete rectangular fins (fin height 20 mm), and Figure 17C shows the results of an example in which straight fins (fin height 15 mm) and rectangular fins (fin height 20 mm) of the present disclosure are arranged alternately. As is clear from comparing Figure 17B and Figure 17C, it can be seen that the high-temperature region is reduced compared to the case with only typical rectangular fins.

[0060] Figures 18A and 18B show the maximum heat source temperature on the surface of the heat dissipation structure and the maximum temperature of the heat dissipation structure (heat sink) obtained from thermal fluid simulations under natural convection (windless) conditions in the analysis models of Figures 16A, 16B, and 16C.

[0061] In the heat sink configuration example of this disclosure, similar to the trend of decreasing temperature in the high-temperature region of the overall temperature distribution of the heat dissipation structure shown in Figures 17A, 17B, and 17C, as shown in Figures 18A and 18B, the temperature decreases compared to a typical rectangular fin only, approaching the case of a straight fin with a large heat dissipation area.

[0062] As described above, the heat sink 1 of this embodiment can achieve both suppression of radio wave propagation in all directions and improvement of heat dissipation characteristics. Furthermore, in the heat sink 1 of this embodiment, the generation of EBG by the heat dissipation fins near the antenna height causes the heat dissipation fins themselves to function as an effective electromagnetic barrier, eliminating the need for separate barriers to suppress inter-antenna coupling and surface waves. Therefore, the heat sink 1 of this embodiment can improve the design flexibility of the heat sink 1.

[0063] <Embodiment 2> This embodiment will be explained using Figures 19 to 23. This embodiment is an array antenna device 7, which is a representative example of a wireless device when the heat sink 1 illustrated in this disclosure is applied to both polarization antenna element groups.

[0064] Figure 19 shows a Vivaldi antenna element with an exponential metal pattern, which is used as an example of an antenna element capable of broadband operation. Antenna element 11 in Figure 19 is a representative example of a radiating element, and is a Vivaldi antenna element with excellent broadband characteristics, having exponential metal patterns 12a and 12b on a dielectric substrate. The antenna feed line 13 is connected to the metal pattern 12b.

[0065] Here, Figure 20 is a schematic diagram of the surface impedance at the fin end face of a heat dissipation fin structure having EBG characteristics. As shown in Figure 20, the heat dissipation fins 107 provided on the upper part of the heat sink 106, in particular, when the fin height of the heat dissipation fins 107 is set to (1+2N) / 4 of the wavelength λ at a predetermined frequency (where N is an integer greater than or equal to 0), impedance conversion provides a high-impedance surface with a very high surface impedance at the heat dissipation reflective surface (fin end face) composed of the heat dissipation fin group.

[0066] In the heat sink 1 illustrated in this disclosure, as shown in Figure 11, there is a mixture of first heat sink fins 3 and second heat sink fins 4 with fin heights of λ / 4 and λ / 6, but it is presumed that a high impedance surface similar to that of the fin end faces in Figure 20 is achieved.

[0067] In this case, an artificial magnetic conductor (AMC) is formed, and the phase of the reflected wave at the fin end face exhibits a unique characteristic, being 0° instead of the 180° reflection phase of a normal conductor wall. This characteristic is suitable for the surface near the array antenna device 7 because the reflected wave operates without canceling out the desired radio waves around the antenna element.

[0068] Figures 21A, 21B, 21C, and 21D are perspective views, side views from two directions, and plan views of an electromagnetic field simulation model of an array antenna device (with 3x2 elements and 2x2 elements per orthogonal polarization) in which Vivaldi antenna elements are arranged orthogonally on a heat sink as illustrated in this disclosure.

[0069] Figures 22A, 22B, and 22C show the simulation results of radiation patterns during operation of a 3x2 array Vivaldi antenna with only a metal surface without fins (dashed line) and a continuous row of fins with a fin height of 20 mm (solid line), for comparison of the effects of the heat sink configuration example of the present disclosure.

[0070] At all frequencies—3.4GHz, 3.7GHz, and 4.0GHz—degradation of the radiation pattern and antenna gain occurs compared to when an ideal reflector without fins is present.

[0071] On the other hand, Figures 23A, 23B, and 23C show the simulation results of the radiation pattern when a 3x2 array Vivaldi antenna is operating with only a typical finless metal surface (dashed line) and the present disclosure, i.e., with a continuous row of fins with a fin height of 15 mm (solid line).

[0072] It can be seen that the radiation pattern and antenna gain are maintained at a level comparable to an ideal reflector without fins at all frequencies: 3.4GHz, 3.7GHz, and 4.0GHz. Similar results are obtained with orthogonal 2x2 elements.

[0073] From the above, the heat sink 1 of this embodiment enhances heat dissipation characteristics while maintaining the dual-polarization antenna characteristics in the array antenna device 7. Here, as shown in Figure 21A and others, the first heat dissipation fin 3 is divided in the x-axis direction, but it is presumed that if the first heat dissipation fin 3 has a fin length equivalent to at least two rows of the second heat dissipation fin 4, the desired radio wave propagation can be blocked. In this embodiment, an example configuration in which an antenna element 11 is applied to the heat sink 1 as a representative example of a radiating element has been described, but a reflective element may also be applied to the heat sink 1 to form a reflective structure such as a metasurface.

[0074] <Embodiment 3> Figure 24 is a schematic diagram showing the refrigerant flow in a flow path when a refrigerant flow path is provided inside a typical rectangular heat dissipation fin. Figure 25 is a schematic diagram showing the refrigerant flow in a flow path when a refrigerant flow path is provided inside the first heat dissipation fin in the configuration example of this disclosure. In Figures 24 and 25, the flow of refrigerant is indicated by arrows, and the flow path is indicated by a dashed line.

[0075] As shown in Figure 24, the length of the fins of the rectangular heat dissipation fins 109 provided on the heat sink 108 is greater than the length of the fins of the first heat dissipation fins 3 provided on the heat sink 2, as shown in Figure 25.

[0076] Therefore, as is clear from comparing Figure 24 and Figure 25, when the refrigerant flows through the flow path 3a inside the first heat dissipation fin 3, the resistance in the flow path is reduced and the flow of the refrigerant is improved compared to when the refrigerant flows through the flow path 109a inside the heat dissipation fin 109. This allows for more efficient heat exchange between the refrigerant and the heat dissipation structure, resulting in improved heat dissipation performance.

[0077] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0078] For example, in Embodiment 3, the refrigerant is flowed through the internal flow paths of the heat sink 2 and the first heat sink fin 3, but the refrigerant may also be flowed through the internal flow paths of the second heat sink fin 4.

[0079] For example, the fin height h1 of the first heat dissipation fin 3 in the above embodiment is illustrative and may be less than or equal to λ × (N / 2 + A × 1 / 5) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

[0080] For example, the fin height h2 of the second heat dissipation fin 4 in the above embodiment is illustrative and may be less than or equal to λ × (N / 2 + A × 1 / 4) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

[0081] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features described with reference to any one drawing can be combined with features shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features may be omitted.

[0082] Some or all of the embodiments described above may also be described as follows, but are not limited to these. <Note 1> A heat sink that supports the heat source, The heat sink is provided with a first heat sink fin that extends in a first direction within the plane of the heat sink, A second heat dissipation fin is provided on the heat sink and extends in the first direction, It has, The heat sink, the first heat sink fin, and the second heat sink fin are made of a solid material having thermal conductivity and electrical conductivity. The first heat dissipation fin and the second heat dissipation fin are arranged in a predetermined order in a second direction within the plane of the heat dissipation plate, forming a heat dissipation fin structure. The fin length of the second heat dissipation fin in the first direction is shorter than the fin length of the first heat dissipation fin in the first direction. The fin height of the first heat dissipation fin is lower than the fin height of the second heat dissipation fin.

[0083] <Note 2> The heat sink according to Appendix 1, wherein the first heat dissipation fin and the second heat dissipation fin are arranged alternately in the second direction.

[0084] <Note 3> A heat sink as described in Appendix 1 or 2, wherein the first direction and the second direction are orthogonal to each other.

[0085] <Note 4> A heat sink according to any one of the appendices 1 to 3, wherein the fin height of the first heat sink and the fin height of the second heat sink are such that the heat sink structure exhibits an electromagnetic band gap for a predetermined frequency.

[0086] <Note 5> The heat sink described in any of the appendices 1 to 4, wherein the fin height of the second heat dissipation fin is λ × (N / 2 + A × 1 / 4) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

[0087] <Note 6> The heat sink described in any of the appendices 1 to 5, wherein the fin height of the first heat dissipation fin is less than or equal to λ × (N / 2 + A × 1 / 5) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

[0088] <Note 7> A heat sink according to any one of the appendices 1 to 6, wherein the distance between the first heat sink and the second heat sink in the second direction is smaller than the fin height of the first heat sink.

[0089] <Note 8> The heat sink described in any of the appendices 1 to 7, wherein the shape of the second heat dissipation fin is rectangular or rod-shaped.

[0090] <Note 9> A heat sink according to any one of the appendices 1 to 8, wherein a coolant flow path is provided inside the first heat dissipation fin or the second heat dissipation fin.

[0091] <Note 10> A heat sink as described in any of the appendices 1 to 9, A radiating element or a reflective element is arranged inside the heat dissipation fin structure of the heat sink. A wireless device equipped with the following features. [Explanation of symbols]

[0092] 1 Heatsink 2 Heat sink 3. First heat dissipation fin, 3a. Flow channel 4. Second heat dissipation fin 6. Heat dissipation fin structure 7. Array antenna device 11 Antenna elements f Operating frequency h1 Fin height of the first heat sink fin h2 Fin height of the second heat sink fin L1 Fin length of the first heat dissipation fin L2 Second heat dissipation fin length λ Wavelength corresponding to the operating frequency

Claims

1. A heat sink that supports the heat source, A first heat dissipation fin is provided on the heat sink and extends in a first direction within the plane of the heat sink, A second heat dissipation fin is provided on the heat sink and extends in the first direction, It has, The heat sink, the first heat sink fin, and the second heat sink fin are made of a solid material having thermal conductivity and electrical conductivity. The first heat dissipation fin and the second heat dissipation fin are arranged in a predetermined order in a second direction within the plane of the heat dissipation plate, forming a heat dissipation fin structure. The fin length of the second heat dissipation fin in the first direction is shorter than the fin length of the first heat dissipation fin in the first direction. A heat sink in which the fin height of the first heat sink is lower than the fin height of the second heat sink.

2. The heat sink according to claim 1, wherein the first heat sink and the second heat sink are arranged alternately in the second direction.

3. The heat sink according to claim 1 or 2, wherein the first direction and the second direction are orthogonal to each other.

4. The heat sink according to claim 1 or 2, wherein the fin height of the first heat sink and the fin height of the second heat sink are such that the heat sink structure exhibits an electromagnetic band gap for a predetermined frequency.

5. The heat sink according to claim 1 or 2, wherein the fin height of the second heat sink is λ × (N / 2 + A × 1 / 4) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

6. The heat sink according to claim 1 or 2, wherein the fin height of the first heat sink is less than or equal to λ × (N / 2 + A × 1 / 5) (where λ is the wavelength corresponding to a predetermined frequency, N is an integer of 0 or more, and A is an arbitrary constant).

7. The heat sink according to claim 1 or 2, wherein the distance between the first heat sink and the second heat sink in the second direction is smaller than the fin height of the first heat sink.

8. The heat sink according to claim 1 or 2, wherein the shape of the second heat dissipation fin is rectangular or rod-shaped.

9. The heat sink according to claim 1 or 2, wherein a coolant flow path is provided inside the first heat sink or the second heat sink.

10. A heat sink according to claim 1 or 2, A radiating element or a reflective element is arranged inside the heat dissipation fin structure of the heat sink. A wireless device equipped with the following features.

Images