Antenna device

Abstract

To provide an antenna device that prevents snow accretion on a cover without using paint.SOLUTION: An antenna device of an embodiment comprises a base plate, an antenna element, a cover, and a heater, and the base plate has an upper plate part and a lower plate part that face each other with a storage cavity sandwiched therebetween. The antenna element is attached to the base plate while arranged in the storage cavity, and the cover is attached to the base plate while surrounding the storage cavity with a connected body with the base plate. The cover includes a front plate part that covers the storage cavity from the front side from the upper plate part up to the lower plate part with respect to a height direction, and the front plate part is inclined with respect to the height direction in an inclined state where it is located closer to the front side as approaching the upper plate part. The heater is arranged above the antenna element in the storage cavity.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to an antenna device.

Background Art

[0002] In a glide slope antenna device, which is a type of ILS (Instrument Landing System) device used at airports and the like, three antenna devices are attached to a tower. In the antenna device of the glide slope antenna device, a cover is attached to a base plate from the front side, and a storage cavity is surrounded by a connecting body of the base plate and the cover. Further, in the antenna device, an antenna element is disposed in the storage cavity, and radio waves are radiated from the antenna element to the front side. Then, the radio waves radiated from the antenna element pass through the cover and are emitted to the outside of the storage cavity.

[0003] In the antenna device of the glide slope antenna device as described above, from the viewpoint of reducing the labor of snow removal work and the like, suppressing snow accumulation on the cover has been demanded. By applying a paint having ski properties to the cover or the like, snow accumulation on the cover can be suppressed, but the ski effect of the paint decreases over time. For this reason, it has been demanded to suppress snow accumulation on the cover without using paint.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide an antenna device that suppresses snow accumulation on the cover without using paint.

Means for Solving the Problem

[0006] According to an embodiment, the antenna device includes a base plate, an antenna element, a cover, and a heater. The base plate includes an upper plate portion and a lower plate portion, and the upper plate portion faces the lower plate portion across a storage cavity in the height direction. The antenna element is attached to the base plate in a state of being disposed in the storage cavity and radiates radio waves forward. The cover is attached to the base plate from the front side in a state of surrounding the storage cavity by a connecting body with the base plate, and the radio waves radiated from the antenna element pass through the cover. The cover includes a front plate portion that covers the storage cavity from the front side across the upper plate portion to the lower plate portion in the height direction, and the front plate portion is in an inclined state where it is positioned more forward as it approaches the upper plate portion and is inclined with respect to the height direction. The heater is disposed above the antenna element in the height direction in the storage cavity.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments and the like will be described with reference to the drawings.

[0009] First, the usage mode of the antenna device according to the embodiment will be described. The antenna device of the embodiment is mounted on a glide slope antenna device, which is a type of ILS (Instrument Landing System) device used at an airport or the like. FIG. 1 shows a glide slope antenna device 1 as a usage mode of the antenna device according to the embodiment. The glide slope antenna device 1 is installed on the side of a runway at an airport or the like.

[0010] As shown in FIG. 1, the glide slope antenna device 1 includes a tower 2 and three antenna devices 3 attached to the tower 2. In the glide slope antenna device 1, the three antenna devices 3 are arranged at intervals in the vertical direction (height direction). In one example, the height of the tower 2, that is, the dimension of the tower 2 along the vertical direction, is about 16 m. The glide slope antenna device 1 uses the antenna device 3 to perform wireless communication with an aircraft landing on the runway. At this time, the glide slope antenna device 1 transmits a wireless signal to the aircraft landing on the runway, etc., and gives an instruction regarding the approach route to the runway, such as the approach angle to the runway, to the aircraft.

[0011] Next, the antenna device 3 mounted on the grid slope antenna device 1 will be described. FIGS. 2 to 4 show an example of the configuration of the antenna device 3 according to the embodiment. As shown in FIGS. 2 to 4, in the antenna device 3, the front-rear direction (the directions indicated by the arrows C1 and C2) is defined. And in the antenna device 3, one side in the front-rear direction becomes the front side (arrow C1 side), and the side opposite to the front side becomes the rear side (arrow C2 side). The front side is also referred to as the front surface side, and the rear side is also referred to as the back surface side.

[0012] Also, in the antenna device 3, the width direction (the directions indicated by the arrows W1 and W2) that intersects (is orthogonal or substantially orthogonal) to the front-rear direction, and the height direction (the directions indicated by the arrows H1 and H2) that intersects both the front-rear direction and the width direction are defined. And in the antenna device 3, one side in the height direction becomes the upper side (arrow H1 side), and the side opposite to the upper side becomes the lower side (arrow H2 side). Here, FIG. 2 is a perspective view, and FIG. 3 shows a state viewed from one side in the width direction. Also, FIG. 4 shows, in a perspective view, a state cut by a cross section orthogonal or substantially orthogonal to the width direction. In the grid slope antenna device 1, for example, the antenna device 3 is attached to the tower 2 in a state where the front-rear direction and the width direction are along the horizontal plane, and the height direction is along the vertical direction.

[0013] As shown in FIGS. 2 to 4, the antenna device 3 includes a frame body (housing) 5, a base plate 6, an antenna element 7, and a cover 8. The frame body 5 is composed of an upper frame portion 11 and a lower frame portion 12. In the frame body 5, the rear end portion of the upper frame portion 11 is connected to the rear end portion of the lower frame portion 12. The upper frame portion 11 is in an inclined state where it is located on the upper side in the height direction as it goes toward the front side, and is inclined with respect to the height direction. Also, the lower frame portion 12 is in an inclined state where it is located on the lower side in the height direction as it goes toward the front side, and is inclined with respect to the height direction.

[0014] Here, when a virtual plane C (see FIG. 3) orthogonal to the height direction is defined, the upper frame portion 11 is arranged symmetric or substantially symmetric with respect to the lower frame portion 12 with the plane C as the central plane. Also, the front end of the lower frame portion 12 is located below the front end of the upper frame portion 11 in the height direction. However, the front end of the lower frame portion 12 is not displaced or hardly displaced in the front-rear direction with respect to the front end of the upper frame portion 11.

[0015] FIG. 5 shows the antenna device 3 in a perspective view with the antenna element 7, the cover 8, etc. omitted, and FIG. 6 shows the frame body 5 of the antenna device 3 in a perspective view. In an example of FIGS. 2 to 6, the upper frame portion 11 is composed of four columnar portions 21, 22, 23, 24. Each of the columnar portions 21, 22 extends along the width direction. The columnar portion 22 is located away from the columnar portion 21 toward the front side and away from the columnar portion 21 in the upper side in the height direction. In the upper frame portion 11, the rear end is formed by the columnar portion 21, and the front end and the upper end are formed by the columnar portion 22.

[0016] Also, in the upper frame portion 11, each of the columnar portions 23, 24 extends from the columnar portion 21 to the columnar portion 22, and the columnar portions 23, 24 are located away from each other in the width direction. The rear end portions of each of the columnar portions 23, 24 are connected to the columnar portion 21, and the front end portions of each of the columnar portions 23, 24 are connected to the columnar portion 22. Each of the columnar portions 23, 24 is inclined with respect to the height direction in an inclined state where it is located on the upper side in the height direction as it approaches the columnar portion 22. That is, each of the columnar portions 23, 24 is inclined with respect to the height direction in an inclined state where it is located on the upper side in the height direction as it goes toward the front side.

[0017] Also, a through space 25 penetrating the upper frame portion 11 in the height direction is formed in the upper frame portion 11. In the upper frame portion 11, the columnar portion 22 faces the columnar portion 21 with the through space 25 interposed therebetween, and the columnar portion 24 faces the columnar portion 23 with the through space 25 interposed therebetween in the width direction. For this reason, in the upper frame portion 11, the through space 25 is surrounded by the connecting body of the four columnar portions 21 to 24.

[0018] In one example, the upper frame portion 11 is not provided with the columnar portion 22, and the upper frame portion 11 is constituted by three columnar portions 21, 23, and 24. In this case, in the upper frame portion 11, the through space 25 is formed between the columnar portions 23 and 24 in the width direction and on the front side with respect to the columnar portion 21. Then, the front end of the upper frame portion 11 is formed by the columnar portions 23 and 24, and the through space 25 opens toward the front side between the front end of the columnar portion 23 and the front end of the columnar portion 24.

[0019] Also, in one example of FIGS. 2 to 6, the lower frame portion 12 is composed of four columnar portions 31, 32, 33, and 34. Each of the columnar portions 31 and 32 extends along the width direction. The columnar portion 32 is located away from the columnar portion 31 toward the front side and away from the columnar portion 31 toward the lower side in the height direction. In the lower frame portion 12, the rear end is formed by the columnar portion 31, and the front end and the lower end are formed by the columnar portion 32.

[0020] Also, in the lower frame portion 12, each of the columnar portions 33 and 34 extends from the columnar portion 31 to the columnar portion 32, and the columnar portions 33 and 34 are located away from each other in the width direction. The rear end portion of each of the columnar portions 33 and 34 is connected to the columnar portion 31, and the front end portion of each of the columnar portions 33 and 34 is connected to the columnar portion 32. Each of the columnar portions 33 and 34 is inclined with respect to the height direction in an inclined state where it is located closer to the lower side in the height direction as it approaches the columnar portion 32. That is, each of the columnar portions 33 and 34 is inclined with respect to the height direction in an inclined state where it is located closer to the lower side in the height direction as it approaches the front side.

[0021] Also, a through space 35 that penetrates the lower frame portion 12 in the height direction is formed in the lower frame portion 12. In the lower frame portion 12, the columnar portion 32 faces the columnar portion 31 with the through space 35 interposed therebetween, and the columnar portion 34 faces the columnar portion 33 with the through space 35 interposed therebetween in the width direction. Therefore, in the lower frame portion 12, the through space 35 is surrounded by the connecting body of the four columnar portions 31 to 34.

[0022] In one example, the lower frame portion 12 is not provided with the columnar portion 32, and the lower frame portion 12 is constituted by the three columnar portions 31, 33, and 34. In this case, in the lower frame portion 12, the through space 35 is formed between the columnar portions 33 and 34 in the width direction and on the front side with respect to the columnar portion 31. Then, the front ends of the columnar portions 33 and 34 form the front end of the lower frame portion 12, and the through space 35 opens toward the front side between the front end of the columnar portion 33 and the front end of the columnar portion 34.

[0023] In the antenna device 3, the base plate 6 is attached to the frame body 5, and the cover 8 is attached to the base plate 6 from the front side. And in the antenna device 3, a storage cavity 40 is formed inside the connected body where the cover 8 is attached to the base plate 6. For this reason, the storage cavity 40 is surrounded by the connected body of the base plate 6 and the cover 8. Also, in the antenna device, the cover 8 is disposed between the upper frame portion 11 and the lower frame portion 12 in the height direction. And the upper frame portion 11 is disposed close to the cover 8 from the upper side in the height direction, and the lower frame portion 12 is disposed close to the cover 8 from the lower side in the height direction.

[0024] In one example of FIGS. 2 to 5, the base plate 6 includes an upper plate portion 41, a lower plate portion 42, and a rear plate portion 43. The upper plate portion 41 is attached to the upper frame portion 11, and the lower plate portion 42 is attached to the lower frame portion 12. The upper plate portion 41 covers the storage cavity 40 from the upper side in the height direction and is adjacent to the storage cavity 40 from the upper side in the height direction. And the lower plate portion 42 covers the storage cavity 40 from the lower side in the height direction and is adjacent to the storage cavity 40 from the lower side in the height direction. For this reason, the upper plate portion 41 faces the lower plate portion 42 with the storage cavity 40 interposed therebetween in the height direction. Also, the rear plate portion 43 covers the storage cavity 40 from the rear side and is adjacent to the storage cavity 40 from the rear side.

[0025] In the base plate 6, the rear plate portion 43 extends along the height direction. And, at the upper end portion of the rear plate portion 43, the rear end portion of the upper plate portion 41 is connected, and at the lower end portion of the rear plate portion 43, the rear end portion of the lower plate portion 42 is connected. The upper plate portion 41 is in an inclined state where it is positioned on the upper side in the height direction as it moves away from the rear plate portion 43, and is inclined with respect to the height direction. That is, the upper plate portion 41 is in an inclined state where it is positioned on the upper side in the height direction as it moves toward the front side, and is inclined with respect to the height direction. Also, the lower plate portion 42 is in an inclined state where it is positioned on the lower side in the height direction as it moves away from the rear plate portion 43, and is inclined with respect to the height direction. That is, the lower plate portion 42 is in an inclined state where it is positioned on the lower side in the height direction as it moves toward the front side, and is inclined with respect to the height direction.

[0026] In the antenna device 3, the front end of the upper plate portion 41 is positioned on the front side with respect to the front end of the lower plate portion 42. Also, in one example, in the base plate 6, at least the inner surface is formed of a material that reflects radio waves. Here, the inner surface of the base plate 6 corresponds to the surface adjacent to the storage cavity 40 in the base plate 6. Examples of the material that reflects radio waves include metals that reflect radio waves such as aluminum.

[0027] In the antenna device 3, the antenna element 7 is attached to the base plate 6 and disposed in the storage cavity 40. The antenna element 7 is disposed at the central portion of the storage cavity 40 in the height direction. In an example of FIGS. 2 to 4, the antenna element 7 is attached to the rear plate portion 43 of the base plate 6, and the aforementioned virtual plane C passes through the antenna element 7. The antenna element 7 emits radio waves toward the front side. In one example, the base plate 6 is formed of a material that reflects radio waves, and in the storage cavity 40, the base plate 6 can reflect the radio waves radiated from the antenna element 7.

[0028] Power lines and signal lines (both not shown) are connected to the antenna element 7. Power is supplied to the antenna element 7 from a power source (not shown) through the power line, and a signal is transmitted to the antenna element 7 from a signal processing device (not shown) or the like through the signal line. The antenna element 7 converts the signal transmitted through the signal line into a wireless signal and radiates radio waves that become the wireless signal. In the antenna device 3, a cable (not shown) that houses the power line and the signal line connected to the antenna element 7 inside penetrates the base plate 6 and extends to the outside of the storage cavity 40.

[0029] In the glide slope antenna device 1, the cables extending from each of the antenna devices 3 are extended vertically downward along the tower 2 to the ground surface. Also, in the antenna device 3, in the extending portion of the cable to the outside of the storage cavity 40, the space between the cable and the base plate 6 is kept liquid-tight by a sealing member (not shown) such as packing. Thereby, the inflow of liquid into the storage cavity 40 through the extending portion of the cable to the outside of the storage cavity 40 is suppressed.

[0030] The cover 8 is formed of a material through which radio waves can pass, and is formed of, for example, fiber reinforced plastics (FRP). The radio waves radiated from the antenna element 7 pass through the cover 8 and are emitted to the outside of the storage cavity 40. Thereby, radio waves that become wireless signals are transmitted from the antenna device 3. In an example of FIGS. 2 to 4, the cover 8 includes a front plate portion 45 and a pair of side plate portions 46 and 47.

[0031] The front plate portion 45 covers the storage cavity 40 from the front side and is adjacent to the storage cavity 40 from the front side. And the front plate portion 45 covers the storage cavity 40 from the upper plate portion 41 to the lower plate portion 42 in the height direction, covering the storage cavity 40 from the upper end portion to the lower end portion of the storage cavity 40. For this reason, the upper end of the front plate portion 45 is located on the upper side in the height direction with respect to the antenna element 7 and is located on the upper side in the height direction with respect to the virtual plane C described above. And the lower end of the front plate portion 45 is located on the lower side in the height direction with respect to the antenna element 7 and is located on the lower side in the height direction with respect to the virtual plane C described above. The radio wave from the antenna element 7 mainly passes through the front plate portion 45 and is emitted to the outside of the storage cavity 40.

[0032] Each of the side plate portions 46 and 47 is connected to the front plate portion 45 and extends rearward from the connection portion to the front plate portion 45. Also, the side plate portions 46 and 47 are arranged apart from each other in the width direction and face each other with the storage cavity 40 interposed therebetween in the width direction. For this reason, the side plate portion (the first side plate portion) 46 covers the storage cavity 40 from one side in the width direction and is adjacent to the storage cavity 40 from one side in the width direction. And the side plate portion (the second side plate portion) 47 covers the storage cavity 40 from the side opposite to the side plate portion 46 in the width direction and is adjacent to the storage cavity 40 from the side opposite to the side plate portion 46 in the width direction. Also, each of the side plate portions 46 and 47 covers the storage cavity 40 from the upper plate portion 41 to the lower plate portion 42 in the height direction, covering the storage cavity 40 from the upper end portion to the lower end portion of the storage cavity 40.

[0033] Also, in an example of FIGS. 2 to 5, the antenna device 3 includes a pair of brackets 51 and 52. Each of the brackets 51 and 52 has higher thermal conductivity than the cover 8. Each of the brackets 51 and 52 is formed of a material having a higher thermal conductivity than the material forming the cover 8 and is formed of, for example, aluminum. The cover 8 is attached to the base plate 6 with each of the brackets 51 and 52 interposed therebetween.

[0034] The bracket (upper bracket) 51 is disposed above the antenna element 7 in the height direction. The bracket 51 is attached to the cover 8 in a state of abutting against the upper end portion of the front plate portion 45. Further, the bracket (lower bracket) 52 is disposed below the antenna element 7 in the height direction. The bracket 52 is attached to the cover 8 in a state of abutting against the lower end portion of the front plate portion 45. FIG. 7 shows the upper end portion of the front plate portion 45 of the cover 8, the bracket (upper bracket) 51, and the configuration in the vicinity thereof in the antenna device 3. In FIG. 7, a state of being cut by a cross section orthogonal or substantially orthogonal to the width direction is shown in a perspective view.

[0035] As shown in FIGS. 4 and 7 and the like, the bracket 51 includes a contact plate portion 55 and an extended plate portion 56. The contact plate portion 55 is disposed on the front side with respect to the extended plate portion 56. The contact plate portion 55 of the bracket 51 abuts against the upper end portion of the front plate portion 45 of the cover 8. In an example of FIGS. 4 and 7 and the like, the contact plate portion 55 is disposed outside the storage cavity 40 and abuts against the outer surface of the front plate portion 45. In another example, the contact plate portion 55 is inserted into the storage cavity 40 and abuts against the inner surface of the front plate portion 45. Further, in the bracket 51, the extended plate portion 56 is inserted into the storage cavity 40. And the extended plate portion 56 is adjacent to the front end portion of the upper plate portion 41 of the base plate 6 from the side where the storage cavity 40 is located.

[0036] Also, as shown in FIG. 4 and the like, the bracket 52 includes a contact plate portion 57 and an extended plate portion 58. The contact plate portion 57 is disposed on the front side with respect to the extended plate portion 58. The contact plate portion 57 of the bracket 52 abuts against the lower end portion of the front plate portion 45 of the cover 8. In an example of FIG. 4 and the like, the contact plate portion 57 is disposed outside the storage cavity 40 and abuts against the outer surface of the front plate portion 45. In another example, the contact plate portion 57 is inserted into the storage cavity 40 and abuts against the inner surface of the front plate portion 45. Further, in the bracket 52, the extended plate portion 58 is inserted into the storage cavity 40. And the extended plate portion 58 is adjacent to the front end portion of the lower plate portion 42 of the base plate 6 from the side where the storage cavity 40 is located.

[0037] In addition, in the antenna device 3 of an example shown in FIGS. 2 to 7, seal members 61, 62, 63, 64 such as gaskets are provided. The seal member 61 is sandwiched between the base plate 6 and the side plate portion 46 of the cover 8, and the seal member 61 keeps the space between the base plate 6 and the side plate portion 46 liquid-tight. Thereby, the inflow of liquid into the storage cavity 40 through a gap or the like between the base plate 6 and the side plate portion 46 is suppressed. Further, the seal member 62 is sandwiched between the base plate 6 and the side plate portion 47 of the cover 8, and the seal member 62 keeps the space between the base plate 6 and the side plate portion 47 liquid-tight. Thereby, the inflow of liquid into the storage cavity 40 through a gap or the like between the base plate 6 and the side plate portion 47 is suppressed.

[0038] The seal member 63 is sandwiched between the bracket 51 and the upper plate portion 41 of the base plate 6, and the seal member 63 keeps the space between the bracket 51 and the upper plate portion 41 liquid-tight. Thereby, the inflow of liquid into the storage cavity 40 through a gap or the like between the bracket 51 and the upper plate portion 41 is suppressed. The seal member 64 is sandwiched between the bracket 52 and the lower plate portion 42 of the base plate 6, and the seal member 64 keeps the space between the bracket 52 and the lower plate portion 42 liquid-tight. Thereby, the inflow of liquid into the storage cavity 40 through a gap or the like between the bracket 52 and the lower plate portion 42 is suppressed. As described above, in an example shown in FIGS. 2 to 7, the inflow of liquid into the storage cavity 40 through the gap formed in the connection portion of the cover 8 to the base plate 6 is suppressed by the seal members 61 to 64.

[0039] In addition, in the present embodiment, the front plate portion 45 of the cover 8 is inclined with respect to the height direction and the front-rear direction. And the front plate portion 45 is in an inclined state of being positioned more forward as it approaches the upper plate portion 41, and is inclined with respect to the height direction. That is, the front plate portion 45 is in an inclined state of being positioned more forward as it goes upward in the height direction, and is inclined with respect to the height direction. Therefore, in the front plate portion 45, it is positioned more rearward as it approaches the lower plate portion 42. In an example shown in FIGS. 2 to 4, the front plate portion 45 has a flat plate shape or a substantially flat plate shape inclined with respect to the height direction and the front-rear direction.

[0040] Since the front plate portion 45 is inclined as described above, in the front plate portion 45, the upper end is located on the front side with respect to the lower end. And in the front plate portion 45, the upper end is located at the most front side, and the lower end is located at the most rear side. In an example of FIGS. 2 to 4, the upper end of the front plate portion 45 is arranged close to the front end of the upper plate portion 41 from the front side. And the lower end of the front plate portion 45 is arranged close to the front end of the lower plate portion 42 from the front side.

[0041] Also, in the antenna device 3, the lower frame portion 12 protrudes forward with respect to the lower plate portion 42 of the base plate 6 and the lower end of the front plate portion 45 of the cover 8. And the front end of the lower frame portion 12 forms the protruding end of the protruding portion protruding from the lower end of the front plate portion 45 of the cover 8. Because of such a configuration, the lower plate portion 42 of the base plate 6 and the lower end of the front plate portion 45 of the cover 8 are located away from the front end (protruding end) of the lower frame portion 12 toward the rear side.

[0042] Also, in the antenna device 3, the upper frame portion 11 does not protrude forward with respect to the upper end of the front plate portion 45 of the cover 8, or hardly protrudes. And the front end of the upper frame portion 11 is not displaced in the front-rear direction with respect to the upper end of the front plate portion 45 of the cover 8, or hardly displaced. In an example of FIGS. 2 to 4 and FIG. 7, the upper end of the front plate portion 45 of the cover 8 is arranged close to the front end of the upper frame portion 11 from the lower side in the height direction.

[0043] Further, in the region on the rear side with respect to the lower end of the front plate portion 45, the lower plate portion 42 of the base plate 6 covers the through space 35 of the lower frame portion 12 from above in the height direction. And in the region on the front side with respect to the lower end of the front plate portion 45, that is, in the region between the lower end of the front plate portion 45 and the front end of the lower frame portion 12, the through space 35 of the lower frame portion 12 is not covered by the lower plate portion 42 or the like. For this reason, in the region between the lower end of the front plate portion 45 and the front end of the lower frame portion 12, the through space 35 of the lower frame portion 12 opens to both the upper side and the lower side in the height direction. In an example of FIGS. 2 to 7, a non-covered portion of the through space 35 where the through space 35 is not covered from either the upper side or the lower side in the height direction is formed between the lower end of the front plate portion 45 and the columnar portion 32 of the lower frame portion 12.

[0044] In the antenna device 3, in the region on the rear side with respect to the upper end of the front plate portion 45, the upper plate portion 41 of the base plate 6 covers the through space 25 of the upper frame portion 11 from below in the height direction. Further, in the present embodiment, as described above, since the upper end of the front plate portion 45 of the cover 8 is arranged close to the front end of the upper frame portion 11 from below in the height direction, the upper end of the front plate portion 45 is arranged close to the columnar portion 22 of the upper frame portion 11 from below in the height direction. And the upper plate portion 41 of the base plate 6 is arranged close to the columnar portion 22 of the upper frame portion 11 and the upper end of the front plate portion 45 from the rear side. Due to such a configuration, a gap is not formed, or hardly formed, between the columnar portion 22 of the upper frame portion 11 and the front end of the upper plate portion 41.

[0045] Further, as shown in FIGS. 4 and 7 and the like, in the present embodiment, the heater 10 is arranged in the storage cavity 40. The heater 10 is arranged at the upper end portion of the storage cavity 40 and is arranged above the antenna element 7 in the height direction. A power line (not shown) is connected to the heater 10. Electric power is supplied to the heater 10 through the power line. When electric power is supplied to the heater 10, heat is generated by the heater 10. In an example, the power line connected to the heater 10 is housed inside the cable together with the power line and the signal line connected to the antenna element 7 and extends outside the storage cavity 40.

[0046] In this embodiment, the heater 10 is installed on a bracket (upper bracket) 51. As described above, the bracket 51 abuts against the upper end portion of the front plate portion 45. Therefore, the heat generated by the heater 10 is transmitted to the upper end portion of the front plate portion 45 of the cover 8 via the bracket 51. In an example of FIGS. 4 and 7, in the bracket 51, the heater 10 is installed on the extended plate portion 56. And in the extended plate portion 56, the heater 10 is installed at the insertion portion into the storage cavity 40. In one example, in the bracket 51, the contact plate portion 55 is inserted into the inside of the storage cavity 40. And in the contact plate portion 55, the heater 10 is installed at the insertion portion into the storage cavity 40.

[0047] The antenna device 3 as described above may be used at an airport or the like in a state where snow is falling. FIG. 8 shows an example of a state where snow is falling at the location where the antenna device 3 is used in the embodiment. In FIG. 8, the state of the antenna device 3 viewed from one side in the width direction is shown. Also, in FIG. 8, a state where snow is falling and the wind is blowing from the front side toward the antenna device 3 is shown. Therefore, in the state of FIG. 8, an air flow (arrow F1) from the front side toward the antenna device 3 is generated at the location where the antenna device 3 is used.

[0048] In the antenna device 3 of the present embodiment, as described above, the front plate portion 45 of the cover 8 covers the storage cavity 40 from the front side across the upper plate portion 41 to the lower plate portion 42. And the front plate portion 45 is in an inclined state positioned more forward as it approaches the upper plate portion 41, and is inclined with respect to the height direction. For this reason, as shown in FIG. 8, when wind blows toward the antenna device 3 from the front side, at the upper end portion of the front plate portion 45 and the vicinity thereof, due to the collision with the antenna device 3, the air flow from the front side is divided into an air flow (arrow F2) going upward in the height direction (vertically upward) and an air flow (arrow F3) going downward in the height direction (vertically downward). For this reason, in a state where wind blows toward the antenna device 3 from the front side, the upper end portion of the front plate portion 45 and the vicinity thereof become stagnation points in the air flow. In the state of FIG. 8, since the upper end portion of the front plate portion 45 and the vicinity thereof become stagnation points in the air flow, the snow that is falling is likely to accumulate on the upper end portion of the front plate portion 45 and the vicinity thereof on the cover 8. In the state of FIG. 8, snow 70 has accumulated on the upper end portion of the front plate portion 45 and the vicinity thereof.

[0049] On the other hand, since the front plate portion 45 of the cover 8 is inclined with respect to the height direction in the above-described inclined state, in a region that is a certain distance away from the upper end portion of the front plate portion 45, due to the collision with the antenna device 3, the air flow from the front side becomes an air flow (arrow F4) going downward in the height direction (vertically downward), and no air flow going upward in the height direction is generated. For this reason, in a region that is a certain distance away from the upper end portion of the front plate portion 45, the air flow from the front side is not divided due to the collision with the antenna device 3 (cover 8), and it is difficult for a stagnation point in the air flow to occur. Therefore, in the state of FIG. 8, it becomes difficult for the snow that is falling to accumulate on a portion of the cover 8 that is a certain distance downward in the height direction from the upper end portion of the front plate portion 45.

[0050] In the present embodiment, by configuring the cover 8 of the antenna device 3 as described above, the snow accumulation position on the cover 8 in a snowing state is adjusted. That is, the snow accumulation position on the cover 8 is adjusted to a state where snow accumulates only on the upper end portion of the front plate portion 45 and the vicinity thereof, and does not accumulate on a portion that is a certain distance away from the upper end portion of the front plate portion 45.

[0051] Also, in the present embodiment, the heater 10 is disposed above the antenna element 7 in the height direction in the storage cavity 40. For this reason, the heater 10 is disposed at a position close to the upper end portion of the front plate portion 45 which is a position where snow is likely to accumulate on the cover 8. Thereby, even if snow accumulates on the upper end portion of the front plate portion 45 and its vicinity as described above, the snow that has accumulated is appropriately melted by the heat generated by the heater 10.

[0052] As described above, in the present embodiment, snow accumulation on the cover 8 is suppressed without using paint. By suppressing snow accumulation on the cover 8, the labor required for an operator to perform snow removal work on the snow that has accumulated on the antenna device 3 is reduced.

[0053] Also, in the present embodiment, the heater 10 is disposed above the antenna element 7 in the height direction and at a position away from the antenna element 7. For this reason, even if the heater 10 for melting snow is provided, the influence of the heat generated by the heater 10 on radio waves and the like transmitted from the antenna element 7 is appropriately suppressed.

[0054] Also, in the present embodiment, the heater 10 is installed on a bracket (upper bracket) 51 having higher thermal conductivity than the cover 8, and the bracket 51 is attached to the cover 8 in a state of being in contact with the upper end portion of the front plate portion 45. Because of such a configuration, the heat generated by the heater 10 is appropriately transmitted to the upper end portion of the front plate portion 45 via the bracket 51. Thereby, the heat from the heater 10 is appropriately transmitted to a position where snow is likely to accumulate on the cover 8. Therefore, the snow that has accumulated on the upper end portion of the front plate portion 45 and its vicinity as described above is more appropriately melted by the heat transmitted from the heater 10.

[0055] In addition, in the present embodiment, an upper frame portion 11 and a lower frame portion 12 are provided. The lower plate portion 42 of the base plate 6 is attached to the lower frame portion 12. And the upper plate portion 41 of the base plate 6 is attached to the upper frame portion 11, and the cover 8 is disposed between the upper frame portion 11 and the lower frame portion 12 in the height direction. By adopting such a configuration, the strength of the antenna device 3 is appropriately ensured.

[0056] In addition, in the present embodiment, the lower frame portion 12 protrudes forward with respect to the lower plate portion 42 of the base plate 6 and the lower end of the front plate portion 45 of the cover 8. And a through space 35 penetrating the lower frame portion 12 in the height direction is formed in the lower frame portion 12, and in the region between the lower end of the front plate portion 45 and the front end of the lower frame portion 12, the through space 35 of the lower frame portion 12 opens upward and downward in the height direction. Because of such a configuration, in the state of FIG. 8, the air flowing downward in the height direction after colliding with the antenna device 3 (cover 8) passes through the through space 35 of the lower frame portion 12 (arrow F5). Therefore, the air flowing downward in the height direction after colliding with the antenna device 3 (cover 8) appropriately flows downward in the height direction beyond the lower frame portion 12.

[0057] As described above, when air flows, in a region somewhat separated from the upper end portion of the front plate portion 45, it becomes more difficult for a stagnation point to occur in the air flow. Therefore, it becomes more difficult for snow falling to accumulate on a portion of the cover 8 that is somewhat separated downward in the height direction from the upper end portion of the front plate portion 45.

[0058] In addition, in an example of the present embodiment, the base plate 6 can reflect radio waves emitted from the antenna element 7 in the storage cavity 40. Thereby, it is effectively suppressed that radio waves are emitted to the outside of the storage cavity 40 through the base plate 6. Therefore, radio waves transmitted from the antenna device 30 are appropriately emitted toward the front side.

[0059] According to at least one of these embodiments or examples, the cover is attached to the base plate from the front side in a state of surrounding the storage cavity by a connecting body with the base plate. The cover includes a front plate portion that covers the storage cavity from the front side across the upper plate portion to the lower plate portion of the base plate in the height direction, and the front plate portion is in an inclined state of being positioned more forward as it approaches the upper plate portion and is inclined with respect to the height direction. The heater is disposed above the antenna element in the height direction in the storage cavity. Thereby, an antenna device capable of suppressing snow accumulation on the cover without using paint can be provided.

[0060] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and its equivalent scope.

Description of Reference Numerals

[0061] 1... Slide slope antenna device, 3... Antenna device, 5... Frame body (housing), 6... Base plate, 7... Antenna element, 8... Cover, 10... Heater, 11... Upper frame portion, 12... Lower frame portion, 25, 35... Through space, 40... Storage cavity, 41... Upper plate portion, 42... Lower plate portion, 45... Front plate portion, 51... Bracket (upper bracket).

Claims

1. A base plate including an upper plate portion and a lower plate portion, the upper plate portion facing the lower plate portion with a storage cavity therebetween in the height direction, An antenna element attached to the base plate while being disposed in the storage cavity and radiating radio waves forward, A cover attached to the base plate from the front side while surrounding the storage cavity by a connecting body with the base plate, the radio waves radiated from the antenna element passing therethrough, the cover including a front plate portion covering the storage cavity from the front side across the upper plate portion to the lower plate portion in the height direction, and the front plate portion being inclined with respect to the height direction in an inclined state positioned closer to the front side as it approaches the upper plate portion, A heater disposed above the antenna element in the height direction in the storage cavity, An antenna device comprising the above.

2. Further comprising a bracket attached to the cover while being in contact with the upper end portion of the front plate portion of the cover, the bracket having higher thermal conductivity than the cover, The cover is attached to the base plate with the bracket interposed therebetween, The heater is installed on the bracket, The antenna device according to Claim 1.

3. Further comprising a lower frame portion to which the lower plate portion of the base plate is attached, The lower frame portion protrudes forward with respect to the lower plate portion of the base plate and the lower end of the front plate portion of the cover, A through space penetrating the lower frame portion in the height direction is formed in the lower frame portion, The lower plate portion of the base plate covers the through space of the lower frame portion from the upper side in the height direction in a region on the rear side with respect to the lower end of the front plate portion, In a region between the lower end of the front plate portion and the front end of the lower frame portion, the through space of the lower frame portion opens to the upper side and the lower side in the height direction, The antenna device according to Claim 1 or 2.

4. Further comprising an upper frame portion to which the upper plate portion of the base plate is attached and between which and the lower frame portion in the height direction the cover is disposed, The antenna device according to Claim 3.

5. The base plate is capable of reflecting the radio waves emitted from the antenna element in the storage cavity, the antenna device according to Claim 1 or 2.

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