JP2824505B2 - Slot array antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a slot array antenna suitable for a base station antenna for performing radio communication with a terminal station.

[0002]

2. Description of the Related Art As a method of forming an arbitrary antenna pattern (forming a beam), there is an array antenna technique in which a plurality of element antennas are arranged and the amplitude and phase of an electromagnetic wave supplied to each element antenna are controlled.

A microstrip array antenna using a microstrip antenna as an element antenna and a microstrip line as a feeding circuit has been widely used due to its features such as thinness, light weight, and ease of manufacture. However, in a high frequency band such as a millimeter wave, a microstrip line has a large transmission loss due to a dielectric loss and a radiation loss, which causes a decrease in antenna efficiency.

On the other hand, there is a slot array antenna in which a plurality of slots are cut in a part of a waveguide or a resonator wrapped by a conductor such as a waveguide or a parallel plate, and these are operated as element antennas. In such a slot array antenna, by providing a pair of slots separated by a quarter of the propagation wavelength in the waveguide or resonator, the reflected wave generated by the slot pair in the waveguide or resonator is provided. In addition, for example, the direction of the slot of the pair is set to 45 degrees and −4 to the propagation direction, respectively.
By arranging at 5 degrees, this slot pair can function as an element antenna that generates circularly polarized waves. That is, various characteristics according to the formation state of the slot pair can be exhibited.

[0005] Therefore, in an indoor wireless LAN that connects a wireless line to a terminal station dispersedly installed at an arbitrary position in a room and a base station antenna installed on the ceiling of the room, the indoor shape and the arrangement state of the terminal station are different. By using a base station antenna in which a slot pair is formed so as to have a corresponding antenna pattern, relatively stable wireless communication can be realized.

[0006]

However, in order to take advantage of the characteristics of wireless communication, it is desirable to be able to maintain a stable communication state without making fine adjustments to the base station antenna even if the position of the terminal station changes. When the slot array antenna as described above is used as a base station antenna, there is a case where even if the position of the terminal station is slightly changed, the communication state is deteriorated due to the directivity due to the formation state of the slot. It cannot be said that a uniform communication state can be maintained. In addition, a method of securing a stable communication area over a wide area by distributing a plurality of base stations indoors is also conceivable, but considering the cost and operation aspects of line control, the number of base stations can be minimized. It is desirable to suppress.

[0007] Therefore, if one base station antenna can illuminate the entire large room evenly, it becomes an extremely useful base station antenna. In order to illuminate the whole room with uniform irradiation power with one base station antenna, the base station must be illuminated. The station antenna is desirably omnidirectional in a horizontal plane. Therefore,
SUMMARY OF THE INVENTION It is an object of the present invention to provide a slot array antenna which is omnidirectional in a horizontal plane while being a single antenna.

[0008]

In order to solve the above-mentioned problems, a slot array antenna according to the present invention has an external conductor having at least one circular outer surface and an outer peripheral surface continuous with the circular outer surface. (For example, inner cylindrical conductor 1)
And an outer conductor (for example, an outer cylindrical conductor 3) having a circular inner surface and an inner peripheral surface which are opposed to one circular outer surface and an outer peripheral surface of the inner conductor via the dielectric (2), respectively. A plurality of slots (for example, slot pair 4) are formed at least in the circumferential direction at predetermined intervals on the peripheral surface of the conductor,
By feeding power from the center of the disk (2a) of the dielectric formed between the circular outer surface of the inner conductor and the circular inner surface of the outer conductor, the intensity change of the electric field and the magnetic field due to the radio wave radiated from each slot is reduced. It was made substantially even in the circumferential direction.

In the slot array antenna thus configured, a radial waveguide is formed by an electromagnetic wave fed from the center of the dielectric disk portion traveling radially outward through the dielectric disk portion. When the electromagnetic wave reaches the peripheral surface portion via the radial waveguide, the electromagnetic wave proceeds through the cylindrical portion toward the other end surface to form a coaxial waveguide. In the process of the electromagnetic wave propagating through the coaxial waveguide, the electromagnetic waves are radiated to the outside from the slots opened in the outer conductor, and a plurality of these slots are arranged at predetermined intervals in the circumferential direction. The intensity changes of the electric field and the magnetic field due to the radiated radio waves are substantially uniform in the circumferential direction. When the slot of the outer conductor receives an electromagnetic wave due to the reversibility of the transmission and reception of the antenna, the reception can be performed in a reverse process.

[0010]

Next, an embodiment of a slot array antenna according to the present invention will be described in detail with reference to the accompanying drawings. 1A and 1B show a first embodiment of a slot array antenna, in which FIG. 1A is a schematic longitudinal sectional view, FIG. 1B is a schematic transverse sectional view, FIG. 1C is a development view of an outer cylindrical surface conductor, and FIG. It is an enlarged front view of a slot pair.

In this slot array antenna, the thickness of the disk portion 2a and the cylindrical portion 2b is outside the inner cylindrical conductor 1 having a solid cylindrical shape having a diameter larger than the wavelength of the frequency to be used. A dielectric 2 which is thinner than a half of the guide wavelength and which is constant is provided, and an outer cylindrical conductor 3 is provided outside the disk portion 2a and the cylindrical portion 2b of the dielectric 2, and is etched, machined or laser-processed. A plurality of slot pairs 4 are formed in the cylindrical portion 3b of the outer cylindrical conductor 3 by the technique described in (1). Note that each slot pair 4
.. Are separated from each other by a quarter of the wavelength λg of the radio wave propagating in the dielectric 2 in the propagation direction, and include a first slot 4a and a second slot 4b whose directions are orthogonal to each other. is there.

Slot pairs 4 having the same radiation characteristics (equal in size and shape) are arranged at equal intervals of at least one wavelength or less in the circumferential direction so as to be non-directional around the antenna axis. It is arranged in the.
For example, as shown in FIG. 1 (c), if 16 pairs of slot pairs 4 are arranged in the circumferential direction, when the antenna axis of the slot array antenna according to the present invention is arranged vertically, Can be realized. The mode of forming the slots in the antenna axis direction is not particularly limited, and the directional beam shaping in a plane including an axis suitable for the environment (indoor shape, antenna installation position, etc.) in which the slot array antenna is installed is described. In order to do so, the slot pairs 4 are arranged in the axial direction, and the size and the interval between them may be changed depending on the position in the axial direction. For example, in the first embodiment, in order to compensate for the propagation distance of a radio wave becoming longer in proportion to the cosecant of the elevation angle from the lower right direction and to increase the propagation loss, a radio wave that is weaker in the lower direction and stronger in the oblique lower direction is transmitted and received. In order to realize a cosecant beam as possible, as shown in FIG. 1 (c), the coaxial conductors are arranged so that the slot pairs 4 of 20 rows are maximized near the center and have a phase shift of about 90 degrees. Considering that the propagation wave of the wave path gradually weakens, the size and position are adjusted and arranged.

Further, a hole for supplying power by the coaxial line 5 is provided on the power supply side end face (upper side in the illustrated embodiment) of the outer cylindrical conductor 3 so as to be electrically connected to the inner cylindrical conductor 1. That is, the center conductor of the coaxial line 5 is brought into electrical contact with the inner cylindrical conductor 1 and the outer conductor of the coaxial line is brought into electrical contact with the outer cylindrical conductor 3 through this hole. In the embodiment shown in the drawings, by providing a conical protrusion 6 at the center of the upper end surface of the inner cylindrical conductor 1, if the coordination of the radio waves propagating through the coaxial line 5 and the disk portion 2a of the dielectric 2 is good. There is a thing to tighten.

Further, in the first embodiment, a corner cut portion 7a is provided at the joint between the upper disk portion 3a and the cylindrical portion 3b of the outer cylindrical conductor 3, so that the disk portion 2a and the cylindrical portion of the dielectric 2 are provided. This is intended to improve the matching of the radio waves propagating through the 2b.

The slot pair 4 consisting of the first and second slots 4a, 4b controls the intensity and phase of the electromagnetic field on the cylindrical surface of the slot array antenna by adjusting its size, shape and position. Therefore, a desired beam can be relatively easily formed. If the opening of each slot 4a, 4b of the slot pair 4 is enlarged,
The proportion of the radiated electromagnetic wave among the electromagnetic waves that have reached the slot pair 4 can be increased. However, in general, the opening length of the slot is less than half the guide wavelength λg.
Further, in the slot array antenna according to the present invention, the electromagnetic wave propagating through the coaxial waveguide is gradually radiated from the slot pairs 4 and becomes weaker as the distance from the feeding point increases. If the slot pairs 4 are formed so as to gradually increase, a uniform aperture electromagnetic field distribution can be realized.
Regarding the phase distribution control, the slot pairs are made in-phase by setting the interval between the slot pairs to the guide wavelength λg of the waveguide, and by narrowing the interval, the phase of the slot pair on the rear side is advanced and spread from the previous one. The phase can be delayed.

Furthermore, if the interval between the first and second slots 4a and 4b is set to be a quarter of the guide wavelength λg so that the reflected waves from both slots 4a and 4b cancel each other,
Electromagnetic waves traveling through the coaxial waveguide can be satisfactorily prevented from being reflected at each slot pair 4. Moreover, if the first and second slots 4a and 4b forming each slot pair 4 are formed so as to have an inclination of 45 degrees and -45 degrees with respect to the propagation direction, respectively, the space can be temporally improved. Also, since linearly polarized waves shifted by 90 degrees are combined, circularly polarized waves are generated. If slot pairs 4 are used as in the first embodiment, left-handed circularly polarized waves will be generated. The radio wave radiation efficiency of the slot becomes maximum when the length is about half of the guide wavelength λg. Also, the first and the first constituting each slot pair 4
If the slot lengths of the second slots 4a and 4b are close to half the guide wavelength λg, as shown in FIG. 1D, for example, the second slot 4b is perpendicular to the propagation direction so as not to overlap the first slot 4a (see FIG. 1D). (To the right), the arrangement density of the slot pairs 4 in the circumferential direction can be increased.

The slot formed in the cylindrical portion 3b of the outer cylindrical conductor 3 is not limited to the slot pair 4 composed of the first and second slots 4a and 4b, but a single slot or a crossing of two slots. A cross slot may be mixed.

In the slot array antenna configured as described above, the electromagnetic wave fed from the outer conductor side to the center of the dielectric disk portion 2a travels radially outward through the disk portion 2a of the dielectric material 2. When the electromagnetic wave reaches the peripheral surface portion via the radial waveguide, the electromagnetic wave proceeds through the cylindrical portion 2b of the dielectric 2 toward the other end surface, thereby forming a coaxial waveguide. During the propagation of the electromagnetic wave through the coaxial waveguide, the electromagnetic wave is radiated to the outside from the slot pairs 4 opened in the outer conductor. That is, the cylindrical portion 3b of the external cylindrical conductor 3
By appropriately setting the slot formation state with respect to, it is possible to realize a slot array antenna having arbitrary radiation characteristics in a vertical plane while maintaining omnidirectionality in a horizontal plane, so that a single base station and multiple If the slot array antenna according to the present invention is used as an antenna for an indoor wireless LAN base station or a mobile communication base station antenna for performing wireless communication with a terminal station, high quality and efficient wireless communication can be expected.

Further, the slot array antenna according to the present invention operates on the same principle in the case of reception due to the reversibility of transmission and reception of the antenna. For example, as in the above-described embodiment, when a slot pair 4 in which orthogonal first and second slots 4a and 4b are arranged as a circularly polarized antenna and separated by a quarter of the guide wavelength is provided, each slot 4 is circularly polarized.
Since the electromagnetic waves excited in the slots a and 4b have a phase difference of 90 degrees and the interval between the slots in the waveguide is a quarter wavelength, the electromagnetic waves excited in the slots 4a and 4b reinforce each other in one direction. Weaken in the direction. By such a function, for example, only the left-handed polarized signal is excited toward the feeding point side in each slot pair 4..., And operates as a receiving antenna.

Next, another embodiment of the slot array antenna according to the present invention will be described with reference to FIG. 2 (a) to 2 (e), those which are not particularly denoted by reference numerals are the same as those in FIG. 1 (a). Further, the place where the antenna is installed is arbitrary, but in FIG. 2, it is fixed to the ceiling 8 and is shown as an arrangement for receiving a signal or power supply.

In the second embodiment of the slot array antenna shown in FIG. 2A, the non-feed side of the inner cylindrical conductor has a convex spherical shape 9. By appropriately setting the shape of the end face on the non-feeding side as described above, it becomes possible to control a diffracted wave or to provide a structure for mounting a radio wave absorber or other devices. In the third embodiment of the slot array antenna shown in FIG. 2B, the non-feed side of the inner cylindrical conductor is concave and a deep open space 10 is provided. In this case, the weight and economy of the antenna can be reduced. If the inner cylindrical conductor 1 has a hollow portion, the physical strength is reduced. Therefore, the open space 10 of the inner cylindrical conductor 1 is made of a relatively lightweight dielectric (Teflon, foamed Teflon, styrofoam, rubber, etc.). You may fill it. In the fourth embodiment of the slot array antenna shown in FIG. 2C, the inner cylindrical conductor 1 has a hollow shape having a closed space 11. In this case, the weight and economy of the antenna can be reduced. If the inside of the inner cylindrical conductor 1 is hollow, the physical strength is reduced. Therefore, the closed space 11 of the inner cylindrical conductor 1 may be filled with a relatively lightweight dielectric.

In the fifth embodiment of the slot array antenna shown in FIG. 2D, a non-feed side end face of the inner cylindrical conductor 1 and an outer cylindrical conductor are formed in order to form a radial waveguide also on the non-feed side end face. 3, a lower disk portion 2c of the dielectric 2 is interposed between the lower disk portion 3c and the non-power-supply side lower disk portion 3c.
Slot pairs 4 are also set up in the lower disk portion 3c. In this way, the electromagnetic wave that has reached the lower end portion of the cylindrical portion 2b of the dielectric 2 travels inward in the radial direction on the lower disk portion 2c connected to the end portion, and the slot pair formed on the outer conductor surface 4 will be gradually emitted.

That is, the slot array formed on the lower end surface of the slot array antenna can effectively improve the directivity in the downward direction and the circular polarization axis ratio. The arrangement of the plurality of slot pairs 4 provided in the lower disk portion 3c is as shown in FIG. 3 and is arranged such that the number of arrays is constant regardless of the position of the same diameter as shown in FIG. , (B), the array is arranged so that the number of arrays decreases as approaching the center, or (c), it is arranged in a spiral. Arranging the slot pairs 4 as shown in (b) is effective in coping with the reduction of the area for opening the slots as approaching the center, and arranging the slot pairs 4 as shown in (c). This is effective for improving the circular polarization axis ratio in the downward direction. The slot formed on the lower end face of the antenna is not limited to the slot pair 4 and may be a single slot, a cross slot, or a mixture of them.

Further, in the fifth embodiment, the cylindrical portion 3 of the external cylindrical conductor 3 is formed in order to improve the matching between radio waves propagating through the cylindrical portion 2b of the dielectric 2 and the lower disk portion 2c.
In addition to providing a corner cut 7b at the joint between the lower disk portion 3c and the lower disk portion 3c, a radio wave absorber 12 is provided at the center of the lower disk portion 2c so as not to reflect a radio wave reaching the center of the lower disk portion 2c. It is provided. The radio wave absorber 12
Instead, a reflector may be provided so that the radio wave that has reached there may be effectively contributed to radiation.

In the sixth embodiment of the slot array antenna shown in FIG. 2E, a radial waveguide similar to that of the fifth embodiment is formed on the non-feeding side end face portion. As shown, the inner cylindrical conductor 1 is hollow having a closed space 11. In this way, it is possible to improve the directivity in the downward direction, the circular polarization axis ratio, and reduce the weight and economy of the antenna. If the inside of the inner cylindrical conductor 1 is hollow,
Since the physical strength is reduced, the closed space 11 of the inner cylindrical conductor 1 may be filled with a relatively lightweight dielectric.

The method of installing the slot array antenna according to the present invention on the ceiling 8 is not limited to the method of supporting with the coaxial line 5 as shown in FIG. There may be a method of supporting with a type of power supply line, a method of supporting with a supporting rod provided on an external conductor, a method of bonding with an adhesive or an adhesive tape, a setting method using these methods in combination, or the like.

Further, an embodiment of the slot array antenna according to the present invention when power is supplied from the inner conductor side will be described with reference to FIG. 4A to 4G.
In FIG. 1A, those not particularly denoted by reference numerals are those shown in FIG.
This is the same as the configuration described above. Further, the place where the antenna is grounded is arbitrary, but in FIG. 4, it is fixed to the ceiling 8 and is shown as an arrangement for receiving supply of signals and power. Therefore, the vertical direction of the antenna viewed from the feeding position is opposite to that in FIGS.

In the seventh embodiment of the slot array antenna shown in FIG. 4A, a feed line is provided inside the inner cylindrical conductor 1, and power is fed from the inner conductor side to the center of the dielectric disk portion 2b. is there. Also, a plurality of slot pairs 4 are provided in the outer conductor disk portion 3a as shown in FIG.
Are gradually radiated from the slot pairs 4 provided in the disk portion of the outer conductor while traveling radially outward along the disk portion 2a of the outer conductor 2a to effectively improve the downward directivity and the circular polarization axis ratio. It is.

The eighth embodiment of the slot array antenna shown in FIG. 4 (b) is a slot array antenna of the seventh embodiment in which the non-feed side of the inner cylindrical conductor is concave and a deep open space 10 is provided. is there. In this case, the weight and economy of the antenna can be reduced. If the inner cylindrical conductor 1 has a hollow portion, the physical strength is reduced. Therefore, the open space 10 of the inner cylindrical conductor 1 may be filled with a relatively lightweight dielectric.

In the ninth embodiment of the slot array antenna shown in FIG. 4C, the inner cylindrical conductor 1 of the slot array antenna of the seventh embodiment has a hollow shape having a closed space 11. In this case, the weight and economy of the antenna can be reduced. If the inside of the inner cylindrical conductor 1 is hollow, the physical strength is reduced. Therefore, the closed space 11 of the inner cylindrical conductor 1 may be filled with a relatively lightweight dielectric.

In the tenth embodiment of the slot array antenna shown in FIG. 4D, an inner cylindrical conductor 1 is formed in order to form a radial waveguide also on the non-feed side end face of the slot array antenna of the seventh embodiment. Between the non-power-feeding-side end face portion and the non-power-feeding-side upper disk portion 3c of the external cylindrical conductor 3;
The upper disk portion 2c of the dielectric 2 is interposed and the dielectric 2
A radio wave absorber 12 is provided outside a wire path passing through the center of the upper disk portion 2c. In this way, the electromagnetic wave that has reached the upper end portion of the cylindrical portion 2b of the dielectric 2 travels inward in the radial direction through the upper disk portion 2c connected to the end portion and is absorbed by the radio wave absorber 12 in the central portion. Therefore, unnecessary reflection generated at the end of the cylindrical waveguide can be suppressed.

In the eleventh embodiment of the slot array antenna shown in FIG. 4 (e), the inner cylindrical conductor 1 of the slot array antenna of the tenth embodiment has a hollow shape having a closed space 11. In this case, the weight and economy of the antenna can be reduced. If the inside of the inner cylindrical conductor 1 is hollow, the physical strength is reduced. Therefore, the closed space 11 of the inner cylindrical conductor 1 may be filled with a relatively lightweight dielectric.

In the twelfth embodiment of the slot array antenna shown in FIG. 4F, the transceiver system 14 is housed in the closed space 11 of the inner cylindrical conductor 1 of the slot array antenna of the eighth embodiment. . This makes it possible to reduce the size and weight of the entire antenna. The cable 15 for supplying power to the antenna and transferring signals is connected to the transceiver through the upper end face.

In the thirteenth embodiment of the slot array antenna shown in FIG. 4G, a transceiver system 14 is housed in the closed space 11 of the inner cylindrical conductor 1 of the slot array antenna of the tenth embodiment. . This makes it possible to reduce the size and weight of the entire antenna. The cable 15 for supplying power to the antenna and transferring signals is connected to the transceiver through the upper end face.

The method of installing the slot array antenna according to the present invention on the ceiling 8 is limited to a method of supporting the coaxial line 5 as shown in FIG. 4 or a cable 15 for transmitting and receiving power and signals. Not supported, a method of supporting with another type of power supply line such as a waveguide, a method of supporting with a supporting rod or the like provided on a conductor portion or a dielectric portion,
A method of bonding with an adhesive or an adhesive tape, an installation method using these methods in combination, or the like may be used.

In the above embodiments, the slot pairs 4 are arranged in the horizontal and vertical directions, but the present invention is not limited to this. FIG.
Shows another example of an array of slot pairs 4...
(A)-(d) is a development view of the outer cylindrical conductor 3, respectively.
For example, there is a type in which slot pairs 4 are spirally arranged around an axis as shown in FIG. In this case, an improvement in the circular polarization axis ratio in the downward direction can be expected. Further, there is a type in which slot pairs 4 are alternately arranged as shown in FIG. In this way, it can be expected that the density of the arrangement of the slot pairs is increased and the degree of freedom of the arrangement is increased. Also,
As shown in (c), some slot pairs are thinned out and arranged. In this way, it is possible to expect effects such as facilitating the production when the number of slot pairs is large. Further, there is a type in which the cross slot 16 and the single slot 17 are mixedly arranged as shown in FIG. By doing so, it is possible to expect the effect that the propagated wave reaching the end of the cylindrical waveguide can be contributed to radiation without waste. Thus, depending on the usage environment of the slot array antenna,
An appropriate slot pair arrangement may be selected.

In each of the above embodiments, the first slot 4a and the second slot 4a of each slot pair 4...
b generates left-handed polarization, but the slot pairs 4 are not limited to this. FIG.
Shows another example of the slot pair. For example, as shown in FIG. 1D, an orthogonal slot pair 18 which generates right-handed circularly polarized light obtained by inverting the slot pair shown in FIG.
A parallel slot pair 19 that generates linear polarization as shown in FIG.
A non-orthogonal slot pair 20 that generates elliptical polarization as shown in FIG.

That is, the slot array antenna according to the present invention is not limited to the circularly polarized antenna, but may be a linearly polarized antenna or an elliptically polarized antenna in an arbitrary direction depending on the use form. Also, when used as a circularly polarized antenna, each slot pair is not limited to a circularly polarized element antenna. Depending on the case, it may be designed as a slot pair of linear or elliptical polarization.

When the direction of the electromagnetic wave propagating in the waveguide and the angle of the direction of each slot forming the slot pair are different, the magnitude of the reflected wave by each slot is made equal. As shown, a slot pair 21 in which the size of each slot is different is also conceivable.

FIG. 7 shows an example of a method for feeding a slot array antenna according to the present invention. FIG. 7A shows a feeding method using the coaxial line 5 as described in the first embodiment. . (B) shows the disk conductor 3 of the outer cylindrical conductor 3.
a, and electrically connect the circular waveguide 22 to the same axis.
_In this method, power is supplied in an axially symmetric waveguide mode such as ₀₁ or TM ₀₁ mode.

[0041]

FIG. 8 shows a schematic configuration of an example of the slot array antenna according to the first embodiment. That is, as shown in (a), a radius of about 2.
A bell-shaped Teflon 25 having a constant diameter of 28 mm and an outer diameter of 38 mm and a constant thickness of 5 mm is fitted into a copper cylinder 24 having a diameter of 28 mm and a length of 250 mm having a conical protrusion 23 having a diameter of 5 mm and a height of about 2.5 mm without any gap. And a copper cap 2 having a hole 26 for passing a semi-rigid cable in the center.
7 is fitted without any gap to form an antenna base.

Also, a dielectric constant of about 2.17 mm of about 2.17
An array of slot pairs of 20 rows and 16 columns as shown in FIG. 7B is etched on a microstrip substrate 28 in which a copper foil is laminated on one side of a thick glass cloth Teflon, and is etched on the Teflon 24 of the antenna base. Adhesive tape is applied from above to wrap around the peripheral surface, and adhesive tape is applied and fixed to the nine surfaces of the lined line, and a conductive glued copper tape is adhered to the lined line and the contact surface with the copper cap 27 to be electrically connected. Power supply is about 2.5
A semi-rigid cable having a center conductor extended by mm is inserted into the center hole 26 of the copper cap 27 of the antenna base, and the center conductor of the semi-rigid cable is electrically connected to the tip of the projection 23 of the antenna cylinder 24, and the outer conductor is connected to the copper cap 27. Bonding. In order to prevent radio waves reaching the end of the coaxial waveguide from being radiated to the outside or reflected into the waveguide, a portion below the outer cylindrical conductor 28 is about 15 m long.
m radio wave absorber 2 made of cylindrical carbon-containing foamed urethane with a diameter of 38 mm and a height of 30 mm
9 is fixed without any gap.

FIG. 9 shows the measured data of the directivity pattern in the vertical plane of the slot array antenna configured as described above. Although the present slot array antenna is a circularly polarized antenna, FIG. 9 shows the pattern of the vertical polarization component by a solid line and the pattern of the horizontal polarization component by a dotted line. The dotted line shows the cosecant beam pattern that can be theoretically realized with this array arrangement. In the present embodiment, the directivity is not as designed because of insufficient manufacturing accuracy and design, but a cosecant beam is generally obtained. Note that the horizontal axis θ of the graph represents an angle from vertically downward.

[0044]

As described above, according to the present invention, a radial waveguide is formed by an electromagnetic wave fed to the center of a dielectric disk part traveling radially outward on the dielectric disk part. When the electromagnetic wave reaches the peripheral surface portion through the radial waveguide, the coaxial waveguide is formed by advancing the cylindrical portion toward the other end surface, so that the electromagnetic wave propagates outside the coaxial waveguide in the process of being propagated through the coaxial waveguide. Since electromagnetic waves are radiated from the slots opened in the conductor to the outside and a plurality of these slots are arranged at predetermined intervals in the circumferential direction,
The electric and magnetic field intensity changes due to radio waves radiated from each slot are substantially uniform in the circumferential direction.

That is, according to the slot array antenna of the present invention, omnidirectionality in a horizontal plane can be realized even with a single antenna. Further, if a pair of slots perpendicular to the direction is formed on the outer peripheral surface of the outer conductor while being separated from each other by a quarter of the propagation wavelength of the waveguide, circular polarization can be easily realized. By adjusting the size and position of the slot pair, it is possible to easily obtain a desired in-plane beam pattern such as a cosecant beam that weakly illuminates directly below and strongly illuminates obliquely downward. It is extremely expensive.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a slot array antenna according to the present invention, in which (a) is a longitudinal sectional view, (b) is a transverse sectional view, and (c) is a development of a peripheral portion of an outer cylindrical conductor. Figure,
(D) is an enlarged front view of the slot pair.

2A is a longitudinal sectional view of a slot array antenna according to a second embodiment of the present invention, FIG. 2B is a longitudinal sectional view of a slot array antenna according to a third embodiment of the present invention, and FIG.
5 is a longitudinal sectional view of a fourth embodiment of the slot array antenna according to the present invention, FIG. 5D is a longitudinal sectional view of a fifth embodiment of the slot array antenna according to the present invention, and FIG. 5E is a slot array antenna according to the present invention. It is a longitudinal section of a 6th embodiment.

3A and 3B are enlarged front views of a lower disk portion of an outer cylindrical conductor, in which FIG. 3A shows a case where the number of circumferential arrays is constant, FIG. 3B shows a case where the number of circumferential arrays differs depending on a radial position, and FIG. )
Is an array in which the array is spirally arranged.

4A is a longitudinal sectional view of a slot array antenna according to a seventh embodiment of the present invention, FIG. 4B is a longitudinal sectional view of an eighth embodiment of the slot array antenna according to the present invention, and FIG.
9 is a longitudinal sectional view of a ninth embodiment of the slot array antenna according to the present invention, FIG. 9D is a longitudinal sectional view of the tenth embodiment of the slot array antenna according to the present invention, and FIG. 11F is a longitudinal sectional view of the eleventh embodiment, (f) is a longitudinal sectional view of the twelfth embodiment of the slot array antenna according to the present invention, and (g) is a longitudinal sectional view of the thirteenth embodiment of the slot array antenna according to the present invention. FIG.

FIG. 5 is a development view of a peripheral surface portion of the outer cylindrical conductor, and FIG.
The figure shows a spiral arrangement, (b) shows a brick-laying arrangement, (c) shows a thinning-out arrangement, and (d) shows a cross-shaped slot or a mixed arrangement of slots.

FIG. 6 is an explanatory view of the arrangement of slot pairs;
Is an orthogonal slot pair for right-hand circular polarization, (b) is a parallel slot pair for linear polarization, (c) is a non-orthogonal slot pair for elliptical polarization, and (d) is a slot pair consisting of slots of different sizes. It is shown.

FIGS. 7A and 7B are enlarged longitudinal sectional views of a power supply unit, in which FIG. 7A illustrates power supply by a coaxial line, and FIG. 7B illustrates power supply by a circular waveguide.

FIGS. 8A and 8B show an example of a slot array antenna according to the first embodiment. FIG. 8A is a longitudinal sectional view of an antenna base portion, and FIG. 8B is a developed view of an outer peripheral conductor.

FIG. 9 is a characteristic diagram illustrating a measured directivity pattern of the slot array antenna according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal cylindrical conductor 2 Dielectric 2a Dielectric disk part 3 External cylindrical conductor 4 Slot pair 4a 1st slot 4b 2nd slot

Claims (5)

(57) [Claims] 1. An end- shaped cylindrical inner conductor having at least one circular outer surface and an outer peripheral surface continuous with the circular outer surface;
Through one of the circular outer surface and an outer peripheral surface and each dielectric of the internal conductor consists of a outer conductor having a disc portion and a cylindrical portion that faces, as well as opening a plurality of slots in the cylindrical portion of the outer conductor, outer A slot array antenna wherein power is supplied from the center of the disk portion of the conductor and the center of the circular outer surface of the inner conductor . 2. The wavelength λ of a radio wave propagating through a dielectric waveguide formed between a cylindrical portion of an outer conductor and an outer peripheral surface of an inner conductor.
2. The slot according to claim 1, wherein a plurality of slot pairs each including two slots formed in the propagation direction and separated from each other by a quarter of g in the propagation direction are provided in the cylindrical portion of the outer conductor. Array antenna. Wherein the inner conductor of the circular end faces at both ends, the outer conductor is provided with a disk at both ends, it is assumed that faces each ends through the dielectric, a plurality in the non-feeding side end surface portion of the outer Bushirube body 3. The slot of claim 1 or claim 2, wherein
The slot array antenna according to 1. 4. The slot array antenna according to claim 1, wherein the inner conductor has a hollow shape having an inner space. 5. The slot array antenna according to claim 4, wherein a transceiver system is accommodated in an inner space of the inner conductor.