JP2001111330A - Microstrip array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microstrip array antenna excellent in radiating efficiency. SOLUTION: A power supplying strip line 13 extended linearly and ten pieces of radiating antenna elements 14a-14j perpendicularly projecting from the line 13 are formed on a dielectric substrate 12 whose one face is provided with a ground conductive layer (ground plate) 11. Also, two small rectangular notches are formed near the center of the longitudinal side of each antenna element. The shape of each radiating antenna elements 14a-14j has H shape when the power supplying strip line 13 is horizontally placed. Thus, the current passage can be made longer as compared to the case without providing any notch, and a distance between adjacent array antennas can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar array antenna using a microstrip conductor which can be used as a transmitting and receiving antenna of a radar mounted on an automobile.

[0002]

2. Description of the Related Art Conventionally, US Pat. No. 4,063,245 is known as a planar array antenna using a microstrip conductor. As shown in FIG. 7, the antenna is linearly extended on a dielectric substrate 1 having a ground conductor layer 2 formed on one surface, and is connected in a straight line at one end and open at the other end. The formed microstrip line 3 is formed. Each microstrip line 3 is formed with a linear array to which a plurality of antenna elements 4a to 4e protruding in a branch shape in the lateral direction are connected. The microstrip line 3 of each linear array is connected to the feed strip line 5,
The synthesized signal is output from the center 6 of the line 5 to form a two-dimensional array antenna.

The antenna elements 4a to 4e have a wavelength λ of a design frequency.
_g (lambda _g is the wavelength of propagating a microstrip line at the design frequency) are arranged at intervals of, (a distance from the connection point to the open end) its length is set to about half i.e. lambda _g / 2 of lambda _g I have. Further, since the excitation amplitude of each element can be controlled by changing the width of the antenna elements 4a to 4e, the directional characteristics required for the antenna, that is, the gain (side level) and the sidelobe level can be adjusted for the purpose (specification). Can be tailored. For example, in this figure, the antenna element
4a, 4e, etc., the width of the element at both ends is narrowed, the excitation amplitude is reduced, the width of the element near the center like the antenna element 4c is widened, and the antenna element 4e is positioned at λ _g from the open end 7. By arranging them, standing wave excitation can be realized, and the overall amplitude distribution in each linear array can be formed into a mountain shape that becomes larger near the center. With this amplitude distribution, low side lobe characteristics can be realized.

FIG. 8 is a plan view showing the configuration of another conventional array antenna. As in the conventional example, an array antenna is constituted by a linear microstrip line 53 and a plurality of antenna elements 54a to 54t protruding in a lateral direction with respect to the microstrip line 53. One end of the feed line 53 is connected to the input / output port 56 and the other end is
8a to realize traveling wave excitation. Antenna element group 54a~54j the wavelength lambda _g intervals along one side of the feed line 53 is connected to the feed line 53 protrudes perpendicularly. Further group of antenna elements 54k~54t is the wavelength lambda _g intervals along the other side of the feed line 53 is connected to the feed line 53 protrudes perpendicularly. The positions at which the antenna element groups 54a to 54j and the antenna element groups 54k to 54t are connected to the feed lines 53 are shifted by λ _g / 2.

[0005] With the above configuration, the number of antenna elements within a certain line length can be increased, and the end of the antenna, which causes a decrease in efficiency when a traveling wave is excited by an antenna having a relatively short array length, is reached. And the array length is relatively short (about 10λ _{g in} FIG. 8).
Even in such a case, an efficient antenna can be realized.

[0006]

The above-mentioned microstrip array antenna has a feature that it is thin and has excellent productivity, and is applied to many systems in a microwave band. In the millimeter wave band, it is applied to a vehicle-mounted radar or the like as a sensor for collision prevention or ACC (Adaptive Cruise Control).

At this time, when the interval between adjacent array antennas is reduced, there is a problem that mutual coupling increases and the gain of the array antenna decreases. Further, in an antenna element having a large width, a connection portion connected to a feed strip line is connected with a wide width, and there is a problem that it is difficult to perform impedance matching with a feed strip line having a constant impedance.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a microstrip array antenna having good radiation efficiency.

[0009]

According to a first aspect of the present invention, there is provided a dielectric substrate having a conductor ground plate formed on a back surface thereof and a dielectric substrate having the same. In a microstrip array antenna formed from a strip conductor formed on a substrate, the strip conductor includes a feed strip line disposed linearly and at least one first side of both sides of the feed strip line. A plurality of radiating antenna elements connected and arranged from the side at predetermined intervals along the radiating antenna element, each radiating antenna element has one end connected to the feed strip line and the other end opened, and has a preset length. At about an integral multiple of half the wavelength propagating through the feed stripline at the operating frequency,
A strip having a width distribution corresponding to a distribution related to the position of the excitation amplitude of each radiating antenna element whose width is set in advance so as to provide a desired directional characteristic, and a cutout provided to increase the actual resonance wavelength It is characterized by being composed of a conductor.

According to a second aspect of the present invention, the radiating antenna has a rectangular shape, and the cutout is provided in the middle of a side in the length direction of the radiating antenna.

According to a third aspect of the present invention, the radiating antenna has a rectangular shape, and the cutout has a plurality of streamlines extending substantially in the longitudinal direction provided in an inner region of the radiating antenna. Features.

According to a fourth aspect of the present invention, the radiating antenna has a rectangular shape, a plurality of cutouts are provided in an inner region of the radiating antenna, and the radiating antenna has a rectangular portion in a short width direction. Are arranged so that the conduction current goes straight while bending in the longitudinal direction.

According to a fifth aspect of the present invention, each radiating antenna element is formed such that the electric field radiation edge line forms an angle other than 0 degree (parallel) with the length direction of the feed strip line. It is characterized by.

The invention according to claim 6 is characterized in that the electric field radiation edge line of each radiating antenna element is substantially at 45 degrees to the feed strip line.

As a second invention group of the present invention, the structure of the invention according to claim 7 comprises a dielectric substrate having a conductor ground plate formed on the back surface and a strip conductor formed on the dielectric substrate. In the formed microstrip array antenna, the strip conductors are arranged at predetermined intervals along at least one first side of both sides of the feed strip line arranged in a linear manner and both sides of the feed strip line. And a plurality of radiating antenna elements connected and arranged from
One end of each radiating antenna element is connected to the feed strip line and the other end is open, and the length is approximately 1/1 / s of the wavelength propagating through the feed strip line at a preset operating frequency.
A feed strip having a width which is an integer multiple of 2 and whose width at the open end corresponds to a distribution relating to the position of the excitation amplitude of each radiating antenna element preset to provide a desired directional characteristic; The width of one end connected to the line is constituted by a strip conductor having a constant width.

According to the present invention, each radiating antenna element is formed such that the electric field radiation edge line at the open end forms an angle other than 0 degree (parallel) with the length direction of the feed strip line. It is characterized by having been done.

The ninth aspect of the present invention is characterized in that the electric field radiation edge line at the open end of each radiating antenna element is substantially at 45 degrees to the feed strip line.

[0018]

According to the first to sixth aspects of the present invention, a plurality of radiating antenna elements are provided at predetermined intervals along at least one of the first sides of both sides of the feed strip line. Since they are connected and arranged, and the width of the radiation antenna element is changed corresponding to a predetermined excitation amplitude, desired directivity can be provided. At this time, since the notch is provided so as to extend the actual resonance wavelength, the current path becomes longer, and the resonance frequency can be lowered. As a result, the length of the antenna element can be reduced, the distance between adjacent array antennas can be increased, and the amount of coupling between elements can be reduced as compared with the case where no notch is provided.

As such a notch, there is one in which the radiating antenna has a rectangular shape and the notch is provided in the middle of a side in the length direction of the radiating antenna. Further, the radiation antenna may have a rectangular shape, and the cutout may be a plurality of streamlines extending in a substantially longitudinal direction provided in an internal region of the radiation antenna. The radiating antenna has a rectangular shape, a plurality of cutouts, and is provided in an inner region of the radiating antenna, and has a rectangular portion in a short width direction. In each case, the current is straight while bending in the length direction, and the current path is lengthened.

When the radiation antenna element has an electric field radiation edge line which is an open end, the electric field radiation edge line is zero with respect to the length direction of the feed strip line.
By forming an angle that is not degrees (parallel), or even forming an angle of about 45 degrees, the electric field in the direction orthogonal to the field emission edge line is inclined not obliquely but orthogonally to the feed strip line, and furthermore, 45 degrees. It is possible to generate a polarized wave directed to the inclined direction. This makes it possible to efficiently eliminate the reception of radio waves from oncoming vehicles when the feed stripline is disposed perpendicular to the ground and used as an antenna for a radar of an automobile.

[Inventions of Claims 7 to 9] A plurality of radiating antenna elements are connected to and arranged at predetermined intervals along at least one first side of both sides of the feed strip line. Then, the width of the open end of the radiating antenna element is changed in accordance with the predetermined excitation amplitude, and the width of one end connected to the feed strip line is fixed, so that the input impedance of each radiating antenna element is fixed. While
Desired directivity can be provided. In this case, the radiation antenna element has a trapezoidal shape.

When the radiating antenna element has an electric field radiating edge line which is an open end with respect to the length direction of the feed strip line,
By forming an angle that is not degrees (parallel), or even forming an angle of about 45 degrees, the electric field in the direction orthogonal to the field emission edge line is inclined not obliquely but orthogonally to the feed strip line, and furthermore, 45 degrees. It is possible to generate a polarized wave directed to the inclined direction. This makes it possible to efficiently eliminate the reception of radio waves from oncoming vehicles when the feed stripline is disposed perpendicular to the ground and used as an antenna for a radar of an automobile.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. FIG. 1 mainly shows claims 1, 2, 5,
6 is a perspective view showing a configuration of a microstrip array antenna 10 according to a preferred embodiment (first embodiment) of the invention, FIG. 2 (a) is a plan view of the same, and FIG.
It is -A sectional drawing. On a dielectric substrate 12 having a ground conductor layer (ground plate) 11 formed on one surface, a feed strip line 13 extending linearly, and ten radiating antenna elements 14 a to 14 j protruding from the line 13. Are formed.

On one first side 131 of the feeding strip line 13, a strip-shaped first
The radiating antenna element groups 14a to 14e are the feed strip lines 1
3 projecting vertically. The interval d is, for example, a wavelength lambda _g propagating through the feeding strip line 13 at the design frequency, the length (the distance from the connection point center p to the open end q) is set to about half the wavelength lambda _g . The open ends of the projecting radiating antenna element groups 14a to 14e are all parallel and parallel to the feed strip line 13. Similarly, on the other second side 132 of the feed strip line 13, strip-shaped second radiating antenna element groups 14f to 14j are disposed in parallel with the first radiating antenna element groups 14a to 14e. Are parallel to each other and parallel to the feed strip line 13, and are parallel to one side of the open end of the first radiating element group. First radiation antenna element group 14
a to 14e and the second radiation antenna element groups 14f to 14j
Are shifted from each other by, for example, d / 2.

The strip-shaped radiating antenna elements 14a to 14j
The widths increase in the order of 14a, 14f, 14b, 14g,..., 14e, 14j. Two small rectangular cutouts are provided near the center of each side of the antenna element in the longitudinal direction. The shape of the radiating antenna elements 14a to 14j is in the shape of "work" when the feed strip line 13 is placed in the left-right direction.

The power input from the input terminal 15 is sequentially coupled and radiated to the radiating antenna elements 14a, 14f, 14b,... Which are partly protruded, and the remaining power is transmitted in the traveling direction (see FIG. 2). (To the right), gradually attenuates, and the residual power reaches the termination 16. Part of the input power is coupled to the antenna element 14 and radiated, and most of the remaining power is transmitted. Also, due to the impedance mismatch, a part of the power is reflected and returns to the input terminal. That is, the amount of radiation from the antenna element is represented by the following equation: radiation amount = input−transmission amount−reflection amount, and is uniquely obtained by determining the transmission / reflection amount with respect to the input of the radiation antenna element. If the reflection is extremely small compared to radiation or transmission, the amount of radiation 放射 input−transmission amount, and if only the amount of transmission is determined, the amount of radiation is uniquely determined.

Here, the radiation antenna element 14 according to the present invention is used.
Has a relation that the radiation amount monotonously increases as the width increases. That is, when the width is determined, the radiation amount is uniquely determined. In the design of the array antenna shown in FIG. 1, a desired directivity is obtained by determining the width of each radiation antenna element according to a predetermined excitation amplitude (radiation amount) of each radiation antenna element determined in advance. Can be realized.

FIG. 3 shows another example of a radiating antenna element provided with a notch. FIG. 3A shows a radiating antenna element 141 having two streamline-like cutouts according to claim 3 of the present invention. The radiating antenna element 141 is preferably formed by bending three parallel thin antenna elements projecting perpendicularly to the feed strip line 13. FIG. 3B shows a radiating antenna element 142 according to claim 4 of the present invention, having three cross-shaped notches. The radiation antenna element 142 is connected to the feed strip line 1.
The three parallel thin antenna elements projecting perpendicularly to 3 are bent and formed. In each case, the current path can be lengthened while maintaining the same overall size as compared to a radiating antenna element having no notch.

In addition to those shown in FIGS. 3 (a) and 3 (b), various types of radiating antenna elements having notches for lengthening the current path can be considered. In FIGS. 3A and 3B, the current path is illustrated as being “bent” or “bent” in appearance, and the symmetry, the length of the notch, and the number may be arbitrary.

With the above configuration, the excitation amplitude (radiation amount) of each radiating antenna element can be controlled by changing the width of each radiating antenna element, and an antenna element having a long current path can be used. Directional characteristics, ie, gain and side lobe levels (specifications)
And a microstrip array antenna with good radiation efficiency.
Note that the radiation antenna elements 14a to 14j are mainly
A radio wave having a polarization plane is radiated or received in a direction perpendicular to the feed stripline 13 (the direction of arrow E in FIG. 2).

FIG. 4A is a plan view mainly showing a configuration of a microstrip array antenna 20 according to a preferred embodiment (second embodiment) according to the seventh to ninth aspects of the present invention, and FIG. FIG. A feed strip line 23 extending linearly and ten radiating antenna elements 24a to 24j protruding from the line 23 are formed on a dielectric substrate 22 having a ground conductor layer 21 formed on one surface. I have.

On one first side 231 of the feed strip line 23, there are first radiating antenna element groups 24a to 24e in the shape of a trapezoid on the substrate 22, and the height direction of the trapezoid is the feed strip line. Projection is made perpendicular to 23. The interval is the wavelength lambda _g propagating through the feeding strip line 23 at the design frequency, the length (the distance from the connection point center p to the open end q) is set to about half the wavelength lambda _g. One side of the open ends of the projecting radiating element groups 24a to 24e is all parallel to the feed strip line. Similarly, on the other second side 232 of the feed strip line 23, similarly-shaped trapezoidal second radiating antenna element groups 24 f to 24 j are provided, and the height direction of the isosceles trapezoid is perpendicular to the feed strip line 23. It is projected so that it becomes. One side of the open end is all parallel to the feed stripline, and is parallel to one side of the open end of the first radiating element group. Each of the first radiating antenna element groups 24a to 24e and each of the second radiating antenna element groups 24f to 24j are displaced by, for example, d / 2.

The radiating antenna element 24a~24j, as shown in FIG. 4, the length being connected to the sides of the feeding stripline 23 is constant at W _0, of each of the base length W _{a,
W f, W b, W g} , ..., W e, W j is designed to be greater in this order. In the present embodiment has a W _a = W _0.

[0034] With the above configuration, the width W _a of the open end of each radiating antenna _{element, W f, W b, W} g, ..., controls the excitation amplitude of each element by changing the W _e, W _j Therefore, the directional characteristics required for the antenna, that is, the gain and the level of the side lobe, can be made according to the purpose (specification).

In the above two embodiments, only the case where the field emission edge line is parallel to the length direction of the feed strip line is illustrated. However, by using the radiation antenna element shown in FIG. It is also possible to use a microstrip array antenna having a polarization inclined at 45 degrees. That is, as shown in FIG. 5 (a), the rectangular shape is inclined 45 degrees with respect to the feed strip line 33, connected to the feed strip line near the apex angle of 1, and provided with a notch near the center of the long side. The radiating antenna element 341 can achieve the purpose. 5B, the radiation antenna element 342 having a rectangular shape inclined at 45 degrees to the feed strip line 33 and having a cutout near the center of the long side as shown in FIG. . These all belong to the first invention group of the present invention. Similarly, FIG.
(b) Similar to (c), curving and bending the current path, 45
A radiation antenna element inclined at an angle is also possible.

Further, as shown in FIG. 5C, a trapezoidal radiating antenna element whose base and height are inclined at 45 degrees with respect to the feed strip line 43 is used to form a bias at 45 degrees with respect to the feed strip line. It is also possible to use a microstrip array antenna having waves. In this case, the object can be achieved by changing the length W of the open end (bottom side) of each radiation antenna element. This belongs to the second invention group of the present invention.

It should be noted that, as shown in FIG.
6 may be provided with a matching terminating element 61 for absorbing residual power, or a microstrip antenna element 62 or the like, for example, to radiate power effectively.

In each of the above embodiments, the radiating antenna elements are provided on both sides of the feed strip line, but may be provided on at least one side. The width of the radiating antenna element, length, spacing, is to be determined by the characteristics of the antenna in relation to the wavelength lambda _g. Integer multiples of the lengths described above can also be used. Also, the number of radiating antenna elements connected to the feed stripline is arbitrary.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a microstrip array antenna according to a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view of the microstrip array antenna according to the first embodiment.

FIG. 3 is a plan view showing an example of another radiation antenna element of the microstrip array antenna according to the first embodiment.

FIG. 4 is a plan view and a cross-sectional view illustrating a configuration of a microstrip array antenna according to a second embodiment of the present invention.

FIG. 5 is a plan view showing another example of a radiation antenna element of the microstrip array antenna according to the first and second embodiments of the present invention.

FIG. 6 is a plan view showing a terminal portion of a feed strip line of the microstrip array antenna.

FIG. 7 is a perspective view of a microstrip array antenna according to a conventional example.

FIG. 8 is a plan view of a microstrip array antenna according to another conventional example.

[Explanation of symbols]

 10, 20 microstrip array antenna 11, 21 ground conductor layer (ground plate) 12, 22 dielectric substrate 13, 23 feed stripline 14a-14j, 24a-24j radiation antenna element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Watanabe 41-cho, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun Aichi Prefecture Inside Toyota Central R & D Laboratories Co., Ltd. No. 41, Chochu-Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kazuo Sato 41, Nagakute-cho, Aichi-gun, Aichi Prefecture AB06 CA03 HA04 HA05 HA10 JA02 JA06 JA07 5J045 AA02 AA07 AB05 AB06 CA04 DA10 DA12 FA02 HA03 LA01 NA01 NA07

Claims (9)

[Claims] 1. A microstrip array antenna comprising a dielectric substrate having a conductor ground plate formed on a back surface thereof and a strip conductor formed on the dielectric substrate, wherein the strip conductor has a linear shape. And a plurality of radiating antenna elements connected and arranged at predetermined intervals along at least one first side of both sides of the power supply strip line, the power supply strip line being provided, and Each radiating antenna element has one end connected to the feed strip line and the other end open, and a length that is an integer multiple of approximately 波長 of a wavelength propagating through the feed strip line at a preset operating frequency; The width has a distribution corresponding to the distribution related to the position of the excitation amplitude of each radiating antenna element preset to provide a desired directional characteristic,
A microstrip array antenna comprising a strip conductor provided with a notch so as to extend an actual resonance wavelength. 2. The microstrip array antenna according to claim 1, wherein the radiating antenna has a rectangular shape, and the cutout is provided in a middle of a longitudinal side of the radiating antenna. . 3. The radiating antenna has a rectangular shape, and the cutout has a plurality of streamlines extending in a substantially longitudinal direction provided in an inner region of the radiating antenna. 2. The microstrip array antenna according to 1. 4. The radiation antenna has a rectangular shape, a plurality of the notches are provided in an inner region of the radiation antenna, and the radiation antenna has a rectangular portion in a short width direction.
2. The microstrip array antenna according to claim 1, wherein the conduction current is arranged so as to go straight while bending in the length direction. 5. Each of the radiating antenna elements is formed such that an electric field radiation edge line forms an angle other than 0 degree (parallel) with a length direction of a feed strip line. The microstrip array antenna according to claim 4. 6. The microstrip array antenna according to claim 5, wherein the electric field radiation edge line of each of the radiation antenna elements forms an angle of about 45 degrees with the feed strip line. 7. A microstrip array antenna formed from a dielectric substrate having a conductor ground plate formed on the back surface thereof and a strip conductor formed on the dielectric substrate, wherein the strip conductor has a linear shape. And a plurality of radiating antenna elements connected and arranged at predetermined intervals along at least one first side of both sides of the power supply strip line, the power supply strip line being provided, and Each radiating antenna element has one end connected to the feed strip line and the other end open, and a length that is an integer multiple of approximately 波長 of a wavelength propagating through the feed strip line at a preset operating frequency; A width distribution corresponding to the distribution related to the position of the excitation amplitude of each radiating antenna element, which is set so that the width of the other open end provides a desired directional characteristic. Has the feeding strip line and connected to the width of one end of a microstrip array antenna, characterized in that it is constituted by a strip conductor is constant. 8. Each of the radiation antenna elements is formed such that an electric field radiation edge line at the open end forms an angle other than 0 degree (parallel) with a length direction of the feed strip line. The microstrip array antenna according to claim 7. 9. The microstrip array antenna according to claim 8, wherein the electric field radiation edge line at the open end of each of the radiation antenna elements forms an angle of about 45 degrees with the feed strip line.