JP2001111336A - Microstrip array antenna - Google Patents

Abstract

(57) [Object] To provide a microstrip array antenna operating in a wide frequency band. A feed strip line (13) and a plurality of radiating antenna elements (14a to 14) are provided at a predetermined interval along a side of the feed strip line (13).
14j and the parasitic antenna elements 17a to 17j are formed in parallel with each other with a slight gap g therebetween. The radiating antenna elements 14a to 14j are rectangular in shape, and have a length corresponding to a distribution related to the position of the excitation amplitude of each radiating antenna element whose length is an integral multiple of approximately 概 of the radio wave wavelength at the set frequency. Having. The parasitic antenna element has a rectangular shape substantially the same shape as the corresponding radiation antenna element, and has a length in the range of 0.9 to 1.1 times the length of the corresponding radiation antenna element and a width corresponding to the corresponding radiation antenna element. The dimensions are approximately the same as the width of the antenna element.

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. 21, 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 line with one end connected and the other end opened. 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, and the combined signal is output from the center 6 of the line 5, forming 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. 22 is a plan view showing the structure 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 connected to the matching terminating element 58a 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. 22 can be reduced, and the array length is relatively short (about 10 in FIG. 22).
λ _g ), an efficient antenna can be realized. In the conventional example shown in FIGS. 21 and 22, the antenna element
4a-4e and 54a-54t mainly emit radio waves from their open ends,
That is, it can be approximately regarded as a magnetic dipole element,
It has a plane of polarization in a direction orthogonal to the microstrip line 3 and the feed line 53.

Also, as shown in FIG. 23, the antenna element is inclined with respect to the feed line, and the angle between the feed line and the antenna element on both sides is made ± 45 degrees with respect to the feed line. An antenna configured to generate circularly polarized waves is also known. The antenna elements 74a and 74d are arranged symmetrically with respect to a line AA passing through the center of the microstrip line and at an interval of λ _g / 4. That is, the electric field Ea in the +45 degree direction with respect to the microstrip line 73 radiated by the antenna element 74a and the electric field Ed in the -45 degree direction with respect to the microstrip line 73 radiated by the antenna element 74d have a phase difference of 90 degrees. And a circularly polarized wave is radiated to have a main beam in the vertical direction.

Further, JP Daniel, E. Penard, M. Ne
delec and JP Mutzig, "Designof Low Cost Printed
Antenna Arrays, "Proc. ISAP, pp.121-124, Aug. 198
5 shows an array antenna 1 having the structure shown in FIGS.
00 and 200 are described. Dielectric substrate 101,
The microstrip lines 103 and 203
10 square microstrip antenna elements 1
04 and 204 are connected so that power is supplied from the corner. A plurality of microstrip antenna elements 104, 2
04 is arranged in microstrip lines 103 and 203
Are arranged symmetrically with respect to the input / output ends 102 and 202 formed at the center of the line. In FIG. 24 (a), the respective microstrip antenna element 104 is connected to one side of the microstrip line 103 at intervals of a wavelength lambda _g propagating through the microstrip line 103, prior to the connection point (output end 102 The impedance converter 105 having a length of λ _g / 4 is formed on the side (close to). Further, in FIG. 24 (b), the respective microstrip antenna element 204 is connected to the alternate sides of the sides of the microstrip line 203 feed line 203 at half the interval of the wavelength lambda _g propagating a previous connection points (The side close to the input / output end 202) has an impedance converter 2 having a length of λ _g / 4.
05 is formed.

By adopting the above-described configuration, FIG.
In 4 (a), degenerate modes of TM ₀₁ and TM ₁₀ modes orthogonal to each microstrip antenna element 104 are excited, and a radio wave polarized in a direction perpendicular to the feed line 103 as a synthetic polarization is generated. Similarly, also in FIG. 24B, a radio wave polarized in a direction perpendicular to the feed line 203 is generated. 24A and 24B, the impedance converter 105,
By adjusting the conversion impedance of each of the microstrip antenna elements 104, 20
4 can be controlled to obtain desired directivity characteristics. Further, by forming the arrangement as shown in FIG. 24B, the microstrip antenna elements 204a and 204a
Polarization crossing components orthogonal to the main polarization of 04b (polarization in the direction perpendicular to the feed line 203) are excited in opposite phases, and cancel each other out, so that the cross polarization level can be lowered.

[0009]

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).

However, since the wavelength is short in the millimeter-wave band, if a dimensional deviation in manufacturing occurs, the operating frequency is deviated from the set frequency, so that there is a problem that the device cannot be used. In addition, in the case of an on-vehicle radar, it is necessary to use linearly polarized waves obliquely at 45 degrees to the ground in order to avoid interference with radio waves radiated from an oncoming vehicle equipped with a radar traveling from the front. However, in the conventional configuration, regardless of the standing wave excitation type or the traveling wave excitation type, the antenna element has a structure extending at right angles from the feed line, so that only polarization in the direction perpendicular to the microstrip line is generated. Can not. That is, a desired polarization direction cannot be obtained. Further, as described above, a method of arranging the antenna elements obliquely on both sides at an angle symmetrical with respect to the microstrip line has also been proposed. However, this method generates a circularly polarized wave. In the arrangement, linear polarization cannot be generated.

In the case of using the microstrip antenna element shown in FIG. 24, power is supplied at the corner of the microstrip antenna element to generate a degenerate mode as shown in FIG. Performs the same operation as the element shown in FIG. Therefore, as in the case of the array antennas of FIGS. 21 and 22, only polarized waves in a direction perpendicular to the feed line can be generated. In addition, since the excitation amplitude of each microstrip antenna element is controlled by an impedance converter inserted in the microstrip line, if the impedance is low, the line width becomes large, which hinders the arrangement of the microstrip antenna elements. In addition, when the impedance is high, the line width becomes narrow, and there is a problem that it cannot be manufactured due to manufacturing limitations. Further, since each antenna element operates within a narrow frequency band, a high degree of manufacturing accuracy was required. Further, when a metal object or other object is present around a place where the antenna is mounted on a vehicle, the resonance frequency of the antenna fluctuates due to the influence of the metal object or the other object, causing a problem that the antenna gain is reduced.

SUMMARY OF THE INVENTION 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 which operates in a wide frequency band, and which has excellent reflection characteristics and good radiation efficiency. It is to provide an array antenna. Also,
Another object is to make it possible to obtain a polarization in a direction inclined with respect to the microstrip line.

[0013]

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 strip formed on the dielectric substrate. In the microstrip array antenna formed from the conductor and the strip conductor, the strip conductor is provided at a predetermined interval along 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, and a plurality of parasitic antenna elements adjacent to each other in parallel with a slight gap from each of the plurality of radiating antenna elements, and each radiating antenna element is The length is an integral multiple of approximately one-half the wavelength propagating through the feed stripline at a preset operating frequency, and the width is preset to provide desired directional characteristics. The passive antenna elements each have a rectangular shape of substantially the same shape as the corresponding radiation antenna element, and have a length corresponding to the width of the strip conductor corresponding to the distribution of the excitation amplitude of each of the radiation antenna elements. Is in the range of 0.9 to 1.1 times the length of the corresponding radiating antenna element, and the width thereof is substantially the same as the width of the corresponding radiating antenna element.

According to a second aspect of the present invention, in the first aspect of the invention, the plurality of antenna elements are arranged such that the field emission edge line forms an angle other than 0 degree (parallel) with the length direction of the feed strip line. It is characterized by being connected and arranged from the first side.

According to a third aspect of the present invention, there is provided a first dielectric substrate having a conductor ground plate formed on a back surface thereof,
A first strip conductor formed on a dielectric substrate of
A microstructure formed from a second dielectric substrate placed in parallel with a certain gap above the first dielectric substrate, and a second strip conductor formed on the second dielectric substrate. In the strip array antenna, the first strip conductor includes a feed strip line arranged linearly and at least one of first and second sides of the feed strip line.
A plurality of radiating antenna elements connected and arranged from the side at predetermined intervals along the side, and the radiating antenna has an approximate length of a wavelength propagating through the feed strip line at a preset operating frequency. It is an integral multiple of 1/2,
A second strip conductor having a width distribution corresponding to a distribution relating to a position of an excitation amplitude of each radiation antenna element whose width is preset to provide a desired directional characteristic;
Is a plurality of parasitic antenna elements having a rectangular shape arranged in parallel directly above and corresponding to each of the plurality of radiating antenna elements on the first dielectric substrate. And the length is in the range of 0.9 times to 1.1 times the length of the corresponding radiating antenna element, and the width is the same as that of the corresponding radiating antenna element. It is characterized in that it has approximately the same dimensions as the width.

Further, the invention according to claim 4 is the same as the invention according to claim 3.
In the invention, a plurality of antenna elements are connected and arranged from the first side such that the field emission edge line forms an angle other than 0 degree (parallel) with the length direction of the feed strip line.

According to a fifth aspect of the present invention, the electric field radiating edge line of the radiating antenna element is approximately 45 degrees with respect to the feed strip line.
It is characterized by a degree.

A sixth aspect of the present invention is characterized in that the radiating antenna element has a rectangular shape having different lengths and widths, is connected to a feed strip line near one apex angle, and the other end is open.

The invention according to claim 7 is characterized in that the side forming the apex angle connected to the feed strip line of the radiating antenna element forms approximately 45 degrees with the feed strip line.

According to an eighth aspect of the present invention, the radiating antenna element is
A first strip formed along a first side of the feed strip line;
A radiating antenna element and a second radiating antenna element which is configured in the same manner as the first radiating antenna element and is formed substantially parallel to the second side which is the other side of the feed strip line. It is characterized by comprising.

According to a ninth aspect of the present invention, the radiating antenna element is
A first strip formed along a first side of the feed strip line;
The direction of the electric field radiated by the radiating antenna element is substantially parallel to the direction of the electric field radiated by the second radiating antenna element formed along the second side, which is the other side. .

According to a tenth aspect of the present invention, each of the second radiating antenna elements is arranged at a substantially middle point of an interval in which each of the first radiating antenna elements is arranged along the feed strip line. Features.

[0023]

The plurality of radiating antenna elements are connected to at least one of the first and second sides of the feed strip line.
The antennas are arranged at predetermined intervals along the sides, and the parasitic antenna elements are arranged adjacent to each radiating antenna element with a slight gap. The antenna operates in the band, and even if the resonance frequency of the antenna fluctuates due to the influence of metal objects or other objects around the mounting location on the vehicle, problems such as a decrease in antenna gain do not occur ( Claim 1). Further, by changing the width of the radiation antenna element depending on the position on the feed strip line, desired directivity can be provided.

In addition, the field emission edge line is connected to the side of the feed strip line so as to form an angle other than 0 degree (parallel) with the length direction of the feed strip line. An electric field that is orthogonal to the line can produce a polarization that is oriented in a direction that is obliquely inclined rather than orthogonal to the feed stripline. Therefore, when the antenna is used as an antenna of an automobile radar, it does not receive a radio wave from an oncoming vehicle. still,
The field emission edge line of the radiating antenna element is a contour line of the radiating antenna element, which is a contour element side determined by an operating frequency and which determines a direction of a radiated electric field.

A plurality of radiating antenna elements are provided at predetermined intervals along at least one of the first and second side edges of the feed strip line, and a rectangular parasitic antenna element is provided immediately above each radiating antenna element. Since they are arranged in parallel, if their lengths are different, their resonance frequencies will be different, and they will operate in a wide frequency band, and the antenna's resonance frequency will be affected by the effects of metal and other objects around the vehicle mounting location. Does not cause a problem such as a decrease in the gain of the antenna. Further, as in the first aspect, by changing the width of the radiation antenna element depending on the position on the feed strip line, desired directivity can be provided.

In addition to this, the field emission edge line is connected to the side of the feed strip line so as to form an angle other than 0 degree (parallel) with the length direction of the feed strip line. An electric field that is orthogonal to the line can produce a polarization that is oriented in a direction that is obliquely inclined rather than orthogonal to the feed stripline. Therefore, when the antenna is used as an antenna of an automobile radar, it does not receive a radio wave from an oncoming vehicle. still,
The field emission edge line of the radiating antenna element is a contour line of the radiating antenna element, which is a contour element side determined by an operating frequency and which determines a direction of a radiated electric field.

According to the fifth aspect of the present invention, the electric field radiation edge line of the radiating antenna element has a direction of approximately 45 degrees with respect to the feed strip line. Oriented polarization can be generated. Thus, for example, when the feed stripline is arranged perpendicular to the ground and used as an antenna of a radar of an automobile, reception of radio waves from oncoming vehicles can be eliminated most efficiently.

According to the sixth aspect of the present invention, the radiation antenna element has a rectangular shape having different lengths and widths, that is, a rectangular shape.
Near the apex angle and connected to the feed stripline and the other end is open, the lengths of both parallel sides in the length direction are almost the same, which allows the single mode radio wave polarized in the length direction to be transmitted. And a directional characteristic having a low cross polarization level can be obtained.

According to the seventh aspect of the present invention, the side forming the apex angle, which is the portion where the radiating antenna element is connected to the feed strip line, forms approximately 45 degrees with respect to the length direction of the feed strip line. Therefore, the polarization direction can be set to approximately 45 degrees, and the same effect as that of claim 5 can be obtained.

According to the invention of claim 8, since the radiating antenna elements having the same length direction are arranged on both sides of the feed strip line, the radiation capability of radio waves is improved and the receiving sensitivity is improved. Can be done. Claim 9
Also in the invention of the first aspect, the polarization direction of the radio wave by the first radiation antenna element and the second radiation antenna element becomes the same, so that the radio wave radiation ability and reception sensitivity can be improved.

According to the tenth aspect of the present invention, since the radiating antenna elements on both sides are alternately arranged at equal intervals along the feed strip line, efficient radiation and reception of radio waves can be achieved, and a desired directivity can be obtained. The characteristics can be improved.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments.

FIG. 1 shows a microstrip array antenna 1 according to a first embodiment which is a preferred embodiment according to the first, eighth, ninth and tenth aspects of the present invention.
0 (a) is a plan view, FIG. 2 (b) is a plan view of the same, and FIG.
FIG. 3A is a sectional view taken along line A ₂ -A ₂ , and FIG. 3 is an enlarged view of a portion B ₂ in FIG. A feed strip line 13 extending linearly and ten radiating antenna elements 14a to 14j connected to the line 13 are formed on a dielectric substrate 12 having a ground conductor layer (ground plate) 11 formed on one surface. Are formed.

The first side 131 of the feed strip line 13 has a rectangular first shape on the dielectric substrate 12.
The radiating antenna element groups 14a to 14e protrude. The interval d is the wavelength lambda _g propagating through the feeding strip line 13 in the example design frequency, (length of the side toward the open end from the connection point) the length of which is set to about half of the propagation wavelength lambda _g ing. Projecting radiation antenna element group 14a
One side of the open ends of ~ 14e are all parallel. Similarly, on the other second side 132 of the feeding strip line 13, the second radiation antenna element groups 14f to 14j having a rectangular shape
They are arranged in parallel to the radiating antenna element groups 14a to 14e.
The open ends of the rectangular second radiating antenna element groups 14f to 14j are all parallel, and the first radiating antenna element group 14a
14e are parallel to one side of the open end. Each of the first radiating antenna element groups 14a to 14e and each of the second radiating antenna element groups 14f to 14j are displaced by, for example, d / 2.

The radiating antenna elements 14a to 14j are connected at right angles to the sides of the feed strip line 13, as shown in FIG. Further, parallel parasitic antenna elements 17a to 17j having a rectangular shape are arranged adjacent to and parallel to the radiation antenna elements 14a to 14j with a slight gap g. As shown in FIG. 3, the widths of the parasitic antenna elements 17a to 17j are set to be the same as the widths W of the corresponding radiating antenna elements 14a to 14j.
Further, the length L ₀ of the parasitic antenna elements 17a to 17j is determined by adjusting the range of 0.9L or more and 1.1L or less so that the return loss, which is the input characteristic of the array antenna, is minimized in a wide frequency band. You. Here, L is a radiation antenna element 14a-14j corresponding to each parasitic antenna element 17a-17j.
Is the length of

The gap g between the radiating antenna elements 14a to 14j and the corresponding parasitic antenna elements 17a to 17j (the opposing length
L, and L long side of the spacing of _0), the central distance) L _g of the rectangular shape of the deviation (each with parasitic antenna elements 17a~17j corresponding to radiating antenna element 14A～14j, radiation as the smaller antenna The coupling between the elements 14a to 14j and the parasitic antenna elements 17a to 17j increases. The value of the gap g and the deviation L _g is
The frequency band of the microstrip array antenna is determined to be the widest.

The power input from the input terminal 15 is sequentially coupled and radiated to the radiating antenna elements 14a, 14f, 14b,... Which are partially 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. FIG. 4 schematically illustrates this operation of the radiation antenna element 14 alone. A part of the power input from the input terminal (the left side in the figure) is coupled to the antenna element 14 and the parasitic antenna element 17 and radiated, and most of the remaining power is the output terminal (the right side in the figure). Through. 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. In addition,
If the reflection is extremely small compared to radiation or transmission, the amount of radiation.
The input-transmission amount is obtained. If only the transmission amount is obtained, the radiation amount is uniquely obtained.

FIG. 6 shows the radiation amount obtained when the width W of the microstrip antenna element 14 according to the present invention is changed. The horizontal axis of the figure represents the width W of the microstrip antenna element 14 and is a value normalized by the wavelength λ at the design frequency. The vertical axis represents the ratio to the input power.

Referring to FIG. 5, the width of the antenna element with respect to the required excitation amplitude (radiation amount) of the antenna element can be determined. For example, when a radiation amount of 10% is required, the width of the antenna element may be set to 0.118λ. In the design of the array antenna shown in FIG. 1, according to a predetermined excitation amplitude (radiation amount) of each antenna element determined in advance,
By determining the width of each radiating antenna element,
Desired directivity can be realized.

FIG. 6 shows the return loss at the input end 15 of the array antenna in comparison with the case where the parasitic antenna element is provided and the case where the parasitic antenna element is not provided. As a criterion for expecting good operation as an antenna, return loss is-
Considering the range of 10 dB or less, when a parasitic antenna element is provided, the bandwidth is about twice as large as that when no parasitic antenna element is provided by appropriately adjusting L ₀ , g, and L _g. It can be seen that it can be obtained.

By changing the width W of each radiating antenna element, the excitation amplitude (radiation amount) of each element can be changed.
, It is possible to make the directional characteristics required for the antenna, that is, the gain and side lobe levels, according to the purpose (specification). In addition, since this feature can be obtained in a wide frequency band, when an antenna is mounted, deterioration of characteristics due to peripheral objects is small and usefulness is high.

[Second Embodiment] FIG.
8 (a) is a perspective view showing a configuration of a microstrip array antenna 20 according to a second embodiment which is a preferred embodiment of the invention described in 6, 7, 8, 9 and 10, FIG. b) the a ₈ -A ₈ cross-sectional view of (a), FIG. 9 is shown in FIG. 8 (a)
It is an enlarged view of B ₈ parts. Ground conductor layer (ground plate) on one side
A feed strip line 23 extending linearly and ten radiating antenna elements 24a to 24j connected to the line 23 are formed on a dielectric substrate 22 on which the 21 is formed.

A first side 231 of the feed strip line 23 has a rectangular first shape on the dielectric substrate 22.
The radiating antenna element groups 24a to 24e are provided so as to be inclined at an angle of about 45 degrees. The interval d is the wavelength lambda _g propagating through the feeding strip line 23 in the example design frequency, the length (length of a side toward the open end from the connection point)
Is set to about half the wavelength λ _g to propagate. The open ends of the projecting radiating antenna element groups 24a to 24e are all parallel and substantially +4 with respect to the feed strip line 23.
5 degrees. Further, on the other second side 232 of the feed strip line 23, similarly, the second radiation antenna element groups 24f to 24j having a rectangular shape are provided with the first radiation antenna element group 24a.
~ 24e are arranged in parallel. The open ends of the rectangular second radiating antenna element groups 24f to 24j are all parallel to each other and make approximately -135 degrees with respect to the feed strip line 23, and the open ends of the first radiating antenna element groups 24a to 24e. One side is parallel. Each of the second 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 field emission edge line is one side of the contour edge line of each radiation element, and the open end K in FIG. 7 corresponds to the field emission edge line. Note that the other side R may be an electric field emission edge line. Which one becomes the field emission edge line depends on the operating frequency. The direction of the electric field of the radiated radio wave is a direction orthogonal to the electric field radiation edge line.

As shown in FIG. 9, one of the radiating antenna elements 24a to 24j has one apex angle having a length W of the short side of about 1 mm.
/ 2 is connected to the side of the feed strip line 23 with a width of not more than / 2.

Further, parallel parasitic antenna elements 27a to 27j having a rectangular shape are arranged adjacent to and parallel to the radiation antenna elements 24a to 24j with a slight gap g. As shown in FIG. 9, the widths of the parasitic antenna elements 27a to 27j are set to be the same as the widths W of the corresponding radiating antenna elements 24a to 24j. Further, the length L ₀ of the parasitic antenna elements 27a to 27j is set to 0.9 L or more and 1.1 L so that the return loss, which is the input characteristic of the array antenna, is minimized in a wide frequency band.
It is determined by adjusting within the following range. Here, L is a radiation antenna element 24a corresponding to each of the parasitic antenna elements 27a to 27j.
~ 24j long.

The gap g between the radiating antenna elements 24a to 24j and the corresponding parasitic antenna elements 27a to 27j (the opposite length
L, and L long side of the spacing of _0), the central distance) L _g of the rectangular shape of the deviation (each with parasitic antenna elements 27a~27j corresponding to radiating antenna elements 24 a through 24 j, the radiation as smaller antenna The coupling between the elements 24a to 24j and the parasitic antenna elements 27a to 27j increases. The value of the gap g and the deviation L _g is
The frequency band of the microstrip array antenna is determined to be the widest.

The power input from the input end 25 is sequentially coupled and radiated to the radiating antenna elements 24a, 24f, 24b,... Which are partly protruded, and the remaining power is transmitted in the traveling direction (FIG. 8). (Rightward), gradually attenuates, and the residual power reaches the termination 26. This operation is similar to that of the first embodiment.

By changing the width W of each radiating antenna element, the excitation amplitude (radiation amount) of each element can be changed.
, It is possible to make the directional characteristics required for the antenna, that is, the gain and side lobe levels, according to the purpose (specification). Further, the radiating antenna elements 24a to 24j are inclined at an angle of 45 degrees from the open end K with respect to the feed strip line 23.
In order to radiate or receive radio waves having a polarization plane (in the direction of arrow E in FIG. 2), by using such a linear feed strip line 23, it is possible to use an array antenna having a polarization plane oriented obliquely at 45 degrees. realizable. Moreover, since these characteristics can be obtained in a wide frequency band, when the antenna is mounted, there is little deterioration in characteristics due to surrounding objects,
High usefulness.

[Third Embodiment] FIG. 10 shows a third embodiment of the present invention.
FIG. 13 is a perspective view showing a configuration of a microstrip array antenna 30 according to a third embodiment, which is a preferred embodiment of the invention described in FIGS. FIG. 11 shows a plan view and a sectional view of two layers in order to describe the structure of the microstrip array antenna 30 in detail. FIG. 11A is a plan view of a second dielectric substrate 38 having parasitic antenna elements 37a to 37j as an upper layer, and FIG. 11B shows a feed strip line 33 and radiation antenna elements 34a to 34j. the first dielectric substrate 32 a plan view of having, FIG. 11 (c) is a B ₁₁ -B ₁₁ shows by combining the sectional view of the a ₁₁ -A ₁₁ cross-sectional view (b) of (a) . Further, FIG. 12, C ₁₁ parts of FIG. 11 (a), an enlarged view of a D ₁₁ parts of FIG. 11 (b).

On a first dielectric substrate 32 having a ground conductor layer (ground plate) 31 formed on one surface, a feed strip line 33 extending linearly and a 10
The radiation antenna elements 34a to 34j are formed.

On one first side 331 of the feed strip line 33, first radiating antenna element groups 34 a to 34 e having a rectangular shape on the first dielectric substrate 32 are inclined at approximately 45 degrees. It is protruding. The interval d is the wavelength lambda _g propagating through the feeding strip line 33 in the example design frequency, (length of the side toward the open end from the connection point) the length of which is set to about half of the propagation wavelength lambda _g ing.
The open ends of the projecting radiating antenna element groups 34a to 34e are all parallel. Similarly, on the other second side 332 of the feed strip line 33, the second radiating antenna element groups 34f to 34j having a rectangular shape are similarly provided with the first radiating antenna element group 34.
It is arranged in parallel to a to 34e. The open ends of the rectangular second radiation antenna element groups 34f to 34j are all parallel to each other, and are parallel to the open ends of the first radiation antenna element groups 34a to 34e. Each of the first radiating antenna element groups 34a to 34e and each of the second radiating antenna element groups 34f to 34j are displaced by, for example, d / 2.

The radiating antenna elements 34a to 34j are connected at right angles to the sides of the feed slip line 33, as shown in FIG. Further, a second dielectric substrate 38 is provided in parallel above the first dielectric substrate 32, and a radiation antenna provided on the first dielectric substrate 32 is provided on the second dielectric substrate 38. Parasitic parasitic antenna elements 37a to 37j are arranged corresponding to the elements 34a to 34j. As shown in FIG. 12, the widths of the parasitic antenna element groups 37a to 37j are set to be the same as the widths W of the corresponding radiating antenna elements 34a to 34j. Furthermore, the length L of the parasitic antenna elements 37a to 37j
₀ is 0.9L so that the return loss, which is the input characteristic of the array antenna, is minimized in a wide frequency band.
It is determined by adjusting within the range of 1.1L or more. Here, L is the length of the radiation antenna elements 34a to 34j corresponding to the respective parasitic antenna elements 37a to 37j.

The radiating antenna elements 34a to 34j and the corresponding parasitic antenna elements 37a to 37j are arranged so as to substantially overlap each other when viewed from above perpendicularly to the surfaces of the dielectric substrates 32 and 38. That is, in FIG.
The two surfaces and the 38 surface are parallel to each other, and the side indicated as length L in the radiating antenna element 34 on the surface of the dielectric substrate 32 and the length L ₀ in the parasitic antenna element 37 on the surface of the dielectric substrate 38. Are parallel to each other. Also,
The side of the radiating antenna element 34 on the surface of the dielectric substrate 32 indicated by the length W is parallel to the side of the parasitic antenna element 37 on the surface of the dielectric substrate 38 indicated by the length W. Further, each of the rectangular radiation antenna elements 34
A straight line connecting the center of each of the parasitic antenna elements 37 is substantially perpendicular to the surfaces of the dielectric substrates 32 and 38. The side of the length L ₀ of the parasitic antenna element 37 and the radiation antenna element 34
Although the length may be different from the side of length L, when the rectangle with the shorter side is translated in the direction perpendicular to the substrate surface, they are arranged so as to be included in the rectangle with the longer side. I have.

The power input from the input end 35 is sequentially coupled and radiated to the radiating antenna elements 34a, 34f, 34b,... Which are partly protruded, and the remaining power is transmitted in the traveling direction (FIG. 11). (Rightward), gradually attenuates, and the residual power reaches the termination 36. FIG. 13 schematically shows the state of this operation for the radiation antenna element 34 alone.
Shown in The power input from the input terminal (left side in the figure)
Part of which is the antenna element 34 and the parasitic antenna element 3
7 and radiated, most of the remaining power is transmitted to the output terminal (right side in the figure). 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.

FIG. 14 shows the radiation amount obtained when the width W of the microstrip antenna element 34 according to the present invention is changed. The horizontal axis of the figure represents the width W of the microstrip antenna element 34 and is a value normalized by the wavelength λ at the design frequency. The vertical axis represents the ratio to the input power.

Using FIG. 14, the width of the antenna element with respect to the required excitation amplitude (radiation amount) of the antenna element can be determined. For example, when a radiation amount of 10% is required, the width of the antenna element may be set to 0.13λ. In the design of the array antenna shown in FIG. 10, a desired directivity is realized by determining the width of each radiating antenna element according to a predetermined excitation amplitude (radiation amount) of each antenna element determined in advance. can do.

FIG. 15 shows the return loss at the input end 35 of the array antenna in comparison with the case where the parasitic antenna element is provided and the case where the parasitic antenna element is not provided. Considering the range in which the return loss is −10 dB or less as a criterion that can expect good operation as an antenna, if a parasitic antenna element is provided, L ₀ , and a radiating antenna element corresponding to the parasitic antenna element By appropriately adjusting the distance h, the distance h is approximately 2.5 times smaller than when no parasitic antenna element is provided.
It can be seen that double bandwidth can be obtained.

By changing the width W of each radiating antenna element, the excitation amplitude (radiation amount) of each element can be changed.
, It is possible to make the directional characteristics required for the antenna, that is, the gain and side lobe levels, according to the purpose (specification). In addition, since this feature can be obtained in a wide frequency band, when an antenna is mounted, deterioration of characteristics due to peripheral objects is small and usefulness is high.

FIG. 16 shows a fourth embodiment of the present invention.
FIG. 14 is a perspective view showing a configuration of a microstrip array antenna 40 according to a fourth embodiment which is a preferred embodiment of the invention described in FIG. FIG. 17 shows a plan view and a cross-sectional view of two layers in order to describe the structure of the microstrip array antenna 40 in detail. FIG. 17A shows a second dielectric substrate 4 having parasitic antenna elements 47a to 47j as an upper layer.
FIG. 17B is a plan view of the first dielectric substrate 4 having the feed stripline 43 and the radiating antenna elements 44a to 44j.
FIG. 17C is a sectional view taken along line A ₁₇ -A _{17 in} FIG. 17A and FIG.
FIG. ₁₇ is a drawing together with a _17- B ₁₇ sectional view. FIG.
8, C ₁₇ parts of FIG. 17 (a), the is an enlarged view of a D ₁₇ parts of FIG. 17 (b).

On a first dielectric substrate 42 having a ground conductor layer (ground plate) 41 formed on one surface, a feed strip line 43 extending linearly and 10
The radiation antenna elements 44a to 44j are formed.

On one first side 431 of the feed strip line 43, first radiating antenna element groups 44 a to 44 e having a rectangular shape on the first dielectric substrate 42 are inclined at approximately 45 degrees. It is protruding. The interval d is the wavelength lambda _g propagating through the feeding strip line 43 in the example design frequency, (length of the side toward the open end from the connection point) the length of which is set to about half of the propagation wavelength lambda _g ing.
One side of the open ends of the projecting radiating antenna element groups 44a to 44e are all parallel and substantially at +45 degrees with respect to the feed strip line 43. Feed strip line 4
Similarly, rectangular second radiation antenna element groups 44f to 44j are arranged on the other second side 432 of 3 in parallel to the first radiation antenna element groups 44a to 44e. The open ends of the rectangular second radiating antenna element groups 44f to 44j are all parallel to each other and make approximately -135 degrees with respect to the feed strip line 43, and the open ends of the first radiating antenna element groups 44a to 44e. One side is parallel. Each of the first radiating antenna element groups 44a to 44e and each of the second radiating antenna element groups 44f to 44j are displaced by, for example, d / 2. The field emission edge line is one side of the contour edge line of each radiating element,
The open end K shown in FIG. 16 corresponds to this field emission edge line. Note that the other side R may be an electric field emission edge line. Which one becomes the field emission edge line depends on the operating frequency. The direction of the electric field of the radiated radio wave is a direction orthogonal to the electric field radiation edge line. Which of the open end K and the long side R is the field emission edge line depends on the operating frequency. The direction of the electric field of the radiated radio wave is a direction orthogonal to the electric field radiation edge line.

As shown in FIG. 18, the radiation antenna elements 44a to 44j are connected to the side of the feed strip line 43 at one apex angle with a width of about 1/2 or less of the length W of the short side. Have been.

Further, a second dielectric substrate 48 is provided in parallel above the first dielectric substrate 42, and is provided on the first dielectric substrate 42 on the second dielectric substrate 48. Parasitic parasitic antenna elements 47a to 47j are arranged corresponding to the radiating antenna elements 44a to 44j. The width of the parasitic antenna element groups 47a to 47j is, as shown in FIG.
The width is set to be the same as the width W of the corresponding radiating antenna elements 44a to 44j. Further, the length L ₀ of the parasitic antenna elements 47a to 47j
Is determined by adjusting in the range of 0.9L or more and 1.1L or less so that the return loss, which is the input characteristic of the array antenna, is minimized in a wide frequency band. Here, L is the length of the radiation antenna elements 44a to 44j corresponding to the respective parasitic antenna elements 47a to 47j.

The radiating antenna elements 44a to 44j and the corresponding parasitic antenna elements 44a to 47j are arranged so as to substantially overlap each other when viewed from above perpendicularly to the surfaces of the dielectric substrates 42 and 48. That is, in FIG.
The two surfaces and the 48 surface are parallel to each other, and the side indicated as the length L in the radiating antenna element 44 on the dielectric substrate 42 and the length L ₀ in the parasitic antenna element 47 on the dielectric substrate 48 surface. Are parallel to each other. Also,
The side of the radiating antenna element 44 on the surface of the dielectric substrate 42 indicated by the length W is parallel to the side of the parasitic antenna element 47 on the surface of the dielectric substrate 48 indicated by the length W. Further, each of the rectangular radiation antenna elements 44
A straight line connecting the center of each of the parasitic antenna elements 47 is substantially perpendicular to the surfaces of the dielectric substrates 42 and 48. The side of the length L ₀ of the parasitic antenna element 47 and the radiation antenna element 42
Although the length may be different from the side of length L, when the rectangle with the shorter side is translated in the direction perpendicular to the substrate surface, they are arranged so as to be included in the rectangle with the longer side. I have.

The power input from the input terminal 45 is sequentially coupled and radiated to the radiating antenna elements 44a, 44f, 44b,... Partially projecting, and the remaining power is transmitted in the traveling direction (FIG. 17). (Rightward), gradually attenuates, and the residual power reaches the termination 26. This operation is similar to that of the third embodiment.

By changing the width W of each radiating antenna element, the excitation amplitude (radiation amount) of each element can be changed.
, It is possible to make the directional characteristics required for the antenna, that is, the gain and side lobe levels, according to the purpose (specification). Also, the radiating antenna elements 44a to 44j are mainly
A direction at an angle of 45 degrees with respect to the feed strip line 43 (FIG. 1)
7 (in the direction of arrow E in FIG. 7) to radiate or receive radio waves having a polarization plane,
By using No. 3, an array antenna having a plane of polarization oriented obliquely at 45 degrees can be realized. In addition, since these characteristics can be obtained in a wide frequency band, when an antenna is mounted, there is little deterioration in characteristics due to peripheral objects, and the utility is high.

In the above two 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 propagating the feeding stripline. 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. The parasitic antenna element may be designed according to the corresponding radiating antenna element. According to the design, for example, the length L ₀ of the side, the gap g and the deviation L _g , the third and the fourth in the first and second embodiments are used. In the fourth embodiment, the length L ₀ and the distance h can be arbitrarily adjusted.

Alternatively, as shown in FIG. 19A, a matching terminating element 61 for absorbing residual power is provided at the end of the feed strip line, or as shown in FIG. For this purpose, a microstrip antenna element 62 or the like may be provided.

In the present invention, if the length of the parasitic antenna element and the length of the radiating antenna element match, it is possible to contribute to the enhancement of the radiated power. If the length of the parasitic antenna element and the length of the radiating antenna element are not made to coincide with each other, it is not necessary to keep the manufacturing accuracy unnecessarily high since the antenna has a wide frequency band. The rectangular shape connected at one apex angle refers to the radiation antenna element of FIG. 20A, and the radiation antenna element of FIG. In the case of the radiation antenna element of FIG. 20B, a rectangular parasitic antenna element having the size of FIG. 20C may be used.

[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 detailed view of a radiation antenna element and a parasitic antenna element of the microstrip array antenna according to the first embodiment.

FIG. 4 is a principle view showing the operation of the radiation antenna element of the microstrip array antenna according to the first embodiment.

FIG. 5 is a diagram illustrating a radiation amount of a radiation antenna element of the microstrip array antenna according to the first embodiment.

FIG. 6 is a diagram illustrating the return loss at the input end of the microstrip array antenna according to the first embodiment.

FIG. 7 is a perspective view showing a configuration of a microstrip array antenna according to a second embodiment of the present invention.

FIG. 8 is a plan view and a sectional view of a microstrip array antenna according to a second embodiment.

FIG. 9 is a detailed view of a radiation antenna element and a parasitic antenna element of the microstrip array antenna according to the second embodiment.

FIG. 10 is a perspective view showing a configuration of a microstrip array antenna according to a third embodiment of the present invention.

FIG. 11 is a plan view and a sectional view of a microstrip array antenna according to a third embodiment.

FIG. 12 is a detailed view of a radiation antenna element and a parasitic antenna element of the microstrip array antenna according to the third embodiment.

FIG. 13 is a principle view showing the operation of the radiation antenna element of the microstrip array antenna according to the third embodiment.

FIG. 14 is a diagram illustrating a radiation amount of a radiation antenna element of the microstrip array antenna according to the third embodiment.

FIG. 15 is a diagram illustrating the return loss at the input end of the microstrip array antenna according to the third embodiment.

FIG. 16 is a perspective view showing a configuration of a microstrip array antenna according to a fourth embodiment of the present invention.

FIG. 17 is a plan view and a sectional view of a microstrip array antenna according to a fourth embodiment.

FIG. 18 is a detailed view of a radiation antenna element and a parasitic antenna element of the microstrip array antenna according to the fourth embodiment.

FIG. 19 is a plan view showing a deformation at the end of the feed strip line.

FIG. 20 is a comparison diagram of a rectangular antenna element, a non-rectangular antenna element, and a parasitic antenna element connected at one apex angle;

FIG. 21 is a perspective view of a microstrip array antenna according to a conventional example.

FIG. 22 is a plan view of a microstrip array antenna according to another conventional example.

FIG. 23 is a plan view of a microstrip array antenna according to another conventional example.

FIG. 24 is a plan view of a microstrip array antenna according to another conventional example.

FIG. 25 is an explanatory diagram showing the operation principle of a microstrip array antenna according to a conventional example.

[Explanation of symbols]

10, 20, 30, 40 ... microstrip array antenna 11, 21, 31, 41 ... ground conductor layer (ground plate) 12, 22, 32, 38, 42, 48 ... dielectric substrate 13, 23, 33, 43 ... Feed strip lines 14a to 14j, 24a to 24j, 34a to 34j, 4
4a to 44j: radiation antenna elements 17a to 17j, 27a to 27j, 37a to 37j, 4
7a to 47j: parasitic antenna element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kunori Nishikawa 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Toshiaki Watanabe Toshiaki Watanabe Aichi-gun No. 41, Chochu-Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kazuo Sato 41, Nagakute-cho, Aichi-gun, Aichi Prefecture, Nagatsute-cho Yokomichi 41 Toyota Central Research Institute, Inc. F-term (reference) 5J021 AA05 AA09 AB06 CA01 HA04 HA10 JA02 5J045 AA02 DA09 EA07 FA02 HA02 NA07

Claims (10)

[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. A feed strip line disposed, a plurality of radiating antenna elements connected and arranged from a side of the feed strip line at predetermined intervals along at least one first side of both sides of the feed strip line; Each of the radiating antenna elements comprises a plurality of parasitic antenna elements which are adjacent to each other in parallel with a slight gap, and the radiating antenna element propagates through the feed strip line at a predetermined operating frequency in length. It is an integral multiple of approximately one-half of the wavelength and the width is related to the location of the excitation amplitude of each radiating antenna element that is preset to provide the desired directional characteristics. The parasitic antenna elements are each formed in a rectangular shape having substantially the same shape as the corresponding radiating antenna element, and the length thereof is equal to the length of the corresponding radiating antenna element. A microstrip array antenna having a width in a range from 0.9 times to 1.1 times the width thereof, the width being substantially the same as the width of the corresponding radiating antenna element. 2. The plurality of radiating antenna elements are connected and arranged from the first side such that an electric field radiation edge line forms an angle other than 0 degree (parallel) with a length direction of the feed strip line. The microstrip array antenna according to claim 1, wherein: 3. A first dielectric substrate having a ground plane of a conductor formed on a back surface thereof, a first strip conductor formed on the first dielectric substrate, and a portion above the first dielectric substrate. A second dielectric substrate placed in parallel with a certain gap
In the microstrip array antenna formed from the second strip conductor formed on the second dielectric substrate, the first strip conductor includes a feed strip line disposed linearly and the feed strip line. A plurality of radiating antenna elements connected and arranged from the side at predetermined intervals along at least one first side of both sides of the strip line, and the radiating antenna has a predetermined length. Distribution of the excitation amplitude of each radiating antenna element, which is an integral multiple of approximately 波長 of the wavelength propagating through the feed stripline at the operating frequency, and whose width is set in advance so as to provide a desired directional characteristic. A strip conductor having a corresponding width distribution, wherein the second strip conductor is formed of a plurality of radiating antenna elements on a first dielectric substrate. A plurality of parasitic antenna elements having a rectangular shape arranged in parallel directly above each other, wherein the parasitic antenna element has a rectangular shape of substantially the same shape as the corresponding radiating antenna element, and the length thereof is A microstrip array having a length between 0.9 and 1.1 times the length of the corresponding radiating antenna element, the width of which is approximately the same as the width of the corresponding radiating antenna element. antenna. 4. The plurality of radiating antenna elements are connected and arranged from the first side such that an electric field radiation edge line forms an angle other than 0 degree (parallel) with a length direction of the feed strip line. The microstrip array antenna according to claim 3, wherein: 5. The microstrip array antenna according to claim 2, wherein the electric field radiation edge line of the radiation antenna element forms an angle of about 45 degrees with the feed strip line. 6. The radiation antenna element according to claim 2, wherein the radiation antenna element has a rectangular shape different in length and width, and is connected to the feed strip line near one apex angle and the other end is open. The microstrip array antenna according to claim 4. 7. The microstrip array antenna according to claim 6, wherein a side forming an apex angle of the radiation antenna element connected to the feed strip line forms approximately 45 degrees with the feed strip line. . 8. The radiating antenna element includes a first radiating antenna element formed along a first side of the feed strip line, and is configured in the same manner as the first radiating antenna element. 8. The micro device according to claim 1, further comprising a second radiating antenna element formed along a second side, which is the other side of the feed strip line. 9. Strip array antenna. 9. The radiating antenna element includes: a direction of an electric field radiated by a first radiating antenna element formed along a first side of the feed strip line;
9. The electric field direction radiated by the second radiating antenna element formed along the side is substantially parallel.
2. The microstrip array antenna according to 1. 10. The method according to claim 1, wherein each of the second radiating antenna elements is arranged at a substantially middle point of an interval in which each of the first radiating antenna elements is arranged along the feed strip line. The microstrip array antenna according to claim 8.