JP7444657B2 - antenna device - Google Patents

Description

The present invention relates to an antenna device.

Conventionally, when a patch antenna operates, a surface current flows through the ground, and the surface current propagates to the edge of the substrate, causing radiation from the edge of the substrate, which causes a problem in that the directivity of the patch antenna is disturbed.

Therefore, the techniques disclosed in Patent Document 1 and Patent Document 2 involve (1) changing the polarization direction of the radiant energy received by the parasitic element and re-radiating it, and (2) using a resistive circuit or a lossy transmission line. By converting radiant energy into heat, disturbances in directivity are alleviated.

JP2014-168222A Japanese Patent Application Publication No. 2007-158707

By the way, the above-mentioned solution (1) has a problem in that the antenna that radiates the power received in the horizontally polarized wave in the vertically polarized wave receives the power in the vertically polarized wave.

Furthermore, the solution (2) has the problem that the number of components and transmission lines for converting electrical energy into thermal energy increases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an antenna device that makes it possible to easily suppress disturbances in the directional characteristics of a patch antenna.

In order to solve the above problems, the present invention provides an antenna device including at least one radiating element disposed on a dielectric substrate, an end portion of the dielectric substrate in the main polarization direction of the radiating element, and a a plurality of parasitic elements disposed between the radiating element, and the plurality of parasitic elements are disposed at mutually different positions in the main polarization direction so as to combine power generated by excitation. It is characterized in that it constitutes an electrically connected parasitic element unit.
According to such a configuration, it becomes possible to easily suppress disturbances in the directivity characteristics of the patch antenna.

Further, in the present invention, the parasitic element unit is configured to attenuate at least one of the power transmitted from the radiating element toward the end and the power transmitted from the end toward the radiating element. It is characterized by being configured.
According to such a configuration, disturbances in the directional characteristics can be easily suppressed.

Further, in the present invention, the parasitic element unit changes the phase of at least one of the power transmitted from the radiating element toward the end and the power transmitted from the end toward the radiating element. This is characterized in that the directivity characteristics of the radiation element are made to have predetermined characteristics.
According to such a configuration, the directivity characteristics can be set to desired characteristics.

Further, in the present invention, a plurality of patch elements as the radiating elements are arranged in parallel in a first direction, and the parasitic element unit has a plurality of patch elements arranged in parallel in a second direction substantially orthogonal to the first direction. The parasitic element unit is configured to be electrically connected, and a plurality of the parasitic element units are arranged in parallel in the first direction.
According to such a configuration, disturbances in the directional characteristics can be reliably suppressed.

Further, in the present invention, a plurality of patch elements as the radiating elements are arranged in parallel in a first direction different from the main polarization direction, and a plurality of the parasitic element units are arranged in parallel in the first direction, and the parasitic element units are electrically connected to each other. It is characterized by having the plurality of parasitic elements connected to.
According to such a configuration, disturbances in the directional characteristics can be reliably suppressed.

Further, in the present invention, the first direction is substantially orthogonal to the main polarization direction, and the center position in the first direction of a patch element group arranged in parallel in the first direction as the radiating element; The center position of the parasitic element group in the first direction of the feeding element unit arranged in parallel in the first direction is located on the same straight line in the main polarization direction.
According to such a configuration, the centers of the power distributions coincide, and disturbances in the directivity characteristics can be further suppressed.

Further, in the present invention, the parasitic element unit is arranged between the radiating element and one end of the dielectric substrate in the main polarization direction, and between the radiating element and the dielectric substrate in the main polarization direction. and the other end of the body substrate.
According to such a configuration, disturbances in the directional characteristics can be efficiently and reliably suppressed.

Further, the present invention is characterized in that the plurality of patch elements constituting the parasitic element unit are arranged at positions corresponding to peak positions of standing waves generated on the dielectric substrate, respectively. do.
According to such a configuration, disturbances in the directional characteristics can be efficiently and reliably suppressed based on the standing waves.

In addition, the present invention provides that the resonant frequency of a first parasitic element located relatively close to the radiation element in the main polarization direction among the plurality of parasitic elements is the radiation The resonant frequency is higher than the resonant frequency of the second parasitic element located relatively far from the element.
According to such a configuration, it is possible to improve the gain in wide-angle directions other than the front.

Further, the present invention is characterized in that the resonant frequency of the second parasitic element is configured to match the resonant frequency of the radiating element.
According to such a configuration, it is possible to improve the gain in wide-angle directions other than the front, while avoiding increasing the size of the antenna device.

Further, the present invention is characterized in that the power radiated from the first parasitic element is higher than the power radiated from the second parasitic element.
According to such a configuration, a directivity characteristic with high gain in the wide-angle direction can be realized.

Further, the present invention is characterized in that a width of the first parasitic element in the main polarization direction is narrower than a width of the second parasitic element in the main polarization direction.
According to such a configuration, directivity design with high gain in the wide-angle direction can be easily achieved by adjusting the width of the element.

A length of a microstrip line connecting the first parasitic element and the second parasitic element such that the phase difference between the first parasitic element and the second parasitic element is 45 degrees or more and 135 degrees or less. is set.
According to such a configuration, a directional characteristic having a high gain even in a wide-angle direction can be easily designed by adjusting the length of the microstrip line.

According to the present invention, it is possible to provide an antenna device that makes it possible to easily suppress disturbances in the directivity characteristics of a patch antenna.

1 is a diagram showing a configuration example of an antenna device according to a first embodiment of the present invention. 2 is a diagram showing a detailed configuration example of the parasitic element unit shown in FIG. 1. FIG. FIG. 3 is a diagram showing a simulation target for confirming the effects of the first embodiment. 7 is a graph showing changes in directional characteristics depending on the presence or absence of reflection at the edge of a substrate. 4 is a graph showing the simulation results of FIG. 3. It is a figure showing the example of composition of the antenna device concerning a 2nd embodiment of the present invention. It is a figure showing the example of composition of the antenna device concerning a 3rd embodiment of the present invention. It is a figure showing the example of composition of the antenna device concerning a 4th embodiment of the present invention. It is a figure which shows the modified embodiment of a parasitic element unit. It is a figure showing the positional relationship between a standing wave and a parasitic element unit. FIG. 7 is a diagram showing the arrangement relationship of antenna elements and parasitic element units that constitute an antenna device according to a fifth embodiment of the present invention. It is a figure explaining the microstrip line of a parasitic element unit. 12 is a graph showing the simulation results of FIG. 11 when the phase difference is 180 degrees. 12 is a graph showing the simulation results of FIG. 11 when the phase difference is 90 degrees. It is a graph showing the relationship between electric field difference and resonance frequency. It is a graph showing the relationship between the electric field difference and the length of the patch element in the Y direction.

Next, embodiments of the present invention will be described.

(A) Description of the configuration of the first embodiment FIG. 1 is a diagram showing an example of the configuration of an antenna device according to the first embodiment of the present invention. The antenna device is applied to, for example, a vehicle-mounted radar. In the configuration example shown in FIG. 1, the antenna device 1 includes a dielectric substrate 10, transmitting antennas 11-1 to 11-4, and parasitic element unit groups 30-1 to 30-2.

The dielectric substrate 10 is made of, for example, paper epoxy, fluororesin, glass composite, or glass epoxy, and has transmitting antennas 11-1 to 11-4 and , parasitic element unit groups 30-1 to 30-2 are formed, and a back conductor plate is formed on the back surface (the surface not shown in FIG. 1) that functions as a ground plate for transmitting antennas 11-1 to 11-4, etc. has been done. Although omitted in FIG. 1 to simplify the drawing, the transmitting antennas 11-1 to 11-4 and parasitic elements are also formed on the surface where the transmitting antennas 11-1 to 11-4, etc. are formed. A surface conductor plate is formed in an area other than the area where the unit groups 30-1 to 30-2 are formed.

Each of the transmitting antennas 11-1 to 11-4 is composed of six patch elements (radiating elements) connected by a microstrip line. Further, a power feeding section indicated by a black circle is provided near the center of each microstrip line. More specifically, the transmitting antenna 11-1 is configured by six patch elements arranged in parallel in the X direction of FIG. 1 and connected by a microstrip line. The same applies to transmitting antennas 11-2 to 11-4. Note that the configuration of the transmitting antennas 11-1 to 11-4 is merely an example, and it goes without saying that configurations other than those shown in FIG. 1 may be used.

The parasitic element unit group 30-1 is composed of six parasitic element units arranged side by side in the X direction of FIG. Here, the parasitic element unit is configured by two patch elements (parasitic elements) 31 and 32 connected by a microstrip line 33, as shown in an enlarged view in FIG. Note that the length L of the microstrip line 33 shown in FIG. 2 is calculated as L=λ/2+n×λ(n=0, 1, 2, 3...). Each parasitic element unit constituting the parasitic element unit group 30-2 has a similar configuration.

(B) Description of operation of first embodiment Next, operation of the first embodiment will be described. FIG. 3 is a diagram showing a simulation target for confirming the operation of the first embodiment. In the example of FIG. 3, a single patch element 111 as a transmitting antenna is arranged approximately at the center of the dielectric substrate 10. Furthermore, a parasitic element unit 130-1 is arranged between the patch element 111 and the left end of the dielectric substrate 10, and a parasitic element unit 130-1 is arranged between the patch element 111 and the right end of the dielectric substrate 10. -2 is placed. Note that the configurations of parasitic element units 130-1 and 130-2 are the same as in FIG. 2.

FIG. 4 is a diagram showing the directivity characteristics of patch element 111 shown in FIG. 3. Here, the horizontal axis in FIG. 4 indicates the angle (deg) centered on the patch element 111, and the vertical axis indicates the gain (dBi) of the patch element 111. In FIG. 4, the solid line indicates the directivity characteristics when there is no influence from the edge of the dielectric substrate 10, and the broken line indicates the directivity characteristic when there is influence from the edge of the dielectric substrate 10. . Note that, as an example of being affected by the edge of the board, there is a case where parasitic element units 130-1 and 130-2 are not arranged in FIG. 3, for example. In such a case, electric power is generated that is propagated from the patch element 111 through the substrate surface, reaches the edge of the substrate, and is then reflected toward the patch element 111, and radio waves are radiated into space from the edge of the substrate. Radio waves radiated from the transmitting antenna combine with these and affect the directivity characteristics. Furthermore, as an example of not being affected by re-radiation, there is a case where the dielectric substrate 10 in FIG. 3 has a very large size. In the case of such a large size, the electric power is attenuated before reaching the edge of the dielectric substrate 10, so that reflection and radiation from the edge of the substrate do not occur.

As shown in FIG. 4, the directivity characteristics are different when the case where the substrate is influenced by the edge of the substrate is compared with the case where it is not influenced by the edge of the substrate. That is, it can be seen that the reflection from the edge of the dielectric substrate 10 affects the directivity characteristics of the antenna.

FIG. 5 is a diagram for explaining the operation of parasitic element units 130-1 and 130-2 in FIG. 3. The solid line in FIG. 5 shows the directivity characteristics when affected by re-radiation from the edge of the dielectric substrate 10 (when the parasitic element units 130-1 and 130-2 are not arranged), and the broken line shows the parasitic It shows the directivity characteristics when reflection from the substrate edge is reduced by phase adjustment by the element units 130-1 and 130-2. When the parasitic element units 130-1 and 130-2 are arranged in this manner, the characteristics are close to those shown in FIG. 4 when there is no influence from the edge of the substrate (ideal characteristics).

In FIG. 5, the dashed-dotted line shows the case where the directivity characteristic is adjusted to have a peak at ±30deg by the setting of L shown in FIG. This shows the case where the characteristics were adjusted to have a peak at 0 degrees. In this way, in this embodiment, the directivity characteristics can be adjusted to desired characteristics depending on the settings of the parasitic element units 130-1 and 130-2.

Return to Figure 3. In FIG. 3, when a signal is supplied to patch element 111, power is propagated in the Y direction, which is the main polarization direction. At this time, if the parasitic element units 130-1 and 130-2 are not arranged, a part of the signal (travelling wave) transmitted from the patch element 111 is at the left and right ends of the dielectric substrate 10. The reflected wave is propagated toward the patch element 111 as a reflected wave, and the other part is radiated into space from the edge of the substrate. When influenced by such an edge of the substrate, the directivity characteristics change compared to a case where there is no influence from the edge of the substrate, as shown by the solid line in FIG. Note that the main polarization direction in the present invention refers to the main polarization direction of radio waves radiated from the radiating element, and in this embodiment, it is a direction substantially parallel to the Y axis.

On the other hand, in the case where parasitic element units 130-1 and 130-2 are arranged, the parasitic element units 130-1 and 130-2 are set to attenuate traveling waves (or reflected waves). In this case, the characteristics shown by the broken line in FIG. 5 (characteristics similar to the solid line shown in FIG. 4) are obtained. More specifically, a signal transmitted from patch element 111 toward the left side of the figure excites two patch elements that constitute parasitic element unit 130-1. The signals generated in the two patch elements by excitation are set to be combined via the microstrip line. The signal transmitted from the patch element 111 toward the left side of the figure is attenuated by the parasitic element unit 130-1, and the reflected wave is also attenuated by the parasitic element unit 130-1, so the dielectric The effects of reflection from the left side edge of the body substrate 10 and radiation from the edge of the substrate are reduced.

Similarly, the signal transmitted from the patch element 111 toward the right side of the figure is attenuated by the parasitic element unit 130-2, and the reflected wave is also attenuated by the parasitic element unit 130-2. Therefore, the effects of reflection from the right side edge of the dielectric substrate 10 and radiation from the edge of the substrate are reduced.

In addition, when signals generated in two patch elements due to excitation are combined via a microstrip line, for example, by setting them to have a predetermined phase, it is possible to avoid the effects of traveling waves and reflected waves, as described above. It is possible to have a peak at 30 deg as shown by the dashed line in FIG. 5, or to have a peak at 0 deg. Note that not only the phase but also the amplitude may be adjusted. For example, for two parasitic elements that make up a parasitic element unit, the position where each parasitic element is arranged and the width or length of the microstrip line connecting each parasitic element are changed. Good too.

Also in FIG. 1, which is the first embodiment, by the same operation as in FIG. 3, reflections at the ends of the dielectric substrate 10 are reduced, and changes in the directivity characteristics are suppressed. That is, the signals transmitted from the transmitting antennas 11-1 to 11-4 toward the left side of the figure excite the two patch elements of each parasitic element unit constituting the parasitic element unit group 30-1. The signals generated in the two patch elements by excitation are set to be combined via the microstrip line. The signals transmitted from the transmitting antennas 11-1 to 11-4 toward the left side of the figure are attenuated by the parasitic element unit group 30-1, and the reflected waves are similarly attenuated by the parasitic element unit group 30-1. Therefore, the effects of reflection from the left side edge of the dielectric substrate 10 and radiation from the edge of the substrate are reduced.

Similarly, the signals transmitted from the transmitting antennas 11-1 to 11-4 toward the right side of the figure are attenuated by the parasitic element unit group 30-2, and the reflected waves are similarly attenuated by the parasitic element unit group 30-2. 30-2, the effects of reflection from the right side edge of the dielectric substrate 10 and radiation from the edge of the substrate are reduced.

Through the above-described operation, reflection by the substrate edge of the dielectric substrate 10 and radiation from the substrate edge are reduced, thereby suppressing changes in the directivity characteristics of the transmitting antennas 11-1 to 11-4.

As explained above, in the first embodiment of the present invention, the parasitic element unit group 30-1 is arranged between the transmitting antennas 11-1 to 11-4 and the left end of the dielectric substrate 10, and the A parasitic element unit group 30-2 is arranged between the antennas 11-1 to 11-4 and the right end of the dielectric substrate 10. Then, the signals generated by excitation are combined with the patch elements that make up each parasitic element unit via the microstrip line, thereby attenuating the signal propagating to the edge of the substrate, causing reflections at the edge of the substrate, and , the influence of radiation from the edge of the substrate can be reduced.

In addition, by setting the patch element so that the signal generated by excitation has a predetermined phase characteristic when it is synthesized via the microstrip line, it is possible to In addition, the directional characteristics can be adjusted arbitrarily.

Furthermore, in the first embodiment, the directivity characteristics are adjusted using patch elements. Since the patch element is formed by etching when producing the dielectric substrate 10, for example, compared to the conventional technology in which heat energy is converted using a resistance element or the like, It can be configured without using any extra parts.

(C) Description of configuration of second embodiment Next, a second embodiment of the present invention will be described. FIG. 6 is a diagram showing a configuration example of the second embodiment of the present invention. Note that in FIG. 6, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted. In FIG. 6, compared to FIG. 1, the parasitic element unit group 30-1 is replaced with a parasitic element unit group 30-3, which has two fewer parasitic element units, and the parasitic element unit group 30- 2 is replaced with a parasitic element unit group 30-4 having two fewer parasitic element units. The configuration other than these is the same as in FIG. 1.

(D) Description of the operation of the second embodiment The operation of the second embodiment is basically the same as that of the first embodiment shown in FIG. However, in the second embodiment, parasitic elements are placed at positions corresponding to four patch elements arranged in the X direction, two at the top and two at the top and two near the feeding point located at the center of the array of transmitting antennas 11-1 to 11-4. A total of four units are arranged in the X direction, two each on the top and bottom. The amplitude of the traveling waves generated from the transmitting antennas 11-1 to 11-4 is larger as it approaches the feeding point, so by arranging the parasitic element unit for the portion where the amplitude is large, the traveling waves and reflected waves can be efficiently processed. Attenuation can be achieved and the number of parasitic element units can be reduced.

(E) Description of configuration of third embodiment Next, a third embodiment of the present invention will be described. FIG. 7 is a diagram showing a configuration example of the third embodiment of the present invention. Note that in FIG. 7, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and explanations thereof will be omitted. In FIG. 7, compared to FIG. 1, the parasitic element unit group 30-1 is replaced with a parasitic element unit group 30-5, which has two more parasitic element units, and the parasitic element unit group 30- 2 is replaced with a parasitic element unit group 30-6 having two more parasitic element units. The configuration other than these is the same as in FIG. 1.

(F) Description of the operation of the third embodiment The operation of the third embodiment is basically the same as that of the first embodiment shown in FIG. However, in the third embodiment, the traveling waves generated from the upper and lower ends of the transmitting antennas 11-1 to 11-4 pass through the upper and lower ends of the dielectric substrate 10 to the left and right substrates of the dielectric substrate 10. may reach the edges, resulting in reflected waves and radiation from the substrate edges. In the third embodiment, the traveling waves generated from the upper and lower ends of the transmitting antennas 11-1 to 11-4 are attenuated by the parasitic element unit located at a higher (or lower) position. Compared to the first embodiment, changes in directional characteristics can be further reduced.

(G) Description of configuration of fourth embodiment Next, a fourth embodiment of the present invention will be described. FIG. 8 is a diagram showing a configuration example of the fourth embodiment of the present invention. Note that in FIG. 8, parts corresponding to those in FIG. 6 are designated by the same reference numerals, and the explanation thereof will be omitted. In FIG. 8, when compared with FIG. 6, the parasitic element unit group 30-3 is replaced with the parasitic element unit group 30-7, and the parasitic element unit group 30-4 is replaced with the parasitic element unit group 30-8. has been replaced by The configuration other than these is the same as that in FIG. 6.

In the parasitic element unit group 30-7, four patch elements arranged in parallel in the X direction are arranged in two rows in the Y direction, and the four patch elements constituting each row are interconnected by microstrip lines extending in the X direction. It is connected to the. In addition, the two microstrip lines extending in the X direction are electrically connected by microstrip lines each having a convex portion (having a crank shape) in the vertical direction, and are wider than the two microstrip lines extending in the X direction. is getting thicker. Note that the parasitic element unit group 30-8 also has the same configuration as the parasitic element unit group 30-7.

Here, the straight line length GL1 in the X direction connecting the upper side 112 of the patch element 111-1 located at the uppermost side of the transmitting antenna 11-1 and the lower side 113 of the patch element 111-2 located at the lowermost side An array center position 122 is set in the middle. Similarly, the upper side 331 of the patch element (parasitic element) 31-1 located at the uppermost side of the parasitic element unit group 30-7 and the lower side of the patch element (parasitic element) 31-1 located at the lowermost side. The array center position 132 is defined as the middle of the straight line length GL2 in the X direction that connects the array center position GL2. The array center position 122 of the transmitting antenna 11-1 and the array center position 132 of the parasitic element unit group 30-7 are both located on the same virtual straight line IL extending in the Y direction. That is, in the fourth embodiment, the array center positions 122 of the transmitting antennas 11-1 to 11-4 in the X direction and the array center positions 132 of the parasitic element unit groups 30-7 to 30-8 in the X direction are They are lined up in the Y direction.

(H) Description of the operation of the fourth embodiment The operation of the fourth embodiment is basically the same as that of the first embodiment shown in FIG. However, in the fourth embodiment, by using parasitic element unit groups 30-7 and 30-8 having the same shape as the transmitting antennas 11-1 to 11-4, the transmitting antennas 11-1 to 11-4 Similar characteristics make it possible to attenuate traveling waves more efficiently. Therefore, changes in directional characteristics can be further reduced compared to the first embodiment. In addition, by using microstrip lines each having a convex portion in the vertical direction, it is possible to electrically connect the parasitic elements arranged in the Y-axis direction that constitute the parasitic element unit group, and to connect these parasitic elements to each other. The length of the power supply line can be efficiently adjusted in the gap between the power supply elements, and space can be saved.

Furthermore, array center positions 122 in the X direction of transmitting antennas 11-1 to 11-4 (patch elements 111 group) arranged in parallel in the X direction (first direction) orthogonal to the main polarization direction as radiating elements, and Array center positions 132 in the X direction of the feeding element unit groups 30-7 to 30-8 (patch elements (parasitic elements) 31) are located on the same straight line IL in the main polarization direction. That is, the center positions of the transmitting antennas 11-1 to 11-4, which are arranged in an array and have a high power distribution, match the center positions of the parasitic element unit groups 30-7 to 30-8, which are also arranged in an array. In this case, antennas with the same directivity are lined up, and disturbances in directivity can be further suppressed.

In the example of FIG. 8, the number of patch elements arranged in the X direction is 6 for the transmitting antennas 11-1 to 11-4 and 4 for the parasitic element unit groups 30-7 and 30-8. , the number may be other than this. For example, there may be eight transmitting antennas 11-1 to 11-4 and six parasitic element unit groups 30-7 and 30-8.

Even when changing the number of patch elements arranged in the X direction in the example of FIG. 8, the array center position in the X direction of transmitting antennas 11-1 to 11-4 and It is preferable that the array center position in the X direction coincides with the array center position in the Y direction.

(I) Description of Modified Embodiments The above embodiments are merely examples, and it goes without saying that the present invention is not limited to only the above-described cases. For example, in each of the above embodiments, a parasitic element unit having two patch elements is used, but for example, three patch elements 51 to 53 shown in FIG. An element unit may also be used. In the example shown in FIG. 9, the signals excited in the patch elements 51 to 53 can be synthesized with a phase difference of, for example, 120 degrees using a microstrip line. Of course, it is also possible to have a phase difference other than this. Further, in the example of FIG. 9, patch elements 51 to 53 are arranged at equal intervals, but they may be arranged at different intervals.

Further, although the above embodiments do not mention the relationship with standing waves, for example, as shown in FIG. 10, when standing waves occur in the dielectric substrate 10, The arrangement position of the parasitic element unit group may be determined based on the positional relationship. More specifically, by arranging the patch elements that make up the parasitic element unit so that the peaks (the peaks and valleys) of the standing waves are located, the standing waves can be efficiently attenuated. be able to.

(J) Description of the configuration of the fifth embodiment Next, with reference to FIG. 11, it will be explained that among the plurality of patch elements (parasitic elements) constituting the parasitic element unit, the resonant frequency of at least one patch element is A fifth embodiment in which the resonance frequency of the element is different will be described. FIG. 11 is a diagram showing the arrangement relationship of the antenna element 121 and the parasitic element unit 140 that constitute the antenna device according to the fifth embodiment of the present invention. Note that FIG. 11 shows a simulation target similar to that in FIG. 3, and the antenna device of the fifth embodiment applies the arrangement relationship shown in FIG. 11 to the antenna device as shown in FIG.

As shown in FIG. 11, each of the parasitic element units 140-1 to 140-2 includes two patch elements (parasitic elements) 61 and 62. In the fifth embodiment, the resonant frequency of the patch element 61 disposed relatively close to the antenna element 121 in the Y direction is higher than the resonant frequency of the antenna element 121. If the resonance frequencies of patch elements 61 and 62 are made different, the relationship between the amount of re-radiation of patch elements 61 and 62 will change. Note that, in this example, the resonant frequency of the patch element 62 arranged at a position relatively far from the antenna element 121 in the Y direction is configured to match the resonant frequency of the antenna element 121. Note that matching here is not limited to completely the same numerical values, and an error of ± is allowed.

The resonant frequency is determined based on the dielectric constant of the dielectric substrate 10, the thickness of the dielectric substrate 10, and the width of the element in the Y direction. That is, if the configuration of the dielectric substrate 10 is the same, the resonant frequency will be determined based on the width of the patch element. The length of the patch element 61 in the Y direction is defined as a width d1, and the length of the patch element 62 in the Y direction is defined as a width d2. As the width d1 becomes smaller, the resonant frequency becomes higher. The width d1 of the patch element 61 is set narrower than the width d2 of the patch element 61, and the resonant frequency of the patch element 61 is higher than the resonant frequency of the patch element 62. Note that the width d2 of the patch element 62 is the same as the length of the antenna element 121.

FIG. 12 is a diagram illustrating the microstrip line 63 of the parasitic element unit 140. The microstrip line 63 shown in FIG. 12 connects the inside of the notch 611 formed on the left side 610 of the patch element 61 and the inside of the notch 621 formed on the left side 620 of the patch element 62. There is.

In this embodiment, the phase is adjusted by adjusting the length ML of the line passing through the center of the microstrip line 63, shown by the two-dot chain line in FIG. The starting end position of the length ML of the microstrip line 63 in FIG. Located on an extended straight line. The length ML of the microstrip line 63 is an integral multiple of the wavelength λ. For example, if the length ML of the microstrip line 63 is increased by a quarter wavelength of the wavelength λ, the phase difference becomes 90 degrees, and the wavelength λ When extended by half a wavelength, the phase difference becomes 180 degrees.

(K) Description of operation of fifth embodiment Next, in the antenna element 121 and the parasitic element unit 140, the phase difference is adjusted by the length ML of the microstrip line 63, and the width d1 of the patch element 61 in the Y direction is adjusted. A simulation result showing the relationship between the gain and the angle when changing the angle will be described with reference to FIG.

FIG. 13 is a graph showing the simulation results of FIG. 11 when the phase difference is 180 degrees. This simulation is performed under the condition that the antenna element 121 oscillates at a resonant frequency of 24 GHz. In the graph of FIG. 13, cases in which the width d1 of the patch element 61 in the Y direction is 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm are indicated by different line types. has been done. Note that the width d2 in the Y direction of the patch element 62 constituting the same parasitic element unit 140 is 3 mm. That is, a line with a width d1 of 3 mm is the simulation result when the resonant frequencies of the patch elements 61 and 62 are the same. The lines where d1 is 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm are the simulation results when the patch elements 61 and 62 have different resonance frequencies. As can be seen from the graph of FIG. 13, it can be seen that the wide-angle gain tends to be higher when the resonance frequencies are different than when the resonance frequencies are the same. In particular, in the example of FIG. 13, it can be seen that the gain increases significantly at azimuth angles of +25 degrees and -25 degrees.

FIG. 14 is a graph showing the simulation results of FIG. 11 when the phase difference is 90 degrees. Also in the graph of FIG. 14, when the width d1 of the patch element 61 in the Y direction is 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm, different line types are used. It is shown. The width d2 of the patch element 62 in the Y direction is also 3 mm. The graph of FIG. 14 also shows that the wide-angle gain tends to be larger when the resonance frequencies are different than when the resonance frequencies are the same. In the example of FIG. 14, it can be seen that the gain is high in the azimuth ranges of +45 degrees to +60 degrees and -45 degrees to -60 degrees. Further, when the width d1 of the patch element 61 in the Y direction is 2.8 mm or 2.6 mm, the gain is high over the entire wide angle range.

In the fifth embodiment, among the plurality of patch elements (parasitic elements) 61 and 62, the patch element (first parasitic element) located relatively close to the antenna element 121, which is the radiating element, in the main polarization direction. The resonant frequency of the patch element 61 is higher than the resonant frequency of the patch element (second parasitic element) 62 located relatively away from the antenna element 121 in the Y direction (main polarization direction). The results of the graphs in FIGS. 13 and 14 also show that by adopting this configuration, the gain in wide-angle directions other than the front can be improved.

Further, in the fifth embodiment, the width d1 of the patch element (first parasitic element) 61 in the Y direction (main polarization direction) is wider than the width d2 of the patch element (second parasitic element) 62 in the Y direction. It is narrowly structured. Thereby, by adjusting the width d1 of the patch element 61 and the width d2 of the patch element 62, a directivity design with high gain in the wide-angle direction can be easily achieved.

Further, in the fifth embodiment, the patch element 61 and the patch element 62 are arranged such that the phase difference between the patch element (first parasitic element) 61 and the patch element (second parasitic element) 62 is 45 degrees or more and 135 degrees or less. It is preferable that the length ML of the microstrip line 63 connecting the microstrip lines 62 is set. Thereby, a directional characteristic having a high gain even in the wide-angle direction can be easily designed by adjusting the length of the microstrip line. That is, the angle of the peak in the wide-angle direction can be adjusted by the length ML of the microstrip line 63.

In particular, on-vehicle radars placed at the left and right rear ends of the vehicle are required to have high gains in the azimuth ranges of +45 degrees to +60 degrees and -45 degrees to -60 degrees. According to the configuration of the fifth embodiment, by setting the length ML of the microstrip line 63, it is possible to realize an antenna device suitable for a vehicle-mounted radar that has a high gain in the azimuth range.

Further, in the fifth embodiment, the resonant frequency of the patch element (second parasitic element) 62 is configured to match the resonant frequency of the antenna element (radiating element) 121. Thereby, it is possible to improve the gain in wide-angle directions other than the front, while avoiding increasing the size of the antenna device.

Next, a method of setting the resonant frequency in a more preferable range based on the directivity of the antenna device and the relationship between the power re-radiated from each of the patch elements 61 and 62 that constitute the parasitic element unit 140. I will explain about it. FIG. 15 is a graph showing the relationship between electric field difference and resonance frequency. The vertical axis of the graph in FIG. 15 is the electric field difference obtained by subtracting the power radiated from the patch element 62 relatively far from the antenna element 121 from the power radiated from the patch element 61 relatively close to the antenna element 121. . The horizontal axis of the graph in FIG. 15 is the ratio (f2/f1) between the resonant frequency of patch element 61 and the resonant frequency of patch element 62. The resonant frequency f1 is the resonant frequency of the patch element 61, and the resonant frequency f2 is the resonant frequency of the patch element 62.

In the graph of FIG. 15, six points are plotted of the resonance frequency ratio (f2/f1) when the width d1 of the patch element 61 in the Y direction is changed in the simulation results shown in FIG. That is, the leftmost plot in the graph of FIG. 15 is the electric field difference when the resonance frequency ratio (f2/f1) where the resonance frequency of the patch element 61 and the resonance frequency of the patch element 62 match is 1. Similarly, from the left, the respective resonance frequency ratios (f2/f1) when the width d1 of the patch element 61 in the Y direction is 2.8 mm, 2.6 mm, 2.4 mm, 2.2 mm, and 2.0 mm. The electric field difference with respect to is plotted.

As mentioned above, in the graph of FIG. 14, the simulation results show that the gain is higher in the wide-angle range when the width d1 of the patch element 61 in the Y direction is 2.8 mm and 2.6 mm than in other cases. . Applying this result to FIG. 15, by setting the resonance frequency of each of the patch elements 61 and 62 so that the electric field difference is 0 or more, it is possible to achieve higher performance with a higher gain over a wide angle range for the antenna device. It can be seen that a good antenna device can be realized.

In FIG. 15, description has been made based on the relationship between the resonance frequencies of the patch element 61 and the patch element 62 that constitute the parasitic element unit 140. As described above, the resonant frequency of the patch element 61 can be adjusted based on the width d1 of the patch element 61 in the Y direction, and the resonant frequency of the patch element 62 can be adjusted based on the width d2 of the patch element 62 in the Y direction. Can be adjusted.

Next, the relationship between the electric field difference and the length of the patch element in the Y direction will be described with reference to FIG. FIG. 16 is a graph showing the relationship between the electric field difference and the widths d1 and d2 of the patch elements 61 and 62 in the Y direction. Similar to FIG. 15, the vertical axis of the graph in FIG. 16 indicates the power radiated from the patch element 61 relatively close to the antenna element 121 to the power radiated from the patch element 62 relatively far from the antenna element 121. This is the subtracted electric field difference. The horizontal axis is the ratio (d2/d1) of the width d1 of the patch element 61 in the Y direction to the width d2 of the patch element 62 in the Y direction.

The graph in FIG. 16 shows the width ratio ( d2/d1) is shown. In the graph of FIG. 16, the order is reverse to the horizontal axis of the graph of FIG. The leftmost plot is the electric field difference corresponding to the width ratio (d2/d1) when the width d1 of the patch element 61 in the Y direction is 2.0 mm. Similarly, from the left, the respective width ratios (d2/d1) when the width d1 of the patch element 61 in the Y direction corresponds to 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm. The electric field difference corresponding to is plotted.

From the results of the graph in FIG. 16, it can be seen that by setting the width d1 in the direction of patch element 61 and the width d2 in the Y direction of patch element 62 so that the electric field difference is 0 or more, a wide angle range can be achieved for the antenna device. It can be seen that an antenna device with higher gain and better performance can be realized. That is, in the configuration of the fifth embodiment, by configuring the power radiated from the patch element (first parasitic element) 61 to be higher than the power radiated from the patch element (second parasitic element) 62, It is possible to design an antenna device that has directivity with high gain over a wide angle range.

In the fifth embodiment described above, a parasitic element unit in which three patch elements are connected by a microstrip line may be used as shown in FIG. The arrangement position of the parasitic element unit group may be determined based on the positional relationship with the wave.

In the fifth embodiment described above, an example has been shown in which the resonant frequency of the patch element 62 is configured to match the resonant frequency of the antenna element 121, but the resonant frequency of the patch element 61 is The resonant frequency of the patch element 61 may be configured to match the resonant frequency, and the resonant frequency of the patch element 61 may be higher than the resonant frequency of the patch element 62. However, it is preferable to configure the patch element 62 so that its resonant frequency matches the resonant frequency of the antenna element 121 from the viewpoint of downsizing the antenna device 1.

Although the first to fifth embodiments and modified embodiments have been described above, this configuration can be further modified. For example, in each of the above embodiments, there are four transmitting antennas and two parasitic element unit groups, but a combination of numbers other than four and two may be used.

Further, in each of the above embodiments, parasitic element units having the same characteristics are arranged, but for example, parasitic element units having different characteristics may be arranged. For example, in the first embodiment shown in FIG. 1, the characteristics of the parasitic element units constituting the parasitic element unit groups 30-1 and 30-2 are changed between units close to the feeding point and units far from the feeding point. It's okay.

Further, in each of the above embodiments, patch elements having a rectangular shape are used, but patch elements having other shapes may also be used.

Further, in each of the embodiments described above, the parasitic element unit may be grounded to the ground (the ground plane of the transmitting antennas 11-1 to 11-4, etc.).

Further, in each of the above embodiments, the explanation has been given using a transmitting antenna as an example, but the present invention may be applied to a receiving antenna. That is, the present invention can be similarly applied even if some or all of 11-1 to 11 to 4 are receiving antennas.

1 Antenna device 10 Dielectric substrate 11-1 to 11-4 Transmitting antenna 30-1 to 30-8 Parasitic element unit group 33 Microstrip line 51 to 53 Patch element 54 Microstrip line 61 to 62 Patch element 63 Microstrip line 111 Patch element 121 Patch element 130-1 to 130-2 Parasitic element unit 140-1 to 140-2 Parasitic element unit

Claims (12)

In the antenna device,
at least one radiating element disposed on a dielectric substrate;
an end of the dielectric substrate in the main polarization direction of the radiating element, and a plurality of parasitic elements arranged between the radiating element,
The plurality of parasitic elements constitute a parasitic element unit that is arranged at different positions in the main polarization direction and electrically connected to combine power generated by excitation ,
The plurality of parasitic elements constituting the parasitic element unit are arranged at positions corresponding to peak positions of standing waves generated on the dielectric substrate, respectively.
An antenna device characterized by: The parasitic element unit is configured to attenuate at least one of the power transmitted from the radiating element toward the end and the power transmitted from the end toward the radiating element. The antenna device according to claim 1. The parasitic element unit changes the phase of at least one of the power transmitted from the radiating element toward the end and the power transmitted from the end toward the radiating element. 2. The antenna device according to claim 1, wherein the directional characteristics of the antenna are set to be predetermined characteristics. A plurality of patch elements as the radiating elements are arranged in parallel in a first direction,
The parasitic element unit is configured such that the plurality of parasitic elements are arranged in parallel and electrically connected in a second direction substantially perpendicular to the first direction, and the parasitic element unit is arranged in a second direction substantially orthogonal to the first direction. Multiple juxtaposed
The antenna device according to any one of claims 1 to 3, characterized in that: A plurality of patch elements as the radiating elements are arranged in parallel in a first direction different from the main polarization direction,
The parasitic element unit includes the plurality of parasitic elements arranged in parallel in the first direction and electrically connected to each other.
The antenna device according to any one of claims 1 to 3, characterized in that: The first direction is substantially orthogonal to the main polarization direction,
a center position in the first direction of a patch element group arranged in parallel in the first direction as the radiating element; and a center position in the first direction of a parasitic element group arranged in parallel in the first direction of the parasitic element unit. The antenna device according to claim 5, wherein the center position and the center position are located on the same straight line in the main polarization direction. The parasitic element unit is arranged between the radiating element and one end of the dielectric substrate in the main polarization direction, and between the radiating element and one end of the dielectric substrate in the main polarization direction. The antenna device according to any one of claims 4 to 6, wherein the antenna device is arranged between the antenna device and the other. Among the plurality of parasitic elements, the resonant frequency of a first parasitic element located relatively close to the radiating element in the main polarization direction is relatively far from the radiating element in the main polarization direction. 8. The antenna device according to claim 1 , wherein the resonant frequency of the second parasitic element is higher than the resonant frequency of the second parasitic element located at the opposite position. 9. The antenna device according to claim 8 , wherein the resonant frequency of the second parasitic element is configured to match the resonant frequency of the radiating element. The antenna device according to claim 8 or 9 , wherein the power radiated from the first parasitic element is higher than the power radiated from the second parasitic element. The antenna device according to any one of claims 8 to 10 , wherein a width of the first parasitic element in the main polarization direction is narrower than a width of the second parasitic element in the main polarization direction. A length of a microstrip line connecting the first parasitic element and the second parasitic element such that the phase difference between the first parasitic element and the second parasitic element is 45 degrees or more and 135 degrees or less. The antenna device according to any one of claims 8 to 11 , wherein the antenna device is set.

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