JP2023048591A - Antenna device, and radio wave reception method by the same - Google Patents

Abstract

To provide an antenna device capable of reducing a second peak and detecting an arrival azimuth of radio waves with accuracy, and to provide a radio wave reception method by the same.SOLUTION: An antenna device 1 comprises: a first antenna element A1 configured to receive at least circularly-polarized waves; and a plurality of second antenna elements A2 configured to receive at least circularly-polarized waves, being arranged in a ring shape so as to surround the first antenna element A1.SELECTED DRAWING: Figure 2

Description

The present invention relates to an antenna device and a radio wave reception method using the antenna device.

Japanese Patent Laid-Open No. 2004-100002 discloses a direction detection device that detects the direction of arrival of radio waves.

Japanese Patent Application Laid-Open No. 2003-232842

It is not limited to detecting the direction of arrival of radio waves using the methods disclosed in the related art, and it is continuously demanded to detect the direction of arrival of radio waves with high accuracy.

One object of the present disclosure is to provide an antenna device and a radio wave reception method using the antenna device that solve the above-described problems.

According to one embodiment, the antenna device includes a first antenna element configured to be able to receive at least circularly polarized waves, and a ring-shaped arrangement surrounding the first antenna element to receive at least circularly polarized waves. and a plurality of possibly configured second antenna elements.

According to one embodiment, a radio wave reception method using an antenna device includes: a first antenna element configured to receive at least circularly polarized waves; A plurality of second antenna elements configured to receive polarized waves receive radio waves, and based on the phase difference between a plurality of received signals of each of the first antenna element and the plurality of second antenna elements, The direction of arrival of the radio wave is detected.

According to the embodiment, it is possible to provide an antenna device and a radio wave reception method using the antenna device that can detect the direction of arrival of radio waves with high accuracy by reducing the second peak.

1 is a block diagram showing a configuration example of an antenna device according to a first embodiment; FIG. 2 is a schematic diagram showing the periphery of an antenna element of the antenna device according to the first embodiment; FIG. FIG. 4 is a diagram for explaining detection of an arrival direction of radio waves by the antenna device according to the first embodiment; FIG. 10 is a schematic diagram showing the result of simulating the influence of the presence or absence of an antenna element in the central portion on the evaluation function; FIG. 10 is a schematic diagram showing the result of simulating the effect on the evaluation function due to the difference in opening diameter of a ring formed by a plurality of antenna elements; FIG. 4 is a schematic diagram showing the periphery of an antenna element of a first modified example of the antenna device according to the first embodiment; FIG. 5 is a schematic diagram showing the periphery of an antenna element of a second modification of the antenna device according to the first embodiment; FIG. 10 is a schematic diagram showing the result of simulating the effect on the evaluation function due to the difference in the number of antenna elements arranged in a ring. FIG. 9 is a schematic diagram showing the periphery of an antenna element of a third modification of the antenna device according to the first embodiment;

Hereinafter, embodiments will be described with reference to the drawings. Since the drawings are simplified, the technical scope of the embodiments should not be narrowly interpreted based on the description of the drawings. Also, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

For the sake of convenience, the following embodiments will be divided into a plurality of sections or embodiments when necessary. However, unless otherwise specified, they are not unrelated to each other, and one is a part or all of the other in terms of modified examples, application examples, detailed explanations, supplementary explanations, and the like. In addition, in the following embodiments, when referring to the number of elements (including the number, numerical value, amount, range, etc.), when it is particularly specified, when it is clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

Furthermore, in the following embodiments, the constituent elements (including operation steps and the like) are not necessarily essential, unless otherwise specified or clearly considered essential in principle. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., unless otherwise specified or in principle clearly considered otherwise, the shape is substantially the same. It shall include things that are similar or similar to, etc. This also applies to the above numbers and the like (including numbers, numerical values, amounts, ranges, etc.).

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration example of an antenna device (antenna device) 1 according to the first embodiment. As shown in FIG. 1, the antenna device 1 includes an antenna element (first antenna element) A1, antenna elements (second antenna elements) A2_1 to A2_n, a receiver 21, receivers 22_1 to 22_n, signal processing a unit 100; Note that n is an arbitrary integer of 2 or more. In this embodiment, a case where n=7 will be described as an example. Moreover, the signal processing unit 100 includes at least a direction detection unit 101 .

Antenna elements A1, A2_1 to A2_7 receive radio waves from the outside of antenna device 1, respectively. A signal received by the antenna element A1 is amplified and frequency-converted by the receiver 21, and then converted into a digital signal. A plurality of signals received by each of the antenna elements A2_1 to A2_7 are amplified and frequency-converted by the receivers 22_1 to 22_7, respectively, and then converted into digital signals.

The signal processing unit 100 performs predetermined signal processing on a plurality of output signals output from each of the receivers 21, 22_1 to 22_7 (in other words, a plurality of signals received by each of the antenna elements A1, A2_1 to A2_7). conduct. Here, the azimuth detection section 101 provided in the signal processing section 100 detects the direction of arrival of radio waves based on the phase differences of the signals received by the antenna elements A1 and A2_1 to A2_7.

FIG. 2 is a schematic diagram showing the vicinity of the antenna element of the antenna device 1. As shown in FIG.
As shown in FIG. 2, the antenna element A1 is arranged in the central portion of the antenna arrangement area of the base (fixing portion) 11. As shown in FIG. The antenna elements A2_1 to A2_7 are arranged in a ring to surround the antenna element A1. Also, the antenna elements A1, A2_1 to A2_7 are arranged so that their central axes are parallel to each other.

All of the antenna elements A1, A2_1 to A2_7 are configured to be able to receive radio waves over a wide band and have relatively stable gains. Further, each of the antenna elements A1, A2_1 to A2_7 is configured to be able to receive circularly polarized waves. As a result, it is possible to detect the azimuth direction (horizontal direction) and elevation direction (height direction) of the radio wave. For example, each antenna element A1, A2_1 to A2_7 is a spiral antenna, a patch antenna, or the like.

In the present embodiment, the antenna elements A1, A2_1 to A2_7 are all spiral antennas of the same size. good. Further, for example, the antenna element A1 and the antenna elements A2_1 to A2_7 may have different sizes.

FIG. 3 is a diagram for explaining how the antenna device 1 detects the direction of arrival of radio waves. In the antenna device 1, the receivers 21, 22_1 to 22_7 and the azimuth detection unit 101 constitute, for example, a multi-channel digital oscilloscope or the like, and the azimuth showing the highest value (peak) as the evaluation function is taken as the arrival azimuth of radio waves. presume. In the example of FIG. 3, an azimuth angle of −15 degrees and an elevation angle of 30 degrees are detected as the direction of arrival of radio waves.

Here, the evaluation function is a function used in a high-resolution direction-of-arrival estimation technique typified by, for example, the MUSIC (Multiple Signal Classification) method, and exhibits a sharp peak in the direction from which radio waves arrive.

Since the evaluation function depends on the position of the antenna element and the direction of arrival of the radio wave, depending on the position of the antenna element and the direction of arrival of the radio wave, a different peak from the main peak (second peak ). If the second peak is larger than the main peak, the direction indicating the second peak is incorrectly estimated as the direction of arrival of radio waves. Therefore, it is important to improve the detection accuracy of the direction of arrival of radio waves by reducing the second peak. is.

Normally, when the direction of arrival of radio waves is detected using an antenna device having a plurality of antenna elements arranged in a ring shape, the opening diameter of the ring formed by the plurality of antenna elements (specifically, , and the diameter of a circle passing through the centers of the plurality of antenna elements) to be less than or equal to half the wavelength of radio waves, it is possible to suppress the second peak. However, when a relatively large antenna element such as a spiral antenna for receiving circularly polarized waves is used for each of the plurality of antenna elements arranged in a ring, the shape formed by the plurality of antenna elements It is difficult to adjust the aperture diameter of the ring to less than half the wavelength of radio waves.

Therefore, in the present embodiment, by further arranging the antenna element A1 in the central portion of the plurality of antenna elements A2_1 to A2_7 arranged in a ring shape, the opening diameter of the ring formed by the antenna elements A2_1 to A2_7 is is larger than half the wavelength of the radio wave, the second peak is suppressed.

FIG. 4 is a schematic diagram showing the result of simulating the influence of the presence or absence of the central antenna element on the evaluation function. As shown in FIG. 4, when seven antenna elements A2_1 to A2_7 are arranged in a ring shape and the antenna element A1 is arranged in the center (solid line), the antenna element A1 is arranged in the center. It can be seen that the second peak of the evaluation function is relatively smaller than the main peak, compared to the case without it (broken line). Although not shown, when the seven antenna elements A2_1 to A2_7 are arranged in a ring shape and the antenna element A1 is arranged in the center, the eight antenna elements A2_1 to A2_8 are arranged in a ring shape. The second peak of the evaluation function is relatively smaller than the main peak even when compared with the case where the antenna element A2 is arranged and the antenna element A2 is not arranged in the central portion.

As described above, the antenna device 1 according to the present embodiment includes the antenna element A1 and the antenna elements A2_1 to A2_7 arranged in a ring so as to surround the antenna element A1. Thereby, the antenna device 1 according to the present embodiment can accurately detect the direction of arrival of radio waves over a wide band.

In general, the second peak tends to decrease as the number of antenna elements increases, and tends to decrease as the opening diameter of the ring formed by the plurality of antenna elements decreases.

FIG. 5 is a schematic diagram showing the result of simulating the effect on the evaluation function due to the difference in aperture diameter of the ring formed by a plurality of antenna elements. In the example of FIG. 5, the evaluation function for each direction of arrival of radio waves is It is shown. Referring to FIG. 5, it can be seen that the second peak of the evaluation function becomes smaller relative to the main peak as the aperture diameter of the antenna element becomes smaller.

However, when the number of antenna elements is increased, the opening diameter of the ring formed by the increased number of antenna elements becomes large. In other words, there is a trade-off relationship between an increase in the number of antenna elements and a reduction in the opening diameter of the ring formed by the plurality of antenna elements.

Here, in the antenna device 1 according to the present embodiment, one antenna element A1 out of the plurality of antenna elements A1 and A2_1 to A2_7 is not arranged to form a ring shape, but is arranged at the center of the ring. placed in the department. As a result, compared to the case where all the antenna elements A1, A2_1 to A2_7 are arranged to form the ring shape, the number of antenna elements used to form the ring shape can be reduced without changing the number of antenna elements to be used. By reducing the number by one, the opening diameter of the ring can be reduced. That is, the antenna device 1 according to the present embodiment can suppress the second peak more than an antenna device in which a ring shape is formed using all of the same number of antenna elements. can improve the detection accuracy of

In the present embodiment, the case where one of the plurality of antenna elements is arranged in the central portion of the ring has been described as an example. may be placed in the center of the By increasing the number of antenna elements placed in the center of the ring, the aperture diameter of the ring can be reduced without reducing the number of antenna elements used. can.

<First Modification of Antenna Device 1>
Next, a first modified example of the antenna device 1 will be described.
FIG. 6 is a schematic diagram showing the periphery of an antenna element of an antenna device 1a, which is a first modified example of the antenna device 1. As shown in FIG. Compared to the antenna element periphery of the antenna device 1 , the antenna element periphery of the antenna device 1 a further includes a radio wave absorber 12 and a reflector plate 13 .

The radio wave absorber 12 is formed on the main surface of the pedestal 11 so as to fill the space between the antenna elements A1, A2_1 to A2_7. The reflector 13 is formed on the main surface of the pedestal 11 opposite to the main surface on which the antenna element is arranged. By using these, it is possible to reduce the distortion of the steering vector (vector representing the amplitude ratio and phase difference in each antenna element of the estimated direction of arrival of the radio wave) due to the reflected wave.

<Second Modification of Antenna Device 1>
Next, a second modification of the antenna device 1 will be described.
FIG. 7 is a schematic diagram showing the periphery of an antenna element of an antenna device 1b, which is a second modification of the antenna device 1. As shown in FIG. The area around the antenna elements of the antenna device 1b differs from the area around the antenna elements of the antenna device 1 in the number of antenna elements arranged in a ring shape. Specifically, the antenna device 1b includes an antenna element A1 and three antenna elements A2_1 to A2_3 arranged so as to surround the antenna element A1. The antenna device 1b can also achieve the same effects as the case of the antenna device 1. FIG.

Thus, the number of antenna elements A2_1 to A2_n arranged in a ring (that is, the value of n) can be set arbitrarily. However, the number of antenna elements A2_1 to A2_n arranged in a ring is preferably an odd number (where n is an odd number).

FIG. 8 is a schematic diagram showing the result of simulating the effect on the evaluation function due to the difference in the number of antenna elements arranged in a ring. Note that the example of FIG. 8 shows the evaluation function when the direction of arrival of radio waves is about 5 degrees. Further, in the example of FIG. 8, the solid line represents the simulation results when an odd number of antenna elements A2_1 to A2_7 are arranged in a ring shape, and the antenna element A1 is arranged in the center thereof. The simulation results are shown when the antenna elements A2_1 to A2_8 are arranged in a ring shape, and the antenna element A1 is arranged in the center.

As shown in FIG. 8, when the number of antenna elements arranged in a ring is an odd number (solid line), compared with the case where the number of antenna elements arranged in a ring is an even number (dashed line), the evaluation function It can be seen that the second peak is relatively smaller than the main peak. From this, it can be said that the number of antenna elements arranged in a ring is preferably an odd number. In the example of FIG. 8, seven antenna elements are used as an example in which the number of antenna elements arranged in a ring is an odd number. Any odd number of antenna elements such as may be used.

In the present embodiment, the case where the antenna elements A2_1 to A2_n are arranged in a ring to surround the antenna element A1 has been described as an example, but the present invention is not limited to this. For example, antenna elements A3_1 to A3_m (m is an integer equal to or greater than 2) may be arranged in a ring to surround antenna element A1. That is, the antenna elements A2_1 to A2_n and the antenna elements A3_1 to A3_m may be arranged in a double ring shape so as to surround the antenna element A1. At this time, the opening diameter (diameter) of the ring shape formed by the antenna elements A2_1 to A2_n is different from the opening diameter (diameter) of the ring shape formed by the antenna elements A3_1 to A3_m. At least one of the number of antenna elements A2_1 to A2_n arranged in a ring and the number of antenna elements A3_1 to A3_m arranged in a ring is odd (at least one of m and n is an odd number). is preferably A specific example will be described below with reference to FIG.

<Third Modification of Antenna Device 1>
FIG. 9 is a schematic diagram showing the periphery of an antenna element of an antenna device 1c, which is a third modification of the antenna device 1. As shown in FIG. Around the antenna elements of the antenna device 1c, in addition to the antenna element A1 and the antenna elements A2_1 to A2_n, there are further provided antenna elements A3_1 to A3_m. Note that in the example of FIG. 9, n=3 and m=3.

The antenna elements A2_1 to A2_3 are arranged in a ring to surround the antenna element A1. Further, the antenna elements A3_1 to A3_3 are arranged in a ring shape so as to surround the antenna element A1. The opening diameter D1 of the ring shape formed by the antenna elements A2_1 to A2_3 is different from the opening diameter D2 of the ring shape formed by the antenna elements A3_1 to A3_3.

In the antenna device 1c, at least one of the number of antenna elements A2_1 to A2_3 arranged in a ring and the number of antenna elements A3_1 to A3_3 arranged in a ring is an odd number (in this example, both are odd numbers). ), the second peak is suppressed more effectively.

In FIG. 9, a case in which a plurality of antenna elements are arranged in a double ring shape so as to surround the antenna element A1 provided in the central portion has been described as an example. may be placed in In this case, it is preferable that the number of antenna elements forming at least one ring shape among the three or more ring shapes is an odd number.

Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configurations are not limited to those described above, and various design changes can be made without departing from the gist of the present disclosure. etc. is possible.

1 Antenna device 1a Antenna device 1b Antenna device 1c Antenna device 11 Base 12 Radio wave absorber 13 Reflector 21 Receiver 22_1 to 22_n Receiver A1 Antenna element A2_1 to A2_n Antenna element A3_1 to A3_m Antenna element 100 Signal processing unit 101 Direction detection unit

Claims (10)

a first antenna element configured to receive at least circularly polarized waves;
a plurality of second antenna elements arranged in a ring to surround the first antenna element and configured to receive at least circularly polarized waves;
An antenna device comprising: the number of the plurality of second antenna elements is an odd number;
The antenna device according to claim 1. Further comprising a radio wave absorber formed to fill between the first antenna element and the plurality of second antenna elements,
The antenna device according to claim 1 or 2. Further comprising a reflector plate formed on a surface opposite to a radio wave reception surface by each of the first antenna element and the plurality of second antenna elements,
The antenna device according to any one of claims 1 to 3. The first antenna element and the plurality of second antenna elements are arranged such that their central axes are parallel,
The antenna device according to any one of claims 1 to 4. Both the first antenna element and the plurality of second antenna elements are spiral antennas,
The antenna device according to any one of claims 1 to 5. the first antenna element and the plurality of second antenna elements each have the same size,
An antenna device according to any one of claims 1 to 6. further comprising at least an azimuth detection unit that detects an arrival direction of the radio wave based on a phase difference between a plurality of received signals, which are radio waves respectively received by the first antenna element and the plurality of second antenna elements. ,
An antenna device according to any one of claims 1 to 7. Further comprising a plurality of third antenna elements arranged in a ring to surround the first antenna element and configured to receive at least circularly polarized waves,
The aperture diameter of the ring shape formed by the plurality of second antenna elements and the aperture diameter of the ring shape formed by the plurality of third antenna elements are different,
at least one of the number of the plurality of second antenna elements and the number of the plurality of third antenna elements is an odd number;
An antenna device according to any one of claims 1 to 8. A first antenna element configured to receive at least circularly polarized waves, and a plurality of second antenna elements arranged in a ring to surround the first antenna elements and configured to receive at least circularly polarized waves. , to receive radio waves,
Detecting the direction of arrival of the radio wave based on the phase difference between the plurality of received signals of the first antenna element and the plurality of second antenna elements,
A radio wave reception method by an antenna device.

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