Antenna device

Abstract

To provide an antenna device that is portable and can be easily installed, does not require mechanical direction adjustment, and is capable of receiving satellite broadcasts.SOLUTION: An antenna device includes an antenna unit with planar antennas arranged on four surfaces, and a receiving antenna surface selection unit that combines signals from two adjacent surfaces of the four surfaces, forms a composite surface that serves as a virtual receiving antenna surface midway between each of the two adjacent surfaces, and can switch the receiving antenna surface in the antenna unit between the four surfaces and the four composite surfaces.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna device, and more particularly to an antenna device for receiving satellite broadcasts. [Background technology]

[0002] Various types of antenna devices have been proposed. Representative antenna devices and their features are as follows:

[0003] A parabolic antenna is a concave antenna with a parabolic reflector, and is often used to receive short-frequency radio waves, including those from satellite broadcasting. It has high gain and sharp directionality (Non-Patent Document 1).

[0004] An omni-antenna is an antenna that can transmit and receive radio waves in all directions (360°) and has wide directivity. Therefore, there is no need to adjust the direction of radio wave reception (Patent Document 1).

[0005] A phased array antenna is an antenna that can control the direction of directivity by arranging multiple small antenna elements on a single surface and controlling the phase of each antenna element. There is no mechanical operation, and the high-gain beam is electrically controlled, allowing automatic direction adjustment (Patent Document 2).

[0006] A motorized antenna is an antenna in which the antenna components are operated by a motor. It has been proposed to mechanically control a high-gain beam and automatically adjust its direction (Patent Documents 3 and 4).

[0007] The following describes satellite broadcasting, which is the target of the antenna device of the present invention. Satellite broadcasting (BS / CS) uses radio waves in the 11.7 to 12.75 GHz (12 GHz band), and traditionally, right-handed circular polarization (right-handed circular polarization) has been used. 4K8K satellite broadcasting, which began in 2018, has also begun to use left-handed circular polarization (left-handed circular polarization). Because right-handed and left-handed circular polarization are orthogonal to each other, left-handed circular polarization can transmit different broadcasts at the same frequency as right-handed circular polarization. Currently, there are unused bands in left-handed circular polarization, and their utilization is being discussed.

[0008] As one form of new service, a 12 GHz band satellite broadcasting system has been proposed that enables reception with a small antenna that is portable and easy to install, rather than the conventional parabolic antenna (Non-Patent Document 2). It is desirable that the small receiving antenna envisioned for this system does not require direction adjustment. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-79246 [Patent Document 2] Patent No. 2646983 [Patent Document 3] Patent No. 2618143 [Patent Document 4] Patent No. 2836558 [Non-patent literature]

[0010] [Non-Patent Document 1] ARIB Standard STD-B63 (Chapter 4, Chapter 12) [Non-patent document 2] Masaru Kamei et al., "Proposal for a 12GHz Band Satellite Broadcasting System that Enables Simple Reception - Research and Development of an Ultra-Low C / N Transmission Method and a Small Receiving Antenna -", ITE 2023 Winter Meeting, 13C-6 [Non-patent document 3] Masashi Nagasaka et al., "Basic Study of Planar Antennas for BS Reception", ITE 2023 Annual Conference, 13B-5 Summary of the Invention [Problem to be solved by the invention]

[0011] However, conventional antenna devices are not fully compatible with the new 12 GHz satellite broadcasting system, which is designed to be portable and easy to install. For example, parabolic antennas have high gain, but their sharp directivity requires adjustment of direction. Omnidirectional antennas eliminate the need for direction adjustment, but broadening the directivity reduces the antenna gain. For example, the gain of an isotropic antenna is 0 dBi. Furthermore, phased array antennas can automatically adjust direction by electrically controlling the beam, but require phase shifters, which increase the circuit size and manufacturing costs. Motorized antennas can automatically adjust direction mechanically, but require a drive device, which increases size and manufacturing costs.

[0012] Therefore, in consideration of the above-mentioned problems, an object of the present invention is to realize an antenna device capable of receiving satellite broadcasts that is portable, can be easily installed, does not require mechanical direction adjustment, and has the highest possible gain. [Means for solving the problem]

[0013] In order to solve the above problems, an antenna device according to the present invention comprises: (1) An antenna unit with planar antennas arranged on four sides; a receiving antenna surface selection unit that combines signals from two adjacent surfaces of the four surfaces, forms a composite surface that serves as a virtual receiving antenna surface between each of the two adjacent surfaces, and is capable of switching the receiving antenna surface of the antenna unit between the four surfaces and the four composite surfaces; The antenna device includes:

[0014] (2) In the antenna device of (1) above, it is further preferable that the planar antenna is a circularly polarized planar antenna, and the combining surface is configured by combining signals from two adjacent surfaces with a phase difference of 90 degrees.

[0015] (3) In the antenna device of (1) or (2) above, it is preferable that the receiving antenna surface selection unit includes an amplifier that amplifies the signal of each surface of the antenna unit, a first switch that switches the output destination of the amplifier, the first switch being four first switches that switch the output destination to either two 3 dB hybrids or a second switch, four 3 dB hybrids that combine signals from two adjacent surfaces, and a second switch that switches the output signals of the four first switches and four 3 dB hybrids to select the receiving antenna surface.

[0016] (4) It is preferable that the antenna device according to any one of (1) to (3) above further comprises a frequency converter that converts the frequency of the signal of the receiving antenna plane selected by the receiving antenna plane selection unit.

[0017] (5) In the antenna device according to any one of (2) to (4) above, it is further preferable that the circularly polarized planar antenna is a microstrip antenna.

[0018] (6) In any of the antenna devices (2) to (5) above, it is preferable that a plurality of the circularly polarized planar antennas are arranged on each surface of the antenna unit, and each surface outputs a composite signal of the plurality of the circularly polarized planar antennas.

[0019] (7) In the antenna device of any one of (2) to (6) above, it is further preferable that the four surfaces on which the circularly polarized planar antenna is arranged have a predetermined inclination angle with respect to the installation surface.

[0020] (8) In any one of the antenna devices (2) to (7) above, it is preferable that the circularly polarized planar antenna receives 12 GHz band satellite broadcasting.

[0021] (9) In any of the antenna devices (1) to (8) above, it is further preferable that the receiving antenna plane with the best reception quality is selected as an initial setting when the antenna is installed. [Effects of the Invention]

[0022] According to the antenna device of the present invention, the antenna device is portable and can be easily installed, and can receive satellite broadcasts without mechanically adjusting the direction. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a configuration example of an antenna device according to an embodiment of the present invention. [Figure 2A] 2 is a plan view illustrating an example of an antenna unit that configures the antenna device. FIG. [Figure 2B] 2 is a side view of an example of an antenna unit that configures the antenna device. FIG. [Figure 3A] This is an example of the radiation surface side of one antenna arrangement surface of the antenna unit. [Figure 3B] This is an example of the rear side of the antenna arrangement surface of one of the antenna units. [Figure 4] This is an example of a planar antenna design. [Figure 5] FIG. 2 is a block diagram showing an example of the configuration of a converter unit of the antenna device. [Figure 6A] 10 is an example of a directivity pattern on one surface of the antenna unit. [Figure 6B] This is an example of a directivity pattern obtained by combining two surfaces of the antenna unit. [Figure 7] 10 is an example of a pattern showing omnidirectional gain in an antenna unit. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0025] (Embodiment) 1 shows an example of the configuration of an antenna device according to one embodiment of the present invention. The antenna device of the present invention is intended to be an antenna device for receiving 12 GHz band satellite broadcasts, and is composed of an antenna unit 10 and a converter unit 20. However, the reception target is not limited to 12 GHz band satellite broadcasts.

[0026] As will be described later, the antenna unit 10 has four antenna arrangement surfaces (surface A, surface B, surface C, and surface D) each with a different receiving direction. A signal (received signal) from an antenna (in this embodiment, a 12 GHz band receiving planar antenna) installed on each antenna arrangement surface is output to the converter unit 20.

[0027] The converter unit 20 includes a receiving antenna surface selection unit 30 and a frequency converter 40. The receiving antenna surface selection unit 30 receives and amplifies signals from each of the four antenna arrangement surfaces, and selects one receiving antenna surface from a total of eight receiving antenna surfaces, which is a combined surface formed by combining signals from the four antenna arrangement surfaces and two adjacent antenna arrangement surfaces. The receiving antenna surface selection unit 30 then outputs the signal received at the selected receiving antenna surface to the frequency converter 40.

[0028] The frequency converter 40 converts the 12 GHz band signal input from the receiving antenna surface selector 30 to a lower frequency suitable for demodulation. Filters, amplifiers, etc. required for frequency conversion and signal level management can be included in the frequency converter 40. The output of the frequency converter 40 is output to the outside as the output signal of the antenna device, and then signal processing for demodulation is performed.

[0029] The antenna device of this embodiment can electrically select and switch the receiving antenna face, making it possible to receive 12 GHz band satellite broadcasts without mechanically adjusting the direction of the device. Furthermore, even in the 45-degree direction (halfway between faces) where gain drops with a single antenna face, reception is possible with the combined face of the two adjacent faces. The antenna device of this embodiment is capable of reception in eight directions, and can improve gain in directions where no antenna is located and reception sensitivity is low.

[0030] Next, each part will be described in detail. Fig. 2A is an example of a plan view of antenna section 10 constituting the antenna device of the present invention, and Fig. 2B is an example of a side view of antenna section 10. Antenna section 10 has four antenna arrangement surfaces (surface A, surface B, surface C, and surface D, which may be collectively referred to as the "four surfaces") each having a plurality of planar antennas 11. Each planar antenna 11 is, for example, a circularly polarized planar antenna having a structure suitable for receiving circularly polarized waves in the 12 GHz band. In this embodiment, three planar antennas 11 are arranged on each surface, but any number of planar antennas 11 can be arranged on each surface.

[0031] In the antenna device of the present invention, the four surrounding antenna arrangement surfaces, each offset by 90 degrees in a plan view, form receiving antenna surfaces. In addition, as will be described later, a virtual receiving antenna surface is created midway between the two antenna arrangement surfaces by combining signals from two adjacent surfaces. As shown in Figure 2A, combining surfaces A and B forms a receiving antenna surface, the AB combined surface, which has directivity midway between the two surfaces (45 degrees: toward the ridge line). The same applies to the combined surfaces of the other two adjacent surfaces.

[0032] In this embodiment, the antenna unit 10 has a quadrangular pyramid shape with a flattened apex. However, this is merely an example, and any other quadrangular pyramid shape may be used. For example, the base of the antenna unit 10 is a square with a side b of 50 mm, and the apex is a square with a side t of 8 mm. The height h of the antenna unit 10 is 23 mm, and the surrounding antenna placement surface is inclined at 43 degrees relative to the base (installation surface). However, the design values ​​(size, etc.) of the antenna unit 10 are not limited to this. The planar antenna 11 is preferably installed on a surface with an elevation angle corresponding to the broadcasting satellite. In this embodiment, the inclination angle of the antenna placement surface is set so that gain is centered in the direction of 43 degrees, which is the average of the antenna elevation angle in Wakkanai (29.1 degrees) and the antenna elevation angle in Ishigaki (57.4 degrees). Note that in this embodiment, 43 degrees was selected assuming that the same small antennas will be used throughout Japan. However, this angle is not necessarily limited to this angle. The angle of the antenna placement surface may be designed to match the elevation angle of the broadcasting satellite at the intended receiving point.

[0033] FIG. 3A shows an example of the front (radiation surface side) of one of the antenna arrangement surfaces constituting the side surface of the antenna unit 10, and FIG. 3B shows an example of the back (feed circuit side) of one of the antenna arrangement surfaces. Each planar antenna 11 is a 12 GHz-band circularly polarized microstrip antenna (MSA). By combining the outputs of three planar antennas 11 (MSA1 to MSA3) into a three-element array, a compact four-sided configuration is possible. In this embodiment, as shown in FIG. 3B, a sequential array arrangement is adopted in which the arrangement of the three planar antennas 11 is rotated by 120° and the phase of the feed line is adjusted to improve reception characteristics. In this embodiment, a combined signal from the three circularly polarized planar antennas is output from each surface.

[0034] FIG. 4 shows a design example of a planar antenna 11. For example, a 12-GHz-band circularly polarized MSA is constructed by stacking a substrate 12 on which a parasitic element is arranged, a substrate 13 on which a driven element is arranged, a ground plate 14 with an asymmetric cross slot, and a substrate 15 on the backside of which a feed line is provided. Substrates 12, 13, and 15 for the elements and feed lines can be made of PTFE (polytetrafluoroethylene). The dimensions of each element are designed taking into account the receiving wavelength and the dielectric constant of the substrate. For example, the radius r of the element can be 3.1 mm, the width of the feed line can be 0.4 mm, the longer slot can be 6.0 mm long and 0.4 mm wide, and the shorter slot can be 4.2 mm long (6.0 mm / √2) and 0.4 mm wide (Non-Patent Document 3). The planar antenna 11 to be installed is not limited to the circularly polarized MSA shown in FIG. 4; any antenna structure can be used. In this embodiment, the MSA is designed for the 12 GHz band, but it can also be applied to other frequency bands by changing the antenna dimensions.

[0035] 5 is a block diagram showing an example of the configuration of the converter unit 20 of the antenna device of the present invention. In the antenna unit 10, signals received at four antenna arrangement surfaces (surface A, surface B, surface C, and surface D) are input to the converter unit 20. The converter unit 20 includes an amplifier (AMP) 31, a first switch (SW1-4) 32, a 3 dB hybrid (3 dB HYB) 33, and a second switch (SW5) 34, which constitute the receiving antenna surface selection unit 30 of FIG. 1, and further includes a frequency converter 40. The converter unit 20 switches the radiation pattern in addition to amplification and frequency conversion.

[0036] The amplifiers (AMP) 31 are provided corresponding to the signals from each antenna arrangement surface of the antenna unit 10, and amplify the antenna reception signals. The amplified signals are output to the first switch (SW1-4) 32.

[0037] The first switches (SW1-4) 32 are provided corresponding to the amplifiers 31, and each has three output terminals. One output terminal (1) is connected to a 3 dB hybrid (3 dB HYB) 33 shared with one of the adjacent antenna arrangement surfaces, and the other output terminal (2) is connected to the input of a second switch (SW5) 34. Furthermore, a further output terminal (3) is connected to the 3 dB hybrid (3 dB HYB) 33 shared with the other adjacent antenna arrangement surface. The first switch 32 can select an output terminal so that the signal input from the amplifier 31 is output from one of the three output terminals.

[0038] The 3dB hybrid (also called a 3dB 90° hybrid coupler) 33 has two inputs and can combine two signals with a 90-degree phase difference and output them. By combining two adjacent signals with a 90-degree phase difference, a virtual antenna plane is created. Which of the two adjacent signals is phase-delayed (or advanced) by 90° is determined by whether right-handed or left-handed circular polarization is being targeted and the relative positions of the two planes. By combining the signals from the appropriate planes with a 90-degree phase shift, a virtual antenna plane with directivity midway between the planes (at an azimuth angle of approximately 45°) can be created. Thus, the output of the 3dB hybrid (3dB HYB) 33 is a signal with the combined plane midway between the planes as the receiving antenna plane, as shown in Figure 2A. The output signal of the 3dB hybrid (3dB HYB) 33 is output to the second switch (SW5) 34.

[0039] In this embodiment, the second switch (SW5) 34 has eight inputs and can select and output one of the eight input signals. That is, it can select one of the output signals of the four first switches (SW1-4) 32 and the output signals of the four 3 dB hybrids (3 dB HYB) 33. Therefore, the second switch (SW5) 34 can switch the receiving antenna plane in eight directions.

[0040] The relationship between the combinations of the first switch (SW1-4) 32 and the second switch (SW5) 34 and the receiving antenna plane is shown in Table 1. The antenna device of the present invention can switch between states 1 to 8 by adjusting the switches, thereby selecting the receiving antenna plane.

[0041] [Table 1]

[0042] In this embodiment, switches are used to prevent distribution loss, but this can also be achieved by replacing the first switches (SW1-4) 32 with distributors.

[0043] The frequency converter 40 converts the signal from the second switch (SW5) 34 (the signal from the selected receiving antenna plane) into a low frequency suitable for demodulation and outputs the converted signal.

[0044] In the present invention, the direction of the receiving antenna plane can be adjusted with a simple configuration that does not require a phase shifter, using a circuit that uses a 3 dB hybrid.

[0045] The manner in which the antenna device of the present invention is used will now be described.

[0046] Since broadcasting satellites are in geostationary orbits, the reception direction is constant. Therefore, when installing the antenna, the initial setting is to adjust switches 32 and 34 to switch between states 1 to 8, and select the receiving antenna face with the best reception quality. After that, the antenna can be used without any direction adjustment.

[0047] Alternatively, positioning information such as GPS may be used to select the receiving antenna surface in the direction from which the signal from the broadcasting satellite arrives.

[0048] (Verification of antenna device characteristics) Examples of calculated radiation patterns for the antenna device of the present invention are shown below. Fig. 6A shows an example of the directivity pattern of one surface (the surface in the X direction in the figure) of antenna unit 10, and Fig. 6B shows an example of the directivity pattern of two combined surfaces of antenna unit 10 (the combined surface in the X and Y directions in the figure), with the patterns displayed in three dimensions.

[0049] Fig. 7 is an example of a pattern showing the gain in all directions of the antenna unit 10 for an elevation angle of 43 degrees. The horizontal axis represents the azimuth angle (plane A is 0 degrees), and the vertical axis represents the gain (dBi). When only four planes, planes A to D, are used, the gain is low (5.8 dBi) in the 45-degree directions between the planes (135 degrees, 225 degrees, 315 degrees), but by forming a composite plane, the gain in the 45-degree direction increases. As a result, the minimum gain is improved by 1.8 dB, and it can be seen that the gain is 7.6 dBi or more for all azimuth angles.

[0050] From the above, it has been confirmed that the present invention can realize a small antenna device for receiving satellite broadcasts that has an improved minimum gain compared to conventional devices and does not require mechanical direction adjustment.

[0051] In the above embodiment, the configuration and operation of the antenna device have been described, but the present invention is not limited to this and may be configured as a method of using the antenna device. That is, for the antenna device of Fig. 1, the state of the first and second switches may be switched as an initial setting when the antenna is installed, and the receiving antenna surface with the best reception quality may be selected.

[0052] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications or alterations are possible without departing from the scope of the claims. For example, the functions included in each block, step, etc. described in the embodiments can be rearranged so as not to be logically inconsistent, and multiple constituent blocks, steps, etc. can be combined or divided into one. [Explanation of symbols]

[0053] 10 Antenna section 11 Planar antenna 20 Converter section 30 Receiving antenna surface selection unit 31 Amplifier (AMP) 32 First Switch 33 3dB Hybrid (3dB HYB) 34 Second Switch 40 Frequency Converter

Claims

1. an antenna unit having planar antennas arranged on four sides; a receiving antenna surface selection unit that combines signals from two adjacent surfaces of the four surfaces, forms a composite surface that serves as a virtual receiving antenna surface between each of the two adjacent surfaces, and is capable of switching the receiving antenna surface of the antenna unit between the four surfaces and the four composite surfaces; An antenna device comprising:

2. 2. The antenna device according to claim 1, the planar antenna is a circularly polarized planar antenna, The antenna device, wherein the combining surface is constructed by combining signals from two adjacent surfaces with a phase difference of 90 degrees.

3. 3. The antenna device according to claim 2, The receiving antenna plane selection unit an amplifier for amplifying signals from each surface of the antenna unit; four first switches for switching the output destination of the amplifier, the first switches switching the output destination to either two 3 dB hybrids or a second switch; Four of the 3 dB hybrids combine signals from two adjacent sides; a second switch for switching between the four first switches and the four output signals of the 3 dB hybrids to select a receiving antenna surface; An antenna device comprising:

4. 4. The antenna device according to claim 3, The antenna device further comprises a frequency converter that converts the frequency of the signal of the receiving antenna plane selected by the receiving antenna plane selection unit.

5. 3. The antenna device according to claim 2, The antenna device, wherein the circularly polarized planar antenna is a microstrip antenna.

6. 3. The antenna device according to claim 2, An antenna device in which a plurality of the circularly polarized planar antennas are arranged on each surface of the antenna unit, and each surface outputs a composite signal of the plurality of the circularly polarized planar antennas.

7. 3. The antenna device according to claim 2, The four surfaces on which the circularly polarized planar antenna is arranged have a predetermined inclination angle with respect to an installation surface.

8. 3. The antenna device according to claim 2, The circularly polarized planar antenna receives 12 GHz band satellite broadcasts.

9. 9. The antenna device according to claim 1, An antenna device in which the receiving antenna surface with the best reception quality is selected as the initial setting when the antenna is installed.

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