Antenna device

Abstract

To provide a device configuration capable of suppressing an increase in the device scale even when the number of antenna elements constituting an array antenna becomes extremely large. [Solution] Stubs 32, 33 are formed on the left and right sides of a waveguide body 31 formed on a circuit board, and switches 51, 52 are provided for exclusively controlling these stubs 32, 33 so that one is an open stub with its tip open and the other is a short stub with its tip shorted. Also, a slot 34 is formed between the stubs 32, 33 of the waveguide body 31, and by using the switches 51, 52 to switch between the open stub and the short stub of the stubs 32, 33, two or more different types of excited electric or magnetic fields are generated in the slot 34, changing the direction of the antenna beam.

Description

[Technical Field]

[0001] The present invention relates to an antenna device capable of controlling the direction of an antenna beam. [Background technology]

[0002] Radio and radar devices often use high-gain antennas to ensure sufficient communication and detection distances. In particular, devices that transmit and receive high-frequency signals often use high-gain antennas to compensate for the large free-space propagation loss of electromagnetic waves.

[0003] In general, a planar antenna can achieve high gain by increasing its area. However, as the gain increases, the beam width narrows, which increases the propagation distance, but also narrows the coverage area in the vertical and horizontal directions relative to the antenna surface. For this reason, devices equipped with high-gain antennas that are required to cover a wide range in the horizontal and vertical directions sometimes perform beam scanning to cover a specified range by appropriately changing the beam direction.

[0004] In a typical transmitting planar antenna, multiple antenna elements are arranged in an array, and beam scanning is performed by controlling the phase and amplitude of the signal input to each antenna element using phase control means and amplitude control means connected to each antenna element. Phase control means and amplitude control means can be divided into analogue and digital control methods.

[0005] FIG. 1 shows an example of the configuration of a beam scanning antenna using a general analog control. The beam scanning antenna of FIG. 1 appropriately sets the phase and amplitude of the signal supplied to each antenna element using phase control means 12-1 to 12-N and amplitude control means 13-1 to 13-N provided for each power supply path to multiple transmitting antenna elements 11-1 to 11-N, thereby controlling the intensity of the composite signal of the beam radiated from each antenna element to be strong in the desired direction. Note that in FIG. 1, the phase control means 12-1 to 12-N are inserted in the path after the signal supplied to each antenna element is converted into a high-frequency signal by mixers 14-1 to 14-N. However, there are various other configurations, such as a configuration in which they are inserted in the path of an intermediate frequency signal before conversion into a high-frequency signal or a configuration in which they are inserted in the path of a local oscillator signal. A beam scanning antenna configured as shown in FIG. 1 is disclosed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-111605 Summary of the Invention [Problem to be solved by the invention]

[0007] Recent advances in devices have made it possible to use high-frequency signals, such as those in the millimeter wave and terahertz bands. These frequency bands have even greater free-space propagation losses, making the use of high-gain antennas essential to compensate for this. Meanwhile, the number of antenna elements required to configure an antenna with a given area is determined by the signal wavelength and the required beam scanning range. Therefore, when using a large-area, high-gain antenna to ensure the propagation distance of ultra-high-frequency band signals, the number of antenna elements required to configure the antenna increases significantly.

[0008] Since beam scanning antennas require connecting phase control means and amplitude control means to each antenna element, beam scanning antennas in the ultra-high frequency band have the problem of requiring a significantly increased number of phase control means and amplitude control means. For example, an antenna transmitting a 100 GHz signal requires the same physical size to ensure the same propagation distance as an antenna transmitting a 10 GHz signal, but the number of elements constituting that antenna is 100 times larger. Therefore, the number of phase control means and amplitude control means required for a beam scanning antenna is also 100 times larger.

[0009] As described above, when a high-gain antenna is required for a beam scanning antenna that handles signals in the millimeter wave or terahertz band, the number of antenna elements constituting the antenna becomes enormous, and the number of phase control means and amplitude control means connected to each antenna element also increases significantly. As a result, there is a problem that the device becomes very large in size. Note that the above explanation is based on an example of the transmitter side of wireless communication, but the same problem occurs on the receiver side.

[0010] The present invention has been made in consideration of the above-described conventional circumstances, and aims to provide an apparatus configuration that can suppress an increase in the size of the apparatus even when the number of antenna elements that make up the array antenna becomes very large. [Means for solving the problem]

[0011] In order to achieve the above object, an antenna device according to one aspect of the present invention is configured as follows: That is, an antenna device capable of controlling the direction of an antenna beam includes a waveguide that propagates a radio frequency signal, the waveguide having a first side along the propagation direction of the radio frequency signal, a second side opposite the first side, and a slot formed between the first side and the second side, the first side and the second side being switchable between a short-circuited state and an open-circuited state, and by switching between the short-circuited state and the open state of the first side and the second side, two or more different types of excited states of electric or magnetic fields are generated in the slot between the first side and the second side, thereby changing the direction of the antenna beam.

[0012] Here, in the above antenna device, the waveguide may be a half-mode waveguide having four faces, one of which is open, the first side and the second side being the left or right face of the half-mode waveguide, and the slot may be formed on the top or bottom face of the half-mode waveguide.

[0013] Furthermore, in the above antenna device, the waveguide may be formed of a conductor formed on a circuit board, stubs may be formed on the first side and the second side of the waveguide, and each of the stubs on the first side and the second side may be switchable between an open stub with an open tip and a short stub with a short-circuited tip, and by switching between the open stub and the short stub among the stubs on the first side and the second side, two or more different types of excited electric or magnetic fields may be generated in the slot between the first side and the second side, thereby changing the direction of the antenna beam.

[0014] Furthermore, the above-described antenna device may be configured to include a switch disposed between each stub on the first side and the second side and a ground conductor, and by making the switch conductive or non-conductive, each stub on the first side and the second side can be switched to an open stub or a short stub.

[0015] In addition, in the above-mentioned antenna device, a plurality of the slots may be formed along the propagation direction of a high-frequency signal in the waveguide, and the first side portion and the second side portion may be configured to be switchable between a short-circuited state and an open state for each portion corresponding to each slot. [Effects of the Invention]

[0016] According to the present invention, even when the number of antenna elements constituting the array antenna is extremely large, it is possible to suppress an increase in the size of the device. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a beam scanning antenna device under general analog control. [Figure 2A] FIG. 1 is a diagram showing a cross section of a typical rectangular waveguide. [Figure 2B] FIG. 2B shows the electric field distribution of the rectangular waveguide of FIG. 2A. [Figure 3A] 3 is a diagram showing a cross section of a half-mode waveguide in the antenna device according to the first embodiment. FIG. [Figure 3B] 3B is a diagram showing the electric field distribution of the half-mode waveguide of FIG. 3A. FIG. [Figure 3C] 3B is a diagram showing an electric field distribution when the open surface is switched in the half-mode waveguide of FIG. 3A. FIG. [Figure 4] 10A and 10B are diagrams illustrating examples of antenna elements of an antenna device according to a second embodiment. [Figure 5] 10A and 10B are diagrams illustrating examples of antenna elements of an antenna device according to a third embodiment. [Figure 6]10A and 10B are diagrams illustrating examples of antenna elements of an antenna device according to a fourth embodiment. [Figure 7] 10A and 10B are diagrams illustrating examples of antenna elements of an antenna device according to a fifth embodiment. [Figure 8] 13A and 13B are diagrams illustrating examples of antenna elements of an antenna device according to a sixth embodiment. [Figure 9] 13A and 13B are diagrams illustrating examples of antenna elements of an antenna device according to a seventh embodiment. [Figure 10] 13A and 13B are diagrams illustrating examples of antenna elements of an antenna device according to an eighth embodiment. [Figure 11] FIG. 13 is a diagram showing the electric field distribution of the antenna element of the antenna device according to the seventh embodiment. [Figure 12] FIG. 13 is a diagram showing the electric field distribution of the antenna element of the antenna device according to the eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] The antenna device according to the present invention is generally configured using a waveguide that propagates high-frequency signals, and a slot formed on one surface of the waveguide functions as an antenna element. Specifically, the antenna device according to the present invention has a slot formed between a first side and a second side of the waveguide, and the first side and the second side are switchable between a low-impedance short-circuit state and a high-impedance open state, and are exclusively controlled so that one is short-circuited and the other is open. By switching between the short-circuited and open states of the first and second side, two or more different electric or magnetic field excitation states are generated in the slot between the first and second side, thereby changing the direction of the antenna beam.

[0019] This eliminates the need to connect phase and amplitude control means to each antenna element to control phase and amplitude, as in conventional beam scanning antennas, making it possible to suppress increases in the size of the device, which is particularly effective when handling high-frequency signals such as those in the millimeter wave and terahertz bands and requiring a high-gain antenna.

[0020] Hereinafter, several embodiments of the antenna device according to the present invention will be described with reference to the drawings. In the following drawings, the propagation direction of the high-frequency signal in the waveguide is defined as the X-axis, and the directions perpendicular to this are defined as the Y-axis and Z-axis. Furthermore, it is assumed that a slot is formed on a surface of the waveguide as viewed from the Z-axis direction (for example, on the top or bottom surface of the waveguide).

[0021] [First embodiment] A well-known typical waveguide is a waveguide surrounded by conductors on all four sides. Among these, a waveguide with a square cross section as shown in Figure 2A is called a "rectangular waveguide." Figure 2B shows the electric field distribution of the fundamental mode, which occurs at the lowest frequency among the modes propagating through a rectangular waveguide, drawn as contour lines viewed from above the wide surface. As shown in Figure 2B, the electric field distribution inside a typical rectangular waveguide is strongest near the center.

[0022] Here, as shown in the cross-sectional structure of Figure 3A, even when one of the four faces of a rectangular waveguide, face 21 (the right face in Figure 3A), is kept at high impedance and electrically open, it still functions as a waveguide and is called a "half-mode waveguide." In this case, the electric field distribution becomes as shown in Figure 3B, with a stronger electric field near face 21 in the open state. Furthermore, by using a switch mechanism that switches between a short-circuited state in which the top and bottom faces are short-circuited by a conductor and an open state in which high impedance is maintained, the left face can be switched from the short-circuited state to the open state, and the right face can be switched from the open state to the short-circuited state, resulting in a reversed electric field distribution as shown in Figure 3C.

[0023] In a half-mode waveguide, if slots (slots 22-1 and 22-2 in FIG. 3B or slots 23-1 and 23-2 in FIG. 3C) are provided as radiating elements between two surfaces (e.g., the left and right surfaces) that are subject to switching between an open state and a short state (e.g., the top surface), the direction of the electric field excited by the slots will also be reversed. If the phase of the electric field excited by the slots in FIG. 3B is set to 0 degrees as the reference, the phase in FIG. 3C is 180 degrees, and two states of 0 degrees and 180 degrees can be arbitrarily created in the same slot. Therefore, by arranging such slots in an array and appropriately setting the phase of each slot to 0 degrees and 180 degrees, it is possible to control the scanning direction of the beam radiated from the array antenna in any direction. Note that the above explanation focuses on the electric field excited by the slots, but the same applies to the magnetic field excited by the slots.

[0024] The antenna device according to the first embodiment employs a half-mode waveguide that operates as described above. Specifically, the first embodiment includes a half-mode waveguide having four rectangular waveguides, one of which is open, and a switch mechanism for exclusively controlling the right and left sides of the half-mode waveguide so that one is short-circuited with low impedance and the other is open with high impedance. Furthermore, a slot extending in the propagation direction (X-axis direction) of the high-frequency signal is formed on the top or bottom surface of the half-mode waveguide. By switching between the short-circuited and open states on the right and left sides of the half-mode waveguide, two or more different electric or magnetic excitation states are generated in the slot, thereby changing the direction of the antenna beam. Furthermore, an array antenna is realized by forming multiple slots along the propagation direction of the high-frequency signal and providing multiple switch mechanisms corresponding to the slots.

[0025] This configuration enables beam scanning without connecting a phase control means or amplitude control means to each antenna element as in the past, and reduces the increase in device size compared to a conventional beam scanning device. In particular, in the case of antenna devices that require a large number of antenna elements as high-gain antennas used in the millimeter wave band or terahertz band, it is possible to effectively reduce the device size.

[0026] The slot may be located at the midpoint between the left and right faces, or may be shifted left or right from the midpoint. The slot is not limited to a rectangular shape as shown in the figure, but may have other shapes such as an ellipse. The slot is not limited to a shape extending in the same direction as the propagation direction of the high-frequency signal (X-axis direction), but may extend in a direction inclined relative to the propagation direction.

[0027] [Second embodiment] The antenna device according to the second embodiment achieves the same operation as the above-described waveguide (half-mode waveguide) using a circuit board. Generally, SIW (Substrate Integrated Waveguide) is known, which configures a waveguide within a circuit board. In the second embodiment, the antenna element is configured using a waveguide, and the SIW configuration makes it easy to connect the antenna element to circuits and the like associated with the antenna. Furthermore, these can be integrated on the same substrate, which is advantageous for miniaturizing the device and reducing its cost.

[0028] FIG. 4 shows an example of an antenna element of an antenna device according to the second embodiment. In FIG. 4, a conductor of a predetermined width is formed as a waveguide on the upper surface of a circuit board. The waveguide shown in the figure has stubs 32 and 33 of predetermined lengths provided on both the left and right sides of a waveguide body 31, which is the main body portion. Such a waveguide can be created by forming a conductive foil (e.g., a metal foil such as copper) in a predetermined pattern on a circuit board. In this example, four stubs 32 and four stubs 33 are provided on both the left and right sides of the waveguide body 31, but this is merely an example and the number of stubs can be arbitrary.

[0029] Of the stubs 32 and 33 on both the left and right sides, one stub (the right stub 33 in FIG. 4) is connected to the ground conductor 42. That is, in a normal SIW, both the left and right stubs are open stubs with their tips in an open state, but in this embodiment, one stub is an open stub with its tip in an open state, and the other stub is a short stub with its tip in a short state, thereby generating an electric field distribution like that shown in FIG. 3B or 3C inside the SIW. Although not shown, the back surface of the circuit board serves as a ground surface.

[0030] Here, by setting the length d of the stubs 32 and 33 in the Y-axis direction to approximately 1 / 4 of the signal wavelength, the left stub 32, whose tip is open, and the vicinity of the base of the waveguide body 31 can be considered to be in a short-circuit state with low impedance near the signal frequency. Similarly, the right stub 33, whose tip is connected to the ground conductor 42, and the vicinity of the base of the waveguide body 31 can be considered to be in an open state with high impedance near the signal frequency. As a result, the waveguide state shown in Figure 3 can be simulated on a circuit board. Furthermore, by using a switch mechanism to switch between a state where the tips of both stubs 32 and 33 are connected to the ground conductor and a state where the tips are open, the electric field distributions shown in Figures 3B and 3C can be simulated.

[0031] Therefore, by providing a slot 34 between the stubs 32 and 33 of the waveguide body 31 as an antenna element, it becomes possible to switch and control the direction of the electric field or magnetic field excited in the slot 34. Furthermore, by arranging a plurality of such slots to form an array antenna and appropriately setting the direction of the electric field or magnetic field excited in each slot to one of the above two types, beam scanning becomes possible.

[0032] In the above example, the tip of one of the stubs on both sides of the conductor is in contact with the ground conductor, but this is not necessarily the case as long as it can be considered to be connected at the signal frequency. For example, the same operation can be achieved even if the tip of the stub and the ground conductor are connected by a capacitor of a certain size, or if there is a gap between the tip of the stub and the ground conductor that is sufficiently narrow compared to the signal wavelength.

[0033] As described above, in the second embodiment, stubs 32, 33 are formed on the left and right sides of waveguide body 31 formed on a circuit board, and a switch mechanism (a specific example will be described in a later embodiment) is provided for exclusively controlling these stubs 32, 33 so that one becomes an open stub with its tip open and the other becomes a short stub with its tip short-circuited. Also, a slot 34 is formed between stubs 32, 33 of waveguide body 31, and by switching between the open stub and the short stub of stub 32, 33, two or more different types of excited electric or magnetic fields are generated in slot 34, thereby changing the direction of the antenna beam.

[0034] This configuration makes it easy to connect the antenna element to the circuits and other components associated with the antenna. Furthermore, it is possible to integrate these on the same substrate, which is advantageous for reducing the size and cost of the device. In addition, by creating an open-state surface of the waveguide using a stub with a short-circuited tip, it is possible to generate a more stable open-state surface despite the simple configuration.

[0035] In this example, the slot is formed by an opening that exposes the circuit board, but the slot may also be formed by a recess that is recessed to the extent that the circuit board is not exposed. The slot may be located at the midpoint between the left and right stubs, or may be shifted to the left or right from the midpoint. The slot is not limited to a rectangular shape as shown in the figure, but may have other shapes such as an ellipse. The slot is not limited to a shape that extends in the same direction as the propagation direction of the high-frequency signal (X-axis direction), but may also have a shape that extends in a direction inclined relative to the propagation direction.

[0036] Here, for beam scanning, it is necessary to arrange a plurality of the antenna elements described above in an array. In a typical array antenna, antenna elements are arranged at the end of a feed line that distributes signals, and the feed line can have various configurations, such as a configuration that distributes signals in a tournament pattern or a configuration that distributes signals by connecting branch lines with adjusted impedance in series. The antenna element of the present invention can also have a similar configuration, but it is preferable to use a traveling-wave antenna configuration in which multiple slots are arranged in the propagation direction of the high-frequency signal in the waveguide. By adopting such a traveling-wave antenna configuration, it is possible to share the waveguides that constitute the antenna elements and the feed lines that feed signals to each antenna element, making it easy to realize an array antenna.

[0037] [Third embodiment] 5 shows an example of an antenna element of the antenna device according to the third embodiment. As with the second embodiment, the antenna device according to the third embodiment has an SIW structure in which a waveguide is formed on a circuit board. The SIW is composed of a waveguide body 31 formed on the circuit board and stubs 32 and 33 provided on both the left and right sides of the waveguide body 31. A slot 34 is formed between the stubs 32 and 33 of the waveguide body 31.

[0038] In the third embodiment, switches 51 and 52 are further provided between the tips of the stubs 32 and 33 and the ground conductors 41 and 42. The left stub 32 is connected to the ground conductor 41 via the switch 51, and the right stub 33 is connected to the ground conductor 42 via the switch 52. By switching the switches 51 and 52 to conductive (on) or non-conductive (off), the stubs 32 and 33 and the ground conductors 41 and 42 are switched to conductive or non-conductive states.

[0039] For example, when the left switch 51 is non-conductive and the right switch 52 is conductive, the left stub 32 becomes an open stub with its tip open, and the right stub 33 becomes a short stub with its tip connected to the ground conductor. By switching switches 51 and 52 on and off, the electric field distribution in the waveguide changes as shown in Figure 3B or 3C, resulting in a phase shift of approximately 180 degrees in the electric field excited in slot 34. Such switches can be constructed using diodes, transistors, and various other devices, and are easily implemented on a circuit board. Furthermore, the switch and waveguide can be integrated on the same semiconductor substrate.

[0040] [Fourth embodiment] FIG. 6 shows an example of an antenna element of an antenna device according to a fourth embodiment. The antenna device according to the fourth embodiment includes a waveguide body 31 formed on a circuit board and stubs 32 and 33 provided on both the left and right sides of the waveguide body 31. A slot 34 is formed between the stubs 32 and 33 of the waveguide body 31. Switches 51 and 52 are provided between the tips of the stubs 32 and 33 and the ground conductors 41 and 42. The left stub 32 is connected to the ground conductor 41 via the switch 51, and the right stub 33 is connected to the ground conductor 42 via the switch 52. Although not shown, the rear surface of the board serves as a ground plane, and the ground conductors 41 and 42 are connected to the ground plane on the rear surface of the board via through-holes 61 and 62 that penetrate the circuit board. The basic configuration is the same as that of the third embodiment, so a detailed description will be omitted.

[0041] [Fifth embodiment] 7 shows an example of an antenna element of the antenna device according to the fifth embodiment. In the antenna device according to the fifth embodiment, a line 71 with an open tip, a line 72 with its tip connected to the ground plane on the back surface of the circuit board by a through-hole 74 penetrating the circuit board and short-circuited, and an SPDT (Single-Pole Double-Throw) switch 73 are provided on both the left and right sides of a waveguide body 31 formed on a circuit board. The line 71 with its tip open and the line 72 with its tip short-circuited are connected to the waveguide body 31 via the SPDT switch 73.

[0042] At this time, by using the SPDT switch 73 to select either the line 71 with its tip open or the line 72 with its tip shorted, and connecting it to the waveguide body 31, it is possible to create a state in which either an open stub or a short stub is connected to the waveguide body 31. Therefore, by selecting the line 71 with its tip open on one side and the line 72 with its tip shorted on the other side, it is possible to perform the same operation as in the above-mentioned embodiment, and to obtain the same effects as in the above-mentioned embodiment.

[0043] [Sixth embodiment] 8 shows an example of an antenna element of an antenna device according to the sixth embodiment. In the fourth embodiment, the ground conductors 41 and 42 are connected to the ground plane on the back surface of the board by through holes 61 and 62, but in the sixth embodiment, radial stubs 83 and 84 are connected to the ground conductors 81 and 82. In this case, by setting the radial length r of the radial stubs 83 and 84 to approximately ¼ of the signal wavelength, the impedance becomes low with respect to the signal frequency near the bases of the radial stubs 83 and 84, and can be regarded as a short-circuit state.

[0044] According to the sixth embodiment, the ground conductors 81 and 82 have low impedance near the signal frequency and are considered to be in a grounded state, but are isolated from the ground plane in DC. Depending on the configuration of the switches 51 and 52 used, it may be necessary to apply a predetermined bias voltage to the switch terminals for switch operation. In such cases, by using a structure such as that of this embodiment, the ground conductors 81 and 82 are not DC grounded, making it possible to apply a predetermined voltage directly. Note that while an example using a radial stub has been given here, this radial stub can also be used with an open stub on a normal line, which can operate in a similar manner.

[0045] [Seventh embodiment] Fig. 9 shows an example of an antenna element of an antenna device according to the seventh embodiment. In order to perform beam scanning, it is necessary to arrange a plurality of antenna elements in an array. Therefore, in the seventh embodiment, as shown in Fig. 9, a traveling-wave antenna is used in which a plurality of slots 92-1 to 92-4 are arranged in series along the propagation direction (X-axis direction) of the high-frequency signal in a waveguide body 91. In addition, switches 93-1 to 93-4 and 94-1 to 94-4 are connected to the stubs on the left and right sides of the waveguide body 91.

[0046] At this time, by individually controlling switches 93-1 to 93-4 and 94-1 to 94-4 provided at the positions corresponding to slots 92-1 to 92-4, it is possible to excite electric or magnetic fields of two different phases independently in each of slots 92-1 to 92-4. Therefore, beam scanning is possible by setting each switch so that the beam is directed in the desired direction.

[0047] As in this embodiment, by making the array antenna a traveling wave antenna composed of waveguides, it is possible to share the waveguides with slots that operate as antenna elements and the feed lines that feed signals to each antenna element, making it possible to easily realize an array antenna. Furthermore, by arranging such structures in parallel, it is also possible to realize an array antenna in which antenna elements are arranged two-dimensionally.

[0048] In the embodiments described so far, only the essential operation of the antenna element is illustrated, but it goes without saying that an actual antenna requires wiring for switch control, etc. Also, depending on the type of switch used, a capacitor or the like for cutting DC may be added as appropriate.

[0049] [Eighth embodiment] In a traveling-wave antenna in which a plurality of slots 92-1 to 92-4 are arranged in series along the propagation direction (X-axis direction) of a high-frequency signal in the waveguide body 91, as in the seventh embodiment described above, there may occur cases in which the conductive and non-conductive states of the switches are reversed in adjacent slots. As an example, in the switches associated with slots 92-1, 92-3, and 92-4, the switches 93-1, 93-3, and 93-4 on the left side of the slots are conductive and the switches 94-1, 94-3, and 94-4 on the right side are non-conductive, whereas in the switches associated with slot 92-2, the switch 93-2 on the left side is non-conductive and the switch 94-2 on the right side is conductive.

[0050] In this case, the electric field distribution inside the waveguide is as shown in Figure 11, with the electric field distribution in the slot 92-2 region being the left-right reverse of the electric field distributions in the other slots 92-1, 92-3, and 92-4. If a signal is propagating in the +X direction, the electric field distribution must change abruptly when the signal propagates from the slot 92-1 region to the slot 92-2 region, and when the signal propagates from the slot 92-2 region to the slot 92-3 region. On the other hand, when the signal propagates from the slot 92-3 region to the slot 92-4 region, the electric field distribution in the waveguide is in the same direction, so such abrupt change is not necessary. Therefore, the electric field distribution conditions in adjacent slots differ significantly depending on whether the switch is in the same conductive / non-conductive state or not, which may change the antenna characteristics of each slot.

[0051] As a countermeasure, an example of an antenna element of an antenna device according to an eighth embodiment is shown in Fig. 10. In order to address the above problem, the eighth embodiment is a traveling-wave antenna in which a plurality of slots 92-1 to 92-4 are arranged in series along the propagation direction (X-axis direction) of a high-frequency signal in a waveguide body 91, and normal waveguides 101-1 to 101-3 that are not half-mode are arranged between the slots.

[0052] As an example, similar to the previous example, if the left switches 93-1, 93-3, and 93-4 associated with slots 92-1, 92-3, and 92-4 are conductive and the right switches 94-1, 94-3, and 94-4 are nonconductive, while the left switch 93-2 associated with slot 92-2 is nonconductive and the right switch 94-2 is conductive, the electric field distribution will be as shown in FIG. 12. In a conventional waveguide, the electric field is strong near the center. Therefore, by inserting conventional waveguides 101-1 to 101-3 between each slot, the position of the strong electric field is shifted to the center. As a result, the distance traveled by the electric field is approximately the same whether the switches are in the same conductive or nonconductive state between adjacent slots or not, significantly reducing the change in characteristics between the two.

[0053] In the above explanation, the normal waveguides inserted between each slot are SIWs with through-holes on both sides of the waveguide, but it goes without saying that a waveguide consisting of stubs can also achieve the same effect as long as it is not a half-mode waveguide. Also, since the above explanation focuses on explaining the behavior of the electromagnetic field, DC blocking capacitors and the like are omitted, but it goes without saying that the same effect can be achieved by adding a capacitor or something that performs the same function as needed.

[0054] Although the embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take on various other embodiments, and various modifications such as omissions and substitutions can be made without departing from the spirit of the present invention. These embodiments and modifications thereof are included in the scope and spirit of the invention described in this specification, etc., and are included in the invention described in the claims and their equivalents. [Industrial Applicability]

[0055] The present invention can be used in an antenna device capable of controlling the direction of an antenna beam. [Explanation of symbols]

[0056] 11-1 to 11-N: transmitting antenna elements, 12-1 to 12-N: phase control means, 13-1 to 13-N: amplitude control means, 14-1 to 14-N: mixers, 21: open surface, 22-1 to 22-2, 23-1 to 23-2: slots, 31: waveguide body, 32, 33: stubs, 34: slots, 41, 42: ground conductors, 51, 52: switches, 61, 62: through holes, 71: line with open end, 72: line with shorted end, 73: SPDT switch, 74: through holes, 81, 82: ground conductors, 83, 84: radial stubs, 91: ground conductors, 92-1 to 92-4: slots, 93-1 to 93-4, 94-1 to 94-4: switches, 101-1 to 101-3: normal waveguides

Claims

1. In an antenna device capable of controlling the direction of an antenna beam, a waveguide for propagating a high-frequency signal; the waveguide has a first side along a propagation direction of a high-frequency signal, a second side opposite to the first side, and a slot formed between the first side and the second side; the first side and the second side are switchable between a shorted state and an open state; An antenna device characterized in that by switching between a short-circuited state and an open state among the first side portion and the second side portion, two or more different types of electric field or magnetic field excitation states are generated in the slot between the first side portion and the second side portion, thereby changing the direction of the antenna beam.

2. 2. The antenna device according to claim 1, the waveguide is a half-mode waveguide having four faces, one of which is an open face; the first side and the second side are left or right surfaces of the half-mode waveguide; The antenna device is characterized in that the slot is formed on the upper surface or the lower surface of the half-mode waveguide.

3. 2. The antenna device according to claim 1, the waveguide is made of a conductor formed on a circuit board, stubs are formed on the first and second sides of the waveguide; each stub on the first side and the second side is switchable between an open stub whose tip is open and a short stub whose tip is short-circuited; An antenna device characterized in that by switching between an open stub and a short stub among the stubs on the first side and the second side, two or more different types of electric field or magnetic field excitation states are generated in the slot between the first side and the second side, thereby changing the direction of the antenna beam.

4. 3. The antenna device according to claim 2, a switch disposed between each stub on the first side and the second side and a ground conductor; An antenna device, characterized in that by making the switch conductive or non-conductive, each of the stubs on the first side and the second side can be switched to an open stub or a short stub.

5. 5. The antenna device according to claim 1, a plurality of the slots are formed along a propagation direction of a high-frequency signal in the waveguide; The antenna device according to the present invention is characterized in that the first side portion and the second side portion are switchable between a short-circuited state and an open state for each portion corresponding to each slot.

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