Array antenna device

Abstract

An array antenna device according to the present disclosure comprises: a dielectric substrate (1); a plurality of dipole antenna elements (2), (3) which are arranged two-dimensionally in a planar shape on the front surface of the dielectric substrate (1), and have power supply arms (22), (32) and ground arms (21), (31); a ground conductor (4) which is formed on the rear surface of the dielectric substrate (1) and to which the ground arms (21), (31) of the plurality of dipole antenna elements (2), (3) are electrically connected via short-circuit lines (7), (9) corresponding to the ground arms (21), (31); and, a plurality of input units (5) which are provided on the rear surface of the dielectric substrate (1) and which correspond to the respective power supply arms (22), (32) of the plurality of dipole antenna elements (2), (3) and are electrically connected via power supply lines (8), (10) respectively corresponding to the power supply arms (22), (32). The dielectric substrate (1) has cavities (13) directly below respective tip parts (22b), (32b) of the power supply arms (22), (32) of the plurality of dipole antenna elements (2), (3) and directly below respective tip parts (21b), (31b) of the ground arms (21), (31) of the plurality of dipole antenna elements (2), (3).

Description

Array antenna device

[0001] This disclosure relates to an array antenna device, for example, an array antenna device in which a plurality of dipole antenna elements are arranged planarly on the surface of a dielectric substrate.

[0002] As array antenna devices used in wireless communication systems, satellite systems, or radar, a thin, wide-bandwidth planar ultrawideband modular array (PUMA) antenna is proposed in Patent Document 1, and a planar ultrawideband modular antenna (PUMA) array is proposed in Patent Document 2.

[0003] The PUMA antenna described in Patent Document 1 is provided with a conductor (via) that is spaced apart from the feed line (via) and directly connects the feed arm to ground, in addition to the feed line (via), on the feed arm of the antenna element which consists of a feed arm and a ground arm, in order to shift the frequency of common-mode resonance outside the high-frequency band of the operating frequency.

[0004] The PUMA array described in Patent Document 2 includes a metal plate capacitively coupled to a horizontal dipole segment directly fed from an unbalanced RF interface and fixed to the ground plane by plated vias, in order to shift the common-mode resonance frequency outside the low-bandwidth of the operating frequency.

[0005] US Pat. No.8,326,093 B2U.S. Pat. No.10,741914 B2.

[0006] The PUMA antenna shown in Patent Document 1 has a conductor (via) for each antenna element, and the PUMA array shown in Patent Document 2 has a metal plate and plated vias for each dipole segment, which increases the number of vias and presents the challenge of not being easy to manufacture.

[0007] This disclosure has been made in view of the above-mentioned points, and aims to provide an array antenna device that is easy to manufacture, avoids performance degradation due to common-mode resonance, and has a wide bandwidth frequency characteristic.

[0008] The array antenna device according to this disclosure comprises a dielectric substrate, a plurality of dipole antenna elements having feeding arms and grounding arms arranged in a two-dimensional plane on the surface of the dielectric substrate, a ground conductor formed on the back surface of the dielectric substrate to which the grounding arms of the plurality of dipole antenna elements are electrically connected via short-circuit lines corresponding to the grounding arms, and a plurality of signal input sections on the back surface of the dielectric substrate corresponding to each of the feeding arms of the plurality of dipole antenna elements, each of which is electrically connected via a feeding line corresponding to the feeding arm, wherein the dielectric substrate has cavities directly below the tips of each feeding arm of the plurality of dipole antenna elements and directly below the tips of each grounding arm of the plurality of dipole antenna elements.

[0009] According to this disclosure, the common-mode resonance frequency is shifted to a higher frequency, common-mode resonance does not occur within the operating band, performance degradation due to common-mode resonance can be avoided, a wide bandwidth frequency response can be obtained, and it is also easy to manufacture.

[0010] This is a top view of the main part of the array antenna device according to Embodiment 1, shown through the matching layer. This is a top view showing the relationship between two adjacent horizontal polarization dipole antenna elements, two adjacent vertical polarization dipole antenna elements, and a cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view taken along line A-A in Figure 1. This is a cross-sectional view taken along line B-B in Figure 1. This is an image diagram showing the common mode current in the array antenna device according to Embodiment 1. This is a cross-sectional view equivalent to line A-A in Figure 1, showing another configuration example 1 of the multiple dipole antenna elements in the array antenna device according to Embodiment 1. This is a cross-sectional view equivalent to line A-A in Figure 1, showing another configuration example 2 of the multiple dipole antenna elements in the array antenna device according to Embodiment 1. This is a cross-sectional view equivalent to line A-A in Figure 1, showing another embodiment 1 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view equivalent to line A-A in Figure 1, showing another embodiment 2 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view equivalent to line A-A in Figure 1, showing another embodiment 3 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view in Figure 1 showing another embodiment 4 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view in Figure 1 showing another embodiment 5 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view in Figure 1 showing another embodiment 6 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view in Figure 1 showing another embodiment 7 of the cavity in the array antenna device according to Embodiment 1. This is a cross-sectional view in Figure 1 showing an array antenna device according to Embodiment 2. This is an image diagram showing the loop mode current when no cavity is provided in the array antenna device according to Embodiment 2. This is a cross-sectional view in Figure 1 showing another embodiment 1 of the short-circuit line and feed line in the array antenna device according to Embodiment 2. This is a cross-sectional view in Figure 1 showing another embodiment 2 of the short-circuit line and feed line in the array antenna device according to Embodiment 2. This is a cross-sectional view in Figure 1 showing another embodiment 1 of the short-circuit side matching element and feed side matching element in the array antenna device according to Embodiment 2.This is a cross-sectional view in Figure 1, corresponding to line A-A, showing another embodiment 2 of the short-circuit matching element and the feed-side matching element in the array antenna device according to Embodiment 2. This is a cross-sectional view in Figure 1, corresponding to line A-A, showing another embodiment 1 of the second cavity in the array antenna device according to Embodiment 2. This is a cross-sectional view in Figure 1, corresponding to line A-A, showing another embodiment 2 of the second cavity in the array antenna device according to Embodiment 2.

[0011] Embodiment 1. An array antenna device according to Embodiment 1 will be described with reference to Figures 1 to 5. The array antenna device according to Embodiment 1 is a planar tightly coupled dipole array antenna with an orthogonal dual polarization configuration, having horizontal polarization dipole antenna elements arranged in two dimensions on a planar surface and vertical polarization dipole antenna elements arranged in two dimensions on a planar surface.

[0012] Furthermore, the array antenna device may be a tightly coupled dipole array antenna with a single polarization configuration, having either a dipole antenna element for horizontal polarization or a dipole antenna element for vertical polarization. Alternatively, the array antenna device may be a dipole array antenna instead of a tightly coupled dipole array antenna.

[0013] However, a tightly coupled dipole array antenna is preferred as the array antenna device because it functions as an antenna over a wide frequency band. The following description will mainly focus on a planar tightly coupled dipole array antenna with a quadrature two-polarization configuration.

[0014] The array antenna device according to Embodiment 1 comprises a dielectric substrate 1, a plurality of dipole antenna elements 2 for horizontal polarization, a dipole antenna element 3 for vertical polarization, a ground conductor 4, a signal input section 5, and a matching layer 12. The dielectric substrate 1 is a low dielectric constant substrate such as a fluororesin substrate or a glass epoxy substrate. In Embodiment 1, the dielectric substrate 1 is shown as a single-layer substrate, but it may also be a multilayer substrate.

[0015] As shown in Figure 1, multiple horizontal polarization dipole antenna elements 2 are arranged in one direction on the surface of the dielectric substrate 1, and multiple horizontal polarization dipole antenna elements 2 arranged in one direction are arranged in the other direction. Multiple vertical polarization dipole antenna elements 3 are arranged in the other direction on the surface of the dielectric substrate 1, and multiple vertical polarization dipole antenna elements 3 arranged in the other direction are arranged in one direction. For the sake of explanation, one direction will be referred to as the row direction and the other direction as the column direction in the following explanation. Alternatively, one direction may be referred to as the column direction and the other direction as the row direction.

[0016] Multiple horizontal polarization dipole antenna elements 2 are arranged in multiple columns, alternating between columns in each row, and the multiple horizontal polarization dipole antenna elements 2 in each row are arranged in multiple rows, alternating between rows. Multiple horizontal polarization dipole antenna elements 2 are arranged planarly in a matrix of multiple columns and multiple rows.

[0017] Adjacent horizontal polarization dipole antenna elements 2 arranged in the row direction have their tips close together and are capacitively coupled. Adjacent horizontal polarization dipole antenna elements 2 arranged in the row direction constitute a tightly coupled dipole antenna element.

[0018] Multiple vertical polarization dipole antenna elements 3 are arranged in multiple rows, alternating between rows in each column, and the multiple vertical polarization dipole antenna elements 3 in each column are arranged in multiple rows, alternating between rows. Multiple vertical polarization dipole antenna elements 3 are arranged planarly in a matrix of multiple rows and multiple columns.

[0019] Adjacent vertical polarization dipole antenna elements 3 arranged in a row have their tips close together and are capacitively coupled. Adjacent vertical polarization dipole antenna elements 3 arranged in a row constitute a tightly coupled dipole antenna element.

[0020] Multiple horizontal polarization dipole antenna elements 2 and multiple vertical polarization dipole antenna elements 3 are formed by forming a conductive layer on the surface of a dielectric substrate 1 and etching the conductive layer. Specifically, the multiple horizontal polarization dipole antenna elements 2 and multiple vertical polarization dipole antenna elements 3 are arranged in a two-dimensional plane on the surface of the dielectric substrate 1, with adjacent horizontal polarization dipole antenna elements 2 in the row direction being capacitively coupled and tightly coupled, and adjacent vertical polarization dipole antenna elements 3 in the column direction being capacitively coupled and tightly coupled.

[0021] Each of the multiple horizontal polarization dipole antenna elements 2 has a grounding arm 21 and a feeding arm 22 arranged along the row direction. As shown in Figure 2, the grounding arm 21 has a base portion 21a and a tip portion 21b that are formed continuously along the row direction.

[0022] As shown in Figure 2, the power supply arm 22 has a base portion 22a and a tip portion 22b that are continuously formed along the row direction. The grounding arm 21 and the power supply arm 22 have the same planar shape, and the end edge of the base portion 21a of the grounding arm 21 and the end edge of the base portion 22a of the power supply arm 22 are positioned opposite each other.

[0023] In the grounding arm 21, each side of the base portion 21a forms a widening arc from the end edge, and each side of the tip portion 21b forms a tapering straight line that continues from both sides of the base portion 21a to form a vertex. In the power supply arm 22, each side of the base portion 22a forms a widening arc from the end edge, and each side of the tip portion 22b forms a tapering straight line that continues from both sides of the base portion 22a to form a vertex.

[0024] In two horizontally polarized dipole antenna elements 2 adjacent to each other in the row direction, the vertex of the tip 22b of the feed arm 22 of one dipole antenna element 2 and the vertex of the tip 21b of the ground arm 21 of the other dipole antenna element 2 are positioned opposite each other. The tip 22b of the feed arm 22 of one dipole antenna element 2 and the tip 21b of the ground arm 21 of the other dipole antenna element 2 are capacitively coupled.

[0025] Each of the multiple vertical polarization dipole antenna elements 3 has a grounding arm 31 and a feeding arm 32 arranged along the row direction. As shown in Figure 2, the grounding arm 31 has a base portion 31a and a tip portion 31b that are formed continuously along the row direction.

[0026] As shown in Figure 2, the power supply arm 32 has a base portion 32a and a tip portion 32b that are continuously formed along the row direction. The grounding arm 31 and the power supply arm 32 have the same planar shape, and the end edge of the base portion 31a of the grounding arm 31 and the end edge of the base portion 32a of the power supply arm 32 are positioned opposite each other.

[0027] In the grounding arm 31, each side of the base portion 31a forms a curve that widens from the end edge, and each side of the tip portion 31b forms a straight line that tapers from both sides of the base portion 31a and has a vertex. In the power supply arm 32, each side of the base portion 32a forms a curve that widens from the end edge, and each side of the tip portion 32b forms a straight line that tapers from both sides of the base portion 32a and has a vertex.

[0028] In two adjacent vertical polarization dipole antenna elements 3 in the row direction, the vertex of the tip 32b of the feed arm 32 of one dipole antenna element 3 and the vertex of the tip 31b of the ground arm 31 of the other dipole antenna element 3 are positioned opposite each other. The tip 32b of the feed arm 32 of one dipole antenna element 3 and the tip 31b of the ground arm 31 of the other dipole antenna element 3 are capacitively coupled.

[0029] As shown in Figure 2, adjacent horizontal polarization dipole antenna elements 2 and adjacent vertical polarization dipole antenna elements 3 located in the row between them and in the adjacent column are arranged in a + shape, with the sides of the base 31a and base 32a of each forming four semicircular arcs.

[0030] The ground conductor 4 is formed by a conductive layer on the entire back surface of the dielectric substrate 1, except for the areas where multiple horizontal polarization signal input sections 5 and multiple vertical polarization signal input sections are formed. The ground conductor 4 is formed by a metal layer such as aluminum. Each of the multiple horizontal polarization signal input sections 5 is a horizontal polarization signal line formed on the back surface of the dielectric substrate 1, corresponding to the base 22a of the feed arm 22 of the multiple horizontal polarization dipole antenna elements 2, separated from the ground conductor 4 by an insulator 6.

[0031] The region on the back surface of the dielectric substrate 1 where the signal input section 5 for horizontal polarization is formed has a circular planar shape. The signal line, which is the signal input section 5, the insulator 6 surrounding the signal line 5, and the ground conductor 4 surrounding the signal input section 5 form a coaxial structure in which the ground conductor 4 functions as an outer conductor. A power supply circuit (not shown), which is an unbalanced power supply circuit that outputs a transmission signal consisting of microwaves, is formed on the back surface of the dielectric substrate 1. The transmission signal for horizontal polarization from the power supply circuit is input to the signal input section 5.

[0032] Each of the multiple vertical polarization signal input sections is a vertical polarization signal line formed on the back surface of the dielectric substrate 1, corresponding to the base 32a of the feed arm 32 of the multiple vertical polarization dipole antenna elements 3, separated from the ground conductor 4 by an insulator. The region on the back surface of the dielectric substrate 1 where the vertical polarization signal input section is formed has a circular planar shape, and the signal line which is the signal input section, the insulator surrounding the signal line, and the ground conductor 4 surrounding the signal input section form a coaxial structure in which the ground conductor 4 functions as an outer conductor. The vertical polarization transmission signal from the feed circuit is input to the vertical polarization signal input section.

[0033] Each base 21a of the grounding arm 21 in the multiple horizontal polarization dipole antenna elements 2 is electrically connected to and short-circuited to the ground conductor 4 via a horizontal polarization short-circuit line 7, which is a via corresponding to each grounding arm 21. Each base 22a of the feed arm 22 in the multiple horizontal polarization dipole antenna elements 2 is electrically connected to the corresponding horizontal polarization signal input section 5 via a horizontal polarization feed line 8, which is a via corresponding to each feed arm 22.

[0034] Corresponding to each of the multiple horizontal polarization dipole antenna elements 2, the horizontal polarization short-circuit line 7, the horizontal polarization feed line 8, and the signal line which is the signal input section 5 operate as parallel two-wire lines, which are unbalanced microwave transmission lines.

[0035] In adjacent horizontal polarization dipole antenna elements 2, the tip 21b of the grounding arm 21, which is the end of one dipole antenna element 2 that is not connected to the short-circuit line 7, and the tip 22b of the feed arm 22, which is the end of the other dipole antenna element 2 that is not connected to the feed line 8, face each other and approach each other, forming a capacitive coupling.

[0036] Each base 31a of the grounding arm 31 in the multiple vertical polarization dipole antenna elements 3 is electrically connected to and short-circuited to the ground conductor 4 via a vertical polarization short-circuit line 9, which is a via corresponding to each grounding arm 31. Each base 32a of the feed arm 32 in the multiple vertical polarization dipole antenna elements 3 is electrically connected to the corresponding vertical polarization signal input section via a vertical polarization feed line 10, which is a via corresponding to each feed arm 32.

[0037] Corresponding to each of the multiple vertical polarization dipole antenna elements 3, the vertical polarization short-circuit line 9, the vertical polarization feed line 10, and the signal line which is the signal input section for vertical polarization operate as parallel two-wire lines, which are unbalanced microwave transmission lines.

[0038] In adjacent vertical polarization dipole antenna elements 3, the tip 31b of the grounding arm 31, which is the end of one dipole antenna element 3 that is not connected to the short-circuit line 9, and the tip 32b of the feed arm 32, which is the end of the other dipole antenna element 3 that is not connected to the feed line 10, face each other and approach each other, forming a capacitive coupling.

[0039] The planar shapes of the base portions 21a, 22a and the tip portions 21b, 22b of the ground arms 21 and the feeding arms 22 in each of the plurality of dipole antenna elements 2 for horizontal polarization are not limited to the shapes shown in FIGS. 1 and 2. It is only necessary that the ground arm 21 and the feeding arm 22 are arranged in a straight line in the row direction, and in the ground arm 21, the row direction is the longitudinal direction, one end to which the short - circuit line 7 is connected functions as the base portion 21a, and the other end functions as the tip portion 21b. Also, in the feeding arm 22, it is only necessary that the row direction is the longitudinal direction, one end to which the feeding line 8 is connected functions as the base portion 22a, and the other end functions as the tip portion 22b.

[0040] The planar shapes of the base portions 31a, 32a and the tip portions 31b, 32b of the ground arms 31 and the feeding arms 32 in each of the plurality of dipole antenna elements 3 for vertical polarization are not limited to the shapes shown in FIGS. 1 and 2. It is only necessary that the ground arm 31 and the feeding arm 32 are arranged in a straight line in the column direction, and in the ground arm 31, the column direction is the longitudinal direction, one end to which the short - circuit line 9 is connected functions as the base portion 31a, and the other end functions as the tip portion 31b. Also, in the feeding arm 32, it is only necessary that the column direction is the longitudinal direction, one end to which the feeding line 10 is connected functions as the base portion 32a, and the other end functions as the tip portion 32b.

[0041] The dielectric substrate 1 has a plurality of through - holes 11 extending from the front surface to the back surface in a region where neither the plurality of dipole antenna elements 2 for horizontal polarization nor the plurality of dipole antenna elements 3 for vertical polarization exist on the surface. In the first embodiment, each of the plurality of through - holes 11 is formed in a region surrounded by concentric circles having a diameter smaller than the diameter of a circle formed by the side edges of the base portion 21a of the ground arm 21 and the side edges of the base portion 22a of the feeding arm 22 in the dipole antenna element 2 for horizontal polarization adjacent in the row direction, and the side edges of the base portion 31a of the ground arm 31 and the side edges of the base portion 32a of the feeding arm 32 in the dipole antenna element 3 for vertical polarization adjacent in the column direction that sandwich the adjacent dipole antenna element 2 for horizontal polarization. <The through-hole 11 serves to lower the equivalent relative permittivity of the entire dielectric substrate 1. By forming the through-hole 11 in a region where there are no plurality of dipole antenna elements 2 for horizontal polarization and plurality of dipole antenna elements 3 for vertical polarization in the dielectric substrate 1, it is possible to prevent the occurrence of the scan blindness phenomenon due to element-to-element coupling in the dipole antenna element 2 for horizontal polarization and the scan blindness phenomenon due to element-to-element coupling in the dipole antenna element 3 for vertical polarization caused by surface waves within the operating frequency band of the array antenna device.

[0043] The matching layer 12 is formed to cover the plurality of dipole antenna elements 2 for horizontal polarization and the plurality of dipole antenna elements 3 for vertical polarization on the surface of the dielectric substrate 1. The matching layer 12 improves the characteristics in low-frequency and wide-angle beam scanning in the horizontal polarization radiated from the plurality of dipole antenna elements 2 for horizontal polarization and the vertical polarization radiated from the plurality of dipole antenna elements 3 for vertical polarization. The matching layer 12 is a dielectric medium.

[0044] In addition, in the first embodiment, the matching layer 12 is a single dielectric layer, but it is not limited thereto. For example, a multilayer substrate may be used as the dielectric substrate 1 and a plurality of dielectric layers located in the upper layer may be used, or a metasurface obtained by etching a conductor pattern formed on the surface of the dielectric substrate 1 may also be used.

[0045] The dielectric substrate 1 has cavities 13 directly below the tip portions 21b, 31b of the ground arms 21, 31 of the plurality of dipole antenna elements 2, 3 and directly below the tip portions 22b, 32b of the feeding arms 22, 32 of the plurality of dipole antenna elements 2, 3. The cavities 13 are formed below the end portions of the ground arms 21, 31 where the short-circuit lines 7, 9 are not connected, that is, below the tip portions 21b, 31b, and below the end portions of the feeding arms 22, 32 where the feeding lines 8, 10 are not connected, that is, below the tip portions 2, 32b.

[0046] Each cavity 13 has a circular planar shape, as shown by the circular dashed lines in Figures 1 and 2, such that it includes the tip 21b of the ground arm 21 and the tip 22b of the feed arm 22 of adjacent horizontal polarization dipole antenna elements 2 in the row direction, and the tip 31b of the ground arm 31 and the tip 32b of the feed arm 32 of adjacent vertical polarization dipole antenna elements 3 located in the row and adjacent column between the adjacent horizontal polarization dipole antenna elements 2.

[0047] Each cavity 13, as shown in Figure 3, has an exposed surface on the back surface of the dielectric substrate 1 and is a bottomed cylindrical recess drilled from the back surface to the front surface. The relationship between the size of the cavity 13, the distance L (see Figure 3) between the feed line 8 connected to the feed arm 22 of one of the horizontally polarized dipole antenna elements 2 adjacent in the row direction on either side of the cavity 13 and the short-circuit line 7 connected to the ground arm 21 of the other dipole antenna element 2, and the distance L between the feed line 10 connected to the feed arm 32 of one of the vertically polarized dipole antenna elements 3 adjacent in the column direction on either side of the cavity 13 and the short-circuit line 9 connected to the ground arm 31 of the other dipole antenna element 3, satisfies the following equation (1).

[0048]

[0049] In the above equation (1), εr' is the equivalent relative permittivity determined by the relative permittivity of the dielectric substrate 1 and the relative permittivity within the cavity 13, and in Embodiment 1, by the relative permittivity of the air present in the cavity 13, c ０ is the speed of light, f ｈ This is the high-frequency end frequency, or upper limit frequency, within the operating frequency band of the array antenna device.

[0050] In this way, by providing the cavity 13 and lowering the equivalent relative permittivity εr' between the power supply line 8 and the short-circuit line 7 compared to the relative permittivity of the dielectric substrate 1, the resonance frequency fc of the common-mode resonance occurring in the power supply line 8 and the short-circuit line 7 can be shifted to a higher frequency. Furthermore, by lowering the equivalent relative permittivity εr' between the power supply line 10 and the short-circuit line 9 compared to the relative permittivity of the dielectric substrate 1, the resonance frequency fc of the common-mode resonance occurring in the power supply line 10 and the short-circuit line 9 can be shifted to a higher frequency.

[0051] In Embodiment 1, the cavity 13 is formed within the dielectric substrate 1 separated from the through-hole 11, but the cavity 13 and the through-hole 11 may be connected within the dielectric substrate 1. In short, any cavity 13 that can be determined to satisfy the above equation (1) is acceptable.

[0052] The common-mode resonance for a horizontally polarized dipole antenna element 2 adjacent in the row direction will be described. The common-mode resonance for a vertically polarized dipole antenna element 3 adjacent in the column direction is the same as that for a horizontally polarized dipole antenna element 2 adjacent in the row direction, so the explanation will be omitted.

[0053] The dipole antenna element 2 for horizontal polarization is a balanced antenna, and it is desirable that the currents flowing through the feed line 8 and the short-circuit line 7 that transmit the transmission signal to the dipole antenna element 2 for horizontal polarization be in opposite phase. However, when common-mode resonance occurs, strong in-phase currents is and ig flow through the feed line 8 and the short-circuit line 7, as shown by the arrows in Figure 5. As a result, the radiated power of the dipole antenna element 2 for horizontal polarization decreases significantly.

[0054] The resonant frequency f when common-mode resonance occurs. ｃ This can be expressed by the following equation (2).

[0055] In Embodiment 1, the size of the cavity 13 and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined to satisfy the above equation (1). Therefore, the resonant frequency fc in common-mode resonance occurs at a higher frequency than the upper limit frequency when the cavity 13 is not provided. As a result, the high-frequency edge f in the operating frequency band of the array antenna device is ｈ You can set it to a higher value.

[0056] resonance frequency f ｃ The high-frequency end frequency f ｈ It occurs at a higher frequency than that, that is, the resonant frequency f ｃ Since the common-mode resonance is shifted outside the high-frequency band of the operating frequency, no gain reduction due to common-mode resonance occurs within the operating frequency band of the array antenna device. Furthermore, because common-mode resonance does not occur within the operating frequency band of the array antenna device, even when the transmission signal is fed to a parallel two-wire line where the feed line 8 and the short-circuit line 7 are unbalanced microwave transmission lines, the operation of the array antenna device remains stable within its operating frequency band.

[0057] Next, the operation of the array antenna device according to Embodiment 1 will be described. A transmission signal for horizontal polarization is input to the signal input section 5 for horizontal polarization, and a transmission signal for vertical polarization is input to the signal input section for vertical polarization. The feed line 8 and short-circuit line 7 of each of the dipole antenna elements 2 for horizontal polarization operate as parallel two-wire lines, and the feed line 10 and short-circuit line 9 of each of the dipole antenna elements 3 for vertical polarization operate as parallel two-wire lines.

[0058] As a result, the power supplied to the horizontal polarization dipole antenna element 2 via the feed line 8 and the short-circuit line 7 excites the horizontal polarization dipole antenna element 2, and horizontal radio waves for horizontal polarization are radiated into space from the horizontal polarization dipole antenna element 2 via the matching layer 12. In addition, the power supplied to the vertical polarization dipole antenna element 3 via the feed line 10 and the short-circuit line 9 excites the vertical polarization dipole antenna element 3, and vertical radio waves for vertical polarization are radiated into space from the vertical polarization dipole antenna element 3 via the matching layer 12.

[0059] Since the size of the cavity 13 and the positions (distance L) of the feeding lines 8 and short - circuit lines 7 of the adjacent dipole antenna elements 2 and 3 and the positions (distance L) of the feeding line 10 and short - circuit line 9 are determined in a relationship satisfying the above formula (1), the high - frequency end frequency f in the operating frequency band of the array antenna device according to Embodiment 1 ｈ , that is, the upper - limit frequency can be set high, performance degradation due to common - mode resonance can be avoided, and broadband frequency characteristics can be obtained. Moreover, since only a cavity is formed in the dielectric substrate 1, the array antenna device according to Embodiment 1 has excellent manufacturability.

[0060] The array antenna device according to Embodiment 1 is an array antenna device including a plurality of dipole antenna elements 2 and 3 two - dimensionally arranged in a plane on the surface of a dielectric substrate. Since cavities 13 are provided directly below the tip portions 22b and 32b of the feeding arms 22 and 32 of each dipole antenna element 2 and 3 and directly below the tip portions 21b and 31b of the ground arms 21 and 31 of the dipole antenna elements 2 and 3, the resonance frequency fc of common - mode resonance can be shifted to a high frequency, and the high - frequency end frequency f in the operating frequency band of the array antenna device ｈ can be set high, performance degradation due to common - mode resonance can be avoided, and broadband frequency characteristics can be obtained.

[0061] Also, by making the plurality of dipole antenna elements 2 and 3 into closely - coupled dipole antenna elements, they function as an antenna in a wide frequency band. Further, since the product of the distance L between the feeding lines 8 and 10 and the short - circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 and the equivalent relative dielectric constant εr´ between the feeding lines 8 and 10 and the short - circuit lines 7 and 9 is determined to satisfy the above formula (1), the common - mode resonance generated at the frequency of a half - wavelength in the tube does not occur in the operating frequency band of the array antenna device between the feeding lines 8 and 10 and the short - circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3, and performance degradation due to common - mode resonance can be avoided.

[0062] In the array antenna device according to Embodiment 1, the parallel two-wire lines that supply the horizontal polarization transmission signals and vertical polarization transmission signals to the multiple horizontal polarization dipole antenna elements 2 and multiple vertical polarization dipole antenna elements 3 are via feed lines 8 and 10 and short-circuit lines 7 and 9, but for example, merchant baluns or strip lines may also be used.

[0063] Another Configuration Example 1 for Dipole Antenna Elements 2 and 3. Another configuration example 1 for the array antenna device according to Embodiment 1, consisting of multiple horizontally polarized dipole antenna elements 2 and multiple vertically polarized dipole antenna elements 3, will be explained with reference to Figure 6.

[0064] The array antenna device according to Embodiment 1 described above has multiple horizontally polarized dipole antenna elements 2 and multiple vertically polarized dipole antenna elements 3 formed on the same layer on the surface of a dielectric substrate 1, with the tips of adjacent horizontally polarized dipole antenna elements 2 brought close together to capacitively couple, and the tips of adjacent vertically polarized dipole antenna elements 3 brought close together to capacitively couple.

[0065] In contrast, the array antenna device according to the other configuration example 1 differs in that multiple dipole antenna elements 2 for horizontal polarization and multiple dipole antenna elements 3 for vertical polarization are formed in two layers on the surface of the dielectric substrate 1, and in other respects it is the same as the array antenna device according to Embodiment 1 described above.

[0066] Since the multiple horizontal polarization dipole antenna elements 2 and the multiple vertical polarization dipole antenna elements 3 are arranged in basically the same configuration, we will explain using the horizontal polarization dipole antenna elements 2 as an example. In Figure 6, the same reference numerals as those used in Figures 1 to 3 indicate the same or equivalent parts.

[0067] The dielectric substrate 1 is a multilayer substrate having two layers on its surface. Multiple horizontal polarization dipole antenna elements 2 arranged in the row direction are formed alternately on the surface of the upper layer 1a and the surface of the lower layer 1b on the surface of the dielectric substrate 1. As shown in Figure 6, of adjacent horizontal polarization dipole antenna elements 2 arranged in the row direction, one dipole antenna element 2 is formed on the surface of the upper layer 1a on the surface of the dielectric substrate 1, and the other dipole antenna element 2 is formed on the surface of the lower layer 1b on the surface of the dielectric substrate 1.

[0068] The tip 22b of the feed arm 22 of one dipole antenna element 2 and the tip 21b of the ground arm 21 of the other dipole antenna element 2 overlap in the vertical direction, and capacitive coupling occurs at the overlapping portion of the tip 22b of the feed arm 22 of one dipole antenna element 2 and the tip 21b of the ground arm 21 of the other dipole antenna element 2.

[0069] In the array antenna device according to the other configuration example 1 described above, a planar tightly coupled dipole array antenna with orthogonal dual polarization is configured, similar to the array antenna device according to Embodiment 1 described above, and has the same effects.

[0070] Another configuration example 2 for dipole antenna elements 2 and 3. Another configuration example 2 for the multiple horizontally polarized dipole antenna elements 2 and multiple vertically polarized dipole antenna elements 3 in the array antenna device according to Embodiment 1 will be explained with reference to Figure 7.

[0071] The array antenna device according to the other configuration example 2 differs in that the tips of adjacent horizontal polarization dipole antenna elements 2 in a plurality of horizontal polarization dipole antenna elements 2 are capacitively coupled by a capacitive coupling element 14, and the tips of adjacent vertical polarization dipole antenna elements 3 in a plurality of vertical polarization dipole antenna elements 3 are capacitively coupled by a capacitive coupling element, but in other respects it is the same as the array antenna device according to Embodiment 1 described above.

[0072] Since the multiple horizontal polarization dipole antenna elements 2 and the multiple vertical polarization dipole antenna elements 3 are arranged in basically the same configuration, we will explain using the horizontal polarization dipole antenna elements 2 as an example. In Figure 7, the same reference numerals as those used in Figures 1 to 3 indicate the same or equivalent parts.

[0073] The dielectric substrate 1 is a multilayer substrate having two layers on its surface. Multiple horizontal polarization dipole antenna elements 2 arranged in the row direction are formed on the surface of the lower layer 1b on the dielectric substrate 1. Capacitive coupling elements 14 are formed on the surface of the upper layer 1a on the dielectric substrate 1.

[0074] One end of the capacitive coupling element 14 in the row direction overlaps vertically with the tip 22b of the feed arm 22 of one dipole antenna element 2. The other end of the capacitive coupling element 14 in the row direction overlaps vertically with the tip 21b of the ground arm 21 of the other dipole antenna element 2.

[0075] The tip 22b of the feed arm 22 of one dipole antenna element 2 and the tip 21b of the ground arm 21 of the other dipole antenna element 2 are capacitively coupled via a capacitive coupling element 14.

[0076] In the array antenna device according to the other configuration example 2 described above, a planar tightly coupled dipole array antenna with orthogonal bipolarization is configured, similar to the array antenna device according to Embodiment 1 described above, and has the same effects.

[0077] Another embodiment 1 of the cavity 13. Another embodiment 1 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 8. Each cavity 13 in the array antenna device according to Embodiment 1 described above is a bottomed cylindrical recess that has an exposed surface on the back surface of the dielectric substrate 1 and is drilled from the back surface to the front surface.

[0078] In contrast, each cavity 13 in the other embodiment 1 has an exposed surface on the back surface of the dielectric substrate 1 and is a conical recess drilled from the back surface to the front surface. In the array antenna device according to the other embodiment 1, the size of the cavity 13 and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined in a relationship that satisfies the above equation (1). Note that in Figure 8, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0079] In the array antenna device according to this other embodiment 1, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0080] Another embodiment 2 of the cavity 13. Another embodiment 2 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 9. In the other embodiment 2, each cavity 13 has an exposed surface on the back surface of the dielectric substrate 1 and is a cylindrical shape and a conical shape connected to the cylindrical shape drilled from the back surface to the front surface.

[0081] In the array antenna device according to the other embodiment 2, the size of the cavity 13 and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined to satisfy the above equation (1). In Figure 9, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0082] In the array antenna device according to the other embodiment 2 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0083] Another embodiment 3 of the cavity 13. Another embodiment 3 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 10. In each of the other embodiment 3, each cavity 13 has a configuration in which, in the region including the tip 21b of the ground arm 21 and the tip 22b of the feed arm 22 of adjacent horizontal polarization dipole antenna elements 2 in the row direction, and the tip 31b of the ground arm 31 and the tip 32b of the feed arm 32 of adjacent vertical polarization dipole antenna elements 3 located in the row between the adjacent horizontal polarization dipole antenna elements 2 and in adjacent columns, there are multiple bottomed cylindrical recesses on the back surface of the dielectric substrate 1, with an exposed surface to the dielectric substrate 1 and drilled from the back surface to the front surface.

[0084] In the array antenna device according to the other embodiment 3, the number and size of the recesses constituting the cavity 13 and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined in a relationship that satisfies the above equation (1). In Figure 10, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0085] In the array antenna device according to the other embodiment 3 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0086] Another Embodiment 4 of the Cavity 13. Another embodiment 4 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 11. In each cavity 13 of the other embodiment 4, multiple rectangular parallelepiped spaces are arranged in the vertical and horizontal directions parallel to the surface of the dielectric substrate 1 in a region that includes the tip 21b of the ground arm 21 and the tip 22b of the feed arm 22 of adjacent horizontal polarization dipole antenna elements 2 in the row direction, and the tip 31b of the ground arm 31 and the tip 32b of the feed arm 32 of adjacent vertical polarization dipole antenna elements 3 located in the row and adjacent column between the adjacent horizontal polarization dipole antenna elements 2.

[0087] In the array antenna device according to the other embodiment 4, the number and size of the rectangular parallelepiped spaces constituting the cavity 13, and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined in a relationship that satisfies equation (1) above. In Figure 11, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0088] In the array antenna device according to the other embodiment 4 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0089] Another embodiment 5 of the cavity 13. Another embodiment 5 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 12. Each cavity 13 in the array antenna device according to Embodiment 1 described above is a bottomed cylindrical recess that has an exposed surface on the back surface of the dielectric substrate 1 and is drilled from the back surface to the front surface.

[0090] In contrast, the array antenna device according to the other embodiment 5 differs from the array antenna device according to embodiment 1 described above in that each cavity 13 contains a dielectric 15 with a relative permittivity lower than that of the dielectric substrate 1, but is otherwise the same. The dielectric 15 is positioned in the center of the cavity 13 in a planar view and is cylindrical in shape. The upper surface of the dielectric 15 is in contact with the bottom of the cavity 13 in the dielectric substrate 1, and the lower surface of the dielectric 15 is in contact with the surface of the ground conductor 4. In Figure 12, the same reference numerals as those in Figures 1 to 3 indicate the same or corresponding parts.

[0091] In the array antenna device according to another embodiment 5, the size of the cavity 13 and the size of the dielectric 15, as well as the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3, are determined to satisfy the above equation (1). In the above equation (1), the equivalent relative permittivity εr' is the relative permittivity determined by the relative permittivity of the dielectric substrate 1, the relative permittivity of the air present in the cavity 13, and the relative permittivity of the dielectric 15 arranged in the cavity 13.

[0092] In the array antenna device according to the other embodiment 5 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0093] Another Embodiment 6 of the Cavity 13. Another embodiment 6 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 13. In the array antenna device according to Another Embodiment 6, the dielectric 15, which has a relative permittivity lower than that of the dielectric substrate 1 arranged in each cavity 13, is cylindrical in shape and is located in the center of the cavity 13 in a plane, with the lower surface of the dielectric 15 in contact with the surface of the ground conductor 4, and there is a gap between the upper surface of the dielectric 15 and the bottom of the cavity 13 in the dielectric substrate 1. In Figure 13, the same reference numerals as those in Figures 1 to 3 indicate the same or corresponding parts.

[0094] In the array antenna device according to the other embodiment 6, the size of the cavity 13, the size of the dielectric 15, and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined in a relationship that satisfies equation (1) above. In equation (1) above, the equivalent relative permittivity εr' is the relative permittivity determined by the relative permittivity of the dielectric substrate 1, the relative permittivity of the air present in the cavity 13, and the relative permittivity of the dielectric 15 arranged in the cavity 13.

[0095] In the array antenna device according to the other embodiment 6 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0096] Another Embodiment 7 of the Cavity 13. Another embodiment 7 of the multiple cavities 13 in the array antenna device according to Embodiment 1 will be described with reference to Figure 14. In the array antenna device according to Another Embodiment 7, each cavity 13 is filled with a dielectric 15 having a relative permittivity lower than that of the dielectric substrate 1. In Figure 14, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0097] In the array antenna device according to another embodiment 7, the size of the dielectric 15 and the positions of the feed lines 8 and 10 and short-circuit lines 7 and 9 of the adjacent dipole antenna elements 2 and 3 are determined in such a relationship that satisfies equation (1) above. In equation (1) above, the equivalent relative permittivity εr' is the relative permittivity determined by the relative permittivity of the dielectric substrate 1 and the relative permittivity of the dielectric 15 filled in the cavity 13.

[0098] In the array antenna device according to the other embodiment 7 configured in this way, the resonance frequency fc of the common-mode resonance can be shifted to a higher frequency, similar to the array antenna device according to embodiment 1 described above, and has the same effect as the array antenna device according to embodiment 1 described above.

[0099] Embodiment 2. The array antenna device according to Embodiment 2 will be described with reference to Figure 15. In the array antenna device according to Embodiment 2, the top view obtained by passing through the matching layer 12 is substantially the same as the top view obtained by passing through the matching layer 12 in the array antenna device according to Embodiment 1. Therefore, in the following description, Figure 1 will be used with reference.

[0100] In the array antenna device according to Embodiment 1, each feed line 8, 10 and each short-circuit line 7, 9 are vias of the same diameter that penetrate the dielectric substrate 1, and the ground conductor 4 in the array antenna device according to Embodiment 1 has the same thickness throughout. In contrast, in the array antenna device according to Embodiment 2, each feed line 8, 10 and each short-circuit line 7, 9 are vias of different diameters, each feed line 8, 10 and each short-circuit line 7, 9 are connected to a short-circuit matching element 16 and a feed-side matching element 17, and the ground conductor 4 has a second cavity 18 that communicates with the cavity 13. Other aspects are the same as the array antenna device according to Embodiment 1.

[0101] In the following description, we will focus on the differences between this array antenna device and the one according to Embodiment 1. In Figure 15, the same reference numerals as those used in Figures 1 to 3 indicate the same or corresponding parts.

[0102] The short-circuit line 7 for horizontal polarization is formed by vias having a cylindrical large-diameter portion 7a and a cylindrical small-diameter portion 7b that is continuous from one end of the large-diameter portion 7a. The other end of the large-diameter portion 7a of the short-circuit line 7 is electrically connected to the ground conductor 4. One end of the small-diameter portion 7b of the short-circuit line 7 is electrically connected to the base portion 21a of the grounding arm 21 of the corresponding horizontal polarization dipole antenna element 2. In other words, the short-circuit line 7 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a small-diameter portion 7b at the end that connects to the grounding arm 21 of the dipole antenna element 2.

[0103] The feed line 8 for horizontal polarization is formed by vias having a cylindrical large-diameter portion 8a and a cylindrical small-diameter portion 8b that is continuous from one end of the large-diameter portion 8a. The other end of the large-diameter portion 8a of the feed line 8 is electrically connected to the corresponding horizontal polarization signal input section 5. One end of the small-diameter portion 8b of the feed line 8 is electrically connected to the base portion 22a of the feed arm 22 of the corresponding horizontal polarization dipole antenna element 2. In other words, the feed line 8 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a small-diameter portion 8b at the end that connects to the feed arm 22 of the dipole antenna element 2.

[0104] The short-circuit line 9 for vertical polarization is formed by vias having a cylindrical large-diameter section and a cylindrical small-diameter section continuous from one end of the large-diameter section. The other end of the large-diameter section of the short-circuit line 9 is electrically connected to the ground conductor 4. One end of the small-diameter section of the short-circuit line 9 is electrically connected to the base 31a of the ground arm 31 of the corresponding vertical-polarization dipole antenna element 3. In other words, the short-circuit line 9 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a small-diameter section at the end that connects to the ground arm 31 of the dipole antenna element 3.

[0105] The feed line 10 for vertical polarization is formed by vias having a cylindrical large-diameter section and a cylindrical small-diameter section continuous from one end of the large-diameter section. The other end of the large-diameter section of the feed line 10 is electrically connected to the corresponding signal input section for vertical polarization. One end of the small-diameter section of the feed line 10 is electrically connected to the base 32a of the feed arm 32 of the corresponding vertical polarization dipole antenna element 3. In other words, the feed line 10 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a small-diameter section at the end that connects to the feed arm 32 of the dipole antenna element 3.

[0106] The electrical connections between the short-circuit line 7 and the base 21a of the grounding arm 21, the electrical connections between the power supply line 8 and the base 22a of the power supply arm 22, the electrical connections between the short-circuit line 9 and the base 31a of the grounding arm 31, and the electrical connections between the power supply line 10 and the base 32a of the power supply arm 32 are all made by the small-diameter portion of the via, resulting in a small land diameter in each via and avoiding mismatches due to parallel capacitance between land patterns.

[0107] In the short-circuit line 7 and feed line 8 corresponding to each of the multiple horizontal polarization dipole antenna elements 2, a short-circuit matching element 16 is formed, electrically connected to the large-diameter portion 7a of the short-circuit line 7 and projecting toward the feed line 8 along the direction of travel, and a feed-side matching element 17 is formed, electrically connected to the large-diameter portion 8a of the feed line 8 and projecting toward the short-circuit line 7 along the direction of travel. The short-circuit matching element 16 and the feed-side matching element 17 are conductors. The short-circuit matching element 16 and the feed-side matching element 17 are arranged opposite each other and are capacitively coupled.

[0108] In the short-circuit line 9 and feed line 10 corresponding to each of the multiple vertical polarization dipole antenna elements 3, a short-circuit matching element is formed that is electrically connected to the large-diameter portion of the short-circuit line 9 and protrudes toward the feed line 10 along the column direction, and a feed-side matching element is formed that is electrically connected to the large-diameter portion of the feed line 10 and protrudes toward the short-circuit line 9 along the column direction. The short-circuit matching element and the feed-side matching element are conductors. The short-circuit matching element and the feed-side matching element are arranged opposite each other and are capacitively coupled.

[0109] The characteristic impedance Za of the parallel two-wire transmission line consisting of the power supply line 8 and the short-circuit line 7 can be expressed by the following equation (3).

[0110] In equation (3) above, εr is the relative permittivity of the dielectric substrate 1, d is the distance between the central axis of the feed line 8 and the central axis of the short-circuit line 7 or the distance between the central axis of the feed line 10 and the central axis of the short-circuit line 9, and φ is the diameter of the feed lines 8, 10 and the short-circuit lines 7, 9. As is clear from equation (3) above, the smaller the diameter φ of the feed line 8 and the short-circuit line 7, and the larger the distance d between the central axis of the feed line 8 and the central axis of the short-circuit line 7, the higher the characteristic impedance Za of the parallel two-wire line formed by the feed line 8 and the short-circuit line 7. Also, the smaller the diameter φ of the feed line 10 and the short-circuit line 9, and the larger the distance d between the central axis of the feed line 10 and the central axis of the short-circuit line 9, the higher the characteristic impedance Za of the parallel two-wire line formed by the feed line 10 and the short-circuit line 9.

[0111] In Embodiment 2, the feed line 8 has a large-diameter section 8a and a small-diameter section 8b with different diameters, and the short-circuit line 7 has a large-diameter section 7a and a small-diameter section 7b with different diameters. Therefore, the characteristic impedance Za of the parallel two-wire line formed by the feed line 8 and the short-circuit line 7 can be adjusted in the vertical direction, that is, in the front-back direction of the dielectric substrate 1. Furthermore, since parallel capacitance can be added to the feed line 8 and the short-circuit line 7 that constitute the parallel two-wire line by the short-circuit side matching element 16 and the feed side matching element 17, matching between the parallel two-wire line formed by the feed line 8 and the short-circuit line 7 and the coaxial structure including the dipole antenna element 2 for horizontal polarization and the signal input section 5 is easily achieved.

[0112] Furthermore, since the feed line 10 has a large-diameter section and a small-diameter section with different diameters, and the short-circuit line 9 has a large-diameter section and a small-diameter section with different diameters, the characteristic impedance Za of the parallel two-wire line formed by the feed line 10 and the short-circuit line 9 can be adjusted in the vertical direction. In addition, since parallel capacitance can be added to the feed line 10 and the short-circuit line 9 that constitute the parallel two-wire line by the short-circuit side matching element and the feed side matching element, it is easy to match the parallel two-wire line formed by the feed line 10 and the short-circuit line 9 with the coaxial structure including the dipole antenna element 3 for vertical waves and the signal input section.

[0113] The ground conductor 4 has a bottomed second cavity 18 that communicates with the cavity 13. The central axis of the second cavity 18 is coaxial with the central axis of the cavity 13. The second cavity 18 is a bottomed cylindrical recess drilled from the surface to the back side of the ground conductor 4, with a smaller diameter and a circular planar shape than the cavity 13.

[0114] Now, the loop mode current when a second cavity 18 is not formed in the ground conductor 4 will be explained using Figure 16. When loop mode resonance occurs, a loop mode current flows through adjacent horizontal polarization dipole antenna elements 2, as shown by the arrows in Figure 16, from the feed line 8 connected to the feed arm 22 of one horizontal polarization dipole antenna element 2 → the feed arm 22 of one horizontal polarization dipole antenna element 2 → the ground arm 21 of the other horizontal polarization dipole antenna element 2 → the short-circuit line 7 connected to the ground arm 21 of the other horizontal polarization dipole antenna element 2 → the ground conductor 4 → the feed line 8 connected to the feed arm 22 of one horizontal polarization dipole antenna element 2.

[0115] The loop mode current is strongly excited when loop mode resonance occurs, significantly reducing the radiated power of the dipole antenna element 2 for horizontal polarization. Furthermore, the low operating frequency of the array antenna system may be limited by the loop mode current.

[0116] The array antenna device according to Embodiment 2 has a second cavity 18 in which the ground conductor 4 communicates with the cavity 13 in the loop mode current generation path, thereby shifting the frequency at which loop mode resonance occurs to a lower frequency. As a result, the lower limit frequency of the low frequency range in the operating frequency band for horizontal polarization of the array antenna device can be set lower.

[0117] Furthermore, the second cavity 18 does not need to be in communication with cavity 13, and only needs to be formed in the loop mode current generation path, that is, it needs to be formed in the region of the ground conductor 4 located between the short-circuit line 7 electrically connected to the ground arm 21 of one of the adjacent horizontal polarization dipole antenna elements 2 and the feed line 8 electrically connected to the feed arm 22 of the other of the adjacent horizontal polarization dipole antenna elements 2.

[0118] Similarly, in the adjacent vertical polarization dipole antenna element 3, the ground conductor 4 has a second cavity in the loop mode current generation path that communicates with the cavity 13, thereby shifting the frequency at which loop mode resonance occurs to a lower frequency. As a result, the lower limit frequency of the low-frequency range in the operating frequency band for vertical polarization of the array antenna device can be set lower. Note that, even on the vertical polarization side, the second cavity 18 does not need to communicate with cavity 13, but only needs to be formed in the loop mode current generation path.

[0119] The array antenna device according to Embodiment 2 has the same effects as the array antenna device according to Embodiment 1. In addition, the short-circuit lines 7 and 9 have small-diameter sections 7b at the ends that connect to the grounding arms 21 and 31 of the dipole antenna elements 2 and 3, and the feed lines 8 and 10 have small-diameter sections 8b at the ends that connect to the feed arms 22 and 32 of the dipole antenna elements 2 and 3. As a result, the diameter of the lands for the short-circuit lines 7 and 9 and the feed lines 8 and 10 is small, and mismatches due to parallel capacitance between land patterns are avoided.

[0120] Furthermore, in the array antenna device according to Embodiment 2, since the short-circuit lines 7 and 9 and the feed lines 8 and 10 each have different diameters in the front-back direction of the dielectric substrate 1, the characteristic impedance Za of the parallel two-wire line provided by the feed lines 8 and 10 and the short-circuit lines 7 and 9 can be adjusted in the front-back direction of the dielectric substrate 1.

[0121] Furthermore, the array antenna device according to Embodiment 2 has short-circuit matching elements 16 electrically connected to the short-circuit matching elements 7 and 9, and feed lines 8 and 10 corresponding to the dipole antenna elements 2 and 3, respectively, and feed line 17 electrically connected to the feed line 8 and 10 and positioned opposite the short-circuit matching elements 16 that are electrically connected to the short-circuit matching elements 16 that are electrically connected to the short-circuit matching elements 7 and 9, and capacitively coupled to them. As a result, parallel capacitance can be added to the feed lines 8 and 10 and the short-circuit matching elements 7 and 9 that constitute the parallel two-wire line, making it easy to match the parallel two-wire line formed by the feed lines 8 and 10 and the short-circuit matching elements 7 and 9 with the coaxial structure including the dipole antenna element 2 and the signal input section 5.

[0122] Furthermore, since the array antenna device according to Embodiment 2 has a second cavity 18 in which the ground conductor 4 communicates with the cavity 13, the resonant frequency of loop mode resonance can be shifted to a lower frequency range, the lower limit frequency in the low frequency range of the operating frequency band of the array antenna device can be set lower, performance degradation due to loop mode resonance can be avoided, and a wideband frequency characteristic can be obtained.

[0123] In the array antenna device according to Embodiment 2, each short-circuit line 7, 9 and each feed line 8, 10 have a shape having two different diameters, a large diameter section and a small diameter section. However, the dielectric substrate 1 may have a shape having three different diameters, a large diameter section, a medium diameter section, and a small diameter section, or even a shape having four or more different diameters, starting from the back side.

[0124] Another Embodiment 1 of Short-Circuit Lines 7, 9 and Feed Lines 8, 10 Another embodiment 1 of the multiple short-circuit lines 7, 9 and feed lines 8, 10 in the array antenna device according to Embodiment 2 will be described with reference to Figure 17. In the array antenna device according to Embodiment 2 described above, each short-circuit line 7, 9 and each feed line 8, 10 is formed by vias having cylindrical large-diameter portions 7a, 8a and cylindrical small-diameter portions 7b, 8b.

[0125] In contrast, the short-circuit lines 7, 9 and feed lines 8, 10 in the other embodiment 1 differ in that they are formed by vias having a cylindrical large-diameter section and a frustoconical small-diameter section, but in other respects they are the same as the array antenna device according to embodiment 2 described above. Since the short-circuit lines 7 and feed lines 8 for horizontal polarization and the short-circuit lines 9 and feed lines 10 for vertical polarization have basically the same configuration, the short-circuit lines 7 and feed lines 8 for horizontal polarization will be used as an example for explanation. In Figure 17, the same reference numerals as those in Figures 1 and 15 indicate the same or corresponding parts.

[0126] The short-circuit line 7 for horizontal polarization is formed by vias having a cylindrical large-diameter portion 7a and a tapered, frustoconical small-diameter portion 7b that is continuous from one end of the large-diameter portion 7a. The other end of the large-diameter portion 7a of the short-circuit line 7 is electrically connected to the ground conductor 4. One end of the small-diameter portion 7b of the short-circuit line 7 is electrically connected to the base 21a of the grounding arm 21 of the corresponding horizontal polarization dipole antenna element 2. In other words, the short-circuit line 7 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a tapered, frustoconical small-diameter portion 7b at the end that connects to the grounding arm 21 of the dipole antenna element 2.

[0127] The feed line 8 for horizontal polarization is formed by vias having a cylindrical large-diameter portion 8a and a tapered, frustoconical small-diameter portion 8b that is continuous from one end of the large-diameter portion 8a. The other end of the large-diameter portion 8a of the feed line 8 is electrically connected to the corresponding horizontal polarization signal input portion 5. One end of the small-diameter portion 8b of the feed line 8 is electrically connected to the base portion 22a of the feed arm 22 of the corresponding horizontal polarization dipole antenna element 2. In other words, the feed line 8 has vias extending from the front to the back surface of the dielectric substrate 1, and these vias have a tapered, frustoconical small-diameter portion 8b at the end that connects to the feed arm 22 of the dipole antenna element 2.

[0128] In the array antenna device according to this other embodiment 1, similar to the array antenna device according to embodiment 2 described above, the land diameters for the short-circuit lines 7 and 9 and the feed lines 8 and 10 are small, mismatches due to parallel capacitance between land patterns can be avoided, and the device has the same effects as the array antenna device according to embodiment 1 described above.

[0129] Another Embodiment 2 of Short-Circuit Lines 7, 9 and Feed Lines 8, 10 Another embodiment 2 of the multiple short-circuit lines 7, 9 and feed lines 8, 10 in the array antenna device according to Embodiment 2 will be described with reference to Figure 18. Each short-circuit line 7, 9 and each feed line 8, 10 in Another Embodiment 2 differs in that they are formed by vias that are tapered frustoconical in shape from a large diameter to a small diameter, and in other respects they are the same as the array antenna device according to Embodiment 2 described above. Since each short-circuit line 7 and each feed line 8 for horizontal polarization and each short-circuit line 9 and each feed line 10 for vertical polarization have basically the same configuration, the short-circuit line 7 and each feed line 8 for horizontal polarization will be used as an example for explanation. In Figure 18, the same reference numerals as those in Figures 1 and 15 indicate the same or corresponding parts.

[0130] The short-circuit line 7 for horizontal polarization is formed by a via having a large-diameter, frustoconical portion 7a and a tapered, small-diameter, frustoconical portion 7b that is continuous from one end of the large-diameter portion 7a. In other words, it is a via that is tapered, frustoconical in shape from the large-diameter portion 7a to the small-diameter portion 7b. The other end of the large-diameter portion 7a of the short-circuit line 7 is electrically connected to the ground conductor 4. One end of the small-diameter portion 7b of the short-circuit line 7 is electrically connected to the base 21a of the ground arm 21 of the corresponding horizontal polarization dipole antenna element 2. In other words, the short-circuit line 7 has a continuous, tapered, frustoconical via extending from the front to the back surface of the dielectric substrate 1, and the end of the via that connects to the ground arm 21 of the dipole antenna element 2 is tapered.

[0131] The feed line 8 for horizontal polarization is formed by a via having a large-diameter, frustoconical portion 8a and a tapered, small-diameter, frustoconical portion 8b that is continuous from one end of the large-diameter portion 8a. In other words, it is a continuous, tapered, frustoconical via from the large-diameter portion 8a to the small-diameter portion 8b. The other end of the large-diameter portion 8a of the feed line 8 is electrically connected to the corresponding horizontal polarization signal input section 5. One end of the small-diameter portion 8b of the feed line 8 is electrically connected to the base 22a of the feed arm 22 of the corresponding horizontal polarization dipole antenna element 2. In other words, the feed line 8 has a continuous, tapered, frustoconical via extending from the front to the back surface of the dielectric substrate 1, and the end of the via that connects to the feed arm 22 of the dipole antenna element 2 is tapered.

[0132] In the array antenna device according to the other embodiment 2 configured in this way, similar to the array antenna device according to embodiment 2 described above, the land diameters for the short-circuit lines 7 and 9 and the feed lines 8 and 10 are small, mismatches due to parallel capacitance between land patterns can be avoided, and it has the same effects as the array antenna device according to embodiment 1 described above.

[0133] Another embodiment 1 of the short-circuit matching element 16 and feed-side matching element 17. Another embodiment 1 of the multiple short-circuit matching elements 16 and multiple feed-side matching elements 17 in the array antenna device according to Embodiment 2 will be described with reference to Figure 19. In the array antenna device according to Embodiment 2 described above, in the short-circuit lines 7, 9 and feed lines 8, 10 corresponding to each of the multiple dipole antenna elements 2, 3, there is one short-circuit matching element 16 and one feed-side matching element 17 that are arranged opposite each other and capacitively coupled.

[0134] In this configuration, the short-circuit matching element 16 and the power supply matching element 17, which are arranged opposite each other and capacitively coupled in another embodiment 1, consist of two elements. However, there may be more than two elements. The short-circuit matching element 16 and power supply matching element 17 for horizontal polarization and the short-circuit matching element and power supply matching element for vertical polarization have basically the same configuration, so the short-circuit matching element 16 and power supply matching element 17 for horizontal polarization will be used as an example for explanation. In Figure 19, the same reference numerals as those used in Figures 1 and 15 indicate the same or corresponding parts.

[0135] In the short-circuit line 7 and feed line 8 corresponding to each of the multiple horizontal polarization dipole antenna elements 2, two short-circuit matching elements 16 are formed, electrically connected to the large-diameter portion 7a of the short-circuit line 7 and protruding toward the feed line 8 along the direction of travel, and two feed-side matching elements 17 are formed, electrically connected to the large-diameter portion 8a of the feed line 8 and protruding toward the short-circuit line 7 along the direction of travel.

[0136] The two short-circuit matching elements 16 and the two power-feed matching elements 17 are conductors. One of the two short-circuit matching elements 16 and one of the two power-feed matching elements 17 are positioned opposite each other on the same plane, and the two short-circuit matching elements 16 and the one power-feed matching element 17 are capacitively coupled. The other short-circuit matching element 16 and the other power-feed matching element 17 are positioned opposite each other on the same plane, and the two short-circuit matching elements 16 and the other power-feed matching element 17 are capacitively coupled.

[0137] In the array antenna device according to another embodiment 1 configured in this way, parallel capacitance can be added to the feed lines 8, 10 and short-circuit lines 7, 9 that constitute the parallel two-wire line, similar to the array antenna device according to embodiment 2 described above. Therefore, matching between the parallel two-wire line formed by the feed lines 8, 10 and short-circuit lines 7, 9 and the coaxial structure including the dipole antenna element 2 and the signal input section 5 is easy, and it has the same effects as the array antenna device according to embodiment 2 described above.

[0138] Another Embodiment 2 of the Short-Circuit Matching Element 16 and Feed-Circuit Matching Element 17 Another embodiment 2 of the multiple short-circuit matching elements 16 and multiple feed-circuit matching elements 17 in the array antenna device according to Embodiment 2 will be described with reference to Figure 20. In the other embodiment 1 of the short-circuit matching element 16 and feed-circuit matching element 17, one of the two short-circuit matching elements 16 and one of the two feed-circuit matching elements 17 are arranged opposite each other on the same plane, and the other short-circuit matching element 16 of the two short-circuit matching elements 16 and the other feed-circuit matching element 17 are arranged opposite each other on the same plane.

[0139] In contrast, in another embodiment 2 of the short-circuit matching element 16 and the power supply matching element 17, one of the two short-circuit matching elements 16 and one of the two power supply matching elements 17 are arranged opposite each other on different planes and capacitively coupled, while the other of the two short-circuit matching elements 16 and the other of the two power supply matching elements 17 are arranged opposite each other on different planes and capacitively coupled. The short-circuit matching element 16 and power supply matching element 17 for horizontal polarization and the short-circuit matching element and power supply matching element for vertical polarization have basically the same configuration, so their explanation is omitted. Note that in Figure 20, the same reference numerals as those in Figures 1, 15, and 20 indicate the same or corresponding parts.

[0140] In the array antenna device according to another embodiment 2 configured in this manner, parallel capacitance can be added to the feed lines 8, 10 and short-circuit lines 7, 9 that constitute the parallel two-wire line, similar to the array antenna device according to embodiment 2 described above. Therefore, matching between the parallel two-wire line formed by the feed lines 8, 10 and short-circuit lines 7, 9 and the coaxial structure including the dipole antenna element 2 and the signal input section 5 is easy, and it has the same effects as the array antenna device according to embodiment 2 described above.

[0141] Another embodiment of the second cavity 18. Another embodiment of the second cavity 18 in the array antenna device according to Embodiment 2 will be described with reference to Figure 21.

[0142] The array antenna device according to Embodiment 2, which is another embodiment 1 of the second cavity 18, differs from the array antenna device according to Embodiment 2 described above in that it has a dielectric 19 with a relative permittivity lower than that of the dielectric substrate 1 within the second cavity 18, while other aspects are the same as the array antenna device according to Embodiment 2 described above. In Figure 21, the same reference numerals as those in Figures 1 and 15 indicate the same or corresponding parts.

[0143] In the array antenna device according to this other embodiment 1, similar to the array antenna device according to embodiment 2 described above, the ground conductor 4 has a second cavity in the loop mode current generation path, so the frequency at which loop mode resonance occurs is shifted to a lower frequency, and the lower limit frequency of the low frequency range in the operating frequency band of the array antenna device can be set lower, thus having the same effect as the array antenna device according to embodiment 1 described above.

[0144] Another embodiment of the second cavity 18. Another embodiment of the second cavity 18 in the array antenna device according to Embodiment 2 will be described with reference to Figure 22. In the array antenna device according to Embodiment 2 described above, the second cavity 18 is formed by a single bottomed cylindrical recess that communicates with the cavity 13.

[0145] In contrast, the second cavity 18 in the other embodiment 2 is formed using a plurality of bottomed cylindrical recesses that communicate with the cavity 13. In the array antenna device according to the other embodiment 1 configured in this way, as with the array antenna device according to embodiment 2 described above, the ground conductor 4 has a second cavity in the loop mode current generation path, so the frequency at which loop mode resonance occurs is shifted to a lower frequency, and the lower limit frequency of the low frequency in the operating frequency band of the array antenna device can be set lower, thus having the same effect as the array antenna device according to embodiment 1 described above.

[0146] Furthermore, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component of each embodiment.

[0147] The array antenna device described herein is applicable to array antenna devices used in wireless communication systems, satellite systems, or radar systems.

[0148] 1 Dielectric substrate, 2 Dipole antenna element for horizontal polarization, 21 Ground arm, 21a Base, 21b Tip, 22 Feed arm, 22a Base, 22b Tip, 3 Dipole antenna element for vertical polarization, 31 Ground arm, 31a Base, 31b Tip, 32 Feed arm, 32a Base, 32b Tip, 4 Ground conductor, 5 Signal input section, 7 Short circuit line, 8 Feed line, 9 Short circuit line, 10 Feed line, 11 Through hole, 12 Matching layer, 13 Cavity, 14 Dielectric, 15 Dielectric, 16 Short circuit matching element, 17 Feed circuit matching element, 18 Second cavity, 19 Dielectric.

Claims

1. An array antenna device comprising a dielectric substrate, a plurality of dipole antenna elements having feeding arms and grounding arms arranged in a two-dimensional plane on the surface of the dielectric substrate, a ground conductor formed on the back surface of the dielectric substrate to which the grounding arms of the plurality of dipole antenna elements are electrically connected via short-circuit lines corresponding to the grounding arms, and a plurality of signal input sections on the back surface of the dielectric substrate corresponding to each of the feeding arms of the plurality of dipole antenna elements, each of which is electrically connected via a feeding line corresponding to the feeding arm, wherein the dielectric substrate has cavities directly below the tips of each of the feeding arms of the plurality of dipole antenna elements and directly below the tips of each of the grounding arms of the plurality of dipole antenna elements.

2. The array antenna device according to claim 1, wherein the distance L between the feed line connected to the feed arm of one of the adjacent dipole antenna elements among the plurality of dipole antenna elements and the short-circuit line connected to the ground arm of the other dipole antenna element satisfies the following equation (1). However, in equation (1) above, εr' is the equivalent relative permittivity determined by the relative permittivity of the dielectric substrate and the relative permittivity in the cavity, c ０ is the speed of light, f ｈ This is the high-frequency edge of the operating frequency band of the array antenna device.

3. The array antenna device according to claim 1 or claim 2, wherein the cavity is a bottomed recess drilled from the back surface to the front surface of the dielectric substrate.

4. The array antenna device according to any one of claims 1 to 3, wherein the cavity contains a dielectric having a relative permittivity lower than that of the dielectric substrate.

5. The array antenna device according to any one of claims 1 to 4, wherein the short-circuit line has vias extending from the front surface to the back surface of the dielectric substrate, and the via has a small diameter portion at the end connected to the ground arm of the dipole antenna element, and the feed line has vias extending from the front surface to the back surface of the dielectric substrate, and the via has a small diameter portion at the end connected to the feed arm of the dipole antenna element.

6. The array antenna device according to any one of claims 1 to 4, wherein the short-circuit line has frustoconical vias that decrease in diameter from the back surface to the front surface of the dielectric substrate, and the feed line has frustoconical vias that decrease in diameter from the back surface to the front surface of the dielectric substrate.

7. The array antenna device according to any one of claims 1 to 6, wherein each of the plurality of dipole antenna elements has a short-circuit matching element electrically connected to the short-circuit matching element and a feed-side matching element electrically connected to the feed-side matching element, which is positioned opposite the short-circuit matching element electrically connected to the short-circuit matching element and capacitively coupled to it.

8. The array antenna device according to any one of claims 1 to 7, wherein the ground conductor has a second cavity in the region located between a short-circuit line electrically connected to the ground arm of one of the dipole antenna elements that are adjacent in the same direction among the plurality of dipole antenna elements and a feed line electrically connected to the feed arm of the other dipole antenna element of the adjacent dipole antenna element.

9. The array antenna device according to claim 8, wherein the ground conductor has a dielectric having a relative permittivity lower than that of the dielectric substrate in a second cavity communicating with the cavity.

10. The array antenna device according to any one of claims 1 to 9, wherein the plurality of dipole antenna elements constitute a tightly coupled dipole antenna element.

11. The array antenna device according to any one of claims 1 to 10, wherein the short-circuit line and the feed line corresponding to each of the plurality of dipole antenna elements operate as parallel two-wire lines which are unbalanced microwave transmission lines.

12. The dielectric substrate has through holes extending from the front surface to the back surface in regions where the plurality of dipole antenna elements are not present on the surface. This is the array antenna device according to any one of claims 1 to 11.

13. The array antenna device according to any one of claims 1 to 12, wherein the dielectric substrate has a matching layer covering a plurality of dipole antenna elements on its surface.

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