Antenna module and communication device equipped with same

Abstract

An antenna module (100) comprises a dielectric substrate (130), a flat plate-shaped radiation element (121), ground electrodes (GND1, GND2), and power supply wirings (141, 142). The ground electrode (GND1) is disposed at a position facing the radiation element when the dielectric substrate is viewed in a plan view from the normal direction. The power supply wiring (141) is disposed along a first direction leading from the ground electrode (GND1) toward the radiation element and transmits a high-frequency signal to a feeding point (SP1) of the radiation element. The power supply wiring (142) is separated from the power supply wiring (141), arranged along the first direction, and transmits a high-frequency signal to a feeding point (SP2) of the radiation element. The ground electrode (GND2) protrudes from the ground electrode (GND1), and at least a portion of the ground electrode (GND2) is disposed along the power supply wiring (141). The feeding points (SP1, SP2) are offset from the center of the radiation element in mutually different directions. The ground electrode (GND2) is disposed so as to be separated from the power supply wiring (141) in a direction leading from the power supply wiring (142) toward the power supply wiring (141). At least a portion of the ground electrode (GND2) is disposed along the radiation element. The size in a second direction of a part of the ground electrode (GND2) connected with the ground electrode (GND1) is smaller than the size of the ground electrode (GND2) in the first direction.

Description

Antenna module and communication device equipped with same

[0001] The present disclosure relates to an antenna module and a communication device equipped with the same, and more particularly to a technique for improving isolation between polarized waves in a dual-polarized antenna module.

[0002] Japanese Patent Laid-Open Publication No. 2022-123216 (Patent Document 1) discloses an antenna device having a ground conductor arranged to surround at least a part of the periphery of a flat radiation conductor. In the antenna device of Patent Document 1, a feed line to the radiation conductor is sandwiched between ground conductors on both sides and connected to the radiation conductor by a feed coupling part that is wider than the feed line.

[0003] Japanese Patent Application Laid-Open No. 2022-123216

[0004] In the antenna device of Patent Document 1, the radiation conductor has a substantially square shape, and a feed line is connected to each of two adjacent sides. The feed line and the ground conductor form a coplanar waveguide. In other words, the antenna device is a so-called dual-polarized type antenna device that can radiate radio waves in two different polarization directions.

[0005] In the antenna device of Patent Document 1, a continuous conductor is arranged as a ground conductor between two feed lines. In this case, electrode distribution occurs in the ground conductor between the feed lines, and the two feed lines are coupled by the ground conductor, which may reduce isolation between the feed lines.

[0006] The present disclosure has been made to solve such problems, and its purpose is to improve the isolation between the polarized waves in a dual-polarized antenna module.

[0007] An antenna module according to one aspect of the present disclosure includes a dielectric substrate, a radiating element, first and second ground electrodes, and first and second feed wiring. The radiating element has a flat plate shape and is disposed on the dielectric substrate. The first ground electrode is disposed in a position facing the radiating element when the dielectric substrate is viewed from above in a normal direction. The first feed wiring is disposed along a first direction from the first ground electrode toward the radiating element and transmits a high-frequency signal to a first feed point of the radiating element. The second feed wiring is disposed along the first direction and spaced apart from the first feed wiring and transmits a high-frequency signal to a second feed point of the radiating element. The second ground electrode protrudes from the first ground electrode and is at least partially disposed along the first feed wiring. The first feed point and the second feed point are offset in different directions from the center of the radiating element. The second ground electrode is disposed at a distance from the first feed wiring to the second feed wiring in the third direction, and at least a portion of the second ground electrode is disposed along the radiating element. The size of the second ground electrode at a connection portion with the first ground electrode in the second direction is smaller than the size of the second ground electrode in the first direction.

[0008] An antenna module according to another aspect of the present disclosure includes a dielectric substrate, first and second radiating elements, first and second ground electrodes, and first to fourth feed lines. The first and second radiating elements have a flat plate shape and are arranged spaced apart from each other on the dielectric substrate. The first ground electrode is arranged in a position facing the first and second radiating elements when viewed from above in a normal direction of the dielectric substrate. The first feed line is arranged along a first direction from the first ground electrode toward the first radiating element and transmits a high-frequency signal to a first feed point of the first radiating element. The second feed line is arranged along the first direction and spaced apart from the first feed line and transmits a high-frequency signal to a second feed point of the first radiating element. The third feed line is arranged along the first direction from the first ground electrode toward the second radiating element and transmits a high-frequency signal to a third feed point of the second radiating element. The fourth feed wiring is spaced apart from the third feed wiring and arranged along the first direction, and transmits a high-frequency signal to a fourth feed point of the second radiating element. If the direction from the first radiating element toward the second radiating element is defined as the second direction, the second feed wiring is arranged further in the second direction than the first feed wiring, and the fourth feed wiring is arranged further in the second direction than the third feed wiring. The first feed point and the second feed point are offset in different directions from the center of the first radiating element. The third feed point and the fourth feed point are offset in different directions from the center of the second radiating element. The fifth ground electrode protrudes from the first ground electrode and is arranged between the second feed wiring and the third feed wiring. The size of the connection portion of the fifth ground electrode with the first ground electrode in the second direction is smaller than the size of the fifth ground electrode in the first direction. The fifth ground electrode includes a first portion arranged along the second feed wiring, a second portion arranged along the third feed wiring, a third portion arranged along the first radiating element, and a fourth portion arranged along the second radiating element.

[0009] According to the antenna module of the present disclosure, a dual-polarized antenna module is provided with a strip-shaped ground electrode (second ground electrode) at least a portion of which is arranged along both the feed line and the radiating element. This configuration allows high-frequency signals flowing through the feed line to resonate with the ground electrode, thereby suppressing coupling between the feed line and the other feed line. This improves isolation between the polarizations in the dual-polarized antenna module.

[0010] FIG. 1 is an overall schematic diagram of a communication device to which an antenna module according to a first embodiment is applied. FIG. 2 is a plan view of the antenna module according to the first embodiment. FIG. 3 is a diagram for explaining resonance of a ground electrode GND2. FIG. 4 is a plan view of an antenna module of a comparative example. FIG. 5 is a diagram for explaining antenna characteristics of the antenna module according to the first embodiment. FIG. 6 is a diagram showing a modified example of the ground electrode GND2. FIG. 7 is a plan view of an antenna module according to a second embodiment. FIG. 8 is a diagram for explaining antenna characteristics of the antenna module according to the second embodiment. FIG. 9 is a plan view of an antenna module according to a third embodiment. FIG. 10 is a diagram for explaining antenna characteristics of the antenna module according to the third embodiment.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0012] [First Embodiment] (Basic Configuration of Communication Device) Fig. 1 is a block diagram of a communication device 10 to which an antenna module 100 according to a first embodiment is applied. The communication device 10 is, for example, a mobile terminal such as a mobile phone, smartphone, or tablet, or a personal computer with a communication function. An example of the frequency band of radio waves used in the antenna module 100 according to the first embodiment is millimeter-wave radio waves with center frequencies of 28 GHz, 39 GHz, and 60 GHz, but radio waves in other frequency bands are also applicable.

[0013] 1 , a communication device 10 includes an antenna module 100 and a BBIC 200 that constitutes a baseband signal processing circuit. The antenna module 100 includes an RFIC 110 and an antenna device 120. The RFIC 110 is a power supply circuit that supplies a high-frequency signal to the antenna device 120. The communication device 10 upconverts a signal transmitted from the BBIC 200 to the antenna module 100 into a high-frequency signal and radiates the high-frequency signal from the antenna device 120, and downconverts a high-frequency signal received by the antenna device 120 and processes the signal in the BBIC 200.

[0014] The antenna device 120 includes a flat-plate-shaped dielectric substrate 130 and at least one radiating element 121 arranged on the dielectric substrate 130. While FIG. 1 shows an example in which four radiating elements 121 are arranged on the dielectric substrate 130, the number of radiating elements is not limited to this. Also, while FIG. 1 shows an example in which the radiating elements are arranged in a one-dimensional array in a line on the dielectric substrate, the radiating elements may also be arranged in a two-dimensional array on the dielectric substrate. Alternatively, a single radiating element may be arranged on the dielectric substrate. In the first embodiment, the radiating element 121 is a patch antenna having a substantially square flat-plate shape.

[0015] The antenna device 120 is a so-called dual-polarized type antenna device that can radiate two radio waves with different polarization directions from one radiating element 121. A high-frequency signal for a first polarized wave and a high-frequency signal for a second polarized wave are supplied to each radiating element 121 from the RFIC 100.

[0016] The RFIC 110 includes switches 111A to 111H, 113A to 113H, 117A, and 117B, power amplifiers 112AT to 112HT, low-noise amplifiers 112AR to 112HR, attenuators 114A to 114H, phase shifters 115A to 115H, signal combiners / dividers 116A and 116B, mixers 118A and 118B, and amplifier circuits 119A and 119B. Of these, the configuration of switches 111A to 111D, 113A to 113D, and 117A, power amplifiers 112AT to 112DT, low-noise amplifiers 112AR to 112DR, attenuators 114A to 114D, phase shifters 115A to 115D, signal combiner / divider 116A, mixer 118A, and amplifier circuit 119A constitutes a circuit for high-frequency signals for the first polarization. Also, the configuration of switches 111E to 111H, 113E to 113H, and 117B, power amplifiers 112ET to 112HT, low-noise amplifiers 112ER to 112HR, attenuators 114E to 114H, phase shifters 115E to 115H, signal combiner / divider 116B, mixer 118B, and amplifier circuit 119B constitutes a circuit for high-frequency signals for the second polarization.

[0017] When transmitting a high frequency signal, the switches 111A to 111H and 113A to 113H are switched to the power amplifiers 112AT to 112HT, and the switches 117A and 117B are connected to the transmission amplifiers of the amplifier circuits 119A and 119B. When receiving a high frequency signal, the switches 111A to 111H and 113A to 113H are switched to the low noise amplifiers 112AR to 112HR, and the switches 117A and 117B are connected to the reception amplifiers of the amplifier circuits 119A and 119B.

[0018] The signal transmitted from the BBIC 200 is amplified by amplifier circuits 119A, 119B and upconverted by mixers 118A, 118B. The upconverted high-frequency transmission signal is split into four parts by signal combiners / dividers 116A, 116B, passes through the corresponding signal paths, and is fed to different radiating elements 121A, 121B. By individually adjusting the phase shift of phase shifters 115A to 115H arranged on each signal path, the directivity of the radio waves output from the radiating elements on each board can be adjusted. In addition, attenuators 114A to 114H adjust the strength of the transmission signal.

[0019] The received signals, which are high-frequency signals received by each radiating element 121, are transmitted to the RFIC 110 and are combined in the signal combiners / dividers 116A and 116B via four different signal paths. The combined received signals are down-converted in the mixers 118A and 118B, amplified in the amplifier circuits 119A and 119B, and transmitted to the BBIC 200.

[0020] The RFIC 110 is formed as, for example, a one-chip integrated circuit component including the above circuit configuration. Alternatively, the devices (switches, power amplifiers, low-noise amplifiers, attenuators, phase shifters) corresponding to the respective radiating elements 121 in the RFIC 110 may be formed as one-chip integrated circuit components for each corresponding radiating element.

[0021] (Configuration of Antenna Module) Next, the configuration of the antenna module 100 according to the first embodiment will be described in detail with reference to Fig. 2. Fig. 2 is a plan view of the antenna module 100 according to the first embodiment.

[0022] The antenna module 100 includes power supply wiring 141, 142, and ground electrodes GND1 to GND3 in addition to the radiating element 121, the dielectric substrate 130, and the RFIC 110. In the following description, the normal direction of the dielectric substrate 130 (radiation direction of radio waves) is defined as the Z-axis direction, and the planes perpendicular to the Z-axis direction are defined as the X-axis and Y-axis.

[0023] The dielectric substrate 130 may be, for example, a low temperature co-fired ceramics (LTCC) multilayer substrate, a multilayer resin substrate formed by laminating multiple resin layers made of resins such as epoxy or polyimide, a multilayer resin substrate formed by laminating multiple resin layers made of liquid crystal polymer (LCP) having a lower dielectric constant, a multilayer resin substrate formed by laminating multiple resin layers made of fluorine-based resin, a multilayer resin substrate formed by laminating multiple resin layers made of PET (Polyethylene Terephthalate), or a ceramic multilayer substrate other than LTCC. Note that the dielectric substrate 130 does not necessarily have a multilayer structure and may be a single-layer substrate.

[0024] The dielectric substrate 130 has a rectangular shape when viewed from above in the normal direction (Z-axis direction). In the example of Fig. 2, a radiating element 121 is disposed on the upper surface of the dielectric substrate 130 (the surface in the positive direction of the Z-axis). The radiating element 121 may be disposed so as to be exposed on the surface of the dielectric substrate 130 as shown in Fig. 2, or may be disposed inside the dielectric substrate 130. Each side of the approximately square radiating element 121 is disposed so as to be parallel to the X-axis or Y-axis in Fig. 2.

[0025] 2, a ground electrode facing the radiating element 121 is disposed over the entire bottom surface (the surface in the negative direction of the Z axis) of the dielectric substrate 130. The radiating element 121 and the ground electrode form a microstrip antenna. The RFIC 110 is mounted on the bottom surface of the dielectric substrate 130.

[0026] A high frequency signal is transmitted from the RFIC 110 to the radiating element 121 by power supply lines 141 and 142. The power supply lines 141 and 142 extend from the RFIC 110 through the dielectric substrate 130 in the Z-axis direction, pass through the upper surface of the dielectric substrate 130, and are connected to the radiating element 121.

[0027] More specifically, the feed wiring 141 rises to the upper surface of the dielectric substrate 130 at a position close to the end of the dielectric substrate 130 in the negative direction of the Y axis, extends in the positive direction of the Y axis, and is connected to a feed point SP1 at one corner of the radiating element 121. The feed wiring 142 also rises to the upper surface of the dielectric substrate 130 at a position close to the end of the dielectric substrate 130 in the negative direction of the Y axis, extends in the positive direction of the Y axis, and is connected to the radiating element 121 at a feed point SP2 at another corner adjacent to the feed point SP1. In other words, the feed points SP1 and SP2 are offset in different directions from the center of the radiating element 121. The feed wiring 142 is arranged farther away from the feed wiring 141 in the positive direction of the X axis.

[0028] When a high-frequency signal is supplied to feed point SP1, a radio wave whose polarization direction is in one diagonal direction of radiating element 121, as indicated by arrow AR1 in Fig. 2, is radiated in the positive direction of the Z axis. Furthermore, when a high-frequency signal is supplied to feed point SP2, a radio wave whose polarization direction is in the other diagonal direction of radiating element 121, as indicated by arrow AR2 in Fig. 2, is radiated in the positive direction of the Z axis. In other words, antenna module 100 is a so-called dual-polarized type antenna device that can radiate two radio waves with different polarization directions from a single radiating element 121.

[0029] A ground electrode GND1 is arranged along the edge of the upper surface of the dielectric substrate 130 in the negative direction of the Y axis. The ground electrode GND1 is connected to the ground electrode on the lower surface side by a via extending in the normal direction of the dielectric substrate 130 or by a side electrode arranged on the side surface of the dielectric substrate 130. The ground electrode GND1 is arranged opposite one side of the radiating element 121. The feeder wirings 141 and 142 are arranged in the region between the ground electrode GND1 and the radiating element 121.

[0030] Each of the ground electrodes GND2, GND3 is a strip-shaped electrode having a substantially rectangular shape, and protrudes from the ground electrode GND1 in the positive direction of the Y axis. In other words, the size of the connection portion of each of the ground electrodes GND2, GND3 with the ground electrode GND1 in the X axis direction is smaller than the size of the ground electrodes GND2, GND3 in the Y axis direction. The ground electrode GND2 is disposed closer to the power supply wiring 141 and the radiating element 121 at a position in the negative direction of the X axis than the power supply wiring 141. A portion of the ground electrode GND2 is parallel to the portion of the power supply wiring 141 extending in the Y axis direction.

[0031] The ground electrode GND3 is disposed closer to the power supply wiring 142 and the radiating element 121 at a position closer to the positive X-axis direction than the power supply wiring 142. A part of the ground electrode GND3 is parallel to the portion of the power supply wiring 142 that extends in the Y-axis direction.

[0032] The portions of the ground electrodes GND2 and GND3 on the end side in the positive direction of the Y axis face the side of the radiating element 121 along the Y axis, and are capacitively coupled to the radiating element 121 at these portions.

[0033] If the size of the radiating element 121, i.e., the length of one side, is L1, the width of the ground electrodes GND2 and GND3 (i.e., the dimension in the X-axis direction) is set to be less than half of L1. Also, if the distance from the ground electrode GND1 to the farthest end of the ground electrodes GND2 and GND3 in the Y-axis direction, i.e., the protrusion length from the ground electrode GND1 (the dimension in the Y-axis direction), is L2, L2 is set to be greater than 1 time the length of one side of the radiating element 121, L1, but not greater than 1.5 times (1.0 < L2 / L1 ≦ 1.5). Also, the protrusion length L2 of the ground electrodes GND2 and GND3 is shorter than the distance L3 from the ground electrode GND1 to the farthest end of the radiating element 121.

[0034] As described above, when the power feed lines 141 and 142 are arranged in parallel on the upper surface of the dielectric substrate 130, the two power feed lines may be coupled to each other, which may reduce the isolation between the two polarized waves. Also, even when a ground electrode is arranged over the entire area between the two power feed lines as in the above-mentioned Japanese Patent Laid-Open No. 2022-123216 (Patent Document 1), the power feed lines may be coupled to each other due to the current distribution generated in the ground electrode, which may reduce the isolation.

[0035] In the antenna module 100 of embodiment 1, ground electrodes GND2 and GND3 having a strip-like shape of a predetermined length are arranged along the power supply wirings 141 and 142, respectively, and a portion of the ground electrodes GND2 and GND3 is coupled to the radiating element 121.

[0036] By forming the ground electrodes GND2 and GND3 in this manner, the ground electrodes GND2 and GND3 function as resonators due to the inductance components of the ground electrodes GND2 and GND3 and the capacitance component between the radiating element 121. This resonance allows signals corresponding to the resonance frequency of high-frequency signals passing through the feed lines 141 and 142 to be concentrated in the ground electrodes GND2 and GND3, thereby suppressing coupling between the feed lines 141 and 142 for signals corresponding to the resonance frequency. This improves isolation between polarized waves.

[0037] Specifically, as shown in Fig. 3, the length L2 of the ground electrodes GND2 and GND3 in the Y-axis direction is set so that the third harmonic resonance of the resonance generated by the ground electrodes GND2 and GND3 corresponds to the frequency at which isolation improvement is desired. In other words, if the frequency at which isolation improvement is desired is f, L2 is set to be 1 / 4 of the wavelength corresponding to the frequency f / 3, resulting in a length that is 3 / 4 times the wavelength λ corresponding to the frequency f. In this case, as shown by arrows AR21 and AR22 in Fig. 3, a node occurs midway through the ground electrodes GND2 and GND3, causing the current phase to be inverted.

[0038] Here, if the effective wavelength of the radio waves radiated from the radiating element 121 within the dielectric substrate 130 is λ, the size (length of one side) of the radiating element 121 is set to λ / 2, so the length L2 of the ground electrodes GND2 and GND3 is at most approximately 1.5 times the size of the radiating element 121. As described above, the resonant frequency of the ground electrodes GND2 and GND3 is determined by the inductance components of the ground electrodes GND2 and GND3 and the capacitance components between the ground electrodes GND2 and GND3 and the radiating element 121. Therefore, as the capacitive coupling between the ground electrodes GND2 and GND3 and the radiating element 121 increases, the length L2 of the ground electrodes GND2 and GND3 becomes correspondingly shorter. Therefore, L2 is set to be greater than 1 time but not greater than 1.5 times the size of the radiating element 121.

[0039] (Antenna Characteristics) Next, the antenna characteristics of the antenna module of the first embodiment will be described together with a comparative example. Fig. 4 is a plan view of the antenna module 100X of the comparative example. Fig. 5 is a diagram for explaining the antenna characteristics of the antenna module 100 of the first embodiment.

[0040] 4, in the antenna module 100X of the comparative example, the arrangement of the radiating element 121 and the power supply lines 141 and 142 on the dielectric substrate 130 is the same as in the antenna module 100. On the other hand, in the antenna module 100X, similar to JP 2022-123216 A (Patent Document 1), the ground electrode GNDX is arranged to surround the power supply lines 141 and 142 over the entire region in the negative direction of the Y axis from the radiating element 121.

[0041] 5 shows the insertion loss from the power feed line 141 to the power feed line 142, i.e., the isolation characteristics between the power feed lines, and the reflection loss for the antenna modules 100 and 100X. In Fig. 5, the solid line LN10 represents the isolation characteristics for the antenna module 100 of embodiment 1, and the solid line LN11 represents the reflection loss for the antenna module 100. In addition, the dashed line LN15 represents the isolation characteristics for the antenna module 100X of the comparative example, and the dashed line LN16 represents the reflection loss for the antenna module 100X.

[0042] In the example of Fig. 5, the frequency band of the radio waves radiated from the radiating element 121 is the 28 GHz band (26.5 to 29.5 GHz), and by improving the isolation around 31 GHz, which is close to that frequency band, the isolation is improved without interfering with the radiation of radio waves in the target frequency band. Also, in the example of Fig. 5, the dB value of the target isolation is indicated by TG.

[0043] 5, the isolation around 31 GHz in the antenna module 100X of the comparative example is significantly higher than the target value (dashed line LN15), whereas the isolation around 31 GHz in the antenna module 100 of the first embodiment is improved to the target level (solid line LN10).

[0044] When a high-frequency signal is supplied to the power feed line 141, the ground electrode GND2 improves isolation from the power feed line 141 to the power feed line 142. On the other hand, when a high-frequency signal is supplied to the power feed line 142, the ground electrode GND3 improves isolation from the power feed line 142 to the power feed line 141. Note that if only one of the ground electrodes GND2 and GND3 is provided, electrical symmetry is lost, which may result in a decrease in cross polarization discrimination. Therefore, it is preferable to provide both ground electrodes GND2 and GND3.

[0045] As described above, by arranging a ground electrode along the power supply line that supplies a high-frequency signal and capacitively coupling a portion of the ground electrode with the radiating element, the ground electrode can be made to function as a resonator, thereby preventing a signal of a desired frequency from coupling with the other power supply line, thereby improving the isolation between the power supply lines.

[0046] (Variant Example) In the above-described antenna module 100, the ground electrodes GND2 and GND3 that function as resonators are linear electrodes extending in the Y-axis direction, but the ground electrodes GND2 and GND3 are not necessarily limited to linear electrodes as long as they include a linear portion that is equivalent to the distance from the ground electrode GND1 to the farthest end.

[0047] For example, the ground electrode GND21 may be shaped like a substantially L-shape as shown in the left diagram (A) of Fig. 6, or the ground electrode GND22 may be shaped like a substantially J-shape as shown in the right diagram (B) of Fig. 6. In either case of Fig. 6, there is a straight line portion where the distance from the ground electrode GND1 to the farthest end is L2, and third harmonic resonance occurs in this portion. Therefore, even when a ground electrode such as that shown in Fig. 6 is used, isolation at the target frequency can be improved, as in the case of the antenna module 100.

[0048] The "ground electrodes GND1 to GND3" in the first embodiment correspond to examples of the "first ground electrode," the "second ground electrode," and the "third ground electrode" in the present disclosure, respectively. The "power supply wiring 141" and the "power supply wiring 142" in the first embodiment correspond to examples of the "first power supply wiring" and the "second ground electrode" in the present disclosure, respectively. The "power supply point SP1" and the "power supply point SP2" in the first embodiment correspond to examples of the "first power supply point" and the "second ground point," respectively. The "positive direction of the Y-axis" in the first embodiment corresponds to the "first direction" in the present disclosure, the "positive direction of the X-axis" corresponds to the "second direction" in the present disclosure, and the "negative direction of the X-axis" corresponds to the "third direction" in the present disclosure.

[0049] Second Embodiment In a second embodiment, a configuration will be described in which a ground electrode is further disposed between two power supply wirings.

[0050] 7A and 7B are plan views of antenna modules 100A and 100B according to the second embodiment. In the antenna module 100A shown in the upper diagram (A) of Fig. 7A, one ground electrode GND4 is disposed in the region between the power supply wiring 141 and the power supply wiring 142. The ground electrode GND4 protrudes from the ground electrode GND1 in the positive direction of the Y axis and is disposed over the entire region between the power supply wiring 141 and the power supply wiring 142. The end of the ground electrode GND4 on the negative side of the X axis is adjacent to and faces the portion of the power supply wiring 141 along the Y axis. Furthermore, the end of the ground electrode GND4 on the positive side of the X axis is adjacent to and faces the portion of the power supply wiring 142 along the Y axis.

[0051] By arranging such a ground electrode GND4, the portions of the feed lines 141, 142 on the upper surface of the dielectric substrate 130 that extend along the Y axis can be made into coplanar lines, and the impedance of the feed lines 141, 142 can be adjusted. This makes it possible to suppress the generation of unwanted waves radiated from the feed lines due to impedance mismatch between the feed lines 141, 142 and the radiating element 121. This makes it possible to improve the directivity toward the front side (normal direction) of the radiating element.

[0052] 7B, an antenna module 100B has individual ground electrodes provided for each of the power feed lines 141 and 142 in the region between the power feed lines 141 and 142. Specifically, a strip-shaped ground electrode GND41 is arranged along the power feed line 141 for the power feed line 141, and a strip-shaped ground electrode GND42 is arranged along the power feed line 142 for the power feed line 142. The size of each of the ground electrodes GND41 and GND42 in the X-axis direction is smaller than the size in the Y-axis direction.

[0053] In the antenna module 100B, a coplanar line is formed by the power feed line 141 and the ground electrodes GND2 and GND41, and a coplanar line is formed by the power feed line 142 and the ground electrodes GND3 and GND42, so that the impedance of the power feed lines 141 and 142 can be adjusted similarly to the antenna module 100A. Therefore, it is possible to suppress deterioration of directivity caused by unwanted waves resulting from impedance mismatch between the power feed lines 141 and 142 and the radiating element 121.

[0054] (Antenna Characteristics) Fig. 8 is a diagram for explaining the antenna characteristics of the antenna module of embodiment 2. Fig. 8 shows the isolation characteristics (dashed line LN25) and return loss (dashed line LN26) of the antenna module 100 of embodiment 1, as well as the isolation characteristics (solid line LN20) and return characteristics (solid line LN21) of the antenna module 100A of embodiment 2.

[0055] 8, it can be seen that the isolation in the vicinity of 31 GHz is further improved in the antenna module 100A compared to the antenna module 100 of embodiment 1. Therefore, by using a coplanar line as the feed wiring and appropriately adjusting the impedance, it is possible to improve the directivity.

[0056] The "ground electrode GND4" and the "ground electrodes GND41, GND42" in the second embodiment correspond to an example of a "fourth ground electrode" in the present disclosure. The "ground electrode GND41" and the "ground electrode GND42" in the second embodiment correspond to an example of a "first electrode" and a "second electrode" in the present disclosure.

[0057] Third Embodiment In a third embodiment, a configuration in which the features of the present disclosure are applied to an array antenna will be described.

[0058] 9 is a plan view of an antenna module 100C according to embodiment 3. In the antenna module 100C, an example of a configuration in which two radiating elements are arranged in the X-axis direction on a dielectric substrate 130 will be described. Note that the number of radiating elements may be three or more. Also, a plurality of radiating elements may be arranged two-dimensionally.

[0059] 9, radiating elements 121A and 121B are arranged spaced apart in the X-axis direction on dielectric substrate 130. Radiating element 121B is arranged further in the positive direction of the X-axis than radiating element 121A. As with antenna module 100 of embodiment 1, in radiating element 121A, feed lines 141A and 142A are connected to feed points SP1A and SP2A, respectively. In addition, in radiating element 121B, feed lines 141B and 142B are connected to feed points SP1B and SP2B, respectively.

[0060] A strip-shaped ground electrode GND2A is arranged along the power supply wiring 141A in the negative direction of the X axis of the power supply wiring 141A connected to the radiating element 121A. Furthermore, a strip-shaped ground electrode GND3B is arranged along the power supply wiring 142B in the positive direction of the X axis of the power supply wiring 142B connected to the radiating element 121B.

[0061] A strip-shaped ground electrode GND23 is arranged between the power supply wiring 142A connected to the radiating element 121A and the power supply wiring 142B connected to the radiating element 121B. The ground electrode GND23 includes a first portion P1 arranged along the power supply wiring 142A, a second portion P2 arranged along the power supply wiring 141B, a third portion P3 arranged along the radiating element 121A, and a fourth portion P4 arranged along the radiating element 121B.

[0062] In each of the ground electrodes GND2A, GND23, and GND3B, the size in the X-axis direction of the connection portion with the ground electrode GND1 is smaller than the size in the Y-axis direction of the ground electrodes GND2A, GND23, and GND3B.

[0063] That is, the ground electrode GND23 functions as the ground electrode GND3 of the antenna module 100 in the radiating element 121A, and also functions as the ground electrode GND2 of the antenna module 100 in the radiating element 121B. Note that if the dimension of the ground electrode GND23 in the X-axis direction is large, an electrode corresponding to the power supply wiring 142A and an electrode corresponding to the power supply wiring 141B may be provided separately.

[0064] Furthermore, in the region between the power supply wiring 141A and the power supply wiring 142A in the radiating element 121A, a ground electrode GND4A is arranged as described in Fig. 7 of embodiment 2. Furthermore, in the region between the power supply wiring 141B and the power supply wiring 142B in the radiating element 121B, a ground electrode GND4B is arranged.

[0065] In the antenna module 100C, the isolation between the power supply lines in each radiating element can also be improved by the ground electrodes GND2A, GND23, and GND3B. Furthermore, by providing the ground electrodes GND4A and GND4B, the impedance between the radiating element and the power supply line can be adjusted, thereby suppressing unwanted waves caused by impedance mismatch and improving directivity.

[0066] (Antenna Characteristics) Figure 10 is a diagram illustrating the antenna characteristics of the antenna module 100C of embodiment 3. Figure 10 shows the isolation characteristics (solid line LN30) and return loss (dashed line LN31) of each radiating element. Note that because the antenna module 100C has a symmetrical structure, the antenna characteristics of radiating element 121A and radiating element 121B are the same.

[0067] In FIG. 10 as well, the isolation characteristics of each radiating element are lower than the target value, and the isolation between the power supply wirings is improved by the ground electrodes GND2A, GND23, and GND3B.

[0068] As described above, by applying the features of the present disclosure to an array antenna, isolation between feeder lines can be improved.

[0069] The "radiating element 121A" and the "radiating element 121B" in the third embodiment correspond to examples of the "first radiating element" and the "second radiating element" in the present disclosure, respectively. The "power feed wiring 141A," the "power feed wiring 142A," the "power feed wiring 141B," and the "power feed wiring 141B" in the third embodiment correspond to examples of the "first power feed wiring," the "second power feed wiring," the "third power feed wiring," and the "fourth power feed wiring" in the present disclosure, respectively. The "power feed point SP1A," the "power feed point SP2A," the "power feed point SP1B," and the "power feed point SP2B" in the third embodiment correspond to examples of the "first power feed point," the "second power feed point," the "third power feed point," and the "fourth power feed point," respectively. The "ground electrode GND23" in the third embodiment corresponds to an example of the "fifth ground electrode" in the present disclosure.

[0070] Aspects It will be understood by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0071] (Item 1) An antenna module according to one aspect includes a dielectric substrate, a radiating element, first and second ground electrodes, and first and second feed wirings. The radiating element has a flat plate shape and is disposed on the dielectric substrate. The first ground electrode is disposed in a position facing the radiating element when the dielectric substrate is viewed from above in the normal direction. The first feed wiring is disposed along a first direction from the first ground electrode toward the radiating element and transmits a high-frequency signal to a first feed point of the radiating element. The second feed wiring is disposed along the first direction and spaced apart from the first feed wiring and transmits a high-frequency signal to a second feed point of the radiating element. The second ground electrode protrudes from the first ground electrode and is at least partially disposed along the first feed wiring. The first feed point and the second feed point are offset in different directions from the center of the radiating element. The second ground electrode is disposed at a distance from the first feed wiring to the second feed wiring in the third direction, and at least a portion of the second ground electrode is disposed along the radiating element. The size of the second ground electrode at a connection portion with the first ground electrode in the second direction is smaller than the size of the second ground electrode in the first direction.

[0072] (Item 2) In the antenna module described in item 1, the distance from the first ground electrode to the farthest end of the second ground electrode in the first direction is greater than 1 time and less than 1.5 times the size of the radiating element.

[0073] (Item 3) In the antenna module described in item 2, the distance from the first ground electrode to the farthest end of the second ground electrode in the first direction is shorter than the distance from the first ground electrode to the farthest end of the radiating element.

[0074] (4) In the antenna module described in any one of paragraphs 1 to 3, the distance between the radiating element and the portion of the second ground electrode along the radiating element is equal to or less than half the size of the radiating element.

[0075] (Item 5) In the antenna module described in any one of items 1 to 4, the dimension of the second ground electrode along the second direction is equal to or less than half the size of the radiating element.

[0076] (Item 6) The antenna module according to any one of Items 1 to 5 further includes a third ground electrode protruding from the first ground electrode and at least a portion of which is disposed along the second power supply wiring. The third ground electrode is disposed spaced apart from the second power supply wiring in the second direction. The size of the third ground electrode in the second direction at a connection portion with the first ground electrode is smaller than the size of the third ground electrode in the second direction.

[0077] (7) The antenna module according to any one of paragraphs 1 to 6 further includes a fourth ground electrode that protrudes in the first direction from the first ground electrode and is disposed between the first power supply wiring and the second power supply wiring, and at least a portion of the fourth ground electrode is disposed along the first power supply wiring and the second power supply wiring.

[0078] (Item 8) In the antenna module described in Item 7, the fourth ground electrode includes a first electrode arranged along the first power supply wiring and a strip-shaped second electrode arranged along the second power supply wiring, wherein the size of each of the first electrode and the second electrode in the second direction is smaller than the size in the first direction.

[0079] (Item 9) An antenna module according to one aspect includes a dielectric substrate, a first radiating element, a second radiating element, a first ground electrode, a fifth ground electrode, and first to fourth feed lines. The first radiating element and the second radiating element have a flat plate shape and are arranged spaced apart from each other on the dielectric substrate. The first ground electrode is arranged in a position facing the first radiating element and the second radiating element when viewed from a plane normal to the dielectric substrate. The first feed line is arranged along a first direction from the first ground electrode toward the first radiating element and transmits a high-frequency signal to a first feed point of the first radiating element. The second feed line is arranged along the first direction and spaced apart from the first feed line and transmits a high-frequency signal to a second feed point of the first radiating element. The third feed line is arranged along the first direction from the first ground electrode toward the second radiating element and transmits a high-frequency signal to a third feed point of the second radiating element. The fourth feed wiring is spaced apart from the third feed wiring and arranged along the first direction, and transmits a high-frequency signal to a fourth feed point of the second radiating element. If the direction from the first radiating element toward the second radiating element is defined as the second direction, the second feed wiring is arranged further in the second direction than the first feed wiring, and the fourth feed wiring is arranged further in the second direction than the third feed wiring. The first feed point and the second feed point are offset in different directions from the center of the first radiating element. The third feed point and the fourth feed point are offset in different directions from the center of the second radiating element. The fifth ground electrode protrudes from the first ground electrode and is arranged between the second feed wiring and the third feed wiring. The size of the connection portion of the fifth ground electrode with the first ground electrode in the second direction is smaller than the size of the fifth ground electrode in the first direction. The fifth ground electrode includes a first portion arranged along the second feed wiring, a second portion arranged along the third feed wiring, a third portion arranged along the first radiating element, and a fourth portion arranged along the second radiating element.

[0080] (10) The antenna module according to any one of the first to ninth aspects further comprises a power supply circuit that supplies a high frequency signal to each of the radiating elements.

[0081] (Item 11) A communication device equipped with the antenna module according to any one of items 1 to 10.

[0082] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0083] 10 Communication device, 100, 100A to 100C, 100X Antenna module, 110 RFIC, 111A to 111H, 113A to 113H, 117A, 117B Switch, 112AR to 112HR Low noise amplifier, 112AT to 112HT Power amplifier, 114A to 114H Attenuator, 115A to 115H Phase shifter, 116A, 116B Signal combiner / divider, 118A, 118B Mixer, 119A, 119B Amplifier circuit, 120 Antenna device, 121, 121A, 121B Radiating element, 130 Dielectric substrate, 141, 142, 141A, 142A, 141B, 142B Power supply wiring, 200 BBIC, GND1 to GND4, GND21 to GND23, GND41, GND42, GND2A, GND3B, GND4A, GND4B, GNDX: ground electrodes, SP1, SP2, SP1A, SP2A, SP1B, SP2B: power supply points.

Claims

a first ground electrode disposed at a position facing the radiating element when the dielectric substrate is viewed in a planar view from a normal direction; a first feed wiring disposed along a first direction from the first ground electrode toward the radiating element, transmitting a high frequency signal to a first feed point of the radiating element; a second feed wiring spaced apart from the first feed wiring and disposed along the first direction, transmitting a high frequency signal to a second feed point of the radiating element; and a second ground electrode protruding from the first ground electrode, at least a portion of which is disposed along the first feed wiring, wherein the first feed point and the second feed point are offset in different directions from each other from a center of the radiating element, and wherein a direction from the first feed wiring toward the second feed wiring is defined as a second direction and a direction from the second feed wiring toward the first feed wiring is defined as a third direction, the second ground electrode is disposed at a distance from the first feed wiring in the third direction, An antenna module, wherein at least a portion of the second ground electrode is arranged along the radiating element, and a size of a connection portion of the second ground electrode with the first ground electrode in the second direction is smaller than a size of the second ground electrode in the first direction.

2. The antenna module as described in claim 1, wherein the distance from the first ground electrode to the farthest end of the second ground electrode in the first direction is greater than 1 time and less than 1.5 times the size of the radiating element.

3. The antenna module as described in claim 2, wherein the distance from the first ground electrode to the farthest end of the second ground electrode in the first direction is shorter than the distance from the first ground electrode to the farthest end of the radiating element.

4. An antenna module described in any one of claims 1 to 3, wherein the distance between the portion of the second ground electrode along the radiating element and the radiating element is less than or equal to half the size of the radiating element.

5. An antenna module according to any one of claims 1 to 4, wherein the dimension of the second ground electrode along the second direction is equal to or less than half the size of the radiating element.

6. An antenna module as described in any one of claims 1 to 5, further comprising a third ground electrode protruding from the first ground electrode and at least a portion of which is arranged along the second power supply wiring, the third ground electrode being arranged at a distance in the second direction from the second power supply wiring, and the size of the connection portion of the third ground electrode with the first ground electrode in the second direction being smaller than the size of the third ground electrode in the first direction.

7. An antenna module as described in any one of claims 1 to 6, further comprising a fourth ground electrode protruding from the first ground electrode in the first direction and disposed between the first power supply wiring and the second power supply wiring, at least a portion of the fourth ground electrode being disposed along the first power supply wiring and the second power supply wiring.

8. The antenna module described in claim 7, wherein the fourth ground electrode includes a first electrode arranged along the first power supply wiring and a second electrode arranged along the second power supply wiring, and the size of each of the first electrode and the second electrode in the second direction is smaller than the size in the first direction.

9. An antenna module comprising: a dielectric substrate; a first radiating element and a second radiating element, each of which is spaced apart from each other on the dielectric substrate and has a flat shape; a first ground electrode, which is located at a position facing the first radiating element and the second radiating element when the dielectric substrate is viewed in a planar view from a normal direction; a first feed wiring, which is located along a first direction from the first ground electrode to the first radiating element and transmits a high-frequency signal to a first feed point of the first radiating element; a second feed wiring, which is spaced apart from the first feed wiring and located along the first direction and transmits a high-frequency signal to a second feed point of the first radiating element; a third feed wiring, which is located along the first direction from the first ground electrode to the second radiating element and transmits a high-frequency signal to a third feed point of the second radiating element; and a fourth feed wiring, which is spaced apart from the third feed wiring and located along the first direction and transmits a high-frequency signal to a fourth feed point of the second radiating element; the second feed wiring is disposed in the second direction further than the first feed wiring, the fourth feed wiring is disposed in the second direction further than the third feed wiring, the first feed point and the second feed point are offset in directions different from each other from a center of the first radiating element, and the third feed point and the fourth feed point are offset in directions different from each other from a center of the second radiating element, the antenna module further comprising: a fifth ground electrode protruding from the first ground electrode and disposed between the second feed wiring and the third feed wiring, a size of a connection portion of the fifth ground electrode with the first ground electrode in the second direction is smaller than a size of the fifth ground electrode in the first direction, and the fifth ground electrode includes: a first portion disposed along the second feed wiring, a second portion disposed along the third feed wiring, a third portion disposed along the first radiating element, and a fourth portion disposed along the second radiating element.

10. The antenna module according to any one of claims 1 to 9, further comprising a feeding circuit for supplying a high-frequency signal to each of the radiating elements.

11. A communication device equipped with an antenna module according to any one of claims 1 to 10.

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