JP2006005679A - Slot array antenna and wireless communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slot array antenna capable of reducing the SAR, and a wireless communication terminal. <P>SOLUTION: The slot array antenna is provided with a ground plate 101 to which a slot 102 having an electric length L is formed, a feeder 103 which feeds power to the slot 102 arranged to the center of the slot 102, a reflection conductor 104 which faces the ground plate 101 and has a parasitic slot 105, and short-circuiting parts 106-1, 106-2 arranged to the parasitic slot 105. The short-circuiting part 106-1 is arranged between the position corresponding to the feeder 103 of the parasitic slot 105 and one end of the parasitic slot 105. The short-circuiting part 106-2 is arranged between the position corresponding to the feeding point 103 of the parasitic slot 105 and the other end of the parasitic slot 105. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a slot array antenna and a wireless communication terminal, and more particularly to a wireless communication terminal such as a mobile phone and a slot array antenna incorporated therein.

  As shown in FIG. 16, the slot array antenna described in the following Patent Document 1 includes two rectangular plates having the same outer diameter, which are arranged in parallel, on one main surface of each plate. Is attached with a conductive sheet, and one plate is used as the radiating conductor 11 and the other plate is used as the reflecting conductor 12.

  The radiation conductor 11 is provided with a window 13 (slot) in which the center of the main surface of the plate body is punched long in the longitudinal direction, and a feeding point 14 is provided in which the center of the wall 13 in the longitudinal direction protrudes into the window. Yes. The radiation conductor 11 is an antenna body that radiates or receives radio waves.

  The radiating conductor 11 and the reflecting conductor 12 are arranged with an interval D of 0.08 wavelength to 0.25 wavelength of the operating frequency, and this reflecting conductor 12 is opposed to the window 13 formed in the radiating conductor 11. Thus, two windows 5a and 5b are punched out at the center of the main surface.

  Here, an axis perpendicular to the main surface of the radiation conductor 11 is defined as an X axis, and a direction from the reflection conductor 12 toward the radiation conductor 11 is defined as a + X direction. Further, the width direction of the radiation conductor 11 is defined as the Y axis, and the direction from the left side to the right side is defined as the + Y direction. Furthermore, the longitudinal direction of the radiation conductor 11 is taken as the Z axis, and the direction from the lower side to the upper side of the paper is taken as the + Z direction.

  Assuming that this slot array antenna is mounted on a wireless communication terminal such as a cellular phone, the use frequency is 3.75 GHz, the distance D between the radiation conductor 11 and the reflection conductor 12 is 0.06 wavelength, and the radiation of the slot array antenna The characteristics and the near magnetic field distribution are shown.

  In the radiation characteristics of the slot array antenna, as shown in FIG. 17, it is shown that a gain of 9.2 dBi is obtained in the + X direction and an F / B ratio of 12.8 dB is obtained.

As shown in FIG. 18, the magnetic field distribution of the slot array antenna is a magnetic field distribution when the slot array antenna of FIG. 16 is viewed from the + Y direction, and at the boundary between the window 5a and the window 5b of the reflective conductor 12. It can be seen that the magnetic field is concentrated.
JP 2002-084130 A

  However, in the slot array antenna described in Patent Document 1, for example, when mounted on a mobile phone, the reflective conductor 12 is arranged on the side of the mobile phone that includes a microphone, a speaker, and the like, and on the side facing the user (human body) during a call. Since the reflecting conductor 12 is located, there is a problem that when the magnetic field is concentrated on the boundary portion of the reflecting conductor 12, an SAR (Specific Absorption Rate) that is an average energy amount of radio waves absorbed by the human head increases.

  The present invention has been made in view of this point, and an object of the present invention is to provide a slot array antenna and a wireless communication terminal that reduce SAR.

  The slot array antenna of the present invention has a ground plane having a slot, a power feeding portion disposed in a central portion of the slot, and a parasitic slot facing the slot, and is disposed facing the ground plane. A first portion that partially connects the opposing sides of the parasitic slot between the reflective conductor, a position corresponding to the feeding portion of the parasitic slot, and an end portion where the induced current of the parasitic slot is generated. The structure provided with the short circuit part is taken.

  According to this configuration, the maximum electric field generated between the power supply portion of the non-power supply slot and the end where the induced current is generated can be dispersed by the short-circuit portion, so that back lobes can be reduced.

  The slot array antenna of the present invention employs a configuration further including a second short-circuit portion that partially connects the opposite sides of the parasitic slot at a position corresponding to the feeding portion.

  According to this configuration, since the high electric field generated in the portion facing the non-feed slot at the position corresponding to the feed portion can be dispersed by the second short-circuit portion, the back lobe can be further reduced.

  In the slot array antenna of the present invention, the feeding portion is disposed at the central portion of the slot by shifting to one end portion relative to the other end portion, and the position corresponding to the feeding portion of the parasitic slot and the slot A configuration is adopted in which the short-circuit portion is disposed between the other end portion of the parasitic slot corresponding to the other end portion.

  According to this configuration, by shifting to one end portion of the slot and arranging the power feeding portion, impedance matching can be easily achieved, and the position corresponding to the power feeding portion of the non-feed slot according to the shift of the power feeding portion. The maximum electric field between the first and the other end can be reduced by the short-circuit portion.

  The slot array antenna of the present invention employs a configuration in which the first short circuit portion or the second short circuit portion is a switching element that can partially connect and disconnect the opposite sides of the parasitic slot. Furthermore, the slot array antenna of the present invention employs a configuration in which a plurality of switching elements as the first short-circuited portions are arranged in electrical parallel.

  According to these configurations, even if the location where the electric field is maximum in the parasitic slot changes, the short-circuit portion can be constructed corresponding to the location by the switching element, and the maximum electric field generated in the parasitic slot Therefore, the back lobe can be reduced and the SAR can be reduced. Therefore, it is possible to realize a slot array antenna corresponding to a change in use frequency.

  The slot array antenna of the present invention employs a configuration in which the slot and the parasitic slot each have a planar shape that is bent or curved.

  According to this configuration, by making the planar shape of each slot bend or curved, the electrical length of each slot can be set longer without being limited to the length of the size (side) of the ground plane and the reflective conductor. The size of the ground plane and the reflecting conductor can be reduced, and the slot array antenna can be reduced in size.

  The radio communication terminal of the present invention employs a configuration including any of the slot array antennas described above.

  According to this configuration, a wireless communication terminal capable of reducing SAR can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, a back lobe can be reduced and the slot array antenna and radio | wireless communication terminal which can reduce SAR can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that, in the embodiment, the same reference numerals are given to configurations having the same functions, and descriptions thereof are omitted because they are duplicated.

(Embodiment 1)
As shown in FIGS. 1 and 2, the slot array antenna according to Embodiment 1 of the present invention is mainly composed of a ground plane 101 and further includes a reflective conductor 104. The ground plane 101 is a square plate-shaped conductor in the first embodiment. A slot 102 penetrating through the main plate 101 is formed at a central portion of the main plate 101 (a position having a length R from one side of the main plate 101 (here, the upper side in FIG. 1)).

  The slot 102 has an electrical length L, and a power feeding portion (feeding point) 103 that feeds power to the slot 102 is provided at the central portion of two long sides facing each other on the inner wall of the slot 102.

  The reflective conductor 104 is a square plate-like conductor having substantially the same size as that of the ground plane 101, and is disposed with a spacing S (S is 0.01 wavelength or more) substantially parallel to the ground plane 101. The reflection conductor 104 has a parasitic slot 105 passing through the reflection conductor 104 at a position facing the slot of the ground plane 101, that is, in the center of the reflection conductor 104.

  The parasitic slot 105 is provided with short-circuit portions (first short-circuit portion or first short-circuit point) 106-1 and 106-2 at a position where the electric field is maximized. Here, the position where the electric field is maximized is a position where the current is minimized, and in Embodiment 1, it is a position away from both ends of the parasitic slot 105 by 1/4 wavelength of the operating frequency, Between the position corresponding to the power feeding part 103 of the non-feed slot 105 and both ends of the slot where the induced current is generated. The short-circuit portions 106-1 and 106-2 are regions in which two long sides facing each other on the inner wall of the parasitic slot 105 are connected to each other and electrically connected. By providing such short-circuit portions 106-1 and 106-2 in the parasitic slot 105, one parasitic slot 105 is divided into three parasitic slots separated by two short-circuit portions 106-1 and 106-2. It is formed as 105-1 to 105-3. Although the electrical length Ln of the parasitic slot 105 is the same as the electrical length L of the slot 102 in the first embodiment, the present invention is not limited to this, and the electrical length Ln is greater than the electrical length L. It can be long or short.

  Here, in FIG. 1, an axis perpendicular to the ground plane 101 is defined as an X axis, and a direction from the reflective conductor 104 toward the ground plane 101 is defined as a + X direction. Further, the horizontal direction in the figure of the radiation conductor 104 is taken as the Y axis, and the direction from the left side to the right side of the paper is taken as the + Y direction. Further, the vertical direction of the radiation conductor 104 in the drawing is taken as the Z axis, and the direction from the lower side to the upper side in the drawing is taken as the + Z direction.

  Next, the operation of the slot array antenna having the above configuration will be described. When the slot 102 is supplied with power from the power supply unit 103, induced currents having opposite phases are generated from both ends of the slot 102, and the slot 102 operates as a slot antenna. Due to this induced current, at the both ends of the parasitic slot 105 (the left end in FIG. 1 of the parasitic slot 105-1, the lower end in FIG. 2 and the right end in FIG. 1 of the parasitic slot 105-3, the upper end in FIG. 2), the slot 102 A current in phase with the current at both ends of is induced. That is, the end portions of the slot 102 and the parasitic slot 105 along the opposing short sides are in phase.

  In each of the parasitic slots 105-1 to 105-3 that are partitioned by including the short-circuit portions 106-1 and 106-2 in the parasitic slot 105, the short-circuit portions 106-1 and 106-2 are at both ends of the parasitic slot 105. Are provided at positions separated from each other by a quarter wavelength. This position is a position where the electric field in the slot 102 is maximized and the current is minimized, and is also a point where the magnetic field distribution in the slot 102 is in reverse phase.

  Magnetic field components as shown in FIG. 2 are generated at both ends of the parasitic slots 105-1 to 105-3. Here, the ground plane 101 is viewed from the + Z direction, and the reflecting conductor 104 is viewed from the + Z direction, and the cross section at the cutting line BB shown in FIG. The upper end of the parasitic slot 105-1 generates a positive magnetic field component, and the lower other end generates a negative magnetic field component. The upper end of the parasitic slot 105-2 generates a positive magnetic field component, and the lower other end generates a negative magnetic field component. The upper end of the parasitic slot 105-3 generates a positive magnetic field component, and the lower other end generates a negative magnetic field component. That is, opposite-phase magnetic field components are generated at both ends of each of the non-electric field slots 105-1 to 105-3.

  In the slot 102, a wavy magnetic field distribution is generated as indicated by a broken line. In a position corresponding to one end of the non-feed slot 105-1 and the other end of the non-feed slot 105-2 (position where the short-circuit portion 106-1 is located, the position on the two-dot chain line in FIG. 2) The magnetic field component generated at one end of the slot 105-1 and the magnetic field component generated at the slot 102 have different polarities. In an arrangement position corresponding to one end of the parasitic slot 105-2 and the other end of the parasitic slot 105-3 (the position of the short-circuit portion 106-2 on the two-dot chain line in FIG. 2) The magnetic field component generated at the other end of the slot 105-3 and the magnetic field component generated at the slot 102 have different polarities.

  That is, short-circuit portions 106-1 and 106-2 are provided in the parasitic slot 105, and one parasitic slot 105 is divided into three parasitic slots 105-1 to 105-3. The magnetic field components can be polarized in opposite polarities at one end and the other end of 1 to 105-3. Then, by setting this polarization position to a position where the maximum electric field is generated in the parasitic slot 105 (position where the short-circuit portions 106-1 and 106-2 are arranged), the magnetic field generated in the parasitic slot 105 is short-circuited. It can be dispersed in the vicinity of the parts 106-1 and 106-2. As a result, in the slot array antenna, radiation in the −X direction can be suppressed, and the back lobe can be reduced.

  The specific measurement result of the radiation characteristics of the slot array antenna is shown in FIG. Here, the electrical length L of the slot is set to 3/4 wavelength, and a gain of 10 dBi can be obtained in the + X direction, and an F / B ratio of about 20 dB can be obtained. Also for the radiation characteristics shown in FIG. 17, the F / B ratio is greatly improved, the back lobe which is unnecessary radiation can be reduced, and the power can be used efficiently.

  Furthermore, a specific magnetic field distribution state of the slot array antenna is shown in FIG. Here, the ground plane 101 is viewed from the + Z direction, and the reflecting conductor 104 is viewed from the + Z direction, and the cross section at the cutting line BB shown in FIG. As is clear from FIG. 4, the magnetic field generated in the vicinity of the short-circuit portions 106-1 and 106-2 in the parasitic slot 105 can be reduced. For example, when a slot array antenna is mounted on a mobile phone, the reflective conductor 104 is disposed on the side of the mobile phone that includes a microphone or a speaker, and the reflective conductor 104 is provided on the side facing the user (human body) during a call using the mobile phone. Is present, the magnetic field generated in the short-circuit portions 106-1 and 106-2 of the reflective conductor 104 can be reduced, so that the SAR can be reduced.

  As described above, according to the first embodiment, the maximum electric field generated between the feeding part 103 of the parasitic slot 105 and the end where the induced current is generated is distributed by the short-circuit parts 106-1 and 106-2. Therefore, back lobes can be reduced. In addition, the slot array antenna can be mounted on a wireless communication terminal such as a mobile phone, and SAR can be reduced in such a wireless communication terminal.

  In the first embodiment, the shape of the ground plane 101 and the reflective conductor 104 is described as a square shape, but the present invention is not limited to this shape, and the shape of the ground plane 101 and the reflective conductor 104 is a rectangular shape or a circular shape. The shape may be used.

(Embodiment 2)
The slot array antenna according to the second embodiment of the present invention basically has the same configuration as that of the slot array antenna according to the first embodiment. However, as shown in FIG. A short-circuit portion (second short-circuit portion or second short-circuit point) 106-3 is provided at a position opposite to the power-feeding portion 103 provided in FIG. Since the short-circuit portion 106-3 is provided, the parasitic slot 105 is further divided into the parasitic slot 105-2 according to the first embodiment in addition to the parasitic slots 105-1 and 105-3. The slots 105-21 and 105-22 are provided, and a total of four parasitic slots 105-1, 105-21, 105-22, and 105-3 are provided.

  In this slot array antenna, when power is supplied to the power feeding unit 103 of the slot 102, the short-circuiting units 106-1 to 106-3 are provided, so that the parasitic slots 105-1 and 105-21 of the parasitic slot 105 are provided. , 105-22 and 105-3, the magnetic field components at both ends inside the slot are opposite in phase to each other and have a phase different from the magnetic field generated in the slot 102. Therefore, the slot array antenna can enhance the directivity in the X direction, and can disperse the magnetic field generated in the vicinity of each of the short-circuit portions 106-1 to 106-3.

  Specific radiation characteristics of the slot array antenna are shown in FIG. Here, the electrical length L of the slot is set to 3/4 wavelength, and a gain of 10 dBi can be obtained in the + X direction, and an F / B ratio of about 16 dB can be obtained. Also for the radiation characteristics shown in FIG. 17, the F / B ratio can be greatly improved, the backlobe, which is unnecessary radiation, can be reduced, and the power can be used more efficiently.

  A specific magnetic field distribution of the slot array antenna is shown in FIG. Here, the ground plane 101 is viewed from the + Z direction, and the reflecting conductor 104 is viewed from the + Z direction, and the cross section is taken along the cutting line DD shown in FIG. As is apparent from FIG. 7, the magnetic field generated in the vicinity of the short-circuit portions 106-1, 106-2, and 106-3 in the parasitic slot 105 can be reduced.

  As described above, according to the second embodiment, in addition to the effects that can be obtained by the slot array antenna according to the first embodiment, a relatively large electric field is generated at a position corresponding to the power feeding unit 103 of the parasitic slot 105. Since it can disperse | distribute with the short circuit part 106-2, a back lobe can be reduced further. Further, the slot array antenna can be mounted on a wireless communication terminal such as a mobile phone, and the SAR can be further reduced in such a wireless communication terminal.

(Embodiment 3)
The slot array antenna according to the third embodiment of the present invention basically has the same configuration as that of the slot array antenna according to the first embodiment. However, as shown in FIG. A power feeding unit 103 is disposed so as to be shifted to one end (left side in the drawing) as compared with the end (right side in the drawing), and the position corresponding to the power feeding unit 103 in the parasitic slot 105 and the slot 102 of the parasitic slot 105 are arranged. A short-circuit portion 106-2 is disposed between the other end portion and the corresponding other end portion (right side in the figure). At the position corresponding to the power feeding unit 103, the short-circuiting part 106-3 is disposed in the non-feeding slot 105 as in the slot array antenna according to the second embodiment. The power feeding unit 103 has an impedance of 50Ω and is disposed at a position where impedance matching can be performed.

  FIG. 9 shows the impedance characteristics of the real part assumed from the current distribution (magnetic field distribution) of FIG. Since the current is the maximum at both ends of the slot 102, the impedance is infinitely close to 0. Further, at the position where the electric field is maximum in the slot 102 (position at a quarter wavelength away from both ends of the slot 102), the current becomes zero and the impedance becomes maximum. That is, since the impedance varies depending on the position in the slot 102, impedance matching can be easily achieved by shifting the power feeding unit 103 to an appropriate position.

  FIG. 10 shows the magnetic field distribution in the slot 102 when the power supply unit 103 is shifted and power is supplied from the power supply unit 103 to the slot 102 as shown in FIG. Here, the main plate 101 is seen from the + Z direction of a cross section taken along the cutting line EE shown in FIG. As is apparent from FIG. 10, there are two portions (necking) where the magnetic field distribution is small, and this is the position where the electric field in this portion becomes strong. One of the two locations corresponds to a position where the power feeding unit 103 is provided. At a position corresponding to the power supply unit 103, the non-power supply slot 105 is provided with a short-circuit unit 106-3. The parasitic slot 105 is provided with a short-circuit part 106-2 between the position corresponding to the feeder part 103 and the other end of the parasitic slot 105.

  The radiation characteristics of the slot array antenna are shown in FIG. Here, the electrical length L of the slot 102 is set to 3/4 wavelength, and a gain of 9.5 dBi can be obtained in the + X direction, and an F / B ratio of approximately 20 dB can be obtained.

  FIG. 12 shows the magnetic field distribution of the slot array antenna. Here, the ground plane 101 is viewed from the + Z direction, and the reflection conductor 104 is viewed from the + Z direction as viewed from the section line DD shown in FIG. As is apparent from FIG. 12, the magnetic field generated in the vicinity of each of the parasitic slots 106-3 and 106-2 can be reduced.

  As described above, according to the third embodiment, by shifting the position of the power supply unit 103 provided in the slot 102, impedance matching can be easily achieved, and the short-circuit unit 106-3 is provided at a position corresponding to the power supply unit 103. Since the short-circuit portion 106-2 is provided between the position and the other end portion of the parasitic slot 105, a relatively large magnetic field generated in the vicinity of each of the short-circuit portions 106-3 and 106-2 is reduced. The back lobe can be further reduced.

(Embodiment 4)
The slot array antenna according to the fourth embodiment of the present invention will be described with reference to an example in which the configuration of the short-circuit portions 106-1, 106-2, and 106-3 of the slot array antenna according to the second embodiment is changed. As shown in FIG. 13, the slot array antenna according to Embodiment 4 includes short-circuit portions 106-1, 106-2, and 106-3 in the parasitic slot 105.

The short-circuit portion 106-1 is a plurality of switching elements that are electrically connected in parallel and arranged at equal intervals between one end portion (left end in the figure) of the non-feed slot 105 and a position corresponding to the feed portion 103. SW _{11 to} SW _1n are provided. Each of the switching elements SW _{11 to} SW _1n has one end electrically connected to one of the opposing sides and the other end electrically connected to the other of the opposing sides. Although not necessarily limited to this element, in Embodiment 4, a switching diode can be used practically for the switching elements SW _{11 to} SW _1n .

The short-circuit portion 106-2 is a plurality of switching units that are electrically connected in parallel and arranged at equal intervals between the other end portion (right end in the figure) of the parasitic slot 105 and the position corresponding to the feeding portion 103. and a device SW ₂₁ to SW _2n. The plurality of switching elements SW _{21 to} SW _2n are configured by the same switching diode as the switching elements SW _{11 to} SW _1n , respectively.

Short section 106-3, the parasitic slot 105 is configured by the switching element SW ₃ which is disposed at a position corresponding to a power source 103. Switching element SW ₃ is constituted by the switching element SW ₁₁ to SW _1n the same switching diode.

For example, when the frequency f1 and the frequency f2 (f1> f2) are used, at the frequency f1, the switching elements SW ₁₁ disposed at positions separated from the both ends of the parasitic slot 105 to the inside by 1/4 wavelength respectively. SW ₂₁ conducts and is used as the short-circuit portions 106-1 and 106-2. Switching elements SW ₁₁ and SW ₂₁ that are conductive (in a connected state) and switching elements other than the switching element SW ₃ used as the short-circuit portion 106-3 are disconnected. Since the wavelength becomes longer at the frequency f2, the switching elements SW _1n and SW _2n disposed at positions spaced apart from each other by ¼ wavelength from both ends of the parasitic slot 105 to the inside thereof become conductive and the short-circuit portion 106-1. And 106-2. Switching elements other than the switching elements SW _1n and SW _2n that are conducting and the switching element SW ₃ used as the short-circuit portion 106-3 are disconnected.

Next, the operation of the slot array antenna having the above configuration will be described. Here, for convenience of explanation, it is assumed that two different frequencies f1 and f2 (f1> f2) described above are used. First, when using the frequency f1, high frequency, because the wavelength is short, the switching element SW ₁₁ of the short-circuit unit 106-1, the switching element SW ₂₁ of the short-circuit unit 106-2, the switching element SW ₃ of the short circuit portion 106-3 Is turned on (ON), and the other switching elements SW are cut off (OFF). As a result, the slot array antenna according to the second embodiment corresponding to the frequency f1 can be realized, and when the frequency f1 is used, in the vicinity of each of the short-circuit portions 106-1, 106-2, and 106-3. The generated magnetic field can be dispersed.

When the frequency f2 is used, since the frequency is low and the wavelength is long, the switching element SW _{1n of} the short-circuit portion 106-1, the switching element SW _{2n of} the short-circuit portion 106-2, and the switching element SW _{3 of the} short-circuit portion 106-3. Is turned on (ON), and the other switching elements SW are cut off (OFF). As a result, the slot array antenna according to the second embodiment corresponding to the frequency f2 can be realized, and when the frequency f2 is used, in the vicinity of each of the short-circuit portions 106-1, 106-2, and 106-3. The generated magnetic field can be dispersed.

Here, FIG. 14 shows the radiation characteristics of the slot array antenna when the length of one side of the ground plane 101 and the reflecting conductor 104 is 0.84 wavelength. FIG. 14A shows the radiation characteristics when all the switching elements SW of the short-circuit portions 106-1, 106-2, and 106-3 are turned off (opened). Further, FIG. 14 (b), the switching element SW ₃ of the short-circuit unit 106-3 and to ON, one of the switching elements SW ₁₁ to SW _1n the short-circuit portion 106-1 is ON, the further the short-circuit 106-2 The radiation characteristic when any one of the switching elements SW _{21 to} SW _2n is turned on is shown.

  In this manner, each of the short-circuit portions 106-1, 106-2, and 106-3 is configured by the switching element SW, and the switching element SW is turned on and off to change the radiation characteristics according to the use frequency and application. It can be adjusted appropriately. For example, when the slot array antenna according to the fourth embodiment is mounted on a wireless communication terminal such as a mobile phone, it is adjusted to reduce the SAR using the radiation characteristics shown in FIG. The radiation characteristic shown in FIG. 14A suitable for the characteristic is used.

  In the above-described slot array antenna having the magnetic field distribution shown in FIG. 18, the amplitude is maximum at both ends of the windows 5a and 5b, and the phase is reversed. For this reason, in the windows 5a and 5b, the amplitude is 0 and the phase is inverted at a position one quarter wavelength away from both ends thereof. Therefore, when the slot length is ½ wavelength, the amplitude becomes 0 near the feeding point 14 of the window 13, but when the slot length exceeds ½ wavelength, the current near the feeding point 14 and the current in the windows 5 a and 5 b Since the phase of the current at the window end is the same phase, it is also radiated in the −X direction (reflecting conductor side), resulting in a back lobe.

On the other hand, according to the slot array antenna according to the fourth embodiment, when the slot length L is fixed and the use frequency increases, the frequency exceeds 1/2 wavelength, but a plurality of short-circuit portions 106-1 are arranged. one of the switching elements SW ₁₁ to SW _1n has, switching the short circuit 106-2 selects either the multiple array of switching elements SW ₂₁ to SW _2n, corresponding to the position of the quarter wavelength of the used frequency By turning on the element SW, radiation in the −X direction can be suppressed and the back lobe can be reduced. Thereby, reduction of SAR can be guide | induced.

  In the slot array antenna, the radiation characteristics change when the sizes of the ground plane 101 and the radiation conductor 104 change. In particular, the radiation characteristics of the slot array antenna vary depending on the length from the end of the slot 102 to the end of the ground plane 101 (reflection conductor 104). The sizes of the ground plane 101 and the radiation conductor 104 set to have the radiation characteristics shown in FIG. 14 are merely examples, and in the present invention, these sizes may be changed. When the sizes of the ground plane 101 and the radiation conductor 104 are changed, of course, the radiation characteristics of the slot array antenna are different from the radiation characteristics shown in FIG.

As described above, according to the fourth embodiment, the electric field is maximized by each of the switching elements SW _{11 to} SW _1n and SW _{21 to} SW _2n even if the place where the electric field is maximized in the parasitic slot 105 changes. The short-circuit portions 106-1 and 106-2 can be constructed corresponding to the locations, and the maximum electric field generated in the parasitic slot 105 can be reduced, so that the back lobe can be reduced and the SAR can be reduced. Can be reduced. Therefore, it is possible to realize a slot array antenna corresponding to a change in use frequency.

(Embodiment 5)
The slot array antenna according to Embodiment 5 of the present invention is an example in which the shape of the slot 102 of the ground plane 101 and the parasitic slot 105 of the reflecting conductor 104 in the slot array antenna according to Embodiment 4 is changed. .

  As shown in FIG. 15, in the slot array antenna according to the fifth embodiment, the ground plane 101 is a conductor layer (copper foil or the like) formed on a substrate built in a wireless communication terminal device such as a mobile phone. 102 is formed through the main plate.

  The total length of the slot 102 is an electrical length L, the central portion of the slot 102 is disposed along one side of the main plate 101, and both end portions of the slot 102 are bent or curved along the other adjacent side of the main plate 101. Has been. In the fifth embodiment, both end portions are bent at an angle of 90 degrees with respect to the central portion of the slot 102. The overall planar shape of the slot 102 is U-shaped or U-shaped. A power feeding unit 103 is provided at an equal distance from both ends of the slot 102, that is, at the center of the slot 102.

  The size of the reflective conductor 104 is substantially the same as the size of the ground plane 101, and the reflective conductor 104 is disposed substantially parallel to the ground plane 101 with an interval S (S is 0.01 wavelength or more). The reflection conductor 104 is formed with a parasitic slot 105 that penetrates the reflection conductor 104 at a position facing the slot 102 formed in the ground plane 101 and has the same shape as the slot 102.

In the non-feeding slot 105, a short-circuiting part 106-3 is disposed at a position facing the feeding part 103 provided in the slot 102, that is, in the center. It is formed by the short circuit section 106-3 in the same manner as the short circuit portion 106-3 according to the fourth embodiment the switching element SW _3. Further, in the non-feed slot 105, a short-circuit portion 106-1 is disposed between a position corresponding to the power supply portion 103 and one end (left side in the figure), and a position corresponding to the power supply portion 103 and the other end (in the drawing). A short-circuit portion 106-2 is disposed between the right side) and the right side. Like the short circuit portion 106-1 according to the fourth embodiment, the short circuit portion 106-1 is composed of a plurality of switching elements SW ₁₁ to SW _1n, like the short-circuit unit 106-2 according to the fourth embodiment, a short circuit part 106-2 is composed of a plurality of switching elements SW ₂₁ to SW _2n.

  Since the operation of the slot array antenna according to the fifth embodiment is the same as the operation of the slot array antenna according to the fourth embodiment, description thereof is omitted here because it is duplicated.

  As described above, according to the fifth embodiment, the planar shapes of the slot 102 and the parasitic slot 105 are bent or curved, so that the electrical lengths of the slot 102 and the parasitic slot 105 are the sizes of the ground plane 101 and the reflective conductor 104 ( Therefore, the size of the ground plane 101 and the reflection conductor 104 can be reduced, and the slot array antenna can be downsized.

  Since the slot array antenna according to the present invention can reduce the back lobe, it has the effect of reducing the SAR, and is applied not only to the cellular phone but also to a radio communication terminal such as a portable radio. be able to.

The perspective view which shows the structure of the slot array antenna which concerns on Embodiment 1 of this invention. The figure which shows the magnetic field component of the slot array antenna shown in FIG. The figure which shows the radiation characteristic of the slot array antenna which is shown in FIG. The figure which shows the magnetic field distribution of the slot array antenna shown in FIG. The perspective view which shows the structure of the slot array antenna which concerns on Embodiment 2 of this invention. The figure which shows the radiation characteristic of the slot array antenna shown in FIG. The figure which shows the magnetic field distribution of the slot array antenna shown in FIG. The perspective view which shows the structure of the slot array antenna which concerns on Embodiment 3 of this invention. The figure which shows the impedance characteristic of the slot array antenna shown in FIG. The magnetic field distribution of the slot array antenna shown in FIG. The figure which shows the radiation characteristic of the slot array antenna which is shown in FIG. Diagram showing magnetic field distribution in the vicinity of the slot array antenna shown in FIG. The perspective view which shows the structure of the slot array antenna which concerns on Embodiment 4 of this invention. The figure which shows the radiation characteristic of the slot array antenna which is shown in FIG. The perspective view which shows the structure of the slot array antenna which concerns on Embodiment 5 of this invention. The perspective view which shows the structure of the slot array antenna based on a prior art The figure which shows the radiation characteristic of the slot array antenna shown in FIG. The magnetic field distribution of the slot array antenna shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Ground plate 102 Slot 103 Feed part 104 Reflective conductor 105, 105-1, 105-2, 105-21, 105-22, 105-3 Parasitic slot 106-1, 106-2, 106-3 Short-circuit part SW Switching element

Claims (7)

A main plate having a slot;
A power feeding portion disposed in a central portion of the slot;
A reflective conductor having a parasitic slot facing the slot and disposed facing the ground plane;
A first short-circuit part that partially connects opposite sides of the parasitic slot between a position corresponding to the feeder part of the parasitic slot and an end where the induced current of the parasitic slot is generated;
A slot array antenna comprising:   The slot array antenna according to claim 1, further comprising a second short-circuit portion that partially connects opposite sides of the non-feed slot at a position corresponding to the feed portion.   The power feeding portion is arranged at a central portion of the slot, shifted to one end compared to the other end, and the position corresponding to the power feeding portion of the non-feeding slot and the non-feeding portion corresponding to the other end of the slot. The slot array antenna according to claim 1, wherein the short-circuit portion is disposed between the other end portion of the power feeding slot. The first short circuit part or the second short circuit part is:
The slot array antenna according to claim 1 or 2, wherein the slot array antenna is a switching element capable of partially connecting and disconnecting opposite sides of the parasitic slot.   5. The slot array antenna according to claim 4, wherein a plurality of switching elements which are the first short-circuit portions are arranged in electrical parallel.   6. The slot array antenna according to claim 1, wherein each of the slot and the parasitic slot has a planar shape that is bent or curved.   A wireless communication terminal comprising the slot array antenna according to any one of claims 1 to 6.