JP2012090099A - Composite antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite antenna that is small in size, facilitates adjustment of resonance frequency and impedance, and allows multi-resonance operations by a single power feeder and with a single polarization wave, thereby facilitating multi-frequency operations.SOLUTION: A composite antenna includes: a symmetrically-shaped conductive plate 2; two slots 3 and 4 of different lengths that are formed on a symmetric axis A of the conductive plate 2 so as to extend along a direction of the symmetric axis A from both ends of the conductive plate 2 and so as to be symmetric about the symmetric axis A; a short-circuiting portion 5 that is positioned between the two slots 3 and 4 so as to electrically cause a short circuit between upper and lower halves of the conductive plate 2 above and below the two slots 3 and 4; a power feeding portion 6 that is provided in the slot 4, which is shorter of the two slots 3 and 4, and provided so as to be close to the short-circuiting portion 5; and a passive slot 7 that is formed in at least one of the upper and lower halves of the conductive plate 2 above and below the two slots 3 and 4 so as to extend along the direction of the symmetric axis A and so as not to pass across positions, in the direction of the symmetric axis A, where the short-circuiting portion 5 and the power feeding portion 6 are provided.

Description

  The present invention relates to a composite antenna used in a communication system that transmits and receives radio waves of a specific polarization component, and more particularly to a composite antenna that can handle radio waves of a plurality of frequencies.

  FIGS. 21A and 21B show the structure of the slot antenna. As shown in FIGS. 21A and 21B, the slot antenna 191 has a microstrip feed line 193 formed on the surface of the dielectric substrate 192 and a wide conductor plate 194 formed on the back surface of the dielectric substrate 192. A rectangular slot 195 is formed on the conductor plate 194. As an example, Patent Document 1 discloses a cylindrical slot antenna in which a slot is provided in a cylindrical hollow conductor.

  Further, in order to improve the characteristics of the slot antenna and increase the bandwidth, there is known a slot antenna 201 in which a parasitic parasitic slot 202 is formed in parallel with the slot 195 as shown in FIGS. 22 (a) and 22 (b). (For example, Patent Documents 2 to 4).

JP-A-10-56321 JP 2002-299950 A Japanese Patent Laid-Open No. 2003-188639 JP-A-11-163625 JP 2007-166615 A JP 2006-121190 A

  However, since the slot antennas 191 and 201 described above have a three-dimensional structure using the dielectric substrate 192, it is difficult to reduce the size. In particular, the slot antenna 201 having a wide band by adding the rectangular parasitic slot 202 has a problem that it is difficult to reduce the size because the parasitic slot 202 is arranged in a rectangular shape.

  In addition, the slot antennas 191 and 201 using the microstrip feed require high-precision manufacturing techniques such as pattern displacement between the front surface side and the back surface side. In addition, when the bandwidth is increased, it is necessary to adjust the microstrip line and the slot, and there is a problem that it takes time to adjust the resonance frequency and impedance.

  Further, the slot antennas 191 and 201 have a problem that it is difficult to increase the frequency. More specifically, the limit of the number of resonances in the antenna of the cutting elements such as notches and slots is limited to two. Note that many polarization-shared antennas have been developed as multi-frequency shared antennas (for example, Patent Document 5). However, it is difficult for a conventional multi-frequency shared antenna to perform a double resonance operation with a single polarization with a single feed. Met.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and is small in size, easy to adjust the resonance frequency and impedance, and can be operated with multiple resonances with a single polarization with a single power supply and can be easily multi-frequency. It is to provide an antenna.

  The present invention has been devised to achieve the above object, and is formed along a symmetrical axis direction from both sides of the conductive plate on a symmetrical conductive plate and a symmetrical axis of the conductive plate, and Two slots of different lengths formed so as to have a symmetric shape with respect to the axis of symmetry, and between the two slots, are electrically short-circuited between the conductor plates above and below the two slots. And a short-circuit portion that is provided in a shorter one of the two slots, and a power feeding portion that is provided in the vicinity of the short-circuit portion, and at least one of the conductor plates above and below the two slots is symmetrical A parasitic antenna including a parasitic slot formed so as not to cross a position where the short-circuit portion and the feeding portion are provided in the axial direction and in the symmetry axis direction.

  The parasitic slots may be formed in both the upper and lower conductor plates of the two slots, and the parasitic slots may be formed so as to be symmetrical with respect to the symmetry axis.

  The parasitic slot may be formed along a longer slot of the two slots.

  The parasitic slot may be formed in a U-shape or a U-shape in which the short-circuit portion side in the symmetry axis direction is opened.

  The parasitic slot may be formed such that the length along the direction of the symmetry axis is longer than the opening width of the U shape or the U shape.

  The non-feeding slot may be formed such that an end portion on the opening side of the U-shape or the U-shape is positioned in the vicinity of the position where the short-circuit portion or the feeding portion is provided in the direction of the symmetry axis.

  The conductor plate may be formed in a horizontally long rectangular shape in the direction of the symmetry axis.

  The two slots may be formed in a rectangular shape having the same width.

  The two slots may include a lateral M-shaped slot having an open end that gradually increases in diameter and a rectangular slot having an open end opposite to the open end of the lateral M-shaped slot.

  The rectangular slot may include an elongated slot having an open end and a square slot formed continuously with the elongated slot.

  According to the present invention, it is possible to provide a composite antenna that is small in size, can be easily adjusted in resonance frequency and impedance, can be operated in a single resonance with a single polarization, and can be multi-resonated easily.

(A) is a plan view of a composite antenna according to an embodiment of the present invention, (b) is a plan view of a two-resonance notch antenna before forming a parasitic slot, and (c) is a view of the composite antenna of the present invention. It is a figure which shows the characteristic of a return loss. It is a figure which shows the radiation pattern in each frequency of the composite antenna of Fig.1 (a), (a) is XZ plane in frequency 790MHz, (b) is YZ plane in frequency 790MHz, (c) is XZ plane in frequency 1180MHz. (D) is a YZ plane at a frequency of 1180 MHz, (e) is an XZ plane at a frequency of 1740 MHz, and (f) is a radiation pattern of the YZ plane at a frequency of 1740 MHz. (A) is a top view which shows the modification of the composite antenna of Fig.1 (a), (b) is a figure which shows the return loss characteristic. (A) is a top view which shows the modification of the composite antenna of Fig.1 (a), (b) is a figure which shows the return loss characteristic. (A) is a top view which shows the modification of the composite antenna of Fig.1 (a), (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of this invention, (b) is a figure which shows the return loss characteristic. (A) is a top view of the composite antenna which concerns on other embodiment of this invention, (b) is a figure which shows the return loss characteristic. It is a figure which shows the radiation pattern in each frequency of the composite antenna of Fig.18 (a), (a) is XZ plane in frequency 960MHz, (b) is YZ plane in frequency 960MHz, (c) is XZ plane in frequency 1490MHz. (D) is a YZ plane at a frequency of 1490 MHz, (e) is an XZ plane at a frequency of 1960 MHz, and (f) is a radiation pattern of the YZ plane at a frequency of 1960 MHz. (A) is a top view of the composite antenna used as the comparison object of the composite antenna of Fig.18 (a), (b) is a figure which shows the return loss characteristic. It is a figure which shows the conventional slot antenna, (a) is a top view, (b) is the 19B-19B sectional view taken on the line. It is a figure which shows the conventional slot antenna, (a) is a top view, (b) is the 20B-20B sectional view taken on the line.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1A is a plan view of the composite antenna according to the present embodiment, FIG. 1B is a plan view of a two-resonance notch antenna before forming a parasitic slot, and FIG. 1C is a diagram. It is a figure which shows the characteristic of the return loss of the composite antenna of 1 (a). 1A and 1B show the dimensions (millimeters) of the composite antenna 1 of the present embodiment. In other figures, dimensions are indicated in millimeters.

  As shown in FIG. 1A, a composite antenna 1 includes a symmetrical conductor plate 2, two slots 3 and 4 formed in the conductor plate 2, a short-circuit portion 5, a feeding portion 6, and a non-feeding power. Slot 7.

  The conductor plate 2 has a line-symmetric shape with respect to the symmetry axis A. In the present embodiment, the conductor plate 2 is formed in a horizontally long rectangular shape in the direction of the axis of symmetry (the horizontal direction in the figure). The conductor plate 2 is made of, for example, a copper plate or a phosphor bronze plate having a spring property.

  The two slots 3 and 4 are formed on the symmetry axis A of the conductor plate 2 along the symmetry axis direction from both sides of the conductor plate 2 and have a line-symmetric shape with respect to the symmetry axis A. . These two slots 3 and 4 are formed to have different lengths (lengths in the direction of the symmetry axis). Here, the case where the slot 3 on the left side of the figure is formed longer than the slot 4 on the right side of the figure will be described. In the present embodiment, the two slots 3 and 4 are formed in a rectangular shape having the same width. The two slots 3 and 4 are on the axis of symmetry A and have open ends on both sides of the conductor plate 2.

  The short-circuit portion 5 is located between the two slots 3 and 4 and electrically short-circuits between the upper and lower conductor plates 2 of the two slots.

  The power feeding unit 6 is provided in the shorter slot 4 of the two slots 3 and 4 and is provided close to the short-circuit unit 5. The power supply to the power supply unit 6 may be performed using, for example, a coaxial cable, a plurality of single-core cables, a flat cable, or the like.

  By providing two slots 3 and 4, a short-circuit portion 5, and a power feeding portion 6 in the conductor plate 2, one power feeding 2 in which two slots 3 and 4 having different lengths operate as notch elements that resonate at different frequencies, respectively. A resonant notch antenna (hereinafter referred to as a two-resonant notch antenna) 8 is obtained. The length of the two slots 3 and 4 (the position of the short-circuit portion 5 in the direction of the symmetry axis) may be appropriately set according to the desired resonance frequency. Further, in order to operate as the two-resonance notch antenna 8, the distance between the power supply unit 6 and the short-circuit unit 5 is λ / 20 or less with respect to the wavelength λ of the operating frequency (the higher resonance frequency of the two resonance frequencies). (Preferably λ / 40 or less).

  In the composite antenna 1 according to the present embodiment, the two-resonance notch antenna 8 further operates as a third element (that is, resonates at a frequency different from the two resonance frequencies of the two-resonance notch antenna 8). A slot 7 is formed.

  The non-feeding slot 7 does not cross the position where the short-circuit part 5 and the feeding part 6 are provided in at least one of the upper and lower conductor plates 2 of the two slots 3 and 4 along the symmetry axis direction and in the symmetry axis direction. Formed as follows. This is because when the parasitic slot 7 is formed so as to cross the position where the short-circuit part 5 and the feeder part 6 are provided in the direction of the symmetry axis, the parasitic slot 7 does not operate as a third element, This is because the operation (return loss characteristic) is worsened. Further, when the parasitic slot 7 is formed so as to cross both the position where the short-circuit portion 5 is provided and the position where the feeder portion 6 is provided in the direction of the symmetry axis, the operation of the two-resonance notch antenna 8 serving as a base is affected. This is because good three-resonance operation cannot be obtained.

  The parasitic slots 7 are formed in both the upper and lower conductor plates 2 of the two slots 3 and 4, and the parasitic slots 7 may be formed so as to be symmetrical with respect to the symmetry axis A. desirable. This is because the parasitic slot 7 is formed only in one of the upper and lower conductor plates 2 of the two slots 3 and 4, or both of the upper and lower conductor plates 2 of the two slots 3 and 4 are symmetrical with respect to the symmetry axis A. This is because, when the parasitic slot 7 is formed so as not to have a symmetrical shape, an operation at a desired frequency can be obtained, but impedance matching becomes difficult to achieve and a good operation cannot be obtained.

  Furthermore, the parasitic slot 7 is preferably formed along the longer slot 3 of the two slots 3 and 4. This is because when the parasitic slot 7 is formed along the shorter slot 4, an operation at a desired frequency can be obtained but a good operation cannot be obtained.

  Furthermore, the parasitic slot 7 is preferably formed in a U-shape or a U-shape in which the short-circuit portion 5 side in the symmetry axis direction is opened. In order to operate the parasitic slot 7, it is necessary that the current distribution is large at both ends of the parasitic slot 7 and the current distribution is small at the center of the parasitic slot 7. Since the current distribution in the two-resonance notch antenna 8 becomes larger as it is closer to the short-circuit portion 5, the parasitic slot 7 is formed in a U-shape or a U-shape in which the short-circuit portion 5 side is opened. Thus, a suitable current distribution having a large current distribution and a small current distribution in the central portion can be obtained, and the parasitic slot 7 can be favorably operated as the third element.

  If the length of the parasitic slot 7 along the direction of the symmetric axis is short, the central portion of the parasitic slot 7 is close to the short-circuit portion 5 and the current distribution in the central portion becomes large, so that a good operation cannot be obtained. Therefore, it is necessary to lengthen the length of the parasitic slot 7 along the direction of the symmetry axis to some extent and to separate the central portion of the parasitic slot 7 from the short-circuit portion 5. For this reason, it is desirable that the parasitic slot 7 is formed so that the length along the axis of symmetry is longer than the U-shaped or U-shaped opening width. However, if the U-shaped or U-shaped opening width is too small, the operation as the third element may be adversely affected. Therefore, the U-shaped or U-shaped opening width is It is desirable to make it somewhat large (for example, larger than 3 mm).

  In addition, if both ends of the parasitic slot 7 are separated from the short-circuit portion 5, current distribution at both ends becomes small and a good operation cannot be obtained. Therefore, the parasitic slot 7 is located near the short-circuit portion 5 in the symmetry axis direction. It is desirable that the U-shaped or U-shaped opening side end portion be positioned in the vicinity of the power feeding portion 6 when the non-power feeding slot 7 is formed along the slot 4.

  In consideration of the above conditions, in the composite antenna 1 according to the present embodiment, two slots are formed so that both the upper and lower conductor plates 2 of the two slots 3 and 4 are symmetrical with respect to the symmetry axis A. A position where the U-shaped non-feeding slot 7 opened on the side of the short-circuit portion 5 in the direction of the symmetric axis along the longer slot 3 of 3 and 4 is provided with the short-circuit portion 5 and the feed portion 6 in the direction of the symmetric axis. It was formed so as not to cross. In the composite antenna 1, the parasitic slot 7 is formed such that its length along the axis of symmetry is longer than the U-shaped opening width, and the end of the U-shaped opening side is the short-circuit portion 5. It is formed to be in the vicinity.

  FIG. 1C shows the result of simulating the return loss characteristics when the composite antenna 1 is manufactured with the dimensions shown in FIGS. In FIG. 1C, the return loss characteristic in the two-resonance notch antenna 8 before forming the parasitic slot 7 is also shown by a broken line.

  As shown in FIG. 1 (c), in the composite antenna 1, in addition to two peaks due to the operation of the two-resonance notch antenna 8 (peaks near 800 MHz and 1.7 GHz), a third due to the operation of the parasitic slot 7. It can be seen that this peak appears in the vicinity of 1.2 GHz. The return loss at the third peak is about −16 dB, and it can be seen that a satisfactory operation is obtained as the third element. The resonance frequency at which the parasitic slot 7 operates can be arbitrarily adjusted by adjusting the length of the parasitic slot 7.

  The polarization direction of each element (slots 3 and 4 and parasitic slot 7) of the composite antenna 1 is the vertical direction (vertical polarization) in FIG. That is, according to the composite antenna 1, it is possible to perform a multi-resonance operation (three-resonance operation) with a single polarization with one feeding.

  Radiation patterns at each frequency of the composite antenna 1 are shown in FIGS. As shown in FIGS. 2A to 2F, omnidirectionality is obtained in the XZ plane at each frequency, and an 8-shaped directivity is obtained in the YZ plane. The directivity in each plane is in frequency. Regardless, it is almost the same. For this reason, it becomes easy to determine the orientation of the antenna when the composite antenna 1 is mounted.

  Here, the case where the U-shaped parasitic slot 7 is formed has been described. However, as shown in FIG. 3A, the composite antenna 21 having the U-shaped parasitic slot 7 is also illustrated in FIG. As shown in FIG. 3B, the third peak due to the operation of the parasitic slot 7 appears in the vicinity of 1.4 GHz, a return loss of about −19 dB is obtained, and it can be seen that good operation can be obtained.

  FIG. 4A shows a composite antenna 31 in which a U-shaped parasitic slot 7 is formed along the shorter slot 4. Also in this composite antenna 31, as shown in FIG. 4B, a third peak due to the operation of the parasitic slot 7 appears in the vicinity of 2.4 GHz. However, in the composite antenna 31, the length of the parasitic slot 7 is limited, and the current distribution in the central portion of the parasitic slot 7 becomes large (the central portion of the parasitic slot 7 is close to the short-circuit portion 5). Good operation like the antennas 1 and 21 cannot be obtained, and the return loss is about -4 dB.

  When the parasitic slot 7 is formed along the longer slot 3 as in the composite antennas 1 and 21 of FIGS. 1A and 3A, the length of the parasitic slot 7 is adjusted. A resonance frequency between two resonance frequencies in the two resonance notch antenna 8 can be obtained. On the other hand, when the parasitic slot 7 is formed along the shorter slot 4 as in the composite antenna 31 of FIG. 4A, the length of the parasitic slot 7 is limited, so that there are two resonances. The resonance frequency is higher than the two resonance frequencies of the notch antenna 8.

  Further, the length from the folded portion of the U-shape or the U-shape in the parasitic slot 7 may be varied up and down. As an example, FIG. 5 (a) shows a composite antenna 41 in which the length from the U-shaped folded portion in the parasitic slot 7 is varied up and down, and its return loss characteristic is shown in FIG. 5 (b). . The composite antenna 41 is obtained by shortening the length from the folded portion on the side (outside) away from the slot 3 in the composite antenna 1 of FIG.

  In the composite antenna 41, the shorter end portion (outside) from the folded portion is separated from the short-circuit portion 5 and the current distribution becomes small. Therefore, as shown in FIG. It is slightly smaller than the antenna 1 and has a return loss of about −10 dB.

  Here, the position where the parasitic slot 7 is formed, the shape of the parasitic slot 7 and the like are examined. Note that the composite antenna to be compared described below uses the two-resonance notch antenna 8 as a base having the dimensions shown in FIG. 1B and changes only the shape and position of the parasitic slot 7. It is.

  First, the position where the parasitic slot 7 is formed will be considered.

  A composite antenna 51 shown in FIG. 6A is obtained by forming a parasitic slot 7 so as to cross the short-circuit portion 5 in the symmetry axis direction in the composite antenna 1 of FIG. Further, the composite antenna 61 shown in FIG. 7A is a composite antenna 31 of FIG. 4A in which a parasitic slot 7 is formed so as to cross the power feeding section 6 in the direction of the symmetry axis. FIG. 6B shows the return loss characteristic of the composite antenna 51 in FIG. 6A, and FIG. 7B shows the return loss characteristic of the composite antenna 61 in FIG. 7A.

  Comparing FIG. 1C and FIG. 6B, when the parasitic slot 7 crosses the short-circuit portion 5, the return loss at the third peak rapidly decreases from about −16 dB to about −7 dB. I understand that. Further, comparing FIG. 4B and FIG. 7B, it can be seen that the third peak almost disappears when the parasitic slot 7 crosses the feeder section 6.

  8 (a), 9 (a), and 10 (a) show composite antennas 71, 81, and 91 in which a parasitic slot 7 is formed so as to cross both the short-circuit portion 5 and the feeder portion 6. FIG. . The return loss characteristics of these composite antennas 71, 81, 91 are shown in FIGS. 8B, 9B, and 10B, respectively.

  The composite antenna 71 in FIG. 8A is the same as the composite antenna 1 in FIG. 1A in which the length from the folded portion on the side away from the slot 3 (outside) is shortened and the side close to the slot 3 (inside). The non-feeding slot 7 is formed so as to cross both the short-circuit portion 5 and the feeding portion 6 by increasing the length from the folded portion.

  The composite antenna 81 in FIG. 9A has a shorter length from the folded portion on the side (outer side) away from the slot 4 in the composite antenna 31 in FIG. 4A, and is closer to the slot 4 (inner side). The non-feeding slot 7 is formed so as to cross both the short-circuit portion 5 and the feeding portion 6 by increasing the length from the folded portion.

  The composite antenna 91 of FIG. 10A has a U-shaped configuration so as to cross both the short-circuit portion 5 and the feeding portion 6 and to open the opposite side of the short-circuit portion 5 in the direction perpendicular to the symmetry axis direction. A power supply slot 7 is formed.

  As shown in FIG. 8B, FIG. 9B, and FIG. 10B, in these composite antennas 71, 81, and 91, the third peak is small, and good operation is not obtained. I understand. Further, in the composite antennas 71, 81, 91, the peak of the lower frequency of the two peaks of the two-resonance notch antenna 8 serving as the base is reduced or disappears, and the operation of good three-resonance is achieved. It can be seen that it has not been realized.

  As described above, when the parasitic slot 7 crosses the position where the short-circuit portion 5 and the feeder portion 6 are provided in the direction of the symmetry axis, the return loss at the third peak rapidly deteriorates or the two-resonance notch antenna 8 serving as the base As a result, it becomes impossible to realize a satisfactory three-resonance operation. Therefore, it is necessary to form the non-feed slot 7 so as not to cross the short-circuit portion 5 and the feed portion 6.

  The composite antenna 101 shown in FIG. 11 (a) is the same as the composite antenna 1 shown in FIG. 1 (a) except that the end on the U-shaped opening side is separated from the short-circuit portion 5 in the direction of the symmetric axis. And a parasitic slot 7 is formed. Further, the composite antenna 111 shown in FIG. 12 (a) is the same as the composite antenna 1 shown in FIG. 1 (a). ) To form a parasitic slot 7 (the U-shaped opening width of the parasitic slot 7 in the composite antenna 111 is 1 mm). FIG. 11B shows the return loss characteristic of the composite antenna 101 in FIG. 11A, and FIG. 12B shows the return loss characteristic of the composite antenna 111 in FIG.

  Comparing FIG. 1 (b) with FIGS. 11 (b) and 12 (b), it can be seen that the third peak almost disappears in FIGS. 11 (b) and 12 (b). This is presumably because the current distribution is small at both ends of the parasitic slot 7 because the both ends of the parasitic slot 7 are away from the short-circuit portion 5 and a good operation is not obtained. Therefore, in order for the parasitic slot 7 to operate satisfactorily as the third element, it is desirable to form the parasitic slot 7 with the end portion on the U-shaped opening side close to the short-circuit portion 5.

  Next, the shape of the parasitic slot 7 will be examined.

  The composite antenna 121 shown in FIG. 13 (a) removes the slot in a portion extending in parallel with the axis of symmetry on the side (outside) away from the slot 3 in the composite antenna 1 of FIG. This is a parasitic slot 7. Further, the composite antenna 131 shown in FIG. 14A is a linear (rectangular) parasitic slot in which the slot extending in the direction perpendicular to the symmetry axis is further removed from the composite antenna 121 shown in FIG. 13A. 7. FIG. 13B shows the return loss characteristic of the composite antenna 121 in FIG. 13A, and FIG. 14B shows the return loss characteristic of the composite antenna 131 in FIG.

  As shown in FIGS. 13B and 14B, in the composite antennas 121 and 131, the third peak disappears. Although not shown, the third peak did not appear even when the length of the linear parasitic slot 7 in the composite antenna 131 was shortened. This is considered because one end portion of the parasitic slot 7 is far from the short-circuit portion 5 and a sufficient current distribution cannot be obtained at the end portion.

  Thus, in order to operate the parasitic slot 7 as the third element, a certain amount of current distribution is required at both ends of the parasitic slot 7, so that both ends of the parasitic slot 7 are in the direction of the symmetry axis. It is necessary to arrange in the vicinity of the short-circuit part 5 in Further, since the current distribution needs to be small in the central portion of the parasitic slot 7, the shape of the parasitic slot 7 extends from the vicinity of the short-circuit portion 5 to a position away from the short-circuit portion 5, and is folded back again. A shape that returns to the vicinity, that is, a U-shape or a U-shape is desirable.

  A composite antenna 141 shown in FIG. 15A has a U-shaped opening width of 1 mm in the composite antenna 1 shown in FIG. Also, the composite antenna 151 shown in FIG. 16A is obtained by changing the U-shaped opening width to 3 mm in the composite antenna 1 of FIG. Furthermore, the composite antenna 161 shown in FIG. 17A is the composite antenna 21 shown in FIG. In these composite antennas 141, 151, and 161, a parasitic slot 7 is formed at the center portion (the center portion in the vertical direction in the figure) of the upper and lower conductor plates 2 of the slot 3. FIG. 15B shows the return loss characteristic of the composite antenna 141 in FIG. 15A, FIG. 16B shows the return loss characteristic of the composite antenna 151 in FIG. 16A, and FIG. 17A shows the composite antenna. The return loss characteristics of 161 are shown in FIG.

  As shown in FIG. 15 (b), the third peak disappears in the composite antenna 141, and as shown in FIG. 16 (b), the third peak becomes very small in the composite antenna 151. . Further, when FIG. 17B and FIG. 3B are compared, in the composite antenna 161, the third peak rapidly decreases. This is probably because the U-shaped or U-shaped opening width of the parasitic slot 7 is reduced. Further, in the composite antennas 141, 151, 161, since both ends of the parasitic slot 7 are separated from the short-circuit portion 5, this is also considered to be the cause of the third peak becoming small (or disappearing).

  On the other hand, although not shown, the return loss characteristics are similarly simulated when the U-shaped opening width of the parasitic slot 7 is set to 15 mm and 16 mm and when the U-shaped opening width is set to 15 mm. As a result, it was confirmed that good return loss characteristics similar to those of the composite antenna 1 of FIG. 1A and the composite antenna 21 of FIG. 3A (both aperture widths are 17 mm) can be obtained.

  From these results, in order for the parasitic slot 7 to operate well as the third element, it is necessary to increase the U-shaped (or U-shaped) opening width of the parasitic slot 7 to some extent. It can be seen that the opening width is desirably larger than 3 mm, and more desirably, the opening width is desirably 15 mm or more.

  As described above, in the composite antennas 1, 21, 31, and 41 according to the present embodiment, the third feeding notch antenna 8 having two slots 3 and 4 having different lengths is provided with the third antenna. A parasitic slot 7 is formed which operates as an element.

  The composite antennas 1, 21, 31, and 41 are not a three-dimensional structure using a dielectric substrate as in a conventional slot antenna, and can be operated in a plane, and thus can be easily reduced in size. Further, since the parasitic slot 7 operating as the third element can be formed in a U shape or a U shape, it is easy to reduce the size.

  In the composite antennas 1, 21, 31, and 41, since the individual elements (slots 3 and 4 and the parasitic slot 7) are separated by the conductor (conductor plate 2), interference and coupling occur between the elements. The resonance operation of each element is almost independent. Therefore, the frequency and impedance can be adjusted for each element, and the frequency and impedance can be easily adjusted. As a result, development time and costs can be saved.

  Further, in the composite antennas 1, 21, 31, and 41, the polarization directions of the respective elements are the same, and it is possible to perform a multiple resonance operation with a single polarization by one feeding. This makes it easier to determine the orientation of the antenna when mounting.

  Further, according to the composite antennas 1, 21, 31, and 41, it is possible to increase the frequency to three resonances with a simple configuration in which the parasitic slot 7 is formed in the two-resonance notch antenna 8, and manufacturing is easy.

  In the composite antennas 1, 21, 31, and 41, the parasitic slot 7 is formed along the symmetry axis direction so as not to cross the position where the short-circuit portion 5 and the feeding portion 6 are provided in the symmetry axis direction. Therefore, an excellent three-resonance operation can be obtained without affecting the operation of the two-resonance notch antenna 8.

  Further, in the composite antennas 1, 21, 31, and 41, the parasitic slots 7 are formed in both the upper and lower conductor plates 2 of the two slots 3 and 4, and these parasitic slots 7 are arranged with respect to the symmetry axis A. Since it is formed so as to have a symmetric shape, impedance matching is easy to achieve and good operation can be obtained.

  Furthermore, by forming the parasitic slot 7 along the longer slot 3 of the two slots 3 and 4, compared to the case where the parasitic slot 7 is formed along the shorter slot 4, Good return loss characteristics can be obtained, and the third resonance frequency can be set between the two resonance frequencies of the two resonance notch antenna 8.

  Furthermore, by forming the parasitic slot 7 in a U-shape or a U-shape in which the short-circuit portion 5 side is opened in the direction of the symmetry axis, the current distribution is increased at both ends of the parasitic slot 7, The current distribution can be reduced at the central portion of the slot 7, and the parasitic slot 7 can be favorably operated as the third element.

  Further, by forming the parasitic slot 7 such that the length along the axis of symmetry is longer than the U-shaped or U-shaped opening width, the central portion of the parasitic slot 7 is formed. It is possible to operate the parasitic slot 7 favorably as the third element by separating from the short-circuit portion 5.

  Further, the parasitic slot 7 is formed in a U-shaped or U-shaped opening in the vicinity of the short-circuit portion 5 in the direction of the axis of symmetry (in the vicinity of the feeder portion 6 when the parasitic slot 7 is formed along the slot 4). By forming the end portion on the side, the current distribution at both end portions of the parasitic slot 7 can be increased, and the parasitic slot 7 can be operated favorably as the third element.

  In the composite antennas 1, 21, 31, and 41 according to the present embodiment, a single-feed three-resonance operation can be obtained with the same polarization, so that cellular + GPS (Global Positioning System), cellular + wireless LAN (Local Area Network) It can be used for various complex applications such as wireless LAN + GPS. In addition, since it can be easily downsized, it is suitable as a built-in antenna for mobile terminals, a built-in antenna for laptop computers, or an in-vehicle antenna for telematics.

  In addition, when using as cellular + GPS, since the frequency band used by cellular is about 800-900 MHz and about 1.7-1.9 GHz, and the frequency band used by GPS is about 1.5 GHz, for example, in the composite antenna 1, The two notch elements (slots 3 and 4) of the two-resonance notch antenna 8 transmit and receive in two cellular frequency bands, and the third element, the parasitic slot 7 and transmit and receive in the GPS frequency band. do it.

  Next, another embodiment of the present invention will be described.

  The composite antenna 171 shown in FIG. 18A has basically the same configuration as the composite antenna 1 of FIG. 1A, but the shape of the two slots 3 and 4 and the shape of the parasitic slot 7 are different.

  In the composite antenna 171, one slot 3 includes a lateral M-shaped slot 172 having an open end that gradually increases in diameter, and the other slot 4 has an open end opposite to the open end of the lateral M-shaped slot 172. It consists of a rectangular slot 173. Among them, the rectangular slot 173 includes an elongated slot 174 having an open end, and a square slot 175 formed continuously with the elongated slot 174.

  The short-circuit portion 5 is provided between both the slots 172 and 173, and the feeding portion 6 is provided in the short rectangular slot 173 of the both slots 172 and 173 in the vicinity of the short-circuit portion 5. As a result, a two-resonance notch antenna 180 in which both slots 172 and 173 resonate at different resonance frequencies is formed.

  In the two-resonance notch antenna 180, a lateral M-shaped slot 172 having an open end that gradually expands in diameter is formed. 176 and the upper side (or lower side) 177 constituting the outer periphery of the rectangular shape intersect with each other, and the tip (the left end in the drawing) has a sharp shape. The non-feeding slot 7 is formed in a shape along the both sides 176 and 177 constituting the upper and lower conductor plates 2 of the lateral M-shaped slot 172 (a V-shaped shape facing an oblique direction in the drawing).

  As in the case of the composite antenna 1 shown in FIG. 1A, the parasitic slot 7 has a symmetrical axial direction so that both the upper and lower conductor plates 2 of the lateral M-shaped slot 172 have a symmetrical shape with respect to the symmetrical axis A. It is formed so as not to cross the position (26 mm from the right end of the conductor plate 2 in the drawing) where the short-circuit portion 5 is provided (in the left-right direction in the drawing), and the length along the axis of symmetry is an opening It is formed longer than the width, and is formed so that the end on the opening side is in the vicinity of the short-circuit portion 5.

  FIG. 18B shows the return loss characteristics when the composite antenna 171 is manufactured with each dimension shown in FIG. In FIG. 18B, the return loss characteristic in the two-resonance notch antenna 180 before forming the parasitic slot 7 is also shown by a broken line.

  As shown in FIG. 18B, in the composite antenna 171, in addition to two peaks due to the operation of the two-resonance notch antenna 180, a third peak due to the operation of the parasitic slot 7 appears in the vicinity of 1.5 GHz. I understand that. The return loss at the third peak is about −18 dB, and it can be seen that a good operation is obtained as the third element.

  The radiation patterns at each frequency of the composite antenna 171 are shown in FIGS. As shown in FIGS. 19 (a) to 19 (f), in the composite antenna 171, similarly to the composite antenna 1 in FIG. 1 (a), the omnidirectionality in the XZ plane and the 8-shaped directivity in the YZ plane at each frequency. The directivity in each plane is almost the same regardless of the frequency. Therefore, it is easy to determine the direction of the antenna when the composite antenna 171 is mounted.

  As a comparison object of the composite antenna 171 in FIG. 18A, FIG. 20A shows a composite antenna 181 in which a parasitic slot 7 is formed so as to cross both the short-circuit portion 5 and the power supply portion 6. The composite antenna 181 has a shortened length from the folded portion on the side (outside) away from the lateral M-shaped slot 172 in the composite antenna 171 of FIG. The non-feeding slot 7 is formed so as to cross both the short-circuit portion 5 and the feeding portion 6 by increasing the length from the folded portion. FIG. 20B shows the return loss characteristics when the composite antenna 181 is manufactured with the dimensions shown in FIG.

  Comparing FIG. 20B and FIG. 18B, it can be seen that in the composite antenna 181, the third peak is small and a good operation is not obtained. In addition, in the composite antenna 181, it can be seen that the resonance frequencies of the two peaks of the two-resonance notch antenna 180 serving as the base are greatly shifted, and a satisfactory three-resonance operation cannot be realized.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, two notches are formed by forming two slots 3 and 4 having an open end in the conductor plate 2 (laterally M-shaped slot 172 and rectangular slot 173 in the composite antenna 171). Not limited to this, the notch element may be a slot element.

  Further, in the above embodiment, the case where gap power feeding is performed by directly feeding power by connecting a coaxial cable or the like to the power feeding unit 6 is described, but not limited thereto, the conductor plate 2 is formed on the surface of the dielectric substrate, Microstrip power feeding (three-dimensional power feeding) may be performed in which power is fed through a microstrip line provided on the back surface of the dielectric substrate.

  Further, although not mentioned in the above embodiment, the conductor plate 2 may be bent along the axis of symmetry A to form a composite antenna having a bent structure. With the bent structure, for example, even when the composite antenna is installed on an inclined part such as a vehicle windshield, the maximum radiation direction of polarized waves (vertical polarization) transmitted and received by the composite antenna is the horizontal direction. (That is, adjusting the tilt in the maximum radiation direction), and it is possible to efficiently transmit and receive radio waves in the used frequency band. That is, by using a bent structure, a composite antenna having a wide degree of freedom in installation conditions can be realized.

DESCRIPTION OF SYMBOLS 1 Composite antenna 2 Conductor plates 3 and 4 Slot 5 Short-circuit part 6 Feed part 7 Parasitic slot 8 2 Resonance notch antenna

Claims (10)

A symmetrical conductor plate;
Two slots of different lengths formed on the symmetry axis of the conductor plate along the symmetry axis direction from both sides of the conductor plate, and formed so as to be symmetrical with respect to the symmetry axis;
A short-circuit portion located between the two slots and electrically short-circuiting between the conductive plates above and below the two slots;
A power supply unit provided in a shorter one of the two slots and provided in the vicinity of the short-circuit unit;
A parasitic slot formed in at least one of the conductive plates above and below the two slots along the symmetry axis direction so as not to cross the position where the short-circuit portion and the feeding portion are provided in the symmetry axis direction When,
A composite antenna comprising:   2. The composite antenna according to claim 1, wherein the parasitic slots are formed in both of the conductive plates above and below the two slots, and the parasitic slots are formed so as to be symmetrical with respect to the symmetry axis. .   The composite antenna according to claim 1, wherein the parasitic slot is formed along a longer slot of the two slots.   The composite antenna according to any one of claims 1 to 3, wherein the parasitic slot is formed in a U-shape or a U-shape in which the short-circuit portion side in the symmetry axis direction is opened.   5. The composite antenna according to claim 4, wherein the parasitic slot is formed such that a length along a direction of the symmetry axis is longer than a U-shaped or U-shaped opening width.   The non-feed slot is formed so that an end portion on the opening side of a U-shape or a U-shape is positioned in the vicinity of the position where the short-circuit portion or the feed portion is provided in the direction of the axis of symmetry. Or the composite antenna of 5.   The composite antenna according to claim 1, wherein the conductor plate is formed in a horizontally long rectangular shape in the direction of the axis of symmetry.   The composite antenna according to claim 7, wherein the two slots are formed in a rectangular shape having the same width.   8. The composite antenna according to claim 7, wherein the two slots include a lateral M-shaped slot having an open end that gradually increases in diameter, and a rectangular slot having an open end opposite to the open end of the lateral M-shaped slot. .   The composite antenna according to claim 9, wherein the rectangular slot includes an elongated slot having an open end, and a square slot formed continuously to the elongated slot.