JP5113325B2 - Planar antenna - Google Patents

Description

  The present invention relates to a planar antenna having an antenna pattern on a plane of an insulating substrate.

  As a conventional planar antenna of this type, as shown in FIG. 9, a conductive main antenna pattern 2 such as copper is provided in a plane on a plane of an insulating substrate 1 made of glass epoxy resin or the like in a plane, An antenna pattern 2 provided with power feeding portions 3a and 3b has been proposed (see, for example, Patent Document 1).

The main antenna pattern 2 provided in a planar manner on the insulating substrate 1 includes a central radiator 5 provided by being folded back in an inverted U shape at the tip so as to be line symmetric with respect to the line symmetry axis 4. ing. The antenna pattern 2 is line symmetric with respect to the line symmetry axis 4 of the central radiator 5 in a direction intersecting with the left and right folded conductors 5a and 5b to be lined and at a predetermined interval in the longitudinal direction of the folded conductors 5a and 5b. the provided et Re and each connecting conductor 6a, the corresponding folded conductive 5a in 6b, the squares forming the annular connected to 5b antenna elements 7a, Ru Tei includes a 7b. Feeders 3a and 3b are provided at the bases of the left and right folded conductors 5a and 5b to be lined on the line symmetry axis 4 of the central radiator 5, respectively. Connection conductors 12a and 12b are connected to the power feeding parts 3a and 3b by shifting the positions in the longitudinal direction of the line symmetry axis 4 in order to connect the power feeding parts 3a and 3b to the center conductor and the outer conductor of a coaxial terminal (not shown). Has been.

In FIG. 9, four antenna elements 7a and 7b are provided on the left and right of the line symmetry axis 4, respectively. Further, connection conductors 6a and 6b are provided by extending one long side of the antenna elements 7a and 7b.
Japanese Patent No. 3323442

  However, for example, when a terrestrial digital television broadcast is to be received using such a planar antenna, the return loss characteristic is as shown in FIG. That is, a section indicated by a pair of arrows shown in FIG. 10A is a bandwidth, and this bandwidth is narrow. There is also a problem that the return loss characteristic is poor. Further, the impedance characteristic is as shown by a Smith chart in FIG. 10B, and there is a problem that impedance convergence is poor. In FIG. 10A, the horizontal axis indicates the frequency, and the vertical axis indicates the gain.

  The objective of this invention is providing the planar antenna which can improve a return loss characteristic and an impedance characteristic rather than before.

  In the planar antenna of the present invention, a conductive main antenna pattern is provided in a plane in line symmetry on the plane of the insulating substrate. The main antenna pattern is line-symmetric with respect to an imaginary line-symmetry axis, and includes a central radiator that is folded in an inverted U shape at the tip and a plurality of antenna elements. The central radiator includes left and right folded conductors to be lined on a line symmetry axis and inverted U-shaped connecting conductors that connect one end of these folded conductors. The inverted U-shape does not mean that the connecting conductor is curved in a convex shape, but includes cases where the connecting conductor is linear or curved in a concave shape. The left and right folded conductors are provided with a plurality of antenna elements in line symmetry with a predetermined interval in a direction intersecting with the folded conductors and in the longitudinal direction of the folded conductors. Each of the plurality of antenna elements is connected to a corresponding folded conductor by a connection conductor. And the electric power feeding part is provided in the base part of the right and left return | turnback conductor of a line object on the line symmetry axis | shaft of a center radiator, respectively. In addition, in this-application specification, the front-end | tip of a center radiator means the opposite side to the side in which each electric power feeding part of a center radiator is provided.

In the planar antenna according to the present invention, the lateral characteristic adjustment conductive pattern that corresponds to the feeding portion of the main antenna pattern and that is line-symmetric across the axis of line symmetry is provided via an insulating layer at a position that does not intersect the antenna element. Provide. In the present invention, the lateral characteristic adjustment conductive pattern is a pattern made of a conductive material extending continuously or discontinuously in a direction crossing the line symmetry axis, and it is essential to maintain line symmetry. The shape is arbitrary. The characteristic adjustment conductive pattern affects the characteristic by adding a capacitor component or capacitance to the main antenna pattern.

  In this way, when the conductive pattern for characteristic adjustment that is laterally symmetrical with respect to the line symmetry axis is provided across the line symmetry axis through the insulating layer at the position corresponding to the feeding portion of the main antenna pattern, the bandwidth is higher than that of the conventional case. It has been found that the return loss characteristic is improved and the impedance characteristic can be improved.

  In this case, the lateral characteristic adjustment conductive pattern is preferably provided with the insulating substrate as an insulating layer on the surface of the insulating substrate opposite to the surface on which the main antenna pattern is provided. With this configuration, a lateral characteristic adjusting conductive pattern can be provided using the insulating substrate as an insulating layer. In this case, the capacitance between a part of the main antenna pattern and the lateral characteristic adjustment conductive pattern can be adjusted by changing the area of the lateral characteristic adjustment conductive pattern.

  Further, the lateral characteristic adjusting conductive pattern may be provided on an insulating substrate made of an insulating resin material on the surface of the insulating substrate on which the main antenna pattern is provided. In this way, it is possible to change the adjustment amount by changing the thickness of the insulating layer to be formed, and without changing the area of the lateral characteristic adjustment conductive pattern, a part of the main antenna pattern It is possible to adjust the capacitance between the conductive pattern for characteristic adjustment.

  In addition, the insulating layer has a longitudinal characteristic that is parallel to the line symmetry axis with a space on both sides about the line symmetry axis that is line symmetric with respect to the lateral characteristic adjustment conductive pattern and that intersects the antenna element. The conductive patterns for adjustment may be provided in line symmetry. In the present specification, the longitudinal characteristic adjusting conductive pattern means a conductive pattern parallel to a line-symmetrical axis of symmetry. The vertical characteristic adjustment conductive pattern supplements the adjustment by the horizontal characteristic adjustment conductive pattern.

  Further, the lateral characteristic adjustment conductive pattern may have a shape in which a separation portion for separating the horizontal characteristic adjustment conductive pattern is provided at the position of the line symmetry axis. Providing such a separating portion can further increase the bandwidth and improve the return loss characteristic, and in particular improve the impedance characteristic.

In the planar antenna according to the present invention, in a planar antenna having a specific antenna pattern, it is line symmetric across the line symmetry axis through an insulating layer at a position corresponding to the power feeding portion of the main antenna pattern and not intersecting with the antenna element. since lateral characteristic adjustment conductive pattern to be provided than conventional, it is possible to increase bandwidth and improve the return loss characteristic, the advantage that the impedance characteristics can be improved is obtained.

Hereinafter, each example of the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a rear view of a first embodiment of a planar antenna according to the present invention. That is, the present embodiment is an application of the present invention to the back view of FIG. Note that portions corresponding to those in FIG. 9 described above are denoted by the same reference numerals.

  On the insulating substrate 1 made of glass epoxy resin or the like in front of the planar antenna of this example, the main antenna pattern 2 is provided in line symmetry with respect to the line symmetry axis 4 as in FIG. .

  In the present invention, the characteristic adjustment conductive pattern 8 is provided in a line-symmetrical manner across the line-symmetric line symmetry axis 4 via an insulating layer at a position corresponding to the power feeding portions 3a, 3b of the main antenna pattern 2. It has been. In this example, the rectangular lateral characteristic adjusting conductive pattern 8 is provided on the surface of the insulating substrate 1 opposite to the surface on which the main antenna pattern 2 is provided with the insulating substrate 1 as an insulating layer. . The lateral characteristic adjusting conductive pattern 8 can be provided by, for example, printing or bonding a conductive foil. In this case, by changing the size (area) of the lateral characteristic adjustment conductive pattern 8, a portion (mainly the feeding portion) of the main antenna pattern 2 and the lateral characteristic adjustment conductive pattern 8 are arranged. The characteristics can be adjusted by adding the capacitance.

  As described above, the characteristic adjustment in the lateral direction is performed on the insulating substrate 1 so as to be line-symmetrical across the line-symmetrical axis of symmetry 4 through the insulating layer at positions corresponding to the power feeding portions 3a and 3b of the main antenna pattern 2. When the conductive pattern 8 is provided, the antenna characteristics and the characteristic adjustment conductive pattern diagrams are as shown in FIGS. 2 (A), 2 (B), and 2 (C).

  2A shows the return loss characteristic of the planar antenna, FIG. 2B shows the impedance characteristic on the Smith chart of the planar antenna, and FIG. 2C shows the lateral characteristic adjustment conductive property of the planar antenna. Pattern 8 is shown. In FIG. 2A, the horizontal axis indicates the frequency, and the vertical axis indicates the gain.

  As apparent from FIGS. 2A and 2B, the bandwidth is widened and the return loss characteristics are improved and the impedance characteristics are improved as compared with the characteristics of the conventional planar antenna shown in FIGS. Is also improved.

  FIG. 3 is a rear view showing a second example of the planar antenna according to the present invention. Also in the planar antenna of this example, on the front surface of the insulating substrate 1 made of glass epoxy resin or the like, the main antenna pattern 2 is line-symmetric with respect to the line-symmetric axis 4 in the same manner as in FIG. Is provided.

  Also in this example, a lateral characteristic adjusting conductive pattern 8 is provided so as to be line symmetric across the line symmetry axis 4 via an insulating layer at a position corresponding to the power feeding portions 3a and 3b of the main antenna pattern 2. It has been. In this example as well as the first example, the lateral characteristic adjustment conductive pattern 8 is provided with the insulating substrate 1 as an insulating layer on the surface of the insulating substrate 1 opposite to the surface on which the main antenna pattern 2 is provided. It has been. Further, on the surface of the insulating substrate 1 on which the lateral characteristic adjusting conductive pattern 8 is provided, the line symmetrical axis is spaced from both sides with respect to the lateral characteristic adjusting conductive pattern 8 about the line symmetrical axis 4. 4, vertical characteristic adjustment conductive patterns 9a and 9b are provided symmetrically with respect to the antenna elements 7a and 7b in a direction parallel to the line 4. The horizontal characteristic adjusting conductive pattern 8 and the vertical characteristic adjusting conductive patterns 9a and 9b can be provided by, for example, printing or bonding a conductive foil in the same manner as described above. When the vertical characteristic adjustment conductive patterns 9a and 9b are provided so as to be line symmetric with respect to the line symmetry axis 4, the antenna characteristic and characteristic adjustment conductive pattern diagrams are shown in FIGS. As shown in (C).

  4A shows the return loss characteristic of this planar antenna, FIG. 4B shows the impedance characteristic on the Smith chart of this planar antenna, and FIG. 4C shows the lateral characteristic adjustment conductive property of this planar antenna. A pattern 8 and longitudinal characteristic adjusting conductive patterns 9a and 9b are shown. In FIG. 4A, the horizontal axis indicates the frequency, and the vertical axis indicates the gain.

  As is clear from FIGS. 4A and 4B, the bandwidth is further expanded and the return loss characteristics are further increased as compared with the characteristics of the planar antenna of the first example shown in FIGS. It can be seen that the impedance is improved and the impedance characteristics are also improved.

  FIG. 5 is a rear view showing a third example of the planar antenna according to the present invention. On the insulating substrate 1 made of glass epoxy resin or the like in front of the planar antenna of this example, the main antenna pattern 2 is provided so as to be line symmetric with respect to the line symmetry axis 4 as in FIG. .

  Also in the present invention, the characteristic adjustment conductive pattern 8 is provided in a line-symmetrical manner across the line-symmetric line symmetry axis 4 via an insulating layer at a position corresponding to the power feeding portions 3a, 3b of the main antenna pattern 2. It has been. Also in this example, similarly to the first example, the lateral characteristic adjustment conductive pattern 8 is formed by placing the insulating substrate 1 on the surface opposite to the surface on which the main antenna pattern 2 of the insulating substrate 1 is provided. It is provided as. Further, the surface of the insulating substrate 1 on which the lateral characteristic adjustment conductive pattern 8 is provided is spaced apart on both sides around the line symmetry axis 4 that is axisymmetric with respect to the lateral characteristic adjustment conductive pattern 8. Longitudinal characteristic adjusting conductive patterns 9a and 9b that are parallel to the line symmetry axis 4 and intersect the antenna elements 7a and 7b are provided in line symmetry.

  In particular, in this example, the lateral characteristic adjusting conductive pattern 8 is provided with a separating portion 10 for separating the lateral characteristic adjusting conductive pattern 8 at a position where the line symmetry axis 4 is located. Thus, the characteristic adjusting conductive pattern 8 is divided into two characteristic adjusting conductive pattern portions 8a and 8b. Providing such a separating portion 10 not only changes the capacitance added to the antenna pattern 2, but also changes the position of the added capacitance. The antenna characteristic and characteristic adjustment conductive pattern diagrams when the horizontal characteristic adjustment conductive pattern 8 and the vertical characteristic adjustment conductive patterns 9a and 9b of this example are used are shown in FIGS. As shown.

  6A shows the return loss characteristic of the planar antenna, FIG. 6B shows the impedance characteristic on the Smith chart of the planar antenna, and FIG. 6C shows the lateral characteristic adjustment conductive characteristic of the planar antenna. A pattern 8 and longitudinal characteristic adjusting conductive patterns 9a and 9b are shown. In FIG. 6A, the horizontal axis indicates the frequency, and the vertical axis indicates the gain.

  6A and 6B, as compared with the characteristics of the planar antenna of the second example shown in FIGS. 4A and 4B, the bandwidth is further increased and the return loss is increased. It can be seen that the characteristics are improved and the impedance characteristics are also improved.

  7A and 7B show a fourth example of the planar antenna according to the present invention. FIG. 7A is a front view of the planar antenna of this example, and FIG. It is an XX line end view of A).

  In the planar antenna of this example, a lateral characteristic adjusting conductive pattern 8 is provided via an insulating layer 11 on the surface of the insulating substrate 1 on which the main antenna pattern 2 is provided. The insulating layer 11 can be formed by attaching an insulating tape, or may be formed by printing an insulating resin. The insulating layer 11 is preferably provided in a larger area than the lateral characteristic adjusting conductive pattern 8 in order to prevent a short circuit. The thickness of the insulating layer 11 is appropriately set according to the required capacitance.

  Even with the planar antenna having such a structure, the same effect as that of the example shown in FIG. 1 can be obtained. Further, in such a structure, the thickness of the insulating layer 11 can be easily changed, and a part of the main antenna pattern 2 and the horizontal characteristic adjusting conductive pattern can be changed without changing the area of the horizontal characteristic adjusting conductive pattern 8. The electrostatic capacity between 8 can be adjusted.

  In this example, the insulating layer 11 is enlarged and the vertical characteristic adjusting conductive patterns 9a and 9b are added as shown in FIG. 3, or the horizontal characteristic adjusting conductive pattern 8 is shown as shown in FIG. The detaching part 10 can be provided.

  According to the above embodiment, by changing the conductive pattern for characteristic adjustment as shown in FIGS. 2 (C), 4 (C), and 6 (C), FIGS. B) As shown in FIG. 6B, it was found that the impedance of the planar antenna changes so as to converge to the impedance of the connecting coaxial terminal described above.

  FIGS. 8A, 8B, and 8C show antenna characteristics and characteristic adjustment conductive pattern diagrams of a comparative example. In the planar antenna of this comparative example, as shown in FIG. 8 (C), the characteristic adjustment in the vertical direction is not provided on the back surface of the insulating substrate 1 provided with the main antenna pattern 2 as shown in FIG. Only the conductive patterns 9a and 9b are provided.

FIG. 8A shows the return loss characteristics of this planar antenna, FIG. 8B shows the impedance characteristics on the Smith chart of this planar antenna, and FIG. 8C is for adjusting the vertical characteristics of this planar antenna. Conductive patterns 9a and 9b are shown. In FIG. 8A, the horizontal axis indicates the frequency, and the vertical axis indicates the gain. 8A and 8B are compared with FIGS. 10A and 10B, there is no improvement in impedance characteristics even when the vertical characteristic adjustment conductive patterns 9a and 9b are provided. I understand. Therefore, vertically oriented characteristic adjusting conductive pattern 9a, be only set to 9b, can not improve the characteristics.

  In the planar antenna of the present invention, the lateral characteristic adjustment conductive pattern 8 may be provided on both the front and rear surfaces of the insulating substrate 1, and the lateral characteristic adjustment conductive pattern 8 is provided on both the front and rear surfaces of the insulating substrate 1. Longitudinal characteristic adjustment conductive patterns 9a and 9b may be provided.

It is a rear view which shows the 1st example of the planar antenna which concerns on this invention. 1A and 1B show the antenna characteristic and characteristic adjustment conductive pattern diagram of FIG. 1, wherein FIG. 1A is a return loss characteristic diagram of the planar antenna of the first example, and FIG. 1B is an impedance characteristic diagram of the planar antenna on a Smith chart; (C) is a conductive pattern diagram for adjusting the characteristics of the planar antenna. It is a rear view which shows the 2nd example of the planar antenna which concerns on this invention. 3A and 3B show the antenna characteristic and characteristic adjustment conductive pattern diagram of FIG. 3, wherein FIG. 3A is a return loss characteristic diagram of the planar antenna of the second example, and FIG. 3B is an impedance characteristic diagram of the planar antenna on the Smith chart; (C) is a conductive pattern diagram for adjusting the characteristics of the planar antenna. It is a rear view which shows the 3rd example of the planar antenna which concerns on this invention. FIG. 5 shows the antenna characteristics and characteristic adjustment conductive pattern diagram of FIG. 5, (A) is a return loss characteristic diagram of the planar antenna of this third example, (B) impedance characteristic diagram on the Smith chart of this planar antenna, (C) is a conductive pattern diagram for adjusting the characteristics of the planar antenna. The 4th example of the planar antenna which concerns on this invention is shown, (A) is a front view of the planar antenna of this example, (B) is an XX line end view of (A). FIG. 4 shows antenna characteristics and characteristic adjustment conductive pattern diagrams of a comparative example not included in the present invention, in which (A) is a return loss characteristic diagram of the planar antenna of this comparative example, and (B) is a Smith chart of this planar antenna. (C) is a conductive pattern diagram for adjusting the characteristics of the planar antenna. It is a front view of the conventional planar antenna. 9A and 9B show the antenna characteristics of FIG. 9. FIG. 9A is a return loss characteristic diagram of the conventional planar antenna, and FIG. 9B is an impedance characteristic diagram of the planar antenna on the Smith chart.

DESCRIPTION OF SYMBOLS 1 Insulation board | substrate 2 Main antenna pattern 3a, 3b Feed part 4 Line symmetry axis 5a, 5b Folding conductor 6a, 6b Connection conductor 7a, 7b Antenna element 8 Horizontal adjustment pattern 8a, 8b Characteristic adjustment conductive pattern part 9a, 9b Vertical Orientation adjustment pattern 10 Separation part 11 Insulating layer

Claims (3)

A conductive main antenna pattern that is substantially line symmetric with respect to a virtual line target axis is provided on a plane of the insulating substrate in a plane
The main antenna pattern is line-symmetrical with respect to the line-symmetrical axis of the central radiator, which is provided in a reversed U shape at the tip so as to be line-symmetrical with respect to the line-symmetrical axis. Are provided in a direction intersecting with the left and right folded conductors and at a predetermined interval in the longitudinal direction of the folded conductor and are symmetrical with respect to the line target axis. A plurality of antenna elements connected to the folded conductor,
In the planar antenna in which a feeding portion is provided at each of the bases of the folded conductors on the left and right of the line target on the line symmetry axis of the central radiator,
A horizontal orientation that crosses the line symmetry axis and is line symmetric with respect to the line target axis through an insulating layer at a position corresponding to the power feeding portion of the main antenna pattern and not intersecting with the antenna element. A conductive pattern for characteristic adjustment is provided ,
The insulating layer has a vertical characteristic adjustment that extends in parallel with the line symmetry axis and intersects the antenna element with a space on both sides with respect to the horizontal characteristic adjustment conductive pattern with respect to the horizontal characteristic adjustment conductive pattern. A planar antenna provided with conductive patterns for line symmetry with respect to the line target axis.   2. The lateral characteristic adjusting conductive pattern according to claim 1, wherein the insulating substrate is provided as the insulating layer on a surface of the insulating substrate opposite to a surface on which the main antenna pattern is provided. Planar antenna.   The planar antenna according to claim 1, wherein the lateral characteristic adjustment conductive pattern is provided on the surface of the insulating substrate on which the main antenna pattern is provided via the insulating layer.

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