JP2015162849A - planar broadband antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broadband antenna which can be matched over necessarily sufficient wide bands and can be small-sized.SOLUTION: In a planar broadband antenna 1, on one side face of a dielectric substrate 2, an antenna element 3 is provided that becomes an inverse L-shaped monopole antenna and on the other side face of the dielectric substrate 2, a ground plate conductor 4 is provided. A substantially L-shaped ground plate L-shaped protrusion 42 is provided which protrudes toward a non-conductive area formed between a substrate upper end 2T of the dielectric substrate 2 and a conductor edge 41T of a main ground plate part 41. A shape of the ground plate L-shaped protrusion 42 and its relative position (full overlap, partial overlap or proximity) with the antenna element 2 are appropriately set. Thus, line impedance in respective parts of the antenna element 3 functioning as a signal transmission line with radio wave transmission/reception is adjusted and broadband properties are realized.

Description

  The present invention relates to a broadband antenna capable of matching in a wide band.

  In recent years, with the spread of smartphones and the like, attention has been focused on ultra-wideband (UWB) wireless systems that enable high-speed and large-capacity transmission, wireless systems that use white space in the UHF band, cognitive wireless systems, and the like. Since such a communication system is premised on using a very wide band frequency, an antenna having a wide band characteristic is required.

  As an antenna having a wide band characteristic, a spiral antenna in which an antenna element is formed in a spiral shape is known. However, because of the shape of the antenna element formed on the substrate, the vertical and horizontal dimensions are substantially square, so that it is a small antenna. There are cases where there are restrictions on the storage location of the mobile phone, which may not be suitable for use in a portable communication device.

  Further, as shown in FIG. 14, an elliptical radiating element 1002 is formed on the surface of the printed circuit board 1001, and a ground conductor 1003 is formed on the back surface of the printed circuit board 1001. Technology has also been proposed (see, for example, Non-Patent Document 1). In this monopole antenna, the shape of the printed circuit board 1001 is not limited to a square, the degree of freedom of the antenna arrangement location can be increased, and the length of the major axis a and the minor axis b in the ellipse of the radiating element 1002 is increased. The band can be slightly changed by changing the ratio.

Kuramoto, “Broadband antenna for wireless PAN”, IEICE Transactions B Vol. J90-B No. 9, Information and Communication Society of Japan, 2007, p.797-809

  However, in the invention described in Non-Patent Document 1, since the radiating element is an ellipse, the occupied space is increased, and it cannot be said that sufficient miniaturization can be achieved.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a planar wideband antenna that can be miniaturized suitable for mounting on a small apparatus such as a portable communication device and can realize wideband characteristics.

  In order to solve the above-mentioned problems, the invention according to claim 1 is a planar broadband antenna comprising a conductive antenna element on one side of a dielectric substrate and a ground plane conductor on the other side, wherein the ground plane conductor is provided. Forming a conductor edge portion at least apart from one side end of the dielectric substrate, thereby forming a non-conductive region between the one side end of the dielectric substrate and the conductor edge portion, and the antenna. The element includes a vertical portion projecting toward the non-conductive region so as to be orthogonal to the conductor edge portion of the ground plane conductor, and a horizontal portion extending in a direction parallel to the conductor edge portion of the ground plane conductor. An impedance adjustment means for adjusting the line impedance in each part of the antenna element that functions as a transmission path for signals accompanying transmission / reception of radio waves, so as to broaden the matching frequency band. It is characterized by.

  Further, the invention according to claim 2 is the planar wide-band antenna according to claim 1, wherein the impedance adjusting means is a ground plane projection part in which a part of the ground plane conductor protrudes from the conductor edge to the non-conductive region side. In addition, the line impedance is adjusted by arranging each part of the antenna element positioned via the dielectric substrate so that the ground plate protrusion is close to or overlapping.

  According to a third aspect of the present invention, in the planar broadband antenna according to the second aspect of the present invention, the ground plate projection is a projection vertical portion that protrudes toward the non-conductive region so as to be orthogonal to the conductor edge of the ground plate conductor. And a protrusion horizontal portion extending in a direction parallel to the conductor edge of the ground plane conductor, and extending in the protrusion vertical portion of the protrusion vertical portion. The protrusion vertical part inner edge which is a side edge is close to the vertical outer edge which is the anti-extension side edge of the horizontal part in the vertical part of the antenna element, and the protrusion which is the side edge facing the conductor end edge part in the horizontal part of the protrusion The lower edge of the horizontal portion is characterized in that it is made to be close to the upper edge of the horizontal portion, which is the side edge of the anticonductor edge at the horizontal portion of the antenna element.

  According to the wideband antenna according to the present invention, by providing the impedance adjusting means, the inverted L-shaped monopole antenna having a planar structure can be widened, and is suitable for mounting on a small apparatus such as a portable communication device. .

1 shows a first embodiment of a planar broadband antenna according to the present invention, wherein (a) is a plan view showing an antenna element arrangement surface of the broadband antenna, (b) is a side view of the planar broadband antenna, and (c) is a plane. It is a bottom view which shows the ground plane conductor arrangement | positioning surface of a shaped broadband antenna. It is explanatory drawing which shows the relative position of an antenna element and a ground-plate L-shaped projection part. It is a frequency characteristic figure which shows the frequency characteristic of the planar wideband antenna of the structure shown in FIG. 1, and the frequency characteristic of a planar reverse L-shaped monopole antenna without a ground plane L-shaped projection. It is a frequency characteristic figure which shows the characteristic change at the time of increasing / decreasing 1 mm of protrusion horizontal part upper edges T of a base-plate L-shaped protrusion part. It is a frequency characteristic figure which shows the characteristic change at the time of increasing / decreasing 1 mm the protrusion horizontal part lower edge B of a base-plate L-shaped protrusion part. It is a frequency characteristic figure which shows the characteristic change at the time of increasing / decreasing 1 mm of protrusion vertical part outer edges L of a ground-plate L-shaped protrusion part. It is a frequency characteristic figure which shows the characteristic change at the time of increasing / decreasing 1 mm of protrusion horizontal part front-end edge RT of a base-plate L-shaped protrusion part. It is a frequency characteristic figure which shows the characteristic change at the time of increasing / decreasing 1 mm of protrusion vertical part inner edges RB of a base-plate L-shaped protrusion part. It is a frequency characteristic diagram which shows a frequency characteristic at the time of increasing 1 mm of protrusion horizontal part upper edges T of a ground-plate L-shaped protrusion part, and reducing 1 mm of protrusion horizontal part lower edges B. It is a schematic block diagram of the planar wideband antenna which concerns on 2nd Embodiment which made corresponding frequency about 10 times. It is a frequency characteristic figure of the planar broadband antenna concerning a 2nd embodiment. It is explanatory drawing of the planar wideband antenna 1A-1D which is a modification of an antenna element and a ground-plate L-shaped projection part. It is explanatory drawing of the planar wideband antenna 1E which is a modification of an antenna element and a ground-plate L-shaped protrusion part. It is a schematic block diagram of the example of the conventional broadband monopole antenna.

  Next, an embodiment of a planar broadband antenna according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a first embodiment of a planar broadband antenna according to the present invention. The planar broadband antenna 1 is provided with an antenna element 3 that is an inverted L-shaped monopole antenna with one side of the dielectric substrate 2 as an antenna element arrangement surface, and with a ground plane conductor 4 with the other side as a ground plane conductor arrangement surface. Is.

  The dielectric substrate 2 is Teflon (registered trademark) (εr = 2.17, tan δ = 0.0008) having a thickness h of 0.8 mm, and the thickness t of the copper foil constituting the antenna element 3 and the ground plane conductor 4 Is 35 μm, and the dimensions (unit: mm) shown in FIG. 1 are the dielectric substrate 2, antenna element 3, ground plane using HFSS (high-frequency three-dimensional electromagnetic field analysis software) so as to match in the 2 to 6 GHz band. This is a result of designing the conductor 4.

  The ground plane conductor 4 is substantially in contact with the three sides of the dielectric substrate 2 but has a rectangular main ground plane portion 41 in which a conductor edge 41T is formed so as not to be in contact with the other side (the upper end 2T of the substrate); And an L-shaped protrusion 42. Then, the conductor edge 41T of the main ground plate 41 is formed at a distance of 10.9 mm from the substrate upper end 2T, so that the space between the substrate upper end 2T of the dielectric substrate 2 and the conductor edge 41T of the main ground plate 41 is increased. A non-conductive region is formed. The ground plane L-shaped projection 42 is a substantially L-shaped projection that projects from the conductor edge 41T toward the non-conductive region, and is formed of a copper foil that is integral with the main ground plane 41.

  The antenna element 3 functions as an inverted L-shaped monopole antenna. The antenna element 3 is connected to the MSL (microstrip line) portion 31 facing the main ground plate portion 41 and the upper portion of the MSL portion 31. A vertical portion 32 projecting toward the non-conductive region so as to be orthogonal to the conductor edge portion 41, and extending in a direction parallel to the conductor edge portion 41T (or the substrate upper end 2T) connected to the protruding end of the vertical portion 32. And an inverted L-shaped monopole. The antenna element 3 serving as an inverted L-shaped monopole antenna is provided with a feeding point 5 at the lower end of the MSL unit 31 to input a transmission signal and output a reception signal.

  When the planar broadband antenna 1 is used, the direction such as up, down, left, and right is not related, but in the description of the present embodiment, for convenience, the upper end 2T side of the substrate, which is the open end of the non-conductive region, is referred to as “Top. ”” On the opposite side, “Bottom” on the opposite side, and the direction in which the horizontal portion 33 extends with respect to the vertical portion 32 of the antenna element 3 “inside (right in FIG. 1A: right)” The opposite side is called “outside (left: Left in FIG. 1A)”.

  The shape of the base plate L-shaped projecting portion 42 is arbitrarily set such that the base plate L-shaped projecting portion 42 is adjacent to each of the vertical portion 32 and the horizontal portion 33 of the L-shaped antenna element 3 so as to be overlapped, partially overlapped, or not overlapped. I can do it. The ground plane L-shaped protrusion 42 serves as an impedance adjusting means for adjusting the line impedance in each part of the antenna element 3 functioning as a signal transmission path accompanying transmission / reception of radio waves, and the planar broadband antenna 1 having a wide matching frequency band. It can be realized. Further, the horizontal portion 33 of the antenna element 3 is also provided in that the width of the front horizontal portion 331 overlapping the ground plate L-shaped protrusion 42 is changed to the width of the rear horizontal portion 332, and the ground plate L-shaped protrusion is bent and changed. The characteristic impedance of the electric wire is kept constant so that reflection does not occur. In this way, changing the line width of the antenna element 3 also becomes an impedance adjusting means. Note that when the line width of the antenna element 3 is varied, the center line of the line (virtual line connecting the centers in the width direction) does not need to be continuous before and after the portion where the line width changes, and desired characteristics can be obtained. May be changed as appropriate. Also in the antenna element 3 according to the first embodiment shown in FIG. 1, the line width is changed between the MSL portion 31 and the vertical portion 32, but the center line in the MSL portion 31 and the center line in the vertical portion 32 are continuous. There is no design.

  Next, the relative positions of the antenna element 3 and the ground plane L-shaped protrusion 42 are shown in FIG. The ground plane L-shaped projecting portion 42 is the same as the projecting vertical portion 421 projecting toward the non-conductive region so as to be orthogonal to the conductor edge 41T, and the horizontal portion 33 of the antenna element 3 connected to the projecting end of the projecting vertical portion 421. This is an inverted L-shaped copper foil having a protruding lateral portion 422 extending in the direction.

  Then, the protrusion horizontal part upper edge 422T which is the upper edge of the protrusion horizontal part 422, the protrusion horizontal part lower edge 422B which is the lower edge of the protrusion horizontal part 422, the protrusion vertical part outer edge 421L which is the outer edge of the protrusion vertical part 421, and the protrusion horizontal The shape of the ground plate L-shaped protrusion 42 and the antenna element can be changed by changing the positions of the protrusion horizontal edge 422RT that is the protrusion edge of the protrusion 422 and the protrusion inner edge 421RB that is the inner edge of the protrusion vertical 421. The impedance at each part of the antenna element 3 that is regarded as a transmission line can be adjusted arbitrarily.

  In particular, when the protrusion vertical inner edge 421RB of the ground plane L-shaped protrusion 42 is coincident with or inside the vertical inner edge 32R of the antenna element 3, the entire vertical section 32 of the antenna element 3 overlaps the ground plane L-shaped protrusion 42. When the protrusion vertical inner edge 421RB of the ground plane L-shaped protrusion 42 is between the vertical inner edge 32R and the vertical outer edge 32L of the antenna element 3, a part of the vertical part 32 of the antenna element 3 is When the projection vertical inner edge 421RB of the ground plane L-shaped projection 42 coincides with the longitudinal outer edge 32L of the antenna element 3 or is slightly closer to the outside, the antenna is overlapped with the ground plane L-shaped projection 42. The vertical portion 32 of the element 3 and the ground plate L-shaped projection 42 are not overlapped, and the projection horizontal lower edge 422B of the ground plate L-shaped projection 42 is coincident with or below the lateral lower edge 331B of the antenna element 3. In this case, the entire front horizontal portion 331 of the antenna element 3 is overlapped with the ground plate L-shaped projection portion 42, and the projection horizontal portion lower edge 422 B of the ground plate L-shaped projection portion 42 is lateral to the horizontal lower edge 331 B of the antenna element 3. When it is between the upper edge 331T of the part, a part of the front horizontal part 331 of the antenna element 3 is overlapped with the ground plane L-shaped projection part 42, and the projection horizontal part lower edge 422B of the ground plane L-shaped projection part 42 is When the antenna element 3 coincides with the upper edge 331T of the horizontal portion or is slightly close to the upper side, the front horizontal portion 331 of the antenna element 3 and the ground plane L-shaped protrusion 42 are not overlapped.

FIG. 3 shows the frequency characteristics of the planar broadband antenna 1 according to this embodiment described above. By providing the L-shaped projections 42, it can be seen that the aligned below S ₁₁ almost -10dB at fractional bandwidth of about 98% 2.1～6.1GHz. On the other hand, it can be seen that a wide band characteristic cannot be realized with an inverted L-shaped monopole antenna that is not provided with an L-shaped protrusion.

  FIG. 4 shows a case where the protrusion horizontal portion upper edge 42T of the base plate L-shaped protrusion 42 is +1 mm to make the protrusion horizontal portion 422 thicker, and conversely, the protrusion horizontal portion upper edge 42T is −1 mm to make the protrusion horizontal portion This is a frequency characteristic when 422 is narrowed. It can be seen that when the protrusion horizontal part 422 of the base plate L-shaped protrusion part 42 is widened upward and thickened, the matching of 2.1 to 5.7 GHz is improved. When the lateral protrusion 422 of the base plate L-shaped protrusion 42 is widened upward, the substrate upper end 2T of the dielectric substrate 2 is also followed by +1 mm, and the substrate size is changed.

  FIG. 5 shows the case where the protrusion horizontal part lower edge 42B of the base plate L-shaped protrusion part 42 is +1 mm to make the protrusion horizontal part 422 thicker, and conversely the protrusion horizontal part lower edge 42B is -1 mm to make the protrusion horizontal part 422 This is the frequency characteristic when it is made thinner. If the protrusion horizontal part 422 of the ground plane L-shaped projection part 42 is retracted upward to make it thin, and only a part of the projection horizontal part 422 of the ground plane L-shaped projection part 42 and the front horizontal part 331 of the antenna element 3 overlap, Although matching near 3 GHz deteriorates, it can be seen that the matching improves at about 4 GHz or more.

  FIG. 6 shows the case where the protrusion vertical outer edge 42L of the base plate L-shaped protrusion 42 is +1 mm to make the protrusion vertical part 421 thicker, and conversely the protrusion vertical outer edge 42L is -1 mm to make the protrusion vertical part 421 This is the frequency characteristic when it is made thinner. Even if the protrusion vertical part 421 of the base plate L-shaped protrusion part 42 is expanded or narrowed outward, no remarkable characteristic change is seen, compared with the case where the protrusion horizontal part upper edge 42T and the protrusion horizontal part lower edge 42B are changed. Therefore, it is estimated that the effect is small.

  FIG. 7 shows the case where the protrusion horizontal portion tip edge 42RT of the base plate L-shaped protrusion portion 42 is increased by +1 mm to make the protrusion horizontal portion 422 longer, and conversely, the protrusion horizontal portion tip edge 42RT is decreased by -1 mm and the protrusion horizontal portion. This is a frequency characteristic when 422 is shortened. It can be seen that if the lateral protrusion 422 of the base plate L-shaped protrusion 42 is retracted inward and shortened, the alignment deteriorates except in the vicinity of 2.3 GHz.

  FIG. 8 shows the case where the protrusion vertical inner edge 42RB of the base plate L-shaped protrusion 42 is +1 mm to make the protrusion vertical part 421 thicker, and conversely the protrusion vertical inner edge 42RB is −1 mm to make the protrusion vertical part 421 This is the frequency characteristic when it is made thinner. When the protrusion vertical part 421 of the ground plane L-shaped protrusion part 42 is shifted inward to widen the width, the matching in the vicinity of 2.5 GHz is improved, but the entire band becomes narrow. On the other hand, when the protrusion vertical part 421 of the ground plane L-shaped projection part 42 is shifted outward to narrow the width, only the projection vertical part 421 of the ground plane L-shaped projection part 42 and the vertical part 32 of the antenna element 3 overlap each other. Although the overall alignment tends to degrade, it is a broadband.

FIG. 9 shows that the protrusion horizontal part upper edge 42T is increased by +1 mm and the protrusion horizontal part lower edge 42B of the ground plane L-shaped protrusion part 42 is decreased by −1 mm in order to expand the band without deteriorating the matching in the vicinity of 3 GHz. This is a frequency characteristic when the protrusion horizontal part 422 is shifted upward by 1 mm, and for comparison, the protrusion horizontal part upper edge 42T of the base plate L-shaped protrusion part 42 is +1 mm and the protrusion horizontal part 422 is thickened. The frequency characteristic when the protrusion horizontal part lower edge 42B of the ground plane L-shaped protrusion part 42 is -1 mm to make the protrusion horizontal part 422 thinner is also shown. When the protrusion horizontal portion upper edge 42T is set to +1 mm and the protrusion horizontal portion lower edge 42B is set to -1 mm, the S ₁₁ is matched to -10 dB or less in the ratio band 104% of 2.05 to 6.5 GHz, and the band is widened. I understand.

Next, the thickness h of the dielectric substrate (εr = 2.17, tan δ = 0.0008) is maintained at 0.8 mm, the width is increased about 10 times, and the matching frequency is reduced to about 1/10. FIG. 10 shows a planar broadband antenna 1 ′ according to the second embodiment. The dimensions (unit: mm) in this figure are design examples by HFSS. In the planar broadband antenna 1 ', the antenna element 3' and the ground plane L-shaped protrusion 42 'do not overlap with each other, and the two edges are in close proximity or slightly apart from each other. FIG. 11 shows the frequency characteristics of the planar wide-band antenna 1 ′, and the calculation result that the return loss S ₁₁ is matched to −10 dB or less is obtained with a relative band of 105% from 200 MHz to 650 MHz.

  As described above, by changing the shape of the ground plane L-shaped protrusion 42 and the relative position to the antenna element 3, broadband matching exceeding the specific bandwidth of 100% can be realized. Further, it is necessary to consider the influence of the dimensions of the dielectric substrate 2.

  In addition, impedance adjustment for realizing broadband matching exceeding a specific band of 100% is affected by dimensions of various parts such as the width of the protrusion vertical part 421 and the protrusion horizontal part 422 of the base plate L-shaped protrusion 42. However, the positional relationship between the ground plane L-shaped projection 42 and the antenna element 3 is particularly important, and the ground plane L-shaped projection 42 and the antenna element 3 are close to each other, specifically, the ground plane L-shaped projection. The protrusion vertical part inner edge 421RB of the protrusion vertical part 421 of 42 is brought close to the vertical outer edge 32L of the vertical part 32 of the antenna element 3, and the protrusion horizontal part lower edge 422B of the protrusion horizontal part 422 is set to the front horizontal part 331 of the antenna element 3. It is considered that it is easy to obtain a wide band property by making it close to the horizontal portion upper edge 331T.

  Note that the state in which the ground plane L-shaped protrusion 42 and the antenna element 3 are close to each other includes not only the state in which both edges of the ground plane L-shaped projection 42 and the antenna element 3 are aligned, but also the vertical direction of the antenna element 3. In view of the width of the portion 32 and the lateral portion 33, it includes a state where they are overlapped or separated in a very narrow range.

  In the case of the planar broadband antenna 1 according to the first embodiment, the target frequency is 2 to 6.5 GHz and the wavelength is about 100 mm, but the planar broadband antenna 1 ′ according to the second embodiment In this case, the target frequency is 0.2 to 0.65 GHz, and the wavelength is about 1000 mm. However, since both use a dielectric substrate having a thickness of 0.8 mm, the thickness / wavelength is the same as that of the first embodiment. In the case of the planar broadband antenna 1 according to the present embodiment, the ratio is 0.8 / 100, and in the case of the planar broadband antenna 1 ′ according to the second embodiment, the ratio is 0.8 / 1000. Since the distance from the element 3 'is narrow in terms of wavelength, in the planar broadband antenna 1' according to the second embodiment, the distance is narrow when the ground plane L-shaped protrusion 42 'and the antenna element 3' overlap. Too much Element 3 'and the ground plane L-shaped projections 42' and do not overlap, both edges match or slightly spaced proximity state is considered to be a good condition consistent.

  Further, in order to further improve the broadband matching of the planar broadband antenna, the shapes of the antenna element 3 and the ground plane L-shaped protrusion 4 may be modified as shown in FIGS.

  A planar broadband antenna 1 </ b> A shown in FIG. 12A is obtained by extending the MSL portion 31 </ b> A of the antenna element 3 </ b> A to the lower end 2 </ b> B of the dielectric substrate 2 and providing a feeding point 5 at the edge of the dielectric substrate 2. is there. As described above, if the MSL portion 31A is appropriately designed, it is possible to arbitrarily select a power feeding point to the antenna element 3A or to feed power from the side of the dielectric substrate 2.

  The planar broadband antenna 1B shown in FIG. 12B continuously changes its width without any step from the MSL portion 31B to the vertical portion 32B of the antenna element 3B, and has no step even from the front horizontal portion 331B to the rear horizontal portion 332B. The width is changed in a tapered shape. In this way, since the impedance change in the antenna element 3B becomes continuous, it can be expected to improve the broadband characteristics.

  The planar broadband antenna 1C shown in FIG. 12C has a curved edge shape with no corners extending from the outer edge of the protrusion vertical part 421C of the base plate L-shaped protrusion part 42C to the upper edge of the protrusion horizontal part 422C, and the protrusion horizontal part 422C. Further, two corners that are both ends of the substrate upper end 2T of the dielectric substrate 2C are R-shaped along the curved edge of the base plate L-shaped protrusion 42C. The curved edge corners 21 and 22 are used. In this way, it is possible to reduce the size of the entire antenna and to improve the matching of mounting to a device that employs the flat broadband antenna 1C.

  The planar broadband antenna 1D shown in FIG. 12D has a curved edge shape with no corners extending from the vertical portion 32D of the antenna element 3D to the front horizontal portion 331D, and the inner edge of the protrusion vertical portion 421C of the ground plane L-shaped protrusion 42C. From the protrusion to the lower edge of the protrusion horizontal portion 422C, a curved edge with no corners is formed. In this way, the impedance change in the transmission line constituted by the antenna element 3D and the ground plane L-shaped protrusion 42C becomes continuous, and an improvement in broadband characteristics can be expected.

  A planar broadband antenna 1E shown in FIG. 13 is configured such that the inner edge 421L of the protrusion vertical portion 421 of the base plate L-shaped protrusion 42E protrudes outward from the outer edge 41L of the main base plate portion 41. In accordance with the shape of the ground plane L-shaped protrusion 42E, the non-conductive region in the dielectric substrate 2E is also formed to protrude outward from the conductive region. In this way, since the width of the protrusion vertical portion 421 in the base plate L-shaped protrusion 42E can be set wide, an improvement in broadband characteristics can be expected.

  As described above, the planar broadband antenna according to the present invention has been described based on some embodiments. However, the present invention is not limited to these embodiments, and the configuration described in the scope of claims is not changed. It covers all planar broadband antennas that can be realized as far as possible.

1. Planar broadband antenna (first embodiment)
2 Dielectric substrate 2T Upper end of substrate 3 Antenna element 31 MSL part 32 Vertical part 32L Vertical outer edge 32R Vertical inner edge 331 Front horizontal part 331T Horizontal upper edge 331B Horizontal lower edge 332 Rear horizontal part 4 Ground plane conductor 41 Main ground plane part 41T conductor End edge 42 Base plate L-shaped projection 421 Projection vertical part 421L Projection vertical part outer edge 421RB Projection vertical part inner edge 422 Projection lateral part 422T Projection lateral part upper edge 422B Projection lateral part lower edge 422RT Projection lateral part front edge 5 Feeding point

Claims (3)

A planar broadband antenna having a conductive antenna element on one side of a dielectric substrate and a ground plane conductor on the other side,
The ground plane conductor is separated from at least one side edge of the dielectric substrate to form a conductor edge, thereby forming a non-conductive region between the one side edge of the dielectric substrate and the conductor edge. ,
The antenna element has a vertical portion protruding toward the non-conductive region so as to be orthogonal to the conductor edge of the ground plane conductor, and extends in a direction parallel to the conductor edge of the ground plane conductor, connected to the protruding end of the vertical portion. A reverse L-shape having a lateral portion,
A planar wideband antenna characterized in that impedance adjustment means for adjusting line impedance in each part of an antenna element functioning as a transmission path of a signal accompanying transmission / reception of radio waves is provided to widen a matching frequency band.   The impedance adjusting means is a ground plate projection in which a part of the ground plane conductor projects from the conductor edge to the non-conductive region side, and each portion of the antenna element located through the dielectric substrate and the ground plane projection are close to each other or overlap each other. 2. The flat broadband antenna according to claim 1, wherein the line impedance is adjusted to adjust the line impedance. The ground plane projection is a projection vertical portion that protrudes toward the non-conductive region so as to be orthogonal to the conductor edge portion of the ground plane conductor, and a direction that is connected to the projection end of the projection vertical portion and is parallel to the conductor edge portion of the ground plane conductor. An inverted L shape having a protrusion lateral part extending to
A protrusion vertical inner edge that is an extended side edge of the protrusion horizontal part in the protrusion vertical part is brought close to a vertical outer edge that is an anti-extension side edge of the horizontal part in the vertical part of the antenna element, and the conductor in the horizontal part of the protrusion 3. The protrusion horizontal portion lower edge, which is a side edge facing the end edge portion, is made to be close to the horizontal portion upper edge, which is a side edge of the anti-conductor edge portion in the horizontal portion of the antenna element. The described planar broadband antenna.

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