JP5451284B2 - Bowtie antenna - Google Patents

Description

  The present invention relates to a bow tie antenna, and in particular, includes a first conductor and a second conductor provided in an isosceles triangle shape, and apexes formed by a pair of equal sides of an isosceles triangle are opposed to each other, and The present invention relates to a bow tie antenna in which a first conductor and a second conductor are arranged such that bases other than a pair of equal sides of an equilateral triangle are parallel to each other.

For example, the bow tie antenna 1 shown in FIG. 16 has been proposed (Patent Document 1). As shown in FIG. 1, the bow tie antenna 1 includes a first conductor 11 and a second conductor 12. The first conductor 11 and the second conductor 12 are each provided in an isosceles triangle shape. The first conductor 11 and the second conductor 12 are arranged so that a vertex T ₁ formed by a pair of equal sides V ₁ and V _{2 of the} isosceles triangle is opposed to each other.

Further, the first conductor 11 and the second conductor 12 are arranged so that the bases V _{3 of the} isosceles triangles are parallel to each other. The vertices T _{1 of} the first conductor 11 and the second conductor 12 each serve as a feeding point, and incident power is supplied to the bow tie antenna 1 from this feeding point. In the bowtie antenna 1 described above, the angle θ ₁ of the apex T ₁ of the isosceles triangle determines the characteristic impedance, and the height x _{1 of the} isosceles triangle determines the minimum operating frequency.

Next, the solid line in FIG. 2 shows the VSWR characteristics with respect to the frequency of the bow tie antenna 1 (FIG. 16) having the height x ₁ = 160 mm of the isosceles triangle and the length y ₁ = 240 mm of the base V ₃ of the isosceles triangle. The characteristic impedance of the bow tie antenna 1 is 200Ω. As shown in FIG. 2, the bow tie antenna 1 (FIG. 16) exhibits a wide band characteristic that maintains VSWR ≦ 2 at a frequency of 540 MHz or higher.

In addition, as shown in FIG. 17, the present inventor has proposed a bow tie antenna 1 provided with one folded portion 14 (Non-Patent Documents 1, 2, and 3). The VSWR characteristic with respect to the frequency of the conventional bow tie antenna 1 shown in FIG. 17 having the height x ₁ = 160 mm of the isosceles triangle and the length y ₁ = 240 mm of the base V ₃ of the isosceles triangle is shown by a solid line in FIG. The bow tie antenna 1 (FIG. 17) with the folded portion 14 (one) can maintain VSWR ≦ 2 at a frequency of 400 MHz or higher as shown in FIG. 5, and has a wider bandwidth than the bow tie antenna 1 shown in FIG. Can be obtained.

Further, as shown in FIG. 18, the present inventor has proposed a bow tie antenna 1 provided with two folded portions 14 and 15 (non-patent documents 1, 2, and 3). The VSWR characteristic with respect to the frequency of the conventional bow tie antenna 1 shown in FIG. 18 having an isosceles triangle height x ₁ = 160 mm and an isosceles triangle base V ₃ length y ₁ = 240 mm is shown by a solid line in FIG. As shown in FIG. 8, the bow tie antenna 1 (FIG. 18) with the folding portions 14 and 15 (two) has a frequency at which the VSWR falls below 2 and is 300 MHz, which is higher than the bow tie antenna 1 shown in FIGS. Can be lowered.

  All of the above-described bow-tie antennas 1 can provide wideband characteristics as compared with the same dipole antenna having a length of 160 mm. However, the bow-tie antenna 1 has a problem that the antenna area is significantly larger than that of the dipole antenna. Further, in the bow tie antenna 1 with the folded portions 14 and 15 (two) shown in FIG. 18, the band is limited due to the degradation of VSWR near 900 MHz as shown by the solid line in FIG. There is a problem that the broadband characteristic is deteriorated as compared with the bow tie antenna 1 shown in FIG.

JP 2009-010471 A

J.D.karuss "Antennas (2ndedition)", McGraw-Hill, pp.354-358 "Study of miniaturization of wide-band bow tie antenna by folding structure" IEICE General Conference B-1-176, March 20, 2009 "Miniaturized wideband filed bow-tie antenna" IET Electronics Letters, Vlo.45.No.6, pp.28-297, march12.2009 "

  Accordingly, an object of the present invention is to provide a bow tie antenna that is downsized while maintaining wideband characteristics.

The invention according to claim 1 for solving the above-mentioned problem includes a first conductor and a second conductor each having an isosceles triangle shape, and vertices formed by a pair of equal sides of the isosceles triangle are Opposite vertexes formed by a pair of equal sides of the isosceles triangle in the bow tie antenna in which the first conductor and the second conductor are arranged so that the bases of the isosceles triangle are parallel to each other A pair of crease lines that pass through each other and are parallel to the central axis perpendicular to the base and symmetrical with respect to the central axis are provided on the first conductor and the second conductor, The first conductor and the second conductor are bent at right angles along the pair of crease lines so as to have a U-shaped cross section , and the length of the base of the isosceles triangle is between the pair of crease lines. To be more than 4 times the distance Consists in bowtie antenna, characterized in that said pair of fold lines are provided.

According to a second aspect of the invention, the length of the base of the isosceles triangle, so that the following 24 times the distance between the pair of fold lines, and wherein the pair of fold lines are provided The bow tie antenna according to claim 1.

  The invention according to claim 3 is an apex formed by one of a pair of equal sides of the first conductor and a base, and an apex formed by one of the pair of equal sides of the second conductor and a base; The bow tie antenna according to claim 1, further comprising a third linear conductor parallel to the central axis connecting the two.

  The invention according to claim 4 includes a first conductor and a second conductor each having an isosceles triangle shape, and vertices formed by a pair of equal sides of the isosceles triangle face each other, and the isosceles In the bow tie antenna in which the first conductor and the second conductor are arranged so that the bases of the triangles are parallel to each other, the triangles pass through vertices formed by a pair of equal sides of the isosceles triangle and are perpendicular to the bases. A pair of crease lines parallel to the central axis and symmetrical with respect to the central axis are {2 × n (n is an integer of 1 or more) +1} pairs, the first conductor and the second. The bow tie antenna is characterized in that the first conductor and the second conductor are bent at right angles along the pair of crease lines so as to have a bellows cross section.

  As described above, according to the first and second aspects of the invention, it is possible to reduce the size while maintaining a broadband characteristic substantially equivalent to that of a conventional bow-tie antenna that is not bent.

  According to the invention described in claim 3, it is possible to operate at a low frequency by lowering the minimum operating frequency.

  According to the invention described in claim 4, it is possible to reduce the size while maintaining a broadband characteristic substantially equivalent to that of a conventional bow-tie antenna that is not bent.

(A) is a development view of the bow tie antenna of the present invention in the first embodiment, and (B) is a perspective view of the bow tie antenna shown in (A). A conventional product A, which is a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm, and a distance h = 30 mm, is a graph showing 20 mm, 10 mm, and the present invention product a ₁ to a _4, which is a bowtie antenna bent at right angles along a pair of fold lines 5 mm, the VSWR for the frequency. Conventional product A, which is a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm, and this conventional product A is separated from each other by a distance h = The minimum operating frequency of the product A _{1 to} A ₄ of the present invention which is a bow tie antenna bent at right angles along a pair of crease lines of 30 mm, 20 mm, 10 mm, and 5 mm, the degree of miniaturization of the projection area, It is a table | surface which shows the miniaturization degree of the whole antenna. (A) is a development view of the bow tie antenna of the present invention in the second embodiment, and (B) is a perspective view of the bow tie antenna shown in (A). A conventional product B in which a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm is provided with one folded portion, and this conventional product B mutual distance h = 30mm, 20mm, 10mm, and the present invention product B ₁ .about.B ₄ which is a bowtie antenna bent at right angles along a pair of fold lines 5 mm, is a graph showing the VSWR for frequencies. Conventional product A, which is a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm, and one folding part is provided on this conventional product A A conventional product B, and a product B _{1 to} B _{4 according to} the present invention, which is a bow tie antenna obtained by bending the conventional product B at right angles along a pair of crease lines with a distance h of 30 mm, 20 mm, 10 mm, and 5 mm. 5 is a table showing the frequency range in which VSWR ≦ 2, the degree of miniaturization of the projected area, and the degree of miniaturization of the entire antenna. (A) is a development view of the bow tie antenna of the present invention in the third embodiment, and (B) is a perspective view of the bow tie antenna shown in (A). A conventional product C in which a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm is provided with two folded portions, and this conventional product C mutual distance h = 30mm, 20mm, 10mm, and the present invention product C ₁ -C _4, which is a bowtie antenna bent at right angles along a pair of fold lines 5 mm, is a graph showing the VSWR for frequencies. Conventional product A, which is a bow tie antenna having a first conductor and a second conductor of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm, and the conventional product A has two folded portions. The present product C _{1 to} C ₄ , which is a conventional product C, and a bow tie antenna obtained by bending the conventional product C at right angles along a pair of crease lines with a distance h = 30 mm, 20 mm, 10 mm, and 5 mm. 5 is a table showing the frequency range in which VSWR ≦ 2, the degree of miniaturization of the projected area, and the degree of miniaturization of the entire antenna. (A) is a development view of the bow tie antenna of the present invention in the fourth embodiment, and (B) is a perspective view of the bow tie antenna shown in (A). (A) is a development view of the bow tie antenna of the present invention in the fourth embodiment, and (B) is a perspective view of the bow tie antenna shown in (A). A product A _{2 of} the present invention in which a bow tie antenna having a first conductor 11 and a second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm is folded _twice, and quadruple the present invention product D ₂ was bent to the present invention product D ₁ and 6 fold by bending the is a graph showing the VSWR for frequencies. Conventional product A, which is a bow tie antenna having a first conductor 11 and a second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 240 mm, and this conventional product is folded twice. The present invention product A ₂ , the present product product D ₁ folded in quadruple and the present product product D ₂ folded in 6 layers, the minimum operating frequency satisfying VSWR ≦ 2, the miniaturization degree of the projected area, the miniaturization degree of the whole antenna It is a table | surface which shows. The product B _{2 of} the present invention, in which one folded portion is provided on the first conductor 11 and the second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 120 mm and is folded _twice. Further, as shown in FIG. 11, the product E _{1 of} the present invention in which the bow tie antenna 1 provided with one folded portion is folded four times as shown in FIG. 10 and the bow tie antenna 1 provided with one folded portion 6 as shown in FIG. It is a graph which shows VSWR with respect to the frequency of this invention product E2 bent _twice . The product C _{2 of} the present invention in which the first conductor 11 and the second conductor 12 having an isosceles triangle with a height x ₁ = 160 mm and a base length y ₁ = 120 mm are provided with two folded portions and folded _twice. In addition, the comparative product F _{1 in} which the bow tie antenna having two folded portions is folded four times as shown in FIG. 10 and the bow tie antenna 1 having two folded portions are made six times as shown in FIG. and comparative F ₂ by bending is a graph showing the VSWR for frequencies. It is a top view which shows an example of the conventional bowtie antenna. It is a top view which shows an example of the conventional bowtie antenna. It is a top view which shows an example of the conventional bowtie antenna.

  The present inventors have eagerly searched to obtain a bow tie antenna that is reduced in size while maintaining wideband characteristics. In the bow tie antenna, the current distribution on the surface thereof is in relation to the x-axis shown in FIG. Paying attention to the fact that they are line-symmetric and have the same current direction, if they are bent line-symmetrically with respect to the x-axis, the current will not be canceled between the two folded elements, and the characteristics will not deteriorate. I thought of a bow tie antenna as shown below.

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the bow tie antenna 1 of the present invention has a first conductor 11 and a second conductor 12. The first conductor 11 and the second conductor 12 are provided in the shape of an isosceles triangle having the same size and the same shape, and vertices T ₁ formed by equal sides V ₁ and V _{2 of the} isosceles triangle are opposed to each other. As described above, the first conductor 11 and the second conductor 12 are arranged.

Further, the first conductor 11 and the second conductor 12 are arranged so that the bases V _{3 of the} isosceles triangles are parallel to each other. The vertices T _{1 of} the first conductor 11 and the second conductor 12 each serve as a feeding point, and incident power is supplied to the bow tie antenna 1 from this feeding point. Further, the first conductor 11 and the second conductor 12 are parallel to the central axis x passing through the vertex T ₁ formed by a pair of equal isosceles sides V ₁ and V ₂ and perpendicular to the base V _3. In addition, a pair of crease lines L ₁₁ and L ₁₂ that are symmetrical with respect to the central axis x are provided. As shown in FIG. 1B, the first conductor 11 and the second conductor 12 have cross sections. It is bent at right angles along a pair of crease lines L ₁₁ and L ₁₂ so as to form a U shape.

Next, the inventor of the present invention is a conventional product that is a bow tie antenna 1 having a first conductor 11 and a second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a length y ₁ = 240 mm of a base V _3. A (FIG. 16) and the present product A which is a bow tie antenna 1 which is a conventional product A bent at right angles along a pair of crease lines L ₁₁ and L ₁₂ with distances h = 30 mm, 20 mm, 10 mm and 5 mm. The effects of the present invention were confirmed by simulating VSWR with respect to the frequencies _{1 to} A ₄ (FIG. 1). The results are shown in FIG.

As shown in the figure, both the conventional product A and the products A _{1 to} A _{4 of} the present invention have VSWR ≦ 3 at a frequency of about 400 MHz or more, and the products A _{1 to} A ₄ of the present invention have almost the same characteristics as the conventional product A. I found out that Further, by folding along the pair of crease lines L ₁₁ and L ₁₂ , the projected area of the products A _{1 to} A ₄ of the present invention is almost half that of the conventional product A, and the size can be reduced. As is clear from the above, it was found that when VSWR ≦ 3, the products A _{1 to} A ₄ of the present invention can be reduced in size while maintaining substantially the same broadband characteristics as the conventional product A.

Next, consider the case of VSWR ≦ 2. Now, downsizing of the projected area of the bow tie antenna 1 by bending is expressed by the following equation (1).
Projection area miniaturization degree = (y ₁ −h / 2) / 2 × y ₁ (1)
The degree of miniaturization of the entire antenna is expressed by the following formula (2).
Degree of miniaturization of the whole antenna = (Degree of miniaturization of projection area) × (fL / 540 MHz) ² (2)
Note that fL is the lowest operating frequency at which VSWR ≦ 2.

Small degree of overall antenna shown in the above Expression (2) is present as compared to the present invention product A ₁ to A ₄ are approximately equal in conventional bowtie antenna 1 shown in FIG. 16 dimensioned so as to have a frequency characteristic It shows how much the inventions A _{1 to} A ₄ can be miniaturized. In detail, in the bow-tie antenna 1, the minimum operating frequency fL increases in accordance height x ₁ decreases. Therefore, for example, the conventional bow tie antenna 1 shown in FIG. 16 having a frequency characteristic (minimum operating frequency fL = 580 MHz) substantially equal to the product A ₁ of the present invention with h = 30 mm is the conventional product A (minimum operating frequency fL = 540 mHz). The dimension x ₁ is smaller than 160 mm. Small degree of overall antenna determined for the present invention product A ₁ represents a projected area of the present invention product A ₁ for a conventional area bowtie antenna 1 dimension as the lowest frequency fL = 580 MHz. Therefore, if the overall size of the antenna is 100% or less, the projected area can be made smaller than that of the conventional bow tie antenna 1 having the same frequency characteristics, so that the broadband is almost the same as that of the conventional bow tie antenna. It can be said that downsizing can be achieved while maintaining the characteristics.

Accordingly, the present inventors have miniaturization of conventional products A, the projected area of the bow-tie antenna 1 respectively, for the present invention product A ₁ to A _4, seeking a small degree of the entire antenna, the present invention product A ₁ to A ₄ The effect of was confirmed. The results are shown in FIG. As shown in the figure, the deterioration of characteristics due to bending becomes more conspicuous as the distance h is shorter. For this reason, when h = 5 mm, the size is increased rather than the conventional size due to an increase in the minimum operating frequency fL. However, the products A _{1 to} A ₃ of the present invention with y ₁ : h = 24: 1 or more and h ≧ 10 mm have a degree of miniaturization of the whole antenna of less than 100%, and have a broadband characteristic almost equivalent to that of a conventional bow tie antenna. It was possible to reduce the size while maintaining. In particular, when h = 30 mm, the size of the entire antenna is reduced to 50%. When the distance h is large, there is a demerit that the volume increases, but it can be said that the projected area of the antenna can be sufficiently reduced.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. In FIG. 4, the same parts as those of the bow-tie antenna 1 shown in FIG. 1 already described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The difference between the first embodiment and the second embodiment is that the second embodiment further includes one folded portion 14 as a third conductor. The folded portion 14 includes an apex T ₂ formed by a side V ₁ and a base V ₃ , which is one of a pair of equal sides V ₁ and V ₂ of the first conductor 11, and an equal pair of the second conductor 12. is provided in parallel with a straight line to the central axis x connecting the apex T ₂ formed by the side V _1, V while in a side V ₁ and bottom V ₃ of _2, between.

Next, the inventors of the present invention provide a bow tie antenna 1 in which a folded portion 14 is provided on a first conductor 11 and a second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 120 mm. A conventional product B (FIG. 17) and a book that is a bow-tie antenna that is obtained by bending the conventional product B at right angles along a pair of crease lines L ₁₁ and L ₁₂ with distances h = 30 mm, 20 mm, 10 mm, and 5 mm. The effects of the present invention were confirmed by simulating the VSWR with respect to the frequencies of the inventive products B _{1 to} B ₄ (FIG. 4). The results are shown in FIG.

As shown in the figure, both the conventional product B and the products B _{1 to} B _{4 of} the present invention have VSWR ≦ 3 at a frequency of about 300 MHz or more, and the products B _{1 to} B ₄ of the present invention have almost the same characteristics as the conventional product B. I found out that Further, by bending along the pair of crease lines L ₁₁ and L ₁₂ , the projected area of the products B _{1 to} B ₄ of the present invention is almost half that of the conventional product B, and the size can be reduced. As is apparent from the above, it was found that when VSWR ≦ 3, the products B _{1 to} B ₄ of the present invention can be downsized while maintaining substantially the same broadband characteristics as the conventional product B.

Next, consider the case of VSWR ≦ 2. For the conventional products A and B and the products B _{1 to} B ₄ of the present invention, the present inventors respectively reduced the frequency range in which VSWR ≦ 2, the reduction in the projected area of the bow tie antenna 1 shown in Equation (1), Equation (2 ) shows seek small degree of the entire antenna, to confirm the effects of the present invention product B ₁ ~B _4. The results are shown in FIG.

As shown in the figure, the products B _{1 to} B ₄ of the present invention have a lower minimum operating frequency fL that satisfies VSWR ≦ 2 than the conventional product B, and have better characteristics than the conventional products A and B on the low frequency side. Thus, it was found that operation at a lower frequency than the conventional products A and B becomes possible. For this reason, the products B _{1 to} B ₄ of the present invention are further reduced in size from 54.8% of the conventional product B to about 20% of the conventional product A. Further, in the products B ₃ and B ₄ of the present invention having a distance h of 10 mm or less, the VSWR becomes high near 800 MHz and 1000 MHz, and the band limitation due to this becomes more conspicuous as the distance h is lower, but the specific band is still h = 10 mm. Broadband characteristics of 75% and 77% at h = 5 mm are shown. Further, in the products B ₁ and B _{2 of the} present invention in which y ₁ : h is 12: 1 or more, there is no band limitation as described above, and a wider band than the conventional product B can be achieved while downsizing. When the distance h is high, there is a disadvantage that the volume increases, but it can be said that the projected area of the antenna can be sufficiently reduced.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. In FIG. 7, parts that are the same as the bow tie antenna 1 shown in FIG. 1 already described in the first embodiment are given the same reference numerals, and detailed descriptions thereof are omitted. The difference between the first embodiment and the third embodiment is that the third embodiment further includes two folding portions 14 and 15.

The folded portion 14 as the third conductor includes an apex T ₂ formed by a side V ₁ and a base V ₃ , which is one of a pair of equal sides V ₁ and V ₂ of the first conductor 11, The conductor 12 is provided in a straight line parallel to the central axis x connecting the vertex T ₂ formed by the side V ₁ and the base V ₃ , which is one of a pair of equal sides V ₁ and V _2. Yes. The folded portion 15 as the fourth conductor includes an apex T ₃ formed by the side V ₂ and the bottom side V ₃ which are the other of the pair of equal sides V ₁ and V ₂ of the first conductor 11 and the second side. The conductor 12 is provided in a straight line parallel to the central axis x connecting the vertex T ₃ formed by the side V ₂ which is the other of the pair of sides V ₁ and V _{2 which} are equal to each other and the base V _3. Yes.

Next, the present inventors have provided a bow tie in which folded portions 14 and 15 are provided on the first and second conductors 11 and 12 in an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 120 mm. A conventional product C (FIG. 18), which is an antenna, and a bow tie antenna obtained by bending the conventional product C at right angles along a pair of crease lines L ₁₁ and L ₁₂ having a distance h of 30 mm, 20 mm, 10 mm, and 5 mm. The effects of the present invention were confirmed by simulating the VSWR with respect to the frequencies of the products C _{1 to} C ₄ (FIG. 7) of the present invention. The results are shown in FIG.

As shown in the figure, both the conventional product C and the products C _{1 to} C _{4 of} the present invention have VSWR ≦ 3 at a frequency of about 300 MHz or more, and the products C _{1 to} C ₄ of the present invention have almost the same characteristics as the conventional product C. I found out that Further, by folding along the pair of crease lines L ₁₁ and L ₁₂ , the projected area of the products C _{1 to} C ₄ of the present invention is almost half that of the conventional product C, and the size can be reduced. As is apparent from the above, it was found that when VSWR ≦ 3, the products C _{1 to} C ₄ of the present invention can be reduced in size while maintaining a broadband characteristic substantially equivalent to that of the conventional product C.

Next, consider the case of VSWR ≦ 2. For the conventional products A and C and the products C _{1 to} C ₄ of the present invention, the frequency ranges satisfying VSWR ≦ 2, the reduction in the projected area of the bow tie antenna 1 shown in Equation (1), and Equation (2) ) shows seek small degree of the entire antenna, to confirm the effects of the present invention product C ₁ -C _4. The results are shown in FIG.

As shown in the figure, in the products C _{1 to} C ₄ of the present invention, the minimum operating frequency fL satisfying VSWR ≦ 2 is higher than that of the conventional product C, but the increase is very small and the projected area is small. Is less than half due to bending, and the size of the entire antenna is further reduced from 30.9% of the conventional product C to about 15% of the conventional product A. Further, in the present invention products C ₁ and C ₂ in which y ₁ : h is 12: 1 or more, there is no band limitation which is a problem of the conventional product C, and the bandwidth can be made wider than that of the conventional product C while downsizing. did it. However, if the distance h is too low, the VSWR becomes high near 900 MHz. However, the specific bandwidth is 99% at h = 10 mm and 95% at h = 5 mm, showing a wide band characteristic, which is wider than 97% of the conventional product C. It has become. If the distance h is high, there is a demerit that the volume increases, but it can be said that the projected area of the antenna can be sufficiently reduced.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIGS. 10 and 11, the same reference numerals are given to the same parts as the bow-tie antenna shown in FIG. 1 already described in the first embodiment, and the detailed description thereof is omitted. The difference between the first embodiment and the fourth embodiment is that, in the first embodiment, only a pair of crease lines L ₁₁ and L ₁₂ are provided and bent in a U-shaped cross section. In the embodiment, as shown in FIG. 10, three pairs of crease lines L parallel to the central axis x and symmetrical with respect to the central axis x with respect to the first conductor 11 and the second conductor 12. ₁₁ and L ₁₂ , L ₂₁ and L ₂₂ , L ₃₁ and L ₃₂ , and three pairs of crease lines L ₁₁ and L ₁₂ so that the first conductor 11 and the second conductor 12 have a bellows cross section. , L ₂₁ and L ₂₂ , and L ₃₁ and L ₃₂ .

These three pairs of crease lines L ₁₁ and L ₁₂ , L ₂₁ and L ₂₂ , L ₃₁ and L ₃₂ are provided apart from each other. The distance h between the pair of crease lines L ₁₁ and L _12, the distance h between the crease lines L ₁₁ and L _21, and the distance h between the crease lines L ₂₂ and L ₃₂ are provided to be equal to each other. The bow tie antenna 1 shown in FIG. 10 is bent in a bellows shape so that the first conductor 11 and the second conductor 12 are quadrupled along the base direction of the isosceles triangle.

In the example shown in FIG. 10, the first conductor 11 and the second conductor 12 are bent so as to be quadrupled. For example, as shown in FIG. 11, five pairs of fold lines L ₁₁ and L ₁₂ , L ₂₁ and L ₂₂ , L ₃₁ and L ₃₂ , L ₄₁ and L ₄₂ , L ₅₁ and L ₅₂ are provided, and the first conductor 11 and the second conductor 12 have a bellows shape so as to be six layers. You may make it bend | fold.

Next, the present inventor double-folded the bow tie antenna 1 having a first conductor 11 and a second conductor 12 that are isosceles triangles having a height x ₁ = 160 mm and a base length y ₁ = 240 mm. The VSWR with respect to the frequency of the product A _{2 of the} present invention (FIG. 1), the product D _{1 of} the present invention folded in quadruple (FIG. 10) and the product of the present invention D ₂ folded in six (FIG. 11) was simulated. The effect of the present invention was confirmed. The results are shown in FIG. In the products D ₁ and D ₂ of the present invention, the distance h is 20 mm. In addition, the inventor determines the minimum operating frequency fL for VSWR ≦ 2, the miniaturization degree of the projection area, and the miniaturization degree of the entire antenna for the conventional product A, the present invention product A ₂ , and the present product products D ₁ and D _2. seeking respectively, to confirm the effects of the present invention product D ₁ and D _2. The results are shown in FIG.

As shown in these figures, the minimum operating frequency fL of the products D ₁ and D ₂ of the present invention is almost the same as the minimum operating frequency of the product A ₂ of the present invention, but the projected area is dramatically reduced. . For this reason, the miniaturization degree of the whole antenna advances by multiple bending. If the distance h is high, there is a demerit that the volume increases, but it can be said that the projected area of the antenna can be sufficiently reduced.

  In the fourth embodiment described above, an example in which three pairs and five pairs of crease lines are provided has been described, but the present invention is not limited to this. As a crease line, {2 × n (n is an integer of 1 or more) +1} pairs may be provided, and if possible, seven pairs may be provided.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. The difference between the fourth embodiment and the fifth embodiment is that the fourth embodiment further includes one folding portion. Next, the present inventors provide one folded portion 14 on the first conductor 11 and the second conductor 12 of an isosceles triangle having a height x ₁ = 160 mm and a base length y ₁ = 120 mm. The product B ₂ (FIG. 4) of the present invention folded _twice and the bow tie antenna 1 provided with one folded portion are folded four times as shown in FIG. 10 and the folded product E _{2 of} the present invention E _2. As shown in FIG. 11, the present invention product E ₃ folded six times as shown in FIG. 11 and the present invention product C ₂ folded twice of the bow tie antenna 1 provided with two folded portions (FIG. 7). ) And a comparative product A _{1 in} which the bow tie antenna 1 provided with two folded portions is folded four times as shown in FIG. 10 and a bow tie antenna provided with two folded portions as shown in FIG. simulation and Comparative product a ₂ formed by bending, the VSWR for the frequency of the To, the effect of the present invention was confirmed. The results are shown in FIGS.

  As shown in FIG. 14, when one folded portion is provided, it has been found that providing six layers is effective in terms of downsizing although there is some characteristic deterioration. In addition, as shown in FIG. 15, in the case where two folded portions are provided, it has been found that the deterioration of characteristics is larger than the reduction in the projected area of the antenna, and as a result, the size cannot be reduced.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

1 bowtie antenna 11 first conductor 12 second conductor L _11, L ₁₂ a pair of fold lines L _21, L ₂₂ a pair of fold lines L _31, L ₃₂ a pair of fold line L _41, L ₄₂ a pair of fold lines L ₅₁ , L _{52 A} pair of crease lines x Central axis

Claims (4)

A first conductor and a second conductor each having the shape of an isosceles triangle are provided, vertices formed by a pair of equal sides of the isosceles triangle face each other, and the bases of the isosceles triangle are parallel to each other. In the bow tie antenna in which the first conductor and the second conductor are arranged,
A pair of crease lines that pass through vertices formed by a pair of equal sides of the isosceles triangle and are parallel to the central axis perpendicular to the base and symmetrical with respect to the central axis are the first conductors. And provided on the second conductor,
The first conductor and the second conductor are bent at right angles along the pair of crease lines so as to have a U-shaped cross section,
The pair of crease lines is provided so that the length of the base of the isosceles triangle is four times or more the distance between the pair of crease lines . Length of the base of the isosceles triangle, so that the following 24 times the distance between the pair of fold lines, bow tie of claim 1, wherein said pair of fold lines are provided antenna. The central axis connecting between the apex formed by one of a pair of equal sides of the first conductor and the base and the apex formed by one of the pair of equal sides of the second conductor and the base The bow tie antenna according to claim 1, further comprising a third linear conductor parallel to the second conductor. A first conductor and a second conductor each having the shape of an isosceles triangle are provided, vertices formed by a pair of equal sides of the isosceles triangle face each other, and the bases of the isosceles triangle are parallel to each other. In the bow tie antenna in which the first conductor and the second conductor are arranged,
A pair of crease lines which pass through vertices formed by a pair of equal sides of the isosceles triangle and which are parallel to the central axis perpendicular to the base and symmetrical with respect to the central axis are {2 × n ( n is an integer equal to or greater than 1) +1}, the first conductor and the second conductor;
The bow tie antenna, wherein the first conductor and the second conductor are bent at right angles along the pair of crease lines so as to have a bellows-like cross section.

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