JP4599102B2 - Planar antenna - Google Patents

Description

  The present invention relates to a dipole-type and monopole-type planar antenna, and more particularly to a quadrilateral planar antenna that can achieve multiple resonances and a broad band.

  In recent years, in portable radio apparatuses, it is essential to increase the frequency and the bandwidth to support dual bands and multimedia.

(Background Technology 1)
There is a bow tie-shaped element antenna (for example, see Patent Document 1). The element antenna disclosed in Patent Document 1 has two resonance frequencies: a first frequency that is the lowest operating frequency and a second frequency that is approximately three times higher than the first frequency. And the relationship between the wavelength of these frequencies and the dimension of the plate-shaped conductor of an antenna is defined.

(Background Technology 2)
There is a multiband antenna device in which a trapezoidal element is formed with a bow tie type (see, for example, Patent Document 2). In the multiband antenna device of Patent Document 2, a slit is provided in the middle of the hot-side element to divide it into a first antenna element and a second antenna element. And the dimension L11 which combined the 1st antenna element and the 2nd antenna element is match | combined with the 1/4 wavelength of the 880 MHz band for low frequency side mobile phones. In this 880 MHz band, a wide band is obtained from a range of 790 MHz or less to about 930 MHz in a range of VSWR (voltage standing wave ratio) 2.0 or less.
Further, the dimension L12 of the second antenna element is set to the 1/4 wavelength of the 1.6 GHz band for GPS on the high frequency side. In the 1.6 GHz band, a wide band is obtained from a range of VSWR 2.0 or lower from 1.5 GHz or lower to 2.1 GHz or higher.
Japanese Patent Laid-Open No. 2002-158531 (second page, FIG. 6) Japanese Patent Laid-Open No. 2003-318631 (pages 2 and 3, FIGS. 1 and 2)

The element antenna disclosed in the conventional background art 1 has a triangular bow tie shape, and has a high impedance of 60πΩ, which requires a matching circuit.
The multiband antenna device disclosed in the background art 2 can make the resonance frequency on the low frequency side and the resonance frequency on the high frequency side independently in a wide band, but the resonance frequency on the high frequency side can be changed from the resonance frequency on the low frequency side. In a region extending up to this point, the VSWR (voltage standing wave ratio) becomes a predetermined value or more, and the antenna efficiency during that period is poor. Therefore, there is a problem that it is impossible to widen the entire band from the resonance frequency on the low frequency side to the resonance frequency on the high frequency side.

  The present invention has been made to solve the above-described problems, does not require a matching circuit, and realizes a wide band in the entire region from the resonance frequency on the low frequency side to the resonance frequency on the high frequency side. An object of the present invention is to provide a planar antenna that can be used.

In order to achieve the above object, a planar antenna of the present invention has a feeding point, a quadrangular planar first radiating element, and a quadrangular planar second radiating element, and a first resonance on the low frequency side. A dipole type planar antenna which forms a wide band by a frequency and a second resonance frequency on the high frequency side, and has a first side of the quadrilateral of the first radiating element and a length substantially equal to the first side. And the second side of the quadrilateral of the second radiating element having a parallel spacing, a feeding point is provided at the center of the first side, and the parallel spacing is the length of the first side. The total length of the first side and the two sides contacting the first side is the total length of the second side and the two sides contacting the second side. It is approximately equal to the first resonance frequency, and is approximately half the wavelength of the first resonance frequency .

  According to the present invention, it is possible to obtain a planar antenna that does not require a matching circuit and can realize a wide band in the entire region from the resonance frequency on the low frequency side to the resonance frequency on the high frequency side.

  Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1-6 is a figure explaining the dipole type planar antenna which concerns on Example 1 of this invention.
FIG. 1 is a diagram illustrating the configuration of a dipole type planar antenna according to the first embodiment. The antenna 100 includes a trapezoidal planar first radiating element 1, a trapezoidal planar second radiating element 2, and a feeding point 3. The first radiating element 1 is a trapezoidal plane having a short side 11 and a long side 12 of parallel sides of a trapezoid and both sides 13. The dimension of the short side 11 is B, and the dimension of the short side 11 and the both sides 13 is A. The second radiating element 2 has the same shape as the first radiating element 1, and is a trapezoidal plane having a short side 21 and a long side 22 of parallel sides of a trapezoid and both sides 23. The dimension of the short side 21 is B, and the dimension of the short side 21 and both sides 23 is A. The outer angles of the side 13 and the short side 11 are arbitrary values. The outer angles of the side 23 and the short side 21 are also arbitrary values.
The short sides of the first radiating element 1 and the second radiating element 2 are spaced apart by a gap dimension G and face each other in parallel. The feeding point 3 is connected to the central part of the short side 11 and the central part of the short side 21 to supply power.

FIG. 2 is a simulation diagram of VSWR (voltage standing wave ratio). FIG. 2A shows an antenna 100 having a dimension A = 50 mm and a short side dimension B = 15 mm, and a gap dimension G = 4 mm (sample 1), 3 mm (sample 2), 1.5 mm (sample 3), 1 mm. This is a simulation using (Sample 4) as a parameter. The outer angle of both sides and the short side is 60 degrees. In FIG. 2B, A = 50 mm, gap dimension G = 1 mm, short side dimension B = 5 mm (sample 5), 8 mm (sample 6), 10 mm (sample 7), 12 mm (sample 8), 15 mm This is a simulation using (Sample 9) as a parameter. The outer angle of both sides and the short side is 60 degrees. In both cases, the first resonance frequency f1 on the low frequency side is generated in the vicinity of 3 GHz, and the second resonance frequency f2 on the high frequency side is generated in the vicinity of 8 GHz. Here, good antenna characteristics are defined as a case where VSWR = 3 or less indicated by a dotted line. Both the first resonance frequency f1 and the second resonance frequency f2 are VSWR = 3 or less. However, paying attention to the region between f1 and f2, there are cases where VSWR = 3 or less and VSWR = 3 or more. When VSWR = 3 or less, the band is wide over the entire region between f1 and f2, and is marked with a circle. In the case of VSWR = 3 or more, not a wide band over the entire region between f1 and f2, but a cross is attached. It can be seen that Samples 3, 4, 7, 8, and 9 are broadband.
Note that VSWR = 3 or less is synonymous with the impedance being a low value around 50Ω, and the matching circuit can be eliminated.

FIG. 3 summarizes the simulation results of FIG. 2 in a table, and shows the relationship between the gap dimension G and the short side dimension B and the wide band in the region between f1 and f2.
About the samples 1-9, the gap dimension G which is an antenna dimension, the dimension A, and the short side dimension B are shown. Also, it is shown whether the first resonance frequency f1 and the region between the wavelengths λ1, f1 and f2 which are simulation data are in a wide band. Further, as a calculation result, G / B in which the ratio between the gap dimension G and the short side dimension B is calculated, and B / λ1 in which the ratio between the short side dimension B and the wavelength λ1 of the first resonance frequency is calculated are shown.

Sample 1 will be described. The antenna dimensions are G = 4 mm, A = 50 mm, and B = 15 mm. As can be seen from FIG. 2, the simulation data is f1 = 2.5 GHz, and its wavelength λ1 is 3 × 10 8 [m] /2.5 GHz = 120 mm. Moreover, since it is not a wide band over the whole area | region between f1-f2, it attaches and shows x mark. The calculation results are G / B = 4/15 = 0.27, B / λ1 = 15/120 = 0.125 (substantially 0.13). The same applies to Samples 2 to 9, and detailed description thereof is omitted.
Samples 3, 4, 7, 8, and 9 have a wide bandwidth over the entire region between f1 and f2, and the calculation result G / B and B / λ1 columns of the samples are surrounded by dotted lines. The G / B values of Samples 3, 4, 7, 8, and 9 surrounded by the dotted lines are 0.1, 0.07, 0.1, 0.08, and 0.07, respectively, and are approximately 0.1. It is as follows. In addition, the values of B / λ1 of Samples 3, 4, 7, 8, and 9 surrounded by the dotted lines are 0.15, 0.16, 0.1, 0.12, and 0.16, respectively, and are substantially 0. .1 or more.
Therefore, by setting the gap dimension G to approximately 0.1 times or less of the short side dimension B, a wide band over the entire region between f1 and f2 can be obtained. Further, by setting the short side dimension B to approximately 0.1 times or more of the wavelength λ1 of the first resonance frequency, a wide band over the entire region between f1 and f2 can be obtained.

FIG. 4 summarizes the simulation results of FIG. 2 in a table, and shows the relationship between the antenna dimensions and the resonance frequency.
About the samples 1-9, the gap dimension G which is an antenna dimension, the dimension A, and the short side dimension B are shown. Further, the first resonance frequency f1 and wavelength λ1, and the second resonance frequency f2 and wavelength λ2, which are simulation data, are shown. Further, as a calculation result, A / λ1 which calculated the ratio of the dimension A and the wavelength λ1 of the first resonance frequency, A / λ2 which calculated the ratio of the dimension A and the wavelength λ2 of the second resonance frequency, and the short side dimension B B / λ2 calculated from the ratio of the second resonance frequency to the wavelength λ2. As described with reference to FIG. 3, the calculation results A / λ1, A / λ2, and B / λ2 of the samples 3, 4, 7, 8, and 9 in which a wide band over the entire region between f1 and f2 is obtained are surrounded by dotted lines. Is displayed.

  Sample 1 will be described. The antenna dimensions are G = 4 mm, A = 50 mm, and B = 15 mm. As can be seen from FIG. 2, the simulation data is f1 = 2.5 GHz (λ1 = 120 mm) and f2 = 7.7 GHz (λ2 = 39 mm). The calculation results are A / λ1 = 50/120 = 0.42, A / λ2 = 50/39 = 1.28, and B / λ2 = 15/39 = 0.38. The same applies to Samples 2 to 9, and detailed description thereof is omitted.

  Here, A / λ1 is in the range of 0.42 to 0.55 for all samples, and the variation is small. The dimension A is approximately half (half wavelength) of the wavelength λ1 of the first resonance frequency, or approximately It can be said that it is 0.4 to 0.6 times. B / λ2 has a small variation of 0.30 to 0.38 in a range surrounded by a dotted line, that is, a range in which a wide band over the entire region between f1 and f2 is obtained, and it can be said that B and λ2 have a correlation. Therefore, once the length of B is determined, the outline of λ2 can be found.

  Therefore, the dimension A of the antenna can be determined in correspondence with the desired first resonance frequency f1. Further, when the dimension B is determined, the second resonance frequency f2 can be roughly understood.

5 and 6 are diagrams for explaining the radiation pattern of the antenna. FIG. 5A is a perspective view of the antenna 100, showing the X axis, the Y axis, and the Z axis. FIG. 5B is a radiation pattern diagram of vertically polarized waves on the XY plane, and is for a frequency of 3 GHz. FIG. 5C is a radiation pattern diagram of vertically polarized waves on the XY plane, which is for a frequency of 5 GHz. FIG. 5D is a radiation pattern diagram of vertically polarized waves on the XY plane, and is for a frequency of 8 GHz.
At any frequency, the radiation pattern is uniform and no null state occurs at a specific angle. That is, it can be seen that a uniform radiation pattern can be obtained in a wide band.

  According to the first embodiment of the present invention, the dimension A of the antenna can be determined in correspondence with the desired first resonance frequency f1. Further, the dimension B of the antenna can be determined corresponding to the desired second resonance frequency f2. By setting the gap dimension G and the short side dimension B to predetermined values, a wide band over the entire region between f1 and f2 can be obtained. In addition, a uniform radiation pattern can be obtained in a wide band. Further, the impedance becomes a low value around 50Ω, and the matching circuit can be eliminated.

7 and 8 are diagrams illustrating a dipole type planar antenna according to a second embodiment of the present invention.
FIG. 7 is a diagram illustrating the configuration of a dipole type planar antenna according to the second embodiment. The antenna 200 is configured such that the external angles of both sides and the short side of the antenna 100 of the first embodiment are 90 degrees, that is, a rectangular flat radiation element, a rectangular flat first radiation element 4, and a rectangular flat shape. The second radiating element 4 and the feeding point 6. The first radiating element 4 is a rectangular plane including a side 41 on the feeding point 6 side, a side 42 opposite to the feeding point 6, and both side sides 43. The dimension of the side 41 is B, and the dimension of the side 41 and both side sides 43 is A. The second radiating element 5 has the same shape as the first radiating element 4, and is a rectangular plane having a side 51 on the feeding point 6 side, a side 52 opposite to the feeding point 6, and both side sides 53. The dimension of the side 51 is B, and the dimension obtained by combining the side 51 and the both sides 53 is A.
The short sides of the first radiating element 4 and the second radiating element 5 are spaced apart by a gap dimension G and face each other in parallel. The feeding point 6 is connected to the central part of the side 41 and the central part of the side 51 to feed power.

FIG. 8 is a diagram for explaining the VSWR simulation, FIG. 8A is a simulation diagram of the VSWR, and FIG. 8B is a table summarizing the simulation results.
A simulation was conducted for a case where the rectangular antenna 200 had a dimension A = 50 mm, an upper side dimension B = 15 mm, and a gap dimension G = 1 mm. Described as 10. Together with this, sample No. 1 was simulated for the case where the trapezoidal antenna 100 of Example 1 had a dimension A = 50 mm, a short side dimension B = 15 mm, and a gap dimension G = 1 mm. 4 is described.

Sample No. in FIG. As shown in FIG. 10 (rectangle), the first low-frequency resonance frequency f1 = 3.7 GHz (λ1 = 81 mm) and the second high-frequency resonance frequency f2 = 7.5 GHz (λ2 = 40 mm) are generated. A wide band is obtained with VSWR = 3 or less over the entire region between f1 and f2, and a circle is attached. Sample No. As shown in FIG. 4 (trapezoid), the first resonance frequency f1 on the low side f1 = 3.3 GHz (λ1 = 91 mm) and the second resonance frequency f2 on the high side f2 = 7.6 GHz (λ2 = 39 mm) are generated. A wide band is obtained with VSWR = 3 or less over the entire region between f1 and f2, and a circle is attached.
Sample No. 10 (rectangle) and sample no. 4 (trapezoid) gives substantially the same simulation results.

FIG. 8 (b) summarizes the simulation results of FIG. 8 (a) in a table. The gap dimension G and the upper side dimension B (or short side dimension B) and the wide band in the region between f1 and f2 are shown. Represents a relationship. Moreover, the relationship between an antenna dimension and a resonant frequency is represented.
G / B = 0.07 (sample 10) is the same as 0.07 (sample 4), and the gap dimension G of Example 1 is approximately 0.1 times or less of the short side dimension B (upper side dimension B). By satisfying the above, the condition for obtaining a wide band over the entire region between f1 and f2 is included. B / λ1 = 0.16 (sample 10) is the same as 0.16 (sample 4), and the short side dimension B (upper side dimension B) of Example 1 is set to the wavelength λ1 of the first resonance frequency. By making it approximately 0.1 times or more, it is in the condition of obtaining a wide band over the entire region between f1 and f2. A / λ1 = 0.62 (sample 10) is substantially the same as 0.55 (sample 4), and the dimension A of Example 1 is substantially half (half wavelength) of the wavelength λ1 of the first resonance frequency. Or approximately 0.4 to 0.6 times. B / λ2 = 0.38 (sample 10) is the same as 0.38 (sample 4), and the dimension B in Example 1 is 0.30 to 0.38 of the wavelength λ2 of the second resonance frequency. It is in the condition of double.

  According to the rectangular planar antenna according to the second embodiment of the present invention, the dimension A of the antenna can be determined corresponding to the desired first resonance frequency f1. Further, the dimension B of the antenna can be determined corresponding to the desired second resonance frequency f2. Then, by setting the gap dimension G and the upper side dimension B to predetermined values, a wide band over the entire region between f1 and f2 can be obtained.

9 and 10 are diagrams for explaining a monopole type planar antenna according to a third embodiment of the present invention.
FIG. 9 is a diagram illustrating the configuration of the monopole type planar antenna according to the third embodiment. The antenna 300 includes a trapezoidal planar first radiating element 1, a feeding point 3, and a planar ground 7. Similar to the dipole antenna of the first embodiment, the first radiating element 1 is a trapezoidal plane having a short side 11 and a long side 12 of parallel sides of a trapezoid and both sides 13. The dimension of the short side 11 is B, and the dimension of the short side 11 and the both sides 13 is A. The plane ground 7 is a ground plane having a predetermined area.
The short side 11 of the first radiating element 1 and one side of the planar ground 7 are spaced apart by a gap dimension G and face each other in parallel. The feeding point 3 is connected to the central portion of the short side 11 and one side of the planar ground 4 to feed power.

FIG. 10 is a diagram for explaining a VSWR simulation. FIG. 10A is a VSWR simulation diagram, and FIG. 10B is a table summarizing the simulation results.
This is a simulation of the case where the antenna 300 has a dimension A = 50 mm, a short side dimension B = 15 mm, and a gap dimension G = 0.5 mm (sample No. 11).
As shown in FIG. 10A, the first resonance frequency f1 on the low side f1 = 3.3 GHz (λ1 = 91 mm) and the second resonance frequency f2 on the high side f = 7.6 GHz (λ2 = 39 mm) are generated. . A wide band is obtained with VSWR = 3 or less over the entire region between f1 and f2, and a circle is attached.

FIG. 10 (b) summarizes the simulation results of FIG. 10 (a) in a table, and shows the relationship between the gap dimension G and the short side dimension B and the wide band in the region between f1 and f2. Moreover, the relationship between an antenna dimension and a resonant frequency is represented. G / B = 0.03, B / λ1 = 0.13, A / λ1 = 0.55, A / λ2 = 1.28, and B / λ2 = 0.38.
This is in the condition of obtaining a wide band over the entire region between f1 and f2 by setting the gap dimension G of the first embodiment to about 0.1 times or less of the short side dimension B. In addition, the short side dimension B of Example 1 is within the condition of obtaining a wide band over the entire region between f1 and f2 by making the short side dimension B approximately 0.1 times the wavelength λ1 of the first resonance frequency. In addition, the dimension A of Example 1 is in the condition of approximately half (half wavelength) of the wavelength λ1 of the first resonance frequency, or approximately 0.4 to 0.6 times. In addition, the dimension B of Example 1 is in the condition of 0.30 to 0.38 times the wavelength λ2 of the second resonance frequency.

  The first radiating element 1 is not limited to a trapezoidal planar shape, and the same effect can be obtained even when the first radiating element 1 is a rectangular planar shape.

  According to the monopole antenna of Example 3 of the present invention, the dimension A of the antenna can be determined in correspondence with the desired first resonance frequency f1. Further, the dimension B of the antenna can be determined corresponding to the desired second resonance frequency f2. And by setting the gap dimension G and the short side dimension B to predetermined values, a wide band over the entire region between f1 and f2 can be obtained.

The block diagram of the dipole type planar antenna (trapezoid) based on Example 1 of this invention. The simulation figure of VSWR which concerns on Example 1 of this invention. The simulation table | surface which concerns on Example 1 of this invention (The relationship between a gap dimension and a short side dimension, and a broadband). The simulation table | surface (relationship between an antenna dimension and a resonant frequency) which concerns on Example 1 of this invention. FIG. 2B is a diagram (1/2) illustrating a radiation pattern of the antenna according to the first embodiment of the present invention. FIG. 2B is a diagram (2/2) illustrating a radiation pattern of the antenna according to the first embodiment of the present invention. The block diagram of the dipole type planar antenna (rectangular shape) which concerns on Example 2 of this invention. The figure explaining the simulation of VSWR which concerns on Example 2 of this invention. The block diagram of the monopole type planar antenna which concerns on Example 3 of this invention. The figure explaining the simulation of VSWR which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st radiation element 2 2nd radiation element 3 Feeding point 4 1st radiation element 5 2nd radiation element 6 Feeding point 7 Planar ground 11 Short side 12 Long side 13 Side 21 Short side 22 Long side 23 Side 41, 42 Side 43 Side 51, 52 Side 53 Side 100, 200, 300 Antenna

Claims (9)

It has a feeding point, a quadrangular planar first radiating element and a quadrangular planar second radiating element, and a wide band is formed by the first low-frequency resonance frequency and the second high-frequency resonance frequency. A dipole type planar antenna
The first side of the quadrilateral of the first radiating element and the second side of the quadrilateral of the second radiating element having a length substantially equal to the first side are opposed at a parallel interval, A feeding point is provided at the center of the first side,
The parallel interval is set to approximately 1/10 or less of the length of the first side,
The combined length of the first side and both sides contacting the first side is substantially equal to the combined length of the second side and both sides contacting the second side, and the first side A planar antenna characterized by having a wavelength that is approximately a half of the resonance frequency. It has a feeding point, a quadrangular planar first radiating element and a quadrangular planar second radiating element, and a wide band is formed by the first low-frequency resonance frequency and the second high-frequency resonance frequency. A dipole type planar antenna
The first side of the quadrilateral of the first radiating element and the second side of the quadrilateral of the second radiating element having a length substantially equal to the first side are opposed at a parallel interval, A feeding point is provided at the center of the first side,
The parallel interval is set to approximately 1/10 or less of the length of the first side,
The combined length of the first side and both sides contacting the first side is substantially equal to the combined length of the second side and both sides contacting the second side, and the first side The wavelength is approximately half the resonance frequency.
The planar antenna according to claim 1, wherein a length of the first side is approximately 1/10 or more of a wavelength of the first resonance frequency. A monopole having a feeding point, a quadrangular planar first radiating element, and a quadrangular planar ground plane, and constituting a wide band by a first low-frequency resonance frequency and a second high-frequency resonance frequency A type of planar antenna,
The first side of the quadrilateral of the first radiating element is opposed to the opposite side of the ground plane at a parallel interval, and a feeding point is provided at the center of the first side,
The parallel interval is set to approximately 1/10 or less of the length of the first side,
The total length of the first side and both sides in contact with the first side is approximately a half wavelength of the first resonance frequency,
The planar antenna according to claim 1, wherein a length of the first side is approximately 1/10 or more of a wavelength of the first resonance frequency. The quadrilateral of the first radiating element has a trapezoidal shape, and the first side is a short side of the trapezoid,
The planar antenna according to claim 1 or 2 , wherein the quadrilateral of the second radiating element has a trapezoidal shape, and the second side is a short side of the trapezoid. 4. The planar antenna according to claim 3 , wherein the quadrilateral of the first radiating element has a trapezoidal shape, and the first side is a short side of the trapezoid. The quadrangle of the first radiating element is a rectangular shape, and the first side is a side of the rectangle,
3. The planar antenna according to claim 1 , wherein the quadrilateral of the second radiating element is a rectangular shape, and the second one side is one side of the rectangle. 4. The planar antenna according to claim 3 , wherein the quadrangle of the first radiating element is a rectangular shape, and the first side is one side of the rectangle. 5. The first side and the combined length of the both sides in contact with the first side, the claim, wherein the first is approximately 0.4 to 0.6 times the wavelength of the resonance frequency 1 The planar antenna according to claim 1 .   The length of the first side is approximately 0.3 to 0.4 times the wavelength of the second resonance frequency, The length according to any one of claims 1 to 7, Planar antenna.

Images