JP2015008439A - Planar antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar antenna that enables transmission/reception in two frequency bands.SOLUTION: The planar antenna includes a dielectric substrate, a ground plate, two first band elements, two second band elements, two plate elements and a monopole element. Between the two first band elements on one plate surface, the two second band elements are connected at respective interspaced ends to one side of the ground plate and extended in parallel in a direction away from the ground plate. The second band elements are also shorter than the first band elements. Length of the second band elements in the direction of extension is 0.142-0.164 times a wavelength at a center frequency of the higher of the two frequency bands. A gap between the first band elements and the second band elements is up to 0.011 times the wavelength at the center frequency of the higher of the two frequency bands.

Description

  The present invention relates to a planar antenna that can be widened and multi-banded.

  A planar antenna disclosed in Patent Document 1 is known as a planar antenna capable of widening the bandwidth. The planar antenna of Patent Document 1 is provided with a dielectric substrate, a ground plate provided on one plate surface of the dielectric substrate, and provided on one plate surface, one ends of which are separated from each other and connected to one side of the ground plate, In addition, two linear conductors extending in the direction away from the ground plane and one of the plate surfaces are provided separately from each other, connected to the two linear conductors, and arranged outside each other with respect to these connecting portions. Two plate-like elements, and one feed line provided on the other plate surface of the dielectric substrate and extending from the ground plate in the direction of the two plate-like elements. Each of the two plate-like elements has a first edge that is a side in contact with the linear conductor, and a second edge formed so as to start from the top of the ground side of the first edge toward the outside and toward the ground plane. Is provided.

JP 2010-226691 A

  However, the planar antenna of Patent Document 1 can only transmit and receive radio waves in one frequency band. Accordingly, an object of the present invention is to provide a planar antenna that can transmit and receive in two frequency bands.

  The planar antenna of the present invention includes a dielectric substrate, a ground plane, two first strip elements, two second strip elements, two plate elements, and a monopole element. The ground plane is provided on one plate surface of the dielectric substrate. The two first belt-like elements are provided on the one plate surface, one ends thereof are separated from each other, connected to one side of the ground plate, and extended in parallel in a direction away from the ground plate. The two second strip-shaped elements are connected to one side of the ground plane, and are parallel to the direction away from the ground plane, between the two first strip-shaped elements on the one plate surface. It has been extended. Also, the second strip element is shorter than the first strip element. The two plate-like elements are provided separately from each other on the one plate surface, are connected to the two first belt-like elements, and are arranged outside each other with respect to these connection portions. The monopole element is provided on the other plate surface of the dielectric substrate, and is disposed in parallel with the extending direction of the two first strip elements. Each of the two plate-like elements is formed such that a first edge which is a side in contact with the linear conductor and a ground plate side apex of the first edge start from each other and toward the ground plate. Provide with an edge. The length of the second band-shaped element in the extending direction is 0.142 to 0.164 times the wavelength at one of the higher frequency bands of the two frequency bands. The gap between the first band element and the second band element is 0.011 times or less of the wavelength at the center frequency of the higher frequency band of the two frequency bands. The “linear conductor” in Patent Document 1 is referred to as “first strip element” in the present invention, and the “feed line” in Patent Document 1 is referred to as “monopole element” in the present invention. Are the same.

  In the planar antenna of the present invention, the two second strip elements are disposed between the two first strip elements on the one plate surface. The length of the second band-shaped element in the extending direction is 0.142 to 0.164 times the wavelength at any frequency in the higher frequency band, and the first band-shaped element and the second band-shaped element The gap is not more than 0.011 times the wavelength at the center frequency of the higher frequency band. Since it has such arrangement and dimensions, according to the present invention, a planar antenna having good VSWR characteristics in two frequency bands can be realized.

The figure which shows the structural example of the planar antenna of this invention. Sectional drawing of the planar antenna of this invention. The figure which shows the example of the shape of plate-shaped element 1121A and 1121B. The figure explaining the symbol for showing the dimension of the planar antenna 1100. FIG. The figure which shows the example of a dimension, and the calculation result of the frequency characteristic of VSWR. The figure which shows the calculation result of the radiation pattern of the main polarization of XY plane. The figure which shows the calculation result of the radiation pattern of the main polarization of a ZX plane. The figure which shows a calculation result when the parameter L2 is changed among the parameters of FIG. The figure which shows the calculation result when the parameter s is changed among the parameters of FIG. The figure which shows a calculation result when the parameter w2 is changed among the parameters of FIG.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same number is attached | subjected to the structure part which has the same function, and duplication description is abbreviate | omitted.

  FIG. 1 shows a configuration example of a planar antenna of the present invention. The planar antenna 1100 is composed of a dielectric substrate and elements provided on the dielectric substrate. FIG. 1A is a view as seen from one plate surface 17B side of the dielectric substrate 17, and FIG. 1B is a view as seen from the other plate surface 17A side of the dielectric substrate. FIG. 2 is a cross-sectional view of the planar antenna of the present invention, in which the plate surface 17A is disposed on the upper side and the ground plane direction is viewed. 2A is a cross-sectional view taken along T1-T1 'in FIG. 1B, and FIG. 2B is a cross-sectional view taken along T2-T2'. FIG. 3 shows an example of the shape of the plate-like elements 1121A and 1121B.

  The planar antenna 1100 includes a dielectric substrate 17, a ground plane 35, two first strip elements 123A and 123B, two second strip elements 124A and 124B, two plate elements 1121A and 1121B, and a monopole element 1129. To do. In the example of FIG. 1, the dielectric substrate 17 is rectangular, and the plate surfaces 17A and 17B are parallel to the YZ plane. The ground plane 35 is provided on one plate surface 17 </ b> B of the dielectric substrate 17. In the example of FIG. 1, the ground plane 35 is formed along one side of the rectangular plate surface 17B. The two first belt-like elements 123A and 123B are provided on one plate surface 17B, one ends thereof are separated from each other, connected to one side of the ground plate 35, and extended in a direction away from the ground plate 35. . In the example of FIG. 1, the first strip elements 123 </ b> A and 123 </ b> B are extended in a direction (Z direction) parallel to each other and perpendicular to one side to which the ground plane 35 is connected.

  The two second strip elements 124A, 124B are connected to one side of the ground plane 35 with one end being separated from each other between the two first strip elements 123A, 123B on one plate surface 17B, and It extends in parallel to the direction away from the main plate 35. Also, the second strip element is shorter than the first strip element. In the example of FIG. 1, the two second strip elements 124A and 124B extend in a direction perpendicular to one side to which the ground plane 35 is connected, and are parallel to the first strip elements 123A and 123B. In FIG. 1, the second strip elements 124A and 124B are rectangular. However, the second strip elements 124A and 124B are not limited to the rectangular shape, and may have some unevenness on each side as long as there is no problem in impedance matching. The monopole element 1129 is provided on the other plate surface 17A of the dielectric substrate 17, and is disposed in parallel with the extending direction of the two first strip elements 123A and 123B.

  The plate-like elements 1121A and 1121B are provided separately from each other on one plate surface 17B, are connected to the two first belt-like elements 123A and 123B, and are arranged outside each other with respect to these connecting portions. Further, the two plate-like elements 1121A and 1121B are respectively a first edge AB and A′B ′ that are in contact with the first belt-like elements 123A and 123B, and a ground plane 35 of the first edge AB and A′B ′. A second edge AP and A′P ′ are formed so as to start from the side apexes A and A ′ so as to face each other and toward the main plate 35. For example, the plate-like element 1121A has a trapezoidal shape having a short side AB which is a first edge and a long side CP parallel to the short side AB. The second edge is a side AP that connects the short side AB and the vertex A and P on the ground plane 35 side of the long side CP. The plate-like element 1121B has the same shape, and the two plate-like elements 1121A and 1121B are arranged so that the short sides AB and A'B 'face each other in parallel. The plate-like elements are formed so that the first edge, which is the side in contact with the first belt-like elements 123A, 123B, and the apex of the first edge on the ground plane 35 side are outward and toward the ground plane 35. As long as the second edge is provided, the shape need not be limited to that shown in FIG. Since this point is shown in Patent Document 1, detailed description thereof is omitted.

  FIG. 4 is a diagram for explaining symbols for indicating dimensions of the planar antenna 1100. FIG. 5 shows an example of dimensions and calculation results of frequency characteristics of VSWR (Voltage Standing Wave Ratio). FIG. 6 shows the calculation result of the radiation pattern of the main polarization on the XY plane (horizontal radiation pattern when the Z direction is the vertical direction), and FIG. 7 shows the radiation pattern of the main polarization on the ZX plane (Z direction). The calculation result of (radiation pattern in the vertical direction when) is the vertical direction is shown. 6A and 7A show a radiation pattern in a low frequency band, and FIGS. 6B and 7B show a radiation pattern in a high frequency band. 5A is based on the premise that the low frequency band is 0.73 to 0.96 GHz and the high frequency band is 1.94 to 2155 GHz. The thickness of the dielectric substrate 17 was 1.6 mm, and the relative dielectric constant was 3.3. The solid line in FIG. 5B shows the frequency characteristics of the VSWR when the dimensions are shown in FIG. 5A, and the dotted line shows the frequency characteristics of the VSWR when there is no second strip element (in the case of Patent Document 1). . If it is this dimension, since VSWR can be made 2 or less in two frequency bands, it turns out that favorable impedance matching is realizable. In addition, FIG. 6 shows that when the longitudinal direction of the monopole element 1129 is set to the vertical direction, the main polarization can be made omnidirectional in the two frequency bands in the horizontal direction. As long as the shape of the planar antenna 1100 is used, the radiation pattern is not limited to two frequency bands in which the VSWR is 2 or less (regardless of the frequency), and can be made almost omnidirectional. With this planar antenna, it can be seen that the planar antenna can be realized with a length corresponding to 0.234 wavelengths compared to the wavelength of 0.73 GHz, which is the lowest frequency to be communicated, so that the antenna can be downsized.

Next, the frequency characteristics of VSWR when the dimensions related to the second strip elements 124A and 124B are changed will be described. FIG. 8 shows the calculation result when the parameter L2 (the length of the second strip elements 124A and 124B) is changed among the parameters shown in FIG. 5A. FIG. 9 shows the parameter s (the first parameter) among the parameters shown in FIG. FIG. 10 shows a calculation result when changing the gap between the first strip elements 123A and 123B and the second strip elements 124A and 124B. FIG. 10 shows the parameter w2 (the width of the second strip elements 124A and 124B) among the parameters shown in FIG. It is a figure which shows the calculation result when changing). FIG. 9 and FIG. 10 show the length for the wavelength λ ₂ (about 146.5 mm) at the center frequency of the higher frequency band together with the length (mm) of each parameter. 9 and 10, L2 = 22.7 mm, the higher frequency band is 1.94 to 2.15 GHz, and the center frequency of the higher frequency band is 2.045 GHz.

  From the result of FIG. 8, it can be seen that the length L2 (in the extending direction) of the second strip elements 124A and 124B greatly affects the frequency of the higher frequency band. And it is L2 = 20-25 mm that the frequency band where VSWR becomes 2 or less exists in the higher frequency band. When L2 = 20.0 mm, the frequency is 2.27 to 2.34 GHz, the length of L2 with respect to the wavelength at frequency 2.27 GHz is 0.152 wavelength, and the length of L2 with respect to the wavelength at frequency 2.34 GHz is The wavelength is 0.156. When L2 = 22.5 mm, the frequency is 1.97 to 2.18 GHz, the length of L2 with respect to the wavelength at the frequency of 1.97 GHz is 0.148 wavelength, and the length of L2 with respect to the wavelength at the frequency of 2.18 GHz is The wavelength is 0.164. When L2 = 22.7 mm, the frequency is 1.94 to 2.15 GHz, the length of L2 with respect to the wavelength at the frequency of 1.94 GHz is 0.147 wavelength, and the length of L2 with respect to the wavelength at the frequency of 2.15 GHz is The wavelength is 0.163. When L2 = 25.0 mm, the frequency is 1.71 to 1.96 GHz, the length of L2 with respect to the wavelength at the frequency of 1.71 GHz is 0.142 wavelength, and the length of L2 with respect to the wavelength at the frequency of 1.96 GHz is The wavelength is 0.163.

  Thus, at least the length L2 (in the extending direction) of the second strip elements 124A and 124B must be 0.142 to 0.164 times the wavelength at any frequency in the higher frequency band. Don't be. Also, since 0.142 times and 0.164 times are the values that can cause the VSWR to be 2 or less, the length L2 (in the extending direction) of the second band elements 124A and 124B is the center frequency of the higher frequency band. It is better to make it 0.151 to 0.156 times the wavelength of.

  From the results of FIG. 9, it can be seen that if the gap between the first strip elements 123A, 123B and the second strip elements 124A, 124B is excessively widened, the VSWR cannot be maintained at 2 or less. Therefore, it can be seen that at least the gap between the first strip elements 123A and 123B and the second strip elements 124A and 124B must be 0.011 times or less the wavelength at the center frequency of the higher frequency band.

  From the result of FIG. 10, the width of the second strip elements 124A and 124B does not affect the characteristics as compared with the gap between the first strip elements 123A and 123B and the second strip elements 124A and 124B, and what width is it. It can be seen that VSWR is 2 or less at any frequency. That is, it can be seen that the widths of the second strip elements 124A and 124B are parameters that may be appropriately selected at the time of design in accordance with the frequency that is actually desired. However, without greatly changing the characteristics of the VSWR in the lower frequency band when the second band elements 124A and 124B are not provided, an attempt is made to ensure a wide frequency band in which the VSWR is 2 or less in the high frequency band. If it thinks, it is better to make the width | variety of 2nd strip | belt-shaped element 124A, 124B 0.037-0.0444 times the wavelength in the center frequency of a higher frequency band.

  More specifically, the dimensions of the planar antenna are specified using the frequency band and the length. The planar antenna is a planar antenna having a part or all of 730 to 960 MHz as the first frequency band and a part of 1710 to 2340 MHz as the second frequency band. At this time, the length of the second strip elements 124A and 124B in the extending direction is 20.0 to 25.0 mm, and the gap between the first strip elements 123A and 123B and the second strip elements 124A and 124B is 1.6 mm or less. Should. The width of the second strip elements 124A and 124B is preferably 5.5 to 6.5 mm.

  In the planar antenna 1100 of the present invention, the two second strip elements 124A and 124B are disposed between the two first strip elements 123A and 123B on one plate surface. The length of the second strip elements 124A and 124B in the extending direction is 0.142 to 0.164 times the wavelength at the center frequency of the higher frequency band, and the gap between the first strip element and the second strip element Is 0.011 times or less of the wavelength at the center frequency of the higher frequency band. Since it has such an arrangement and dimensions, it is possible to realize a small and omnidirectional planar antenna having excellent VSWR frequency characteristics in two frequency bands.

17 Dielectric substrates 17A and 17B Plate surface 35 Ground plates 123A and 123B First strip elements 124A and 124B Second strip elements 1100 Planar antennas 1121A and 1121B Plate elements 1129 Monopole elements

Claims (5)

A planar antenna for two frequency bands,
A dielectric substrate;
A ground plane provided on one plate surface of the dielectric substrate;
Two first strip-shaped elements provided on the one plate surface, separated from each other, connected to one side of the ground plate, and extended in parallel in a direction away from the ground plate;
Between the two first strip-like elements on the one plate surface, one ends are separated from each other, connected to one side of the ground plate, and extended in parallel in a direction away from the ground plate, Two second strip elements that are shorter than the one strip element;
Two plate-like elements provided separately from each other on the one plate surface, connected to the two first strip-like elements, and arranged on the outside of these connection portions;
A monopole element provided on the other plate surface of the dielectric substrate and parallel to the extending direction of the two first strip-shaped elements;
Each of the two plate-like elements is formed so that the first edge, which is the side in contact with the linear conductor, and the apex on the ground plane side of the first edge are outward from each other and toward the ground plane. With a second edge,
The length in the extending direction of the second band-shaped element is 0.142 to 0.164 times the wavelength at one of the higher frequency bands of the two frequency bands,
The planar antenna, wherein a gap between the first band-shaped element and the second band-shaped element is 0.011 times or less of a wavelength at a center frequency of the higher frequency band of the two frequency bands. The planar antenna according to claim 1,
The planar antenna, wherein the width of the second band-shaped element is 0.0375 to 0.0444 times the wavelength at the center frequency of the higher frequency band of the two frequency bands. The planar antenna according to claim 1 or 2,
The planar antenna, wherein a length in the extending direction of the second band-shaped element is 0.151 to 0.156 times a wavelength at a center frequency of the higher frequency band of the two frequency bands. A planar antenna having a part or all of 730 to 960 MHz as a first frequency band and a part of 1710 to 2340 MHz as a second frequency band,
A dielectric substrate;
A ground plane provided on one plate surface of the dielectric substrate;
Two first strip-shaped elements provided on the one plate surface, separated from each other, connected to one side of the ground plate, and extended in parallel in a direction away from the ground plate;
Between the two first strip-like elements on the one plate surface, one ends are separated from each other, connected to one side of the ground plate, and extended in parallel in a direction away from the ground plate, Two second strip elements that are shorter than the one strip element;
Two plate-like elements provided separately from each other on the one plate surface, connected to the two first strip-like elements, and arranged on the outside of these connection portions;
A monopole element provided on the other plate surface of the dielectric substrate and parallel to the extending direction of the two first strip-shaped elements;
Each of the two plate-like elements is formed so that the first edge, which is the side in contact with the first belt-like element, and the apex on the ground plane side of the first edge start from each other and toward the ground plane. With a second edge
The length in the extending direction of the second strip-shaped element is 20.0 to 25.0 mm,
A planar antenna, wherein a gap between the first strip element and the second strip element is 1.6 mm or less. The planar antenna according to claim 4,
The width of said 2nd strip | belt-shaped element is 5.5-6.5 mm. The planar antenna characterized by the above-mentioned.