JP6314722B2 - Circularly polarized patch antenna and integrated antenna device - Google Patents

Description

  The present invention relates to a circularly polarized patch antenna and an integrated antenna device including the circularly polarized patch antenna.

  Patent Document 1 discloses a method of adjusting the characteristics of a circularly polarized patch antenna in which a radiating element is provided on the front surface of a dielectric substrate and a ground pattern is provided on the back surface.

  In the adjustment method disclosed in Patent Document 1, when the characteristic deviation of the antenna element is large, the characteristic is adjusted by trimming only the radiating element or the radiating element and the ground pattern. On the other hand, when the characteristic deviation of the antenna element is small, the characteristic is adjusted by trimming only the ground pattern.

  In a circularly polarized patch antenna, it is widely known that when the dielectric constant of a dielectric substrate on which a radiating element is mounted is increased, the radiating element can be reduced in size due to the wavelength shortening effect of the dielectric substrate.

Japanese Patent No. 4491914

  In the circularly polarized patch antenna of Patent Document 1, both the radiating element and the ground pattern are smaller than the size of the surface of the dielectric substrate on which the radiating element and the ground pattern are arranged. Therefore, when the dielectric constant of the dielectric substrate in the circularly polarized antenna of Patent Document 1 is increased to reduce the size of the dielectric substrate, the ground pattern also decreases.

  When considering the formation of the degenerate separation portion in a ground pattern smaller than the dielectric substrate, the degeneration separation portion also receives the wavelength shortening effect by the dielectric substrate. Therefore, when the dielectric constant of the dielectric substrate varies, it is necessary to change the size of the degenerate separation portion according to the variation in the dielectric constant.

  In addition, if the dielectric constant of the dielectric substrate is high, the degenerate separation portion formed in the ground pattern becomes very small, so that the allowable range of the size of the degeneration separation portion to satisfy the required performance of the axial ratio is narrow. . Therefore, if a dielectric substrate having a high dielectric constant is used, the size of the degenerative separation portion satisfies the required performance of the axial ratio due to variations in the dielectric constant of the dielectric substrate even if the degeneration separation portion is made with high dimensional accuracy. Sometimes it is not within range.

  Further, in order to make the size of the degeneration / separation unit within a range that satisfies the required performance of the axial ratio, even if the degeneration / separation unit is trimmed, it is necessary to trim a very small portion. Therefore, the trimming processing accuracy must be high. Therefore, adjustment of the axial ratio at the operating frequency is not easy.

  The present invention has been made based on this situation, and the object of the present invention is to provide a circularly polarized patch whose axial ratio can be easily adjusted at an operating frequency even when a dielectric substrate having a high dielectric constant is used. An object is to provide an antenna and an integrated antenna device.

  The above object is achieved by a combination of the features described in the independent claims, and the subclaims define further advantageous embodiments of the invention. Reference numerals in parentheses described in the claims indicate a correspondence relationship with specific means described in the embodiments described later as one aspect, and do not limit the technical scope of the present invention. .

  In order to achieve the above object, the present invention provides a dielectric substrate (4) comprising a first plane (41) and a second plane (42) facing each other, and is disposed on the first plane and is more than the first plane. A ground plane (37) having a small radiating element (5, 50) and an outer portion (37) disposed on the second plane and larger than the second plane and projecting outside the second plane in the plane direction including the second plane. 3, 3 a) and a pair of ground plane-side degenerate separation parts (32, 32 a, 35, 35 a) formed on the outer portion of the ground plane, a circularly polarized patch antenna.

  In the present invention, the ground plane includes an outer portion protruding outside the second plane of the dielectric substrate, and the ground plane-side degenerative separation portion is formed in the outer portion. Since it is provided in the portion protruding to the outside of the dielectric substrate, the ground plane side degeneration / separation part is not easily affected by the wavelength shortening effect by the dielectric substrate. Therefore, even if the dielectric constant of the dielectric substrate varies, the size of the ground plane-side degenerate separation portion is likely to be within an allowable range determined by the required performance of the dielectric constant of the dielectric substrate and the axial ratio.

  In addition, when the ground plane side degeneration / separation part is provided in the outer portion, the change in the axial ratio with respect to the change in the size of the ground plane side degeneration / separation part becomes small. Therefore, even when trimming the base plate side degeneration / separation portion to adjust the axial ratio, the allowable range of trimming is widened, so that adjustment of the axial ratio at the operating frequency is facilitated.

It is a top view of the circularly polarized patch antenna 1 of 1st Embodiment. 1 is a perspective view of a circularly polarized patch antenna 1 of a first embodiment. It is a side view of the circularly polarized patch antenna 1 of 1st Embodiment. It is a figure which shows the change of the axial ratio in an operating frequency with respect to the change of the length of one side of the degeneracy separation part of the circularly polarized wave patch antenna. It is a figure which shows the change of the axial ratio in an operating frequency with respect to the change of the length of the one side of a degeneracy separation part in a comparison structure. It is a top view of the integrated antenna apparatus 100 of 2nd Embodiment. It is a top view of the circularly polarized patch antenna 200 of 3rd Embodiment. 10 is a plan view of a circularly polarized patch antenna according to Modification 1. FIG. FIG. 10 is a plan view of a circularly polarized patch antenna according to Modification 2.

<First Embodiment>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The circularly polarized patch antenna 1 of the first embodiment receives radio waves transmitted from a satellite used in a GPS (Global Positioning System) that is one of satellite positioning systems. In GPS, the 1.5 GHz band is used.

  As shown in FIG. 1, the circularly polarized patch antenna 1 includes a circuit board 2, a ground plane 3, a high dielectric substrate 4, a radiating element 5, and a power feeding unit 6.

  The circuit board 2 is a board generally used for mounting a circuit, an antenna, and the like, and is made of a dielectric material such as a glass epoxy resin. The shape of the circuit board 2 shown in FIG. 1 is a square shape. However, the size and shape of the circuit board 2 are not particularly limited as long as the elements to be mounted on the circuit board 2 can be mounted.

  The ground plane 3 is a foil or a plate made of a conductor such as copper or silver, and is formed on one surface of the circuit board 2. The ground plane 3 has a hexagonal shape in which a pair of diagonals of a square is missing in an isosceles triangle shape. Specifically, assuming that the six sides of the base plate 3 are the first side 31 to the sixth side 36, the first side 31, the third side 33, the fourth side 34, and the sixth side 36 have the same length. Each of the four sides of the square shape formed when the equilateral triangular portion is not missing is configured. The second side 32 and the fifth side 35 are also the same length and are parallel to each other. These 2nd edge | side 32 and the 5th edge | side 35 are equivalent to the ground-plate side degeneracy separation part of a claim.

  As for the size of the ground plane 3, the length between the first side 31 and the fourth side 34 and the length between the third side 33 and the sixth side 36 are 25 mm. That is, the length of one side of the square formed when the isosceles triangular portion is not missing is 25 mm. Therefore, in the present embodiment, the length of one side of the ground plane 3 is about 1/8 of the wavelength of the radio wave on which the circularly polarized patch antenna 1 operates.

  A high dielectric substrate 4 is disposed on the ground plane 3, and a second plane 42 (see FIG. 3) of the high dielectric substrate 4 is in contact with the ground plane 3. In other words, the ground plane 3 is arranged on the second plane 42 of the high dielectric substrate 4. The high dielectric substrate 4 has a dielectric constant higher than that of the circuit board 2, for example, a dielectric constant of 80.

  The shape of the high dielectric substrate 4 is a rectangular parallelepiped shape. Among each surface of the high dielectric substrate 4, a pair of surfaces having the largest area is defined as a first plane 41 and a second plane 42. The first plane 41 and the second plane 42 are parallel to each other. As described above, the second plane 42 is in contact with the ground plane 3. In the first embodiment, the first plane 41 and the second plane 42 are square, and one side is 12 mm here. Therefore, the ground plane 3 having a side of 25 mm is larger than the high dielectric substrate 4.

  Each side of the first plane 41 and the second plane 42 is parallel to the first side 31, the third side 33, the fourth side 34, and the sixth side 36 of the ground plane 3. The length between the first plane 41 and the second plane 42 is the thickness of the high dielectric substrate 4. As shown in FIG. 2, the high dielectric substrate 4 is thicker than the circuit board 2.

  The high dielectric substrate 4 is disposed at the center of the ground plane 3, and each side of the second plane 42 of the high dielectric substrate 4 and the first side 31 and the third side 33 parallel to the respective sides on the ground plane 3. The distances between the fourth side 34 and the sixth side 36 are equal to each other. A portion of the ground plane 3 that protrudes outside the second plane 42 in the plane direction including the second plane 42 of the high dielectric substrate 4 is referred to as an outer portion 37. The second side 32 and the fifth side 35, which are the base plate side degenerate separation parts, are formed on the outer portion 37.

  The radiating element 5 is a foil or a plate made of a conductor such as copper or silver. The shape of the radiating element 5 of the first embodiment is a square, and the length of one side is slightly shorter than the length of one side of the first plane 41. Specifically, the length of one side of the radiating element 5 of the first embodiment is 10 mm. The circularly polarized patch antenna 1 of this embodiment is for GPS, and the operating frequency is in the 1.5 GHz band. When the frequency is 1.5 GHz, the wavelength λ is about 200 mm. However, due to the wavelength shortening effect of the high dielectric substrate 4, the length of one side of the radiating element 5 is much shorter than half of the wavelength λ.

  Each side of the radiating element 5 is disposed so as to be parallel to each side of the first plane 41, and the radiating element 5 is arranged so that the center of the radiating element 5 overlaps the center of the first plane 41. One plane 41 is arranged.

  The power feeding unit 6 is a part that electrically connects the radiating element 5 and the inner conductor of the coaxial cable, and passes through the circuit board 2, the ground plane 3, and the high dielectric substrate 4 as shown in FIG. The feeding point as the tip is connected to the radiating element 5.

  Unlike the widely known circularly polarized patch antenna, the circularly polarized patch antenna 1 configured in this way does not include a degenerate separation unit in the radiating element, but instead serves as a degenerate separation unit on the ground plane 3. A functioning second side 32 and a fifth side 35 are provided. As described above, the circularly polarized wave can be radiated by configuring the degenerate separation portion on the ground plane 3.

(Effect of embodiment)
FIG. 4 is a diagram illustrating a change in the axial ratio at the operating frequency with respect to a change in the length of one side of the degenerate separation unit in the circularly polarized patch antenna 1 of the present embodiment. The length of one side of the degenerate separation part is the length of the equal side of the isosceles triangle missing from the ground plane 3. On the other hand, FIG. 5 is a diagram showing the change in the axial ratio at the operating frequency with respect to the change in the length of one side of the degenerate separation unit in the comparison configuration for comparison with the circularly polarized patch antenna 1 of the present embodiment. . The comparative configuration is a circularly polarized patch antenna in which the ground plane 3 is a square having no isosceles triangular missing portion in the configuration of FIGS. 1 to 3, and the radiating element 5 is provided with a degenerate separation portion instead.

  In FIG. 4, the axial ratio is 6 or less from the vicinity of 7.5 mm to the length slightly exceeding 12 mm, with the length of one side of the degenerate separation part as the center. The axial ratio is the ratio of right-handed polarization and left-handed polarization, and the smaller the axial ratio, the better. If the axial ratio of 6 or less is the required performance, in this embodiment, the required performance is satisfied if the length of one side of the degenerate separation part is between 7.5 mm and slightly longer than 12 mm. become.

  On the other hand, in FIG. 5, the axial ratio is 6 or less in the range where the length of one side of the degenerate separation part is slightly longer than 0.5 mm to 1 mm. Therefore, in the comparative configuration, in order to set the axial ratio to 6 or less, it is necessary to set the length of one side of the degenerate separation part to a length slightly exceeding 0.5 mm to 1 mm.

  As can be seen from the comparison between FIG. 4 and FIG. 5, when the second side 32 and the fifth side 35 functioning as a degenerate separation part are provided on the outer portion 37 of the ground plane 3 as in the present embodiment, the axial ratio at the operating frequency The range of the length of one side of the degenerate separation unit that satisfies the required performance is wider than that of the comparative configuration. Roughly speaking, the allowable range of the length of one side of the degenerate separation unit in the circularly polarized patch antenna 1 of the present embodiment is 10 times wider than the allowable range of the degenerate separation unit in the comparative configuration. This is because the outer portion 37 of the ground plane 3 is not easily affected by the wavelength shortening effect by the high dielectric substrate 4.

  Since the range of the length of one side of the degenerate separation part that satisfies the required performance of the axial ratio at the operating frequency is widened, the axial ratio of the circularly polarized patch antenna 1 can be increased even if the dielectric constant of the high dielectric substrate 4 varies somewhat. , Likely to meet the required performance. Therefore, there is a high possibility that the required performance is satisfied without adjusting the sizes of the second side 32 and the fifth side 35.

  In addition, since the change in the axial ratio with respect to the change in the size of the second side 32 and the fifth side 35 is reduced, the size of the second side 32 and the fifth side 35 is adjusted by trimming to adjust the axial ratio. However, since the allowable range of trimming is widened, adjustment of the axial ratio at the operating frequency is facilitated.

Second Embodiment
Next, a second embodiment will be described. In the following description of the second embodiment, elements having the same reference numerals as those used so far are the same as elements having the same reference numerals in the previous embodiments unless otherwise specified. Further, when only a part of the configuration is described, the above-described embodiment can be applied to the other parts of the configuration.

  In the second embodiment, the integrated antenna device 100 will be described. As shown in FIG. 6, the integrated antenna device 100 includes two antennas, the circularly polarized patch antenna 1 and the inverted L antenna 110 of the first embodiment.

  The inverted L antenna 110 includes a ground plane 3 that is also a constituent element of the circularly polarized patch antenna 1 in addition to the monopole conductor element 120 and the power feeding unit 130. In the inverted L antenna 110, the electrical length of the monopole conductor element 120 is about λ / 4.

  The monopole conductor element 120 is provided on the same surface as the ground plane 3 of the circuit board 2. The shape of the monopole conductor element 120 is a shape obtained by bending a straight linear conductor element in the middle at a right angle, the end on the base side is connected to the power feeding unit 130, and the other end is an open end.

  In this monopole conductor element 120, a portion bent at a right angle is defined as a bent portion 121. Since the end from the base side to the bent part 121 is relatively shorter than from the bent part 121 to the open end, the short part 122, the bent part from the base side end to the bent part 121 The length from 121 to the open end is defined as a longitudinal portion 123.

  The end of the short part 122 opposite to the bent part 121 is connected to the power supply part 130. The power feeding unit 130 is provided in the vicinity of a corner on one side (here, the first side 31) of the ground plane 3 on the side opposite to the second side 32 that functions as the ground plane-side degeneration / separation section. The short part 122 extends perpendicularly to the first side 31 of the ground plane 3 from the power supply part 130. On the other hand, the longitudinal portion 123 is parallel to the first side 31. The length of the longitudinal part 123 is longer than the first side 31, and the second side 32 is located on the side of the open end of the longitudinal part 123. In addition, being located on the side means that a perpendicular that is orthogonal to the straight line including the first side 31 and that passes through the open end of the longitudinal portion 123 intersects the second side 32.

  The power feeding unit 130 has a configuration in which the short part 122 of the monopole conductor element 120 is electrically connected to the inner conductor of the coaxial cable and the outer conductor of the coaxial cable is electrically connected to the ground plane 3.

(Effect of 2nd Embodiment)
In the second embodiment, the open end of the longitudinal portion 123 of the monopole conductor element 120 extends to the side of the second side 32 of the ground plane 3. Therefore, the effective height of the inverted L antenna 110 can be increased as compared with the case where the monopole conductor element 120 is disposed on one side of a square ground plane on which the second side 32 is not provided. In addition, the second side 32 also functions as a degenerate separation unit.

  That is, in the second embodiment, by utilizing the inclination of the second side 32 that functions as the degenerate separation unit of the circularly polarized patch antenna 1, the size of the integrated antenna device 100 is suppressed from increasing. However, the effective height of the inverted L antenna 110 can be increased.

<Third Embodiment>
The third embodiment is an embodiment of the circularly polarized patch antenna 200. As shown in FIG. 7, the circularly polarized patch antenna 200 includes a radiating element 50 in place of the radiating element 5 of the first embodiment. The radiating element 50 is different from the radiating element 5 in that the radiating element 50 includes a pair of element-side degenerate separation parts 51 and 51 diagonally.

  The element-side degeneration / separation sections 51 and 51 have a size that is about the lower limit value of the allowable range determined from the required performance of the axial ratio or a little smaller than that. Therefore, the ground plane 3a also includes a second side 32a and a fifth side 35a that function as a ground plane-side degeneration / separation part.

  However, the lengths of the second side 32a and the fifth side 35a are the same as the lengths of the second side 32 and the fifth side 35 of the first embodiment because the radiating element 50 includes the element-side degenerate separation parts 51 and 51. Shorter than length. Since the second side 32a and the fifth side 35a are shortened, the lengths of the first side 31a, the third side 33a, the fourth side 34a, and the sixth side 36a are the first side 31, the first side 31, It is longer than the third side 33, the fourth side 34, and the sixth side 36.

  Also in the third embodiment, when adjusting the axial ratio, the sizes of the second side 32a and the fifth side 35a are adjusted by trimming. Since the second side 32a and the fifth side 35a are formed on the outer portion 37 of the ground plane 3a, the allowable range of trimming is the same as in the first embodiment. Therefore, it is easy to adjust the axial ratio at the operating frequency.

  In addition, in the third embodiment, since the radiating element 50 includes the element-side degeneration / separation part 51, the second side 32a and the fifth side 35a are shortened. Therefore, the size of the main plate 3a can be increased. By increasing the size of the ground plane 3a, electronic components can be easily arranged on the ground plane 3a.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following modification is also contained in the technical scope of this invention, Furthermore, the summary other than the following is also included. Various modifications can be made without departing from the scope.

<Modifications 1 and 2>
For example, in the above-described first to third embodiments, each of the ground plane-side degenerate separation parts has a shape in which square corners are omitted from an isosceles triangle. However, the shape of the ground plane side degeneration / separation part can be the same as the shape of the degeneration / separation part formed in the radiating element. For example, as shown in FIG. 8, the shape of the ground plane side degeneration / separation part may be a set of rectangular notches extending from a set of squares toward the center (Modification 1). Moreover, as shown in FIG. 9, it is good also as a pair of rectangular-shaped ground-plate side degeneracy separation part which protrudes in the mutually opposite direction with respect to the square diagonal line from a set of corner | angular part of a square (modification 2). In FIG. 8 and FIG. 9, the circuit board is omitted.

<Modification 3>
Furthermore, the shape of the ground plane shown so far was a shape based on a square, but the shape of the ground plane is not limited to a shape based on a square, and it is known to be an element shape that can emit circularly polarized waves. The same shape can be used for the main plate of the present invention. Therefore, the shape of the ground plane may be circular, elliptical, or polygonal. When the shape of the ground plane is set to these shapes, the shape of the ground plane side degeneration / separation portion should be the same as the shape of various degeneration / separation portions formed in the radiating element when the radiating element is set to these shapes. it can.

<Modification 4>
In the above-described embodiment, the size of the ground plane 3 is about 1/8 of the wavelength of the radio wave. However, the size of the ground plane 3 is not limited to the size shown in the above-described embodiment, and if there is an outer portion, Various sizes such as ½ or less of the wavelength and ¼ of the wavelength can be used.

<Modification 5>
Although the circularly polarized patch antenna 1 of the above-described embodiment is for GPS, the present invention can be applied to applications other than GPS, such as an antenna for satellite broadcasting radio.

1: circularly polarized patch antenna, 2: circuit board, 3: ground plane, 3a: ground plane, 4: high dielectric substrate, 5: radiating element, 6: feeder, 37: outer portion, 41: first plane, 42 : Second plane, 50: radiating element, 51: element-side degenerate separation part, 80: dielectric constant, 100: integrated antenna device, 110: inverted L antenna, 120: monopole conductor element, 121: bent part, 122: Short part, 123: Longitudinal part, 130: Feeding part, 200: Circularly polarized patch antenna

Claims (3)

A dielectric substrate (4) comprising a first plane (41) and a second plane (42) facing each other;
A radiating element (5, 50) disposed in the first plane and smaller than the first plane;
A ground plane (3, 3a) provided with an outer portion (37) disposed on the second plane and projecting outside the second plane in a plane direction including the second plane and larger than the second plane;
A circularly polarized patch antenna, comprising: a pair of ground plane-side degenerate separation portions (32, 32a, 35, 35a) formed on the outer portion of the ground plane. In claim 1,
A circularly polarized patch antenna comprising an element-side degenerate separation part (51) formed in the radiating element. An integrated antenna device comprising the circularly polarized patch antenna (1) according to claim 1 or 2 and a monopole conductor element (120),
The ground plane of the circularly polarized patch antenna has a shape in which a pair of squares is missing in a triangular shape and the ground plane side degenerate separation portion is formed.
The monopole conductor element is provided on the same plane as the ground plane, is fed at one end, has an open end at the other end, and has a bent portion (121) between the end on the power feeding side and the open end. The integrated antenna device is characterized in that the ground plane side degeneration / separation part is located on a side of the open end.

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