JP2005252585A - Circularly-polarized wave antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable circularly-polarized wave antenna which can inexpensively be manufactured. <P>SOLUTION: An antenna element 10 placed and fixed on a ground conductor 17 is provided with a radiation conductor plate 11 formed by press-working one metal plate, a feeding pin 12 and four leg pieces 13 to 16. The leg pieces 13 to 16 extend from notch parts 11a to 11d formed in centers of respective sides of the radiation conductor plate 11 in an almost square shape. An interval between the confronted leg pieces 13 and 14 is set to become longer than that between the confronted leg pieces 15 and 16 by a prescribed amount. A diagonal line C where the feeding pin 12 exists is set to make an angle of 45 degrees with respect to a straight line A where the leg pieces 13 and 14 exist at both ends and a straight line B where the leg pieces 15 and 16 exist at both ends. Since a prescribed difference is allowed to arise in resonance length of a resonance mode along the straight line A and a resonance mode along the straight line B, the antenna element can be operated as the circularly-polarized wave antenna. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a circularly polarized antenna having a patch antenna structure suitable for in-vehicle use and the like, and more particularly to a circularly polarized antenna that is advantageous for cost reduction.

  In-vehicle antennas have the advantage that control over the polarization direction is unnecessary even during movement by performing transmission and reception using circularly polarized signals. For this reason, a small circularly polarized antenna having a patch antenna structure has been widely used for in-vehicle use.

  FIG. 6 is a plan view showing a typical conventional example of this type of circularly polarized antenna (see, for example, Patent Document 1). The antenna device 1 shown in FIG. 1 is called a circularly polarized patch antenna, and is provided with a radiation conductor (patch electrode) 3 on one surface of a dielectric substrate 2 by a metal thin film forming technique such as printing. On the other surface of the body substrate 2, a ground conductor (not shown) is provided on almost the entire surface. The radiation conductor 3 is substantially square, and a pair of opposing corners are cut away to form degenerate separation elements 4 and 5. One end of a power supply pin 6 that penetrates the dielectric substrate 2 and the ground conductor is soldered to a predetermined power supply point in the radiation conductor 3, and the other end of the power supply pin 6 is connected to a power supply circuit (not shown). Has been.

The antenna device 1 schematically configured as described above can radiate an electric field by resonating the radiation conductor 3 by supplying a predetermined high-frequency signal to the radiation conductor 3 via the feed pin 6. In the radiation conductor 3, the resonance length of the resonance mode in the diagonal direction in which the degenerate separation elements 4 and 5 exist is shorter than the resonance length of the resonance mode in the other diagonal direction orthogonal to the diagonal line. Therefore, the main mode in which both resonance modes are synthesized by appropriately adjusting the size (notch area) of the degenerate separation elements 4 and 5 and exciting both resonance modes with the same amplitude and a phase difference of about 90 degrees. Is excited, and this antenna device 1 can be operated as a circularly polarized antenna.
JP2000-151261 (2nd page, FIG. 5)

  As described above, the conventional circularly polarized patch antenna (antenna device 1) has a configuration in which the radiation conductor 3 is provided on one surface of the dielectric substrate 2 and the feed pin 6 is connected to the radiation conductor 3. The dielectric substrate 2 with a small dielectric loss is expensive, and the process of forming the radiation conductor 3 by a metal thin film forming technique is complicated, so that this type of antenna device 1 cannot be manufactured at low cost. In particular, when the resonance frequency is high, a dielectric material with as little dielectric loss as possible is required as a material for the dielectric substrate 2 in order to ensure antenna efficiency. Therefore, for example, if an attempt is made to manufacture a circularly polarized antenna for an ETC (automatic toll collection system) having a resonance frequency of 5.8 GHz by using the above-described conventional technique, it becomes extremely expensive.

  The present invention has been made in view of the actual situation of the prior art, and an object thereof is to provide a circularly polarized antenna having a patch antenna structure that can be manufactured at low cost and has high reliability.

  In order to achieve the above-described object, in the circularly polarized antenna of the present invention, a radiation conductor plate made of a metal plate whose outer shape is a substantially regular polygon or a substantially circular shape and disposed on a ground conductor with a predetermined interval, Four feed pins that extend from the feed point of the radiation conductor plate and are connected to the feed circuit, and that support the radiation conductor plate in a state of being insulated from the ground conductor and extending from the outer periphery of the radiation conductor plate. The four leg pieces are arranged on both ends of one of two straight lines passing through the center of the radiation conductor plate and orthogonal to each other on the radiation conductor plate. And the second leg piece, and the third leg piece and the fourth leg piece that are disposed at both ends of the other straight line and are in a symmetrical relationship with the one straight line, and the feeding point And a straight line connecting the center of the radiation conductor plate is an angle of approximately 45 degrees with respect to the two straight lines. The power feed point and arranged to form the resonant length of the resonant modes along the one straight line is set to be longer than the resonant length of the resonant modes along the other linear.

  In the circularly polarized antenna thus configured, the resonance length of the resonance mode along the straight line connecting the first and second leg pieces is the resonance length of the resonance mode along the straight line connecting the third and fourth leg pieces. By designing the antenna to be a predetermined amount longer than the two modes, both resonance modes can be excited with the same amplitude and a phase difference of about 90 degrees, so that it can be operated as a single-point feed type circularly polarized antenna. it can. In addition, this circularly polarized antenna can be manufactured at a very low price by pressing a single metal plate to form a radiation conductor plate, a feed pin, and all four leg pieces, and no expensive dielectric is required. be able to. In addition, this circularly polarized antenna can hold the radiation conductor plate in a stable posture by the four leg pieces, and the antenna characteristics are deteriorated due to variations in dielectric materials and variations in print pattern accuracy. Since it can be avoided, it is easy to ensure high reliability.

  As a specific configuration example, the interval between the first and second leg pieces may be set longer than the interval between the third and fourth leg pieces. In this case, for example, four leg pieces each extend from a notch provided on the outer peripheral edge of the radiation conductor plate, and the positions of the first and second leg pieces among these four notches are provided. What is necessary is just to form the notch part to shallower than the notch part in which the 3rd and 4th leg piece is located.

  As another specific configuration example, capacitors are attached to the tip portions of four leg pieces, and capacitance values added to the first and second leg pieces are set to the third and fourth leg pieces. What is necessary is just to set larger than the capacity | capacitance value added to. In this case, for example, the capacitor is made of a dielectric substrate having solder lands provided at four locations on the upper surface and a ground electrode provided on the lower surface. The capacitor is placed on the ground conductor and four capacitors are formed on the solder land. The solder lands to be soldered and the solder lands to which the first and second leg pieces are soldered may be formed larger than the solder lands to be soldered to the third and fourth leg pieces.

  In the circularly polarized antenna having such a configuration, the outer shape of the radiation conductor plate is substantially square, and four leg pieces are arranged at the center of each side, and a feeding point is provided on one diagonal line of the square. Is preferably arranged. In this way, if the radiation conductor plate is a metal plate having a substantially square outer shape, the design is facilitated and the punching and bending processes can be efficiently performed. An inexpensive circularly polarized antenna can be obtained.

  The circularly polarized wave antenna of the present invention is such that, among the four leg pieces supporting the radiation conductor plate, the distance between the leg pieces facing each other is different, or different capacitance values are added to the adjacent leg pieces. Since a predetermined difference can be generated between the resonance lengths of the two resonance modes orthogonal to each other, it can be operated as a one-point feeding type circularly polarized antenna. Further, by pressing a single metal plate, the radiation conductor plate, the feed pin, and each leg piece can be formed, and an expensive dielectric is unnecessary. Therefore, a circularly polarized antenna having a patch antenna structure that can be manufactured at low cost and has high reliability can be obtained.

  1 is a perspective view of a circularly polarized antenna according to a first embodiment of the present invention, FIG. 2 is a plan view of the circularly polarized antenna, and FIG. It is sectional drawing of a polarization antenna.

  The antenna element 10 of the circularly polarized antenna shown in FIGS. 1 to 3 includes a radiating conductor plate 11, a feeding pin 12, and four leg pieces 13 to 16 formed by pressing a single metal plate. I have. The antenna element 10 is placed and fixed on a substrate 18 having a ground conductor 17 on the upper surface. The radiating conductor plate 11 has a substantially square outer shape, and the leg pieces 13 to 11 are cut and raised downward from the notches 11a to 11d provided at the four outer peripheral edges (centers of the sides of the square). 16 extends. However, as is apparent from FIG. 2, the notches 11a and 11b where the opposing leg pieces 13 and 14 are located are formed shallower than the notch parts 11c and 11d where the opposing leg pieces 15 and 16 are located. Has been. The lower end portions of the leg pieces 13 to 16 are inserted into the mounting holes 19 provided at the corresponding positions of the substrate 18 and soldered. As is apparent from FIG. 3, the leg pieces 13 to 16 are grounded. It is insulated from the conductor 17 and is electrically open. The radiation conductor plate 11 is held in a substantially parallel posture with respect to the ground conductor 17 by the four leg pieces 13 to 16 mechanically fixed to the substrate 18. In addition, a feed pin 12 that is a piece cut and raised downward from a feed point set on one diagonal line of the radiating conductor plate 11 extends, and a lower end portion of the feed pin 12 is in a through hole 18 a of the substrate 18. Soldered. As a result, the power supply pin 12 is connected to a power supply circuit (not shown) provided on the lower surface of the substrate 18, so that a predetermined high-frequency signal can be supplied to the radiation conductor plate 11 via the power supply pin 12.

  In this antenna element 10, the notches 11a and 11b of the radiating conductor plate 11 are formed shallower than the notches 11c and 11d, so that the leg pieces 13 and 14 facing each other are spaced apart from each other. , 16 is set to be a predetermined amount longer than the interval between them. Further, the diagonal line C with the feed pin 12 is set to form an angle of 45 degrees with respect to the straight line A with the leg pieces 13 and 14 at both ends and the straight line B with the leg pieces 15 and 16 at both ends. . Accordingly, a predetermined difference can be generated in the resonance length of two resonance modes (resonance mode along the straight line A and resonance mode along the straight line B) of the radiation conductor plate 11 which are orthogonal to each other. By appropriately adjusting the depth of 11d and the size of the leg pieces 13-16, it is possible to excite both resonance modes with the same amplitude and a phase difference of about 90 degrees. It can be operated as an antenna.

  Further, the antenna element 10 can form all of the radiation conductor plate 11, the feed pin 12, and the four leg pieces 13 to 16 by pressing a single metal plate, and an expensive dielectric is unnecessary. It can be manufactured at a very low cost. Moreover, since the radiation conductor plate 11 of the antenna element 10 is made of a metal plate having a substantially square outer shape, it is easy to design and can be efficiently punched and bent, and therefore has a low manufacturing cost. Further reduction is easy.

  Further, the antenna element 10 can hold the radiation conductor plate 11 in a stable posture by the four leg pieces 13 to 16 and has antenna characteristics caused by variations in dielectric materials, variations in print pattern accuracy, and the like. Therefore, it is easy to ensure high reliability.

  FIG. 4 is a plan view of a circularly polarized antenna according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view of the circularly polarized antenna. Therefore, overlapping description will be omitted as appropriate.

  In the circularly polarized antenna shown in FIGS. 4 and 5, the antenna element 20 is mounted and fixed on the ground conductor 17 of the substrate 18 via the capacitor 21. Further, since the depths of the notches 11a to 11d of the radiating conductor plate 11 are all equal, the distance between the leg pieces 13 and 14 facing each other is equal to the distance between the leg pieces 15 and 16 facing each other. The capacitor 21 is configured by providing solder lands 23a to 23d at four locations on the upper surface of the dielectric substrate 22, and by providing a ground electrode 24 on the lower surface of the dielectric substrate 22, and each on the solder lands 23a to 23d. Leg pieces 13 to 16 are soldered. However, the solder lands 23a and 23b to which the first and second leg pieces 13 and 14 are soldered are formed larger than the solder lands 23c and 23d to which the third and fourth leg pieces 15 and 16 are soldered. Therefore, the capacitance value added to the tip portions of the first and second leg pieces 13 and 14 is slightly larger than the capacitance value added to the tip portions of the third and fourth leg pieces 15 and 16. It has become. Note that the lower end portion of the power supply pin 12 penetrates the dielectric substrate 22 and is soldered in the through hole 18 a of the substrate 18.

  As described above, in the present embodiment, the capacitor 21 is interposed between the antenna element 20 and the ground conductor 17, and the capacitance value added to the pair of opposing leg pieces 13 and 14 is different from that of the other opposing elements. Since it is configured to be larger than the capacitance value added to the pair of leg pieces 15, 16, the resonance length of the resonance mode along the straight line where the leg pieces 13, 14 exist at both ends, the leg pieces 15, This is longer than the resonance length of the resonance mode along the straight line 16. Therefore, by appropriately adjusting the additional capacitance values of the leg pieces 13 and 14 and the leg pieces 15 and 16, it is possible to excite both resonance modes with the same amplitude and a phase difference of about 90 degrees. It can be operated as a circularly polarized antenna.

  In each of the first and second embodiments described above, the case where the outer shape of the radiation conductor plate 11 is substantially square has been described. However, even if the outer shape of the radiation conductor plate is another regular polygon or a circle, It is possible to operate as an inexpensive and highly reliable circularly polarized antenna by appropriately setting the mutual positional relationship, additional capacitance value, feed pin arrangement, etc. of the four leg pieces supporting the radiation conductor plate. it can.

1 is a perspective view of a circularly polarized antenna according to a first embodiment of the present invention. It is a top view of this circularly polarized wave antenna. It is sectional drawing of this circularly polarized wave antenna. It is a top view of the circular polarization antenna concerning the example of a 2nd embodiment of the present invention. It is sectional drawing of this circularly polarized wave antenna. It is a top view of the circularly polarized wave antenna which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Antenna element 11 Radiation conductor plate 11a-11d Notch 12 Feeding pin 13-16 Leg piece 17 Grounding conductor 18 Substrate 21 Capacitor 22 Dielectric substrate 23a-23d Solder land 24 Ground electrode

Claims (6)

A radiating conductor plate having a substantially regular polygonal or substantially circular outer shape and arranged on the ground conductor at a predetermined interval, and extending from a feeding point of the radiating conductor plate and connected to a feeding circuit A feed pin and four leg pieces that extend from the outer periphery of the radiation conductor plate and support the radiation conductor plate in a state of being insulated from the ground conductor;
A first leg piece and a second leg piece arranged on both ends of one of the two straight lines passing through the center of the four leg pieces and orthogonal to each other on the radiation conductor plate; A third leg piece and a fourth leg piece that are disposed at both ends of the other straight line and have a line-symmetrical positional relationship with respect to the one straight line, and the feeding point and the center of the radiation conductor plate The feed point is arranged so that the straight line connecting the two lines forms an angle of approximately 45 degrees with respect to the two straight lines, and the resonance length of the resonance mode along the one straight line is that of the resonance mode along the other straight line. A circularly polarized antenna characterized by being set to be longer than the resonance length.   2. The circularly polarized antenna according to claim 1, wherein an interval between the first and second leg pieces is set longer than an interval between the third and fourth leg pieces.   3. The four leg pieces according to claim 2, wherein each of the four leg pieces extends from a notch provided at an outer peripheral edge of the radiation conductor plate, and the first and second of the four notches are provided. A circularly polarized wave antenna characterized in that a notch where the leg piece is located is formed shallower than the notch where the third and fourth leg pieces are located.   2. The capacitor according to claim 1, wherein a capacitor is attached to a tip portion of the four leg pieces, and a capacitance value added to the first and second leg pieces is added to the third and fourth leg pieces. A circularly polarized antenna characterized in that it is set to be larger than the capacitance value.   5. The capacitor according to claim 4, wherein the capacitor comprises a dielectric substrate having solder lands provided at four locations on the upper surface and a ground electrode provided on the lower surface, and the capacitor is placed on the ground conductor and placed on the solder land. The four leg pieces are soldered, and the solder lands to be soldered to the first and second leg pieces are formed larger than the solder lands to be soldered to the third and fourth leg pieces. A circularly polarized antenna characterized by that. The outer shape of the radiation conductor plate according to any one of claims 1 to 5, wherein the outer shape of the radiation conductor plate is substantially square, the four leg pieces are arranged at the center of each side, and one of the squares The circularly polarized antenna is characterized in that the feeding point is arranged on a diagonal line.

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