Planar antenna

Abstract

To make it possible to improve an antenna characteristic of a planar antenna.SOLUTION: A planar antenna 1 is composed of: a radiation element 01 comprising a square twin loop element; and a reflection plate 12 that faces the radiation element 01 and is arranged behind. The reflection plate 12 is made to be rectangular by processing a metal plate, has nine openings formed at prescribed intervals on a rectangular planar part 12a facing the radiation element 01, and a bent part 12b formed on both sides of the planar part 12a, the bent part being bent toward the side of the radiation element 01. Edges among the openings are formed to be zigzag. Further, on the center of the planar part 12a, a vertical line is formed. Thereby, an antenna characteristic of the planar antenna 1 can be improved.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a planar antenna having a reflector, and more particularly to a planar antenna suitable for receiving terrestrial digital television broadcasts.

Background Art

[0002] As conventional antennas for receiving terrestrial digital television broadcasts, Yagi antennas and planar antennas are known. A planar antenna generally has a thin case, and planar antenna elements are built into the case. In this planar antenna, a conventional planar antenna with a reflector (see Patent Document 1) in which a reflector is arranged on the back side of the antenna element is known.

[0003] The configuration of the planar antenna 200 with a reflector disclosed in Patent Document 1 is shown in FIGS. 30(a), (b), and (c). FIG. 30(a) is a front view of the conventional planar antenna 200 with a reflector, FIG. 30(b) is a rear view of the conventional planar antenna 200 with a reflector, and FIG. 30(c) is a side view of the conventional planar antenna 200 with a reflector. As shown in these figures, the conventional planar antenna 200 with a reflector is composed of a front element 210 that is a radiation element made of a square double-loop element, and a rear element 211 that is a reflector arranged behind the front element 210 facing it.

[0004] The front element 210 is made by processing a metal plate into a rectangle, and is composed of four sides that form a rectangular outer frame and two protrusions 212 formed horizontally at approximately the center. The opposing ends of the protrusions 212 are feeding points 213. Such a front element 210 is a square double-loop element composed of a square loop element formed by the upper outer frame and the protrusions 212 from the protrusions 212, and a square loop element formed by the lower outer frame and the protrusions 212 from the protrusions 212. The rear element 211 is formed into a rectangle by processing a metal plate, and three gap portions 217a, 217b, and 217c are formed in a rectangular portion facing the front element 210. In addition, rising portions 216 that are bent substantially at right angles toward the front element 210 side are formed on both sides of the rectangular portion. The three gap portions 217a, 217b, and 217c make it possible to improve the reflection characteristics of the rear element 211. Feeding lines 214 are respectively connected to two feeding points 213 of the front element 210, and power is supplied from a feeding portion 215 to the ends of the two feeding lines.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a planar antenna capable of improving antenna characteristics.

Means for Solving the Problems

[0007] The planar antenna of the present invention capable of achieving the above object includes a first radiation element including a loop element formed in a triangular loop shape, a second radiation element including a loop element formed in a triangular loop shape, having a shape symmetric to the first radiation element and arranged in a vertical direction with respect to the first radiation element, and a reflector that faces the first radiation element and the second radiation element, is spaced apart by a predetermined distance and arranged at the rear, has a planar portion facing the first radiation element and the second radiation element, and bent portions on both sides of the planar portion bent toward the sides of the first radiation element and the second radiation element, and a plurality of openings are formed in the planar portion, and a main feature is that a vertical line is formed in the vertical direction in the planar portion.

[0008] In the planar antenna of the present invention described above, blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion may be formed at the central portion of the planar portion. Also, in the planar antenna of the present invention described above, blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion are first vertical lines respectively formed in the vertical direction at the upper part of the upper blocking portion and the central part of the lower part of the lower blocking portion, and two second vertical lines formed in the vertical direction between the openings provided with the blocking portions and arranged symmetrically with the width of the lateral width of the blocking portion may be provided. Furthermore, in the planar antenna of the present invention described above, blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion may be two vertical lines arranged symmetrically with the width of the lateral width of the blocking portion. Still further, in the planar antenna of the present invention described above, blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion may be a first vertical line formed in the vertical direction at the central portion of the planar portion and two second vertical lines arranged symmetrically with the width of the lateral width of the blocking portion. Still further, in the planar antenna of the present invention described above, blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion are first vertical lines respectively formed in the vertical direction at the upper part of the upper blocking portion and the central part of the lower part of the lower blocking portion, and two second vertical lines formed in the vertical direction between the openings provided with the blocking portions and arranged symmetrically with the width of the lateral width of the blocking portion. At the same time, Y-shaped lines are symmetrically formed at the uppermost part of the plurality of openings and the central part of the opening below it, and at the lowermost part of the plurality of openings and the central part of the opening above it. By forming the Y-shaped lines, another opening may be formed in the uppermost and lowermost openings. Furthermore, in the planar antenna of the present invention described above, the first radiation element and the second radiation element are each a triangular double-loop element, and the vertices of two triangles facing each other are each a feeding point. The planar antenna further includes a feeding substrate to which two first feeding lines connected to the respective feeding points of the first radiation element and two second feeding lines connected to the respective feeding points of the second radiation element are connected, and the first feeding line and the second feeding line on the feeding substrate may be fed from a feeding unit. Furthermore, in the planar antenna of the present invention described above, an adjustment plate for adjusting impedance may be formed on the feeding substrate. Furthermore, in the planar antenna of the present invention described above, in the plurality of openings formed in the planar portion, the upper and lower horizontal lines of the opening may be formed in a zigzag shape or a waveform. Furthermore, in the planar antenna of the present invention described above, in the plurality of openings formed in the planar portion, the upper and lower horizontal lines of the opening are formed in a zigzag shape or a waveform, and the zigzag shape or the waveform may be formed in a symmetric shape between the upper horizontal line and the lower horizontal line of the opening. Furthermore, in the planar antenna of the present invention described above, it may be configured to be housed in a synthetic resin case having a thin rectangular parallelepiped shape. Furthermore, in the planar antenna of the present invention described above, the first radiation element and the second radiation element are each a triangular double-loop element, and each of the triangular double-loop elements includes an outer element forming an upper side and a lower side, a feeding element forming a triangle connecting both ends of the outer element, an inner element extending from the outer element toward the center side, the outer element, the feeding element, and a slit formed between the outer element and the inner element.

Advantages of the Invention

[0009] In the planar antenna of the present invention, by forming a plurality of openings and vertical lines in the planar portion of the reflector, the antenna characteristics of the planar antenna can be improved. Further, in the opening, by making the sides between the openings into a zigzag shape or a waveform, the size of the planar antenna can be reduced.

Brief Description of the Drawings

[0010]

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Best Mode for Carrying Out the Invention

[0011] <Planar Antenna of the First Embodiment of the Present Invention> The planar antenna 1 of the first embodiment of the present invention is an antenna for receiving terrestrial digital television broadcasts, and the operating frequency band is set to 470 MHz to 710 MHz. The configuration of the planar antenna 1 of the first embodiment is shown in FIGS. 1 to 7. FIG. 1 is a front view showing the configuration of the planar antenna 1 of the first embodiment, FIG. 2 is a rear view showing the configuration of the planar antenna 1 of the first embodiment, FIG. 3 is a top view showing the configuration of the planar antenna 1 of the first embodiment, FIG. 4 is a side view showing the configuration of the planar antenna 1 of the first embodiment, FIG. 5 is a front view showing the configuration of the radiation element 10 of the planar antenna 1 of the first embodiment, FIG. 6 is a front view showing the configuration of the power feeding section of the planar antenna 1 of the first embodiment, FIG. 7(a) is a front view showing the configuration of the reflector 12 of the planar antenna 1 of the first embodiment, and FIG. 7(b) is a bottom view showing the configuration of the reflector 12 of the planar antenna 1 of the first embodiment. As shown in these figures, the planar antenna 1 of the first embodiment includes a radiation element 01 having a first radiation element 10 and a second radiation element 11 each formed of a triangular double loop element, and a reflector 12 disposed at a predetermined interval facing the radiation element 01 and arranged rearward.

[0012] The first radiation element 10 and the second radiation element 11, which are composed of triangular double-loop elements provided in the radiation element 01, are formed in the same shape and arranged on the central axis in the vertical direction at an interval L3. As shown in FIG. 5, two triangular notches 10c or 11c are formed vertically on a rectangular metal plate, and triangular notches are also formed on the left and right sides to form a triangular loop shape. It is composed of four sides, namely, the upper side and the lower side that constitute the outer frame of the triangular loop shape, and the left side and the right side that are the hypotenuses. The left side that is the hypotenuse consists of a hypotenuse extending diagonally downward to the right and a hypotenuse extending diagonally upward to the right toward the center, and the right side that is the hypotenuse consists of a hypotenuse extending diagonally downward to the left and a hypotenuse extending diagonally upward to the left toward the center. Two of the hypotenuses extending diagonally downward to the right toward the center on the left side and the hypotenuses extending diagonally downward to the left toward the center on the right side are the first power supply elements 10a or the second power supply elements 11a. A downward triangular loop element is formed by these two first power supply elements 10a or second power supply elements 11a and the upper side. Also, two of the hypotenuses extending diagonally upward to the right toward the center on the left side and the hypotenuses extending diagonally upward to the left toward the center on the right side are the first power supply elements 10a or the second power supply elements 11a. An upward triangular loop element is formed by these two first power supply elements 10a or second power supply elements 11a and the lower side. Thus, the first radiation element 10 and the second radiation element 11 in the planar antenna 1 of the first embodiment are triangular double-loop elements composed of the above two triangular loop elements, and the opposing vertices of the two opposing triangular loop elements are the two power supply points 10b or power supply points 11b.

[0013] The reflector 12 is made by processing a metal plate into a vertically long rectangle, and has a rectangular planar portion 12a facing the entire surface of the radiation element 01 as shown in Fig. 7(a). Nine openings A1, A2, A3, A4, A5, A6, A7, A8, and A9 are formed at equal intervals or predetermined intervals in the vertical direction on the planar portion 12a. Also, as shown in Fig. 7(b), bent portions 12b bent toward the radiation element 01 side are formed on both sides in the vertical direction of the planar portion 12a. The bent portion 12b is composed of a hypotenuse that rises obliquely from the side of the planar portion 12a and a vertical side that rises vertically from the tip of the hypotenuse. Zigzag or corrugated horizontal lines are formed above and below the nine openings A1 to A9, and the upper and lower horizontal lines of each opening are formed in a symmetric zigzag or corrugated shape. Fig. 7(a) shows an example in which ten zigzag horizontal lines m1, m2, m3, m4, m5, m6, m7, m8, m9, and m10 are formed. The peripheral lengths Lλ of the nine openings A1 to A9 are all the same length. Assuming the wavelength of the center frequency (590 MHz) of the operating frequency band is λ, the peripheral length Lλ is approximately 1λ. Since the upper horizontal line m1 of the uppermost opening A1 and the lower horizontal line m10 of the lowermost opening A9 are formed in a zigzag shape, small triangular openings are formed. By making the number of openings in the reflector 12 nine openings A1 to A9, which is an optimized number, it is possible to improve the reflection characteristics. Also, since the horizontal lines m1 to m10 are formed in a zigzag shape, the lateral width of the reflector 12 can be reduced. As a result, since the lateral width of the planar antenna 1 of the first embodiment can be reduced, the size of the planar antenna 1 can be miniaturized.

[0014] In the nine openings A1 to A9 formed in the planar portion 12a of the reflector 12, blocking portions S1 and S2 are respectively formed at the central portions of the two openings A3 and A7. Further, vertical lines n1, n2, and n3 are formed at the center in the vertical direction of the planar portion 12a. As a result, the openings A1 and A2 are openings that are horizontally divided into two by the vertical line n1, the openings A4, A5, and A6 are openings that are horizontally divided into two by the vertical line n2, and the openings A8 and A9 are openings that are horizontally divided into two by the vertical line n3. Also, in the two openings A3 and A7, since the blocking portion S1 or the blocking portion S2 is formed at the central portion, the openings are such that only both sides of the blocking portion S1 or the blocking portion S2 are open.

[0015] One end of the feeding line 13 is connected to each of the two feeding points 10b of the first radiation element 10, and the other end of the feeding line 13 is connected to each of the two feeding points 11b of the second radiation element 11. A feeding substrate 14 is provided at approximately the central portion of the feeding line 13, a feeding portion 15 is formed on the feeding substrate 14, and power is fed from the feeding portion 15 to approximately the central portions of the two feeding lines 13. The configuration of the feeding portion 15 is enlarged and shown in FIG. 6. Approximately the central portions of the two feeding lines 13 are connected to the upper surface of the feeding substrate 14 by soldering or the like. Two protrusions are formed at approximately the central portions of the two feeding lines 13 so as to face each other. The shield portion of the coaxial cable 16 is soldered to one protrusion of the feeding line 13, and the core wire of the coaxial cable 16 is soldered to the other protrusion of the feeding line 13. The planar antenna 1 of the first embodiment is fed by the coaxial cable 16. The impedance of the feeding portion 15 can be adjusted by the protrusions formed at approximately the central portions of the feeding line 13. Also, adjustment plates 17 for adjusting the impedance of the feeding portion 15 are printed or adhered to both sides of the surface of the feeding substrate 14. However, the adjustment plates 17 may be omitted.

[0016] Regarding the dimensions of each part of the planar antenna 1 of the first embodiment of the present invention, the lateral width of the planar antenna 1 is about 230 mm, and the longitudinal length is about 600 mm. As shown in FIGS. 7(a) and 7(b), the lateral width W2 of the reflector 12 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 12b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal part of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal part of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag horizontal lines m1 to m10 is about 140 mm. Also, the width D of the zigzag horizontal lines m1 to m10 is about 10 mm. The width of the vertical lines n1 to n3 is the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking parts S1 and S2 formed at the central parts of the two openings A3 and A7 is about 110 mm. Also, as shown in FIG. 5, the lateral width W1 of each of the first radiating element 10 and the second radiating element 11 is about 220 mm, and the longitudinal length L2 of each is about 280 mm. The lateral width W1 of the radiating element 01 is about 220 mm, and the longitudinal length L1 is about 600 mm. The distance L3 between the first radiating element 10 and the second radiating element 11 arranged in the longitudinal direction is about 40 mm. Further, as shown in FIG. 6, the lateral width W6 of the power supply substrate 14 is about 110 mm, and the longitudinal length L4 is about 30 mm. The distance H2 between the radiating element 01 and the planar portion 12a of the reflector 12 is about 45 mm. Since the radiating element 01 of the planar antenna 1 of the first embodiment includes two radiating elements, the first radiating element 10 and the second radiating element 11, which are arranged in the longitudinal direction, the gain of the planar antenna 1 of the first embodiment is improved.

[0017] <The planar antenna of the second embodiment of the present invention> The planar antenna 2 of the second embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is 470 MHz to 710 MHz. The planar antenna 2 of the second embodiment is a planar antenna in which the reflector 12 in the planar antenna 1 of the first embodiment is replaced with a reflector 22 having a different configuration, and the configuration except for the reflector 22 is the same as that of the planar antenna 1 of the first embodiment. The configuration of the planar antenna 2 of the second embodiment is shown in FIGS. 8 to 10. FIG. 8 is a front view showing the configuration of the planar antenna 2 of the second embodiment, FIG. 9 is a rear view showing the configuration of the planar antenna 2 of the second embodiment, FIG. 10(a) is a front view showing the configuration of the reflector 22 in the planar antenna 2 of the second embodiment, and FIG. 10(b) is a bottom view showing the configuration of the reflector 22 in the planar antenna 2 of the second embodiment.

[0018] As shown in FIG. 8, the planar antenna 2 of the second embodiment includes a radiating element 01 including a first radiating element 10 and a second radiating element 11 each formed of a triangular double-loop element, similar to the planar antenna 1 of the first embodiment. The planar antenna 2 of the second embodiment is composed of the radiating element 01 and a reflector 22 disposed rearward at a predetermined interval facing the radiating element 01. Since the configuration of the radiating element 01 is the same as that of the radiating element 01 of the planar antenna 1 of the first embodiment, detailed description thereof is omitted. However, the first radiating element 10 in the radiating element 01 is a triangular double-loop element composed of two first power supply elements 10a and a downward triangular loop element formed by the upper side, and two first power supply elements 10a and an upward triangular loop element formed by the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 10b. The second radiating element 11 is also a triangular double-loop element composed of two second power supply elements 11a and a downward triangular loop element formed by the upper side, and two second power supply elements 11a and an upward triangular loop element formed by the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 11b.

[0019] The reflector 22 is made by processing a metal plate into a vertically long rectangle, and has a rectangular planar portion 22a facing the entire surface of the radiation element 01 as shown in Fig. 10(a). Nine openings A1, A2, A3, A4, A5, A6, A7, A8, and A9 are formed at equal intervals or predetermined intervals in the vertical direction on the planar portion 22a. Also, as shown in Fig. 10(b), bent portions 22b bent toward the radiation element 01 side are formed on both sides in the vertical direction of the planar portion 22a. The bent portion 22b is composed of a hypotenuse that rises obliquely from the side of the planar portion 22a and a vertical side that rises vertically from the tip of the hypotenuse. Zigzag or corrugated horizontal lines are formed above and below the nine openings A1 to A9, and the zigzag or corrugated shapes are formed symmetrically between the upper horizontal line and the lower horizontal line of each opening. An example in which ten zigzag horizontal lines m1, m2, m3, m4, m5, m6, m7, m8, m9, and m10 are formed is shown in Fig. 10(a). The peripheral lengths Lλ of the nine openings A1 to A9 are all the same length, and when the wavelength of the center frequency (590 MHz) of the operating frequency band is λ, the peripheral length Lλ is approximately 1λ. Since the upper horizontal line m1 of the uppermost opening A1 and the lower horizontal line m10 of the lowermost opening A9 are formed in a zigzag shape, small triangular openings are formed at the upper end or the lower end. By setting the number of openings in the reflector 22 to nine, which is the optimized number, the reflection characteristics can be improved. Also, since the horizontal lines m1 to m10 are formed in a zigzag shape, the lateral width of the reflector 22 can be reduced. As a result, since the lateral width of the planar antenna 2 of the second embodiment can be reduced, the size of the planar antenna 2 can be miniaturized.

[0020] In the nine openings A1 to A9 formed in the planar portion 22a of the reflector 22, blocking portions S1 and S2 are respectively formed at the central portions of the two openings A3 and A7. Further, a vertical line n1 is formed at the vertical center in the upper portion of the planar portion 22a, and two vertical lines n2 and n3 are symmetrically formed on both sides of the vertical center line in the central portion of the planar portion 22a with a width substantially the same as the lateral width W5 of the blocking portions S1 and S2, and a vertical line n4 is formed at the vertical center in the lower portion of the planar portion 22a. As a result, the openings A1 and A2 are each an opening horizontally divided into two by the vertical line n1, and the opening A3 is an opening with only both sides of the blocking portion S1 opened. Also, the openings A4, A5, and A6 are each an opening horizontally divided into three by the two vertically arranged and symmetrically positioned vertical lines n2 and n3. Further, the opening A7 is an opening with only both sides of the blocking portion S2 opened, and the openings A8 and A9 are each an opening horizontally divided into two by the vertical line n4. Note that the outer edge widths of the two vertical lines n2 and n3 symmetrically arranged in the vertical direction in the central portion of the planar portion 22a are substantially the same as the lateral width W5 of the blocking portions S1 and S2.

[0021] In the planar antenna 2 of the second embodiment, although not shown, similar to the planar antenna 1 of the first embodiment, one end of the feeding line 13 is connected to each of the two feeding points 10b of the first radiating element 10, and the other end of the feeding line 13 is connected to each of the two feeding points 11b of the second radiating element 11. A feeding substrate 14 is provided at substantially the central portion of the feeding line 13, a feeding portion 15 is formed on the feeding substrate 14, and power is fed from the feeding portion 15 to substantially the central portions of the two feeding lines 13. The configuration of the power supply unit 15 is as shown in FIG. 6. The approximate center portions of the two power supply lines 13 are connected to the upper surface of the power supply substrate 14 by soldering or the like. Two protrusions are formed at the approximate center portions of the two power supply lines 13 so as to face each other. The shield portion of the coaxial cable 16 is soldered to one protrusion of the power supply line 13, and the core wire of the coaxial cable 16 is soldered to the other protrusion of the power supply line 13. The planar antenna 2 of the second embodiment is powered by the coaxial cable 16. The impedance of the power supply unit 15 can be adjusted by the protrusions formed at the approximate center portions of the power supply lines 13. Further, adjustment plates 17 for adjusting the impedance of the power supply unit 15 are printed or adhered to both sides of the surface of the power supply substrate 14. However, the adjustment plates 17 may be omitted.

[0022] Regarding the dimensions of each part of the planar antenna 2 of the second embodiment of the present invention, the lateral width of the planar antenna 2 is about 230 mm, and the longitudinal length is about 600 mm. As shown in FIGS. 10(a) and 10(b), the lateral width W2 of the reflector 22 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 22b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal portion of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal portion of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag-shaped horizontal lines m1 to m10 is about 140 mm. Also, the width D of the zigzag-shaped horizontal lines m1 to m10 is about 10 mm. The widths of the vertical lines n1 to n4 are the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking portions S1 and S2 formed at the central portions of the two openings A3 and A7 is about 110 mm. And the outer edge widths of the two symmetrically formed vertical lines n2 and n3 are approximately the same as the lateral width W5 of the blocking portions S1 and S2, which is about 110 mm. Also, although not shown, the respective lateral widths W1 of the first radiation element 10 and the second radiation element 11 are about 220 mm, the respective vertical lengths L2 are about 280 mm, the lateral width W1 of the radiation element 01 is about 220 mm, the vertical length L1 is about 600 mm, and the interval L3 between the first radiation element 10 and the second radiation element 11 arranged in the vertical direction is about 40 mm. Further, the lateral width W6 of the power supply substrate 14 is about 110 mm, the vertical length L4 is about 30 mm, and the interval H2 between the radiation element 01 and the planar portion 22a of the reflector 22 is about 45 mm. Since the radiation element 01 of the planar antenna 2 of the second embodiment includes two radiation elements, i.e., the first radiation element 10 and the second radiation element 11, which are arranged in the vertical direction, the gain of the planar antenna 2 of the second embodiment is improved.

[0023] <Planar Antenna of the Third Embodiment of the Present Invention> The planar antenna 3 of the third embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is 470 MHz to 710 MHz. The planar antenna 3 of the third embodiment is a planar antenna in which the reflector 12 in the planar antenna 1 of the first embodiment is replaced with a reflector 32 having a different configuration, and the configuration except for the reflector 32 is the same as that of the planar antenna 1 of the first embodiment. The configuration of the planar antenna 3 of the third embodiment is shown in FIGS. 11 to 13. FIG. 11 is a front view showing the configuration of the planar antenna 3 of the third embodiment, FIG. 12 is a rear view showing the configuration of the planar antenna 3 of the third embodiment, FIG. 13(a) is a front view showing the configuration of the reflector 32 in the planar antenna 3 of the third embodiment, and FIG. 13(b) is a bottom view showing the configuration of the reflector 32 in the planar antenna 3 of the third embodiment. As shown in FIG. 11, the planar antenna 3 of the third embodiment includes a radiation element 01 including a first radiation element 10 and a second radiation element 11 each formed of a triangular double-loop element, similar to the planar antenna 1 of the first embodiment. The planar antenna 3 of the third embodiment is composed of the radiation element 01 and a reflector 32 arranged at a predetermined interval facing the radiation element 01 and disposed rearward.

[0024] The configuration of the radiation element 01 is the same as that of the radiation element 01 of the planar antenna 1 in the first embodiment, so detailed description thereof will be omitted. The first radiation element 10 in the radiation element 01 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two first power supply elements 10a and the upper side, and the other being an upward triangular loop element formed by two first power supply elements 10a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 10b. Also, the second radiation element 11 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two second power supply elements 11a and the upper side, and the other being an upward triangular loop element formed by two second power supply elements 11a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 11b.

[0025] The reflector 32 is made by processing a metal plate into a vertically long rectangle, and has a rectangular planar portion 32a facing the entire surface of the radiation element 01 as shown in Fig. 13(a). Nine openings A1, A2, A3, A4, A5, A6, A7, A8, and A9 are formed at equal intervals or predetermined intervals in the vertical direction on the planar portion 32a. Also, as shown in Fig. 13(b), bent portions 32b bent toward the radiation element 01 side are formed on both sides in the vertical direction of the planar portion 32a. The bent portion 32b is composed of an inclined side rising obliquely from the side of the planar portion 32a and a vertical side rising vertically from the tip of the inclined side. Zigzag or corrugated horizontal lines are formed above and below the nine openings A1 to A9, and the upper and lower horizontal lines of each opening are formed in a symmetric zigzag or corrugated shape. Fig. 13(a) shows an example in which ten zigzag horizontal lines m1, m2, m3, m4, m5, m6, m7, m8, m9, and m10 are formed. And the peripheral lengths Lλ of the nine openings A1 to A9 are all the same length. Assuming that the wavelength of the center frequency (590 MHz) of the operating frequency band is λ, the peripheral length Lλ is about 1λ. Since the upper horizontal line m1 of the uppermost opening A1 and the lower horizontal line m10 of the lowermost opening A9 are formed in a zigzag shape, small triangular openings are formed at the upper end or the lower end. By setting the number of openings in the reflector 32 to nine openings A1 to A9, which is an optimized number, it is possible to improve the reflection characteristics. Also, since the horizontal lines m1 to m10 are formed in a zigzag shape, the lateral width of the reflector 32 can be reduced. As a result, since the lateral width of the planar antenna 3 of the third embodiment can be reduced, the size of the planar antenna 3 can be miniaturized.

[0026] In the nine openings A1 to A9 formed in the planar portion 32a of the reflector 32, blocking portions S1 and S2 are respectively formed at the central portions of the two openings A3 and A7. Further, on both sides of the planar portion 32a sandwiching the vertical center line in the upper part, two vertical lines n1 and n2 are symmetrically formed with substantially the same width as the lateral width W5 of the blocking portions S1 and S2. On both sides of the planar portion 32a sandwiching the vertical center line in the central part, two vertical lines n3 and n4 are symmetrically formed with substantially the same width as the lateral width W5 of the blocking portions S1 and S2. On both sides of the planar portion 32a sandwiching the vertical center line in the lower part, two vertical lines n5 and n6 are symmetrically formed with substantially the same width as the lateral width W5 of the blocking portions S1 and S2. As a result, the openings A1 and A2 are openings that are horizontally divided into three parts by the two vertically arranged and symmetrically located vertical lines n1 and n2, and the opening A3 is an opening where only both sides of the blocking portion S1 are open. Further, the openings A4, A5, and A6 are openings that are horizontally divided into three parts by the two vertically arranged and symmetrically located vertical lines n3 and n4. Furthermore, the opening A7 is an opening where only both sides of the blocking portion S2 are open, and the openings A8 and A9 are openings that are horizontally divided into three parts by the two vertically arranged and symmetrically located vertical lines n5 and n6. Note that the widths of the outer edges of the vertical lines n1, n3, n5 and the vertical lines n2, n4, n6 symmetrically arranged in the vertical direction on the planar portion 32a are substantially the same as the lateral width W5 of the blocking portions S1 and S2.

[0027] In the planar antenna 3 of the third embodiment, as shown in FIG. 11, similar to the planar antenna 1 of the first embodiment, one end of the feeding line 13 is connected to each of the two feeding points 10b of the first radiation element 10, and the other end of the feeding line 13 is connected to each of the two feeding points 11b of the second radiation element 11. A feeding substrate 14 is provided at substantially the central portion of the feeding line 13, a feeding portion 15 is formed on the feeding substrate 14, and feeding is performed from the feeding portion 15 to substantially the central portions of the two feeding lines 13. The configuration of the power supply unit 15 is as shown in FIG. 6. The approximate center portions of the two power supply lines 13 are connected to the upper surface of the power supply substrate 14 by soldering or the like. Two protrusions are formed at the approximate center portions of the two power supply lines 13 so as to face each other. The shield portion of the coaxial cable 16 is soldered to one protrusion of the power supply line 13, and the core wire of the coaxial cable 16 is soldered to the other protrusion of the power supply line 13. The planar antenna 3 of the third embodiment is powered by the coaxial cable 16. The impedance of the power supply unit 15 can be adjusted by the protrusions formed at the approximate center portions of the power supply lines 13. Further, adjustment plates 17 for adjusting the impedance of the power supply unit 15 are printed or adhered to both sides of the surface of the power supply substrate 14. However, the adjustment plates 17 may be omitted.

[0028] Regarding the dimensions of each part of the planar antenna 3 of the third embodiment of the present invention, the lateral width of the planar antenna 3 is about 230 mm, and the longitudinal length is about 600 mm. As shown in FIGS. 13(a) and 13(b), the lateral width W2 of the reflector 32 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 32b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal part of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal part of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag horizontal lines m1 to m10 is about 140 mm. Further, the width D of the zigzag horizontal lines m1 to m10 is about 10 mm. The width of the vertical lines n1 to n6 is the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking portions S1 and S2 formed at the center portions of the two openings A3 and A7 is about 110 mm. And the outer edge widths of the two symmetrically formed vertical lines n2 and n3 are approximately the same as the lateral width W5 of the blocking portions S1 and S2, which is about 110 mm. Also, although not shown, the respective lateral widths W1 of the first radiation element 10 and the second radiation element 11 are about 220 mm, the respective vertical lengths L2 are about 280 mm, the lateral width W1 of the radiation element 01 is about 220 mm, the vertical length L1 is about 600 mm, and the interval L3 between the first radiation element 10 and the second radiation element 11 arranged in the vertical direction is about 40 mm. Further, the lateral width W6 of the power supply substrate 14 is about 110 mm, the vertical length L4 is about 30 mm, and the interval H2 between the radiation element 01 and the planar portion 22a of the reflector 22 is about 45 mm. Since the radiation element 01 of the planar antenna 3 of the third embodiment includes two radiation elements, i.e., the first radiation element 10 and the second radiation element 11, which are arranged in the vertical direction, the gain of the planar antenna 3 of the third embodiment is improved.

[0029] <Planar Antenna of the Fourth Embodiment of the Present Invention> The planar antenna 4 of the fourth embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is 470 MHz to 710 MHz. The planar antenna 4 of the fourth embodiment is a planar antenna in which the reflector 12 in the planar antenna 1 of the first embodiment is replaced with a reflector 42 having a different configuration, and the configuration except for the reflector 42 is the same as that of the planar antenna 1 of the first embodiment. The configuration of the planar antenna 4 of the fourth embodiment is shown in FIGS. 14 to 16. FIG. 14 is a front view showing the configuration of the planar antenna 4 of the fourth embodiment, FIG. 15 is a rear view showing the configuration of the planar antenna 4 of the fourth embodiment, FIG. 16(a) is a front view showing the configuration of the reflector 42 in the planar antenna 4 of the fourth embodiment, and FIG. 16(b) is a bottom view showing the configuration of the reflector 42 in the planar antenna 4 of the fourth embodiment. As shown in FIG. 14, the planar antenna 4 of the fourth embodiment includes a radiation element 01 including a first radiation element 10 and a second radiation element 11 each formed of a triangular double-loop element, similar to the planar antenna 1 of the first embodiment. The planar antenna 4 of the fourth embodiment is composed of a radiation element 01 and a reflector 42 arranged at a predetermined interval facing the radiation element 01 and disposed rearward.

[0030] The configuration of the radiation element 01 is the same as that of the radiation element 01 of the planar antenna 1 in the first embodiment, and thus the detailed description thereof is omitted. The first radiation element 10 in the radiation element 01 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two first power supply elements 10a and the upper side, and the other being an upward triangular loop element formed by two first power supply elements 10a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 10b. Also, the second radiation element 11 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two second power supply elements 11a and the upper side, and the other being an upward triangular loop element formed by two second power supply elements 11a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 11b.

[0031] The reflector 42 is made by processing a metal plate into a vertically long rectangle, and has a rectangular planar portion 42a facing the entire surface of the radiation element 01 as shown in Fig. 16(a). Nine openings A1, A2, A3, A4, A5, A6, A7, A8, and A9 are formed at equal intervals or predetermined intervals in the vertical direction on the planar portion 42a. Also, as shown in Fig. 16(b), bent portions 42b bent toward the radiation element 01 side are formed on both sides in the vertical direction of the planar portion 42a. The bent portion 42b is composed of an inclined side that rises obliquely from the side of the planar portion 42a and a vertical side that rises vertically from the tip of the inclined side. Zigzag or corrugated horizontal lines are formed above and below the nine openings A1 to A9, and the zigzag or corrugated shapes are formed symmetrically between the upper and lower horizontal lines of each opening. Fig. 16(a) shows an example in which ten zigzag horizontal lines m1, m2, m3, m4, m5, m6, m7, m8, m9, and m10 are formed. The peripheral lengths Lλ of the nine openings A1 to A9 are all the same length. Assuming the wavelength of the center frequency (590 MHz) of the operating frequency band is λ, the peripheral length Lλ is approximately 1λ. Since the upper horizontal line m1 of the uppermost opening A1 and the lower horizontal line m10 of the lowermost opening A9 are formed in a zigzag shape, small triangular openings are formed at the upper or lower end portions. By setting the number of openings in the reflector 42 to the optimized nine openings A1 to A9, it becomes possible to improve the reflection characteristics. Also, since the horizontal lines m1 to m10 are formed in a zigzag shape, the lateral width of the reflector 42 can be reduced. As a result, since the lateral width of the planar antenna 4 of the fourth embodiment can be reduced, the size of the planar antenna 4 can be miniaturized.

[0032] In the nine openings A1 to A9 formed in the planar portion 42a of the reflector 42, closing portions S1 and S2 are respectively formed at the central portions of the two openings A3 and A7. Further, a vertical line n2 is formed substantially on the center line at the vertical center portion above the planar portion 42a, and two vertical lines n1 and n3 are symmetrically formed on both sides sandwiching the center line with substantially the same width as the lateral width W5 of the closing portions S1 and S2. A vertical line n5 is formed substantially on the vertical center line at the central portion of the planar portion 42a, and two vertical lines n4 and n6 are symmetrically formed on both sides sandwiching the vertical center line with substantially the same width as the lateral width W5 of the closing portions S1 and S2. A vertical line n8 is formed substantially on the vertical center line at the lower portion of the planar portion 42a, and two vertical lines n7 and n9 are symmetrically formed on both sides sandwiching the vertical center line with substantially the same width as the lateral width W5 of the closing portions S1 and S2. As a result, the openings A1 and A2 are openings each horizontally divided into four parts by the three vertical lines n1, n2, and n3, and the opening A3 is an opening with only both sides of the closing portion S1 opened. Also, the openings A4, A5, and A6 are openings each horizontally divided into four parts by the three vertical lines n4, n5, and n6. Further, the opening A7 is an opening with only both sides of the closing portion S2 opened, and the openings A8 and A9 are openings each horizontally divided into four parts by the two symmetrically arranged vertical lines n7, n8, and n9. Note that the outer edge widths of the vertical lines n1, n4, n7 and n3, n6, n9 symmetrically arranged in the vertical direction on the planar portion 42a are substantially the same as the lateral width W5 of the closing portions S1 and S2.

[0033] In the planar antenna 4 of the fourth embodiment, as shown in FIG. 14, similar to the planar antenna 1 of the first embodiment, one end of the feeding line 13 is connected to each of the two feeding points 10b of the first radiation element 10, and the other end of the feeding line 13 is connected to each of the two feeding points 11b of the second radiation element 11. A feeding substrate 14 is provided at substantially the central portion of the feeding line 13, a feeding portion 15 is formed on the feeding substrate 14, and feeding is performed from the feeding portion 15 to substantially the central portions of the two feeding lines 13. The configuration of the power supply unit 15 is as shown in FIG. 6. The approximate center portions of the two power supply lines 13 are connected to the upper surface of the power supply substrate 14 by soldering or the like. Two protrusions are formed at the approximate center portions of the two power supply lines 13 so as to face each other. The shield portion of the coaxial cable 16 is soldered to one protrusion of the power supply line 13, and the core wire of the coaxial cable 16 is soldered to the other protrusion of the power supply line 13. The planar antenna 4 of the fourth embodiment is powered by the coaxial cable 16. The impedance of the power supply unit 15 can be adjusted by the protrusions formed at the approximate center portions of the power supply lines 13. Further, adjustment plates 17 for adjusting the impedance of the power supply unit 15 are printed or adhered to both sides of the surface of the power supply substrate 14. However, the adjustment plates 17 may be omitted.

[0034] Regarding the dimensions of each part of the planar antenna 4 of the fourth embodiment of the present invention, the lateral width of the planar antenna 4 is about 230 mm, and the longitudinal length is about 600 mm. As shown in FIGS. 16(a) and 16(b), the lateral width W2 of the reflector 42 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 42b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal part of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal part of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag horizontal lines m1 to m10 is about 140 mm. Further, the width D of the zigzag horizontal lines m1 to m10 is about 10 mm. The width of the vertical lines n1 to n9 is the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking portions S1 and S2 formed at the center portions of the two openings A3 and A7 is about 110 mm. And the width of the outer edges of the three vertical lines is approximately the same as the lateral width W5 of the blocking portions S1 and S2, which is about 110 mm. Also, although not shown, the respective lateral widths W1 of the first radiation element 10 and the second radiation element 11 are about 220 mm, the respective vertical lengths L2 are about 280 mm, the lateral width W1 of the radiation element 01 is about 220 mm, the vertical length L1 is about 600 mm, and the interval L3 between the first radiation element 10 and the second radiation element 11 arranged in the vertical direction is about 40 mm. Further, the lateral width W6 of the power supply substrate 14 is about 110 mm, the vertical length L4 is about 30 mm, and the interval H2 between the radiation element 01 and the planar portion 22a of the reflector 22 is about 45 mm. Since the radiation element 01 of the planar antenna 4 of the fourth embodiment includes two radiation elements, i.e., the first radiation element 10 and the second radiation element 11, which are arranged in the vertical direction, the gain of the planar antenna 4 of the fourth embodiment is improved.

[0035] <Planar Antenna of the Fifth Embodiment of the Present Invention> The planar antenna 5 of the fifth embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is 470 MHz to 710 MHz. The planar antenna 5 of the fifth embodiment is a planar antenna in which the reflector 12 in the planar antenna 1 of the first embodiment is replaced with a reflector 52 having a different configuration, and the configuration except for the reflector 52 is the same as that of the planar antenna 1 of the first embodiment. The configuration of the planar antenna 5 of the fifth embodiment is shown in FIGS. 17 to 19. FIG. 17 is a front view showing the configuration of the planar antenna 5 of the fifth embodiment, FIG. 18 is a rear view showing the configuration of the planar antenna 5 of the fifth embodiment, FIG. 19(a) is a front view showing the configuration of the reflector 52 in the planar antenna 5 of the fifth embodiment, and FIG. 19(b) is a bottom view showing the configuration of the reflector 52 in the planar antenna 5 of the fifth embodiment. As shown in FIG. 17, the planar antenna 5 of the fifth embodiment includes a radiation element 01 including a first radiation element 10 and a second radiation element 11 each formed of a triangular double-loop element, similar to the planar antenna 1 of the first embodiment. The planar antenna 5 of the fifth embodiment is composed of a radiation element 01 and a reflector 52 arranged at a predetermined interval facing the radiation element 01 and disposed rearward.

[0036] The configuration of the radiation element 01 is the same as that of the radiation element 01 of the planar antenna 1 in the first embodiment, and thus the detailed description thereof is omitted. The first radiation element 10 in the radiation element 01 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two first power supply elements 10a and the upper side, and the other being an upward triangular loop element formed by two first power supply elements 10a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 10b. Further, the second radiation element 11 is a triangular double-loop element composed of two triangular loop elements, one being a downward triangular loop element formed by two second power supply elements 11a and the upper side, and the other being an upward triangular loop element formed by two second power supply elements 11a and the lower side. The opposing tops of the two opposing triangular loop elements are two power supply points 11b.

[0037] The reflector 52 is made by processing a metal plate into a vertically long rectangle, and has a rectangular planar portion 52a facing the entire surface of the radiation element 01 as shown in Fig. 19(a). Nine openings A1, A2, A3, A4, A5, A6, A7, A8, and A9 are formed at equal intervals or predetermined intervals in the vertical direction on the planar portion 52a. Also, as shown in Fig. 19(b), bent portions 52b bent toward the radiation element 01 side are formed on both sides in the vertical direction of the planar portion 52a. The bent portion 52b is composed of a hypotenuse that rises obliquely from the side of the planar portion 52a and a vertical side that rises vertically from the tip of the hypotenuse. Zigzag or corrugated horizontal lines are formed above and below the nine openings A1 to A9, and the zigzag or corrugated shapes are formed symmetrically between the upper and lower horizontal lines of each opening. An example in which ten zigzag horizontal lines m1, m2, m3, m4, m5, m6, m7, m8, m9, and m10 are formed is shown in Fig. 19(a). And the peripheral lengths Lλ of the nine openings A1 to A9 are all the same length. Assuming that the wavelength of the center frequency (590 MHz) of the operating frequency band is λ, the peripheral length Lλ is approximately 1λ. Since the upper horizontal line m1 of the uppermost opening A1 and the lower horizontal line m10 of the lowermost opening A9 are formed in a zigzag shape, small triangular openings are formed at the upper or lower end portions. By making the number of openings in the reflector 52 nine, which is an optimized number, it becomes possible to improve the reflection characteristics. Also, since the horizontal lines m1 to m10 are formed in a zigzag shape, the lateral width of the reflector 52 can be reduced. As a result, since the lateral width of the planar antenna 5 of the fifth embodiment can be reduced, the size of the planar antenna 5 can be miniaturized.

[0038] In the nine openings A1 to A9 formed in the planar portion 52a of the reflector 52, closing portions S1 and S2 are respectively formed at the central portions of the two openings A3 and A7. Further, at the upper portion of the planar portion 52a, at the central portion in the vertical direction, a Y-shaped line y1 is formed across the horizontal lines m1 to m3. At the central portion of the planar portion 52a, two vertical lines n1 and n2 are symmetrically formed on both sides sandwiching the center line in the vertical direction with substantially the same width as the lateral width W5 of the closing portions S1 and S2. At the lower portion of the planar portion 52a, at the central portion in the vertical direction, a Y-shaped line y2 is symmetrically formed across the horizontal lines m10 to m8 with respect to the Y-shaped line y1. As a result, the opening A1 is an opening divided horizontally by the Y-shaped line y1 and a small rhombic opening a1, the opening A2 is an opening divided horizontally by the Y-shaped line y1, and the opening A3 is an opening with only both sides of the closing portion S1 opened. Further, the openings A4, A5, and A6 are openings divided horizontally by the three vertical lines n1 and n2, respectively, and the opening A7 is an opening with only both sides of the closing portion S2 opened. Furthermore, the opening A8 is an opening divided horizontally by a Y-shaped line y2 arranged symmetrically with respect to the Y-shaped line y1, and the opening A9 is an opening divided horizontally by the Y-shaped line y2 and a small rhombic opening a9. Note that the outer widths of the vertical lines n1 and n2 arranged symmetrically in the vertical direction in the planar portion 52a are substantially the same as the lateral width W5 of the closing portions S1 and S2.

[0039] In the planar antenna 5 of the fifth embodiment, as shown in FIG. 17, similar to the planar antenna 1 of the first embodiment, one end of the feeding line 13 is connected to each of the two feeding points 10b of the first radiating element 10, and the other end of the feeding line 13 is connected to each of the two feeding points 11b of the second radiating element 11. A feeding substrate 14 is provided at substantially the central portion of the feeding line 13, a feeding portion 15 is formed on the feeding substrate 14, and feeding is performed from the feeding portion 15 to substantially the central portions of the two feeding lines 13. The configuration of the power supply unit 15 is as shown in Fig. 6. The approximate central portions of the two power supply lines 13 are connected to the upper surface of the power supply substrate 14 by soldering or the like. Two protrusions are formed at the approximate central portions of the two power supply lines 13 so as to face each other. The shield portion of the coaxial cable 16 is soldered to one protrusion of the power supply line 13, and the core wire of the coaxial cable 16 is soldered to the other protrusion of the power supply line 13. The planar antenna 4 of the fourth embodiment is powered by the coaxial cable 16. The impedance of the power supply unit 15 can be adjusted by the protrusions formed at the approximate central portions of the power supply lines 13. Further, adjustment plates 17 for adjusting the impedance of the power supply unit 15 are printed or adhered to both sides of the surface of the power supply substrate 14. However, the adjustment plates 17 may be omitted.

[0040] Regarding the dimensions of each part of the planar antenna 5 of the fifth embodiment of the present invention, the lateral width of the planar antenna 5 is about 230 mm, and the longitudinal length is about 600 mm. As shown in Figs. 19(a) and (b), the lateral width W2 of the reflector 52 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 52b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal portion of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal portion of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag horizontal lines m1 to m10 is about 140 mm. Also, the width D of the zigzag horizontal lines m1 to m10 is about 10 mm. The widths of the vertical lines n1 and n2 and the widths of the Y-shaped lines y1 and y2 are the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking portions S1 and S2 formed at the central portions of the two openings A3 and A7 is about 110 mm. And the widths of the outer edges of the two vertical lines n1 and n2 are approximately the same as the lateral width W5 of the blocking portions S1 and S2, which is about 110 mm. Also, although not shown, the respective lateral widths W1 of the first radiation element 10 and the second radiation element 11 are about 220 mm, the respective vertical lengths L2 are about 280 mm, the lateral width W1 of the radiation element 01 is about 220 mm, the vertical length L1 is about 600 mm, and the interval L3 between the first radiation element 10 and the second radiation element 11 arranged in the vertical direction is about 40 mm. Further, the lateral width W6 of the power supply substrate 14 is about 110 mm, the vertical length L4 is about 30 mm, and the interval H2 between the radiation element 01 and the planar portion 22a of the reflector 22 is about 45 mm. Since the radiation element 01 of the planar antenna 5 of the fifth embodiment includes two radiation elements, namely, the first radiation element 10 and the second radiation element 11 arranged in the vertical direction, the gain of the planar antenna 5 of the fifth embodiment is improved.

[0041] <Antenna characteristics of the planar antenna according to the embodiment of the present invention> The frequency characteristics of the voltage standing wave ratio (VSWR) in the planar antenna 1 of the first embodiment of the present invention to the planar antenna 4 of the fourth embodiment of the present invention are shown in FIG. 20, the frequency characteristics of the front-to-back ratio are shown in FIG. 21, and the evaluation values of the front-to-back ratio are shown in FIG. 22. FIG. 20(a) is a graph showing the frequency characteristics of the VSWR, FIG. 20(b) is a chart showing the frequency characteristics of the VSWR, FIG. 21(a) is a graph showing the frequency characteristics of the front-to-back ratio, FIG. 21(b) is a chart showing the frequency characteristics of the front-to-back ratio, FIG. 22(a) is a graph showing the evaluation values of the front-to-back ratio, and FIG. 22(b) is a chart showing the evaluation values of the front-to-back ratio. In FIGS. 20(a) and 20(b), the frequency characteristics of the VSWR of the planar antenna 1 of the first embodiment of the present invention to the planar antenna 4 of the fourth embodiment of the present invention are shown in comparison with a planar antenna having a reflector without a vertical line provided. In FIGS. 20(a) and 20(b), "one vertical line" indicates the planar antenna 1 of the first embodiment, "two vertical lines" indicates the planar antenna 2 of the second embodiment, "two vertical lines in total" indicates the planar antenna 3 of the third embodiment, and "three vertical lines" indicates the planar antenna 4 of the fourth embodiment. Referring to FIGS. 20(a) and (b), it can be seen that the frequency characteristics of the VSWR due to the addition of vertical lines, as a whole, for the planar antenna 1 of the first embodiment to the planar antenna 4 of the fourth embodiment of the present invention, transition between approximately 1.1 and approximately 2.4 in the operating frequency band of 470 MHz to 710 MHz. Also, since the VSWR does not change steeply in the frequency characteristics of the VSWR, it can be seen that it does not specify the resonant frequency. And the frequency characteristics of the VSWR of the planar antenna 2 of the second embodiment are the best. In the case of the "two vertical lines" which is the planar antenna 2 of the second embodiment, the VSWR is approximately 2.1 at 470 MHz, approximately 1.0 at the center frequency of 590 MHz, and approximately 2.0 at 710 MHz.

[0042] In FIGS. 21(a) and (b), the frequency characteristics of the front-to-back ratio of the planar antenna 1 of the first embodiment to the planar antenna 4 of the fourth embodiment of the present invention are shown in comparison with a planar antenna having a reflector without vertical lines provided. In FIGS. 21(a) and (b), "one vertical line" indicates the planar antenna 1 of the first embodiment, "two vertical lines" indicates the planar antenna 2 of the second embodiment, "two vertical lines in total" indicates the planar antenna 3 of the third embodiment, and "three vertical lines" indicates the planar antenna 4 of the fourth embodiment. Referring to FIGS. 21(a) and (b), it can be seen that the frequency characteristics of the front-to-back ratio due to the addition of vertical lines, as a whole, for the planar antenna 1 of the first embodiment to the planar antenna 4 of the fourth embodiment of the present invention, transition between approximately 10.8 dB and approximately 17 dB in the operating frequency band of 470 MHz to 710 MHz, and it is improved compared to the planar antenna without vertical lines.

[0043] The evaluation value of the front-to-back ratio shown in FIGS. 22(a) and (b) is the evaluation value of the front-to-back ratio calculated based on the front-to-back ratio shown in FIGS. 21(a) and (b). The evaluation value of the front-to-back ratio in this case is defined by the following formula (1). Evaluation value of front-to-back ratio = (maximum value of front-to-back ratio) × (sum of VSWR values at each frequency) (1) (1) The evaluation value of the front-to-back ratio calculated by the formula is shown in Fig. 22(b), and its graph is shown in Fig. 22(a). In Figs. 22(a) and (b), "one vertical line" indicates the planar antenna 1 of the first embodiment, "two vertical lines" indicates the planar antenna 2 of the second embodiment, "two vertical lines in total" indicates the planar antenna 3 of the third embodiment, and "three vertical lines" indicates the planar antenna 4 of the fourth embodiment. Referring to Figs. 22(a) and (b), it can be seen that the planar antennas 1 to 4 of the first to fourth embodiments have a higher evaluation value of the front-to-back ratio and an improved front-to-back ratio compared to the planar antenna without vertical lines. And it can be seen that when the number of vertical lines is two or more, the characteristics of the front-to-back ratio are further improved. In the planar antenna 5 of the fifth embodiment of the present invention, since the configuration of the reflector 52 is similar to the configuration of the reflector 22 of the planar antenna 2 of the second embodiment, the antenna characteristics are almost the same as those of the "two vertical lines" of the planar antenna 2 of the second embodiment.

[0044] <Antenna device of the embodiment of the present invention> The configuration of the antenna device 100 of the embodiment of the present invention is shown in Figs. 23 to 26. Fig. 23 is a front view showing the configuration of the antenna device 100 of the embodiment of the present invention, Fig. 24 is a rear view showing the configuration of the antenna device 100 of the embodiment of the present invention, Fig. 25 is a perspective view showing the configuration of the rear case 112 of the antenna device 100, and Fig. 26 is a perspective view showing the configuration of assembling the reflector 52 to the rear case 112 of the antenna device 100. The antenna device 100 according to an embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is set to 470 MHz to 710 MHz. The planar antenna 1 according to the first embodiment to the planar antenna 5 according to the fifth embodiment of the present invention described above can all be housed in an antenna case. In the antenna device 100 according to an embodiment of the present invention shown in FIGS. 23 to 26, the antenna device 100 in which the planar antenna 5 according to the fifth embodiment of the present invention is housed in the antenna case 110 is taken as an example and shown. When any one of the planar antenna 1 according to the first embodiment of the present invention to the planar antenna 4 according to the fourth embodiment of the present invention is housed in the antenna case 110, the configuration of the antenna device 100 is substantially the same configuration. As shown in FIGS. 23 to 26, the antenna device 100 includes an antenna case 110 made of synthetic resin, which is composed of a front case 111 and a rear case 112. The antenna case 110 composed of the front case 111 and the rear case 112 has a rectangular parallelepiped shape in which the thickness is thinner than one fraction or more of the lengths in the vertical and horizontal directions. Although not shown, the front case 111 has a shape that is symmetric with respect to the center line in the major axis direction, and is formed in a box shape with the back side as the opening surface. Further, as shown in FIGS. 25 and 26, the rear case 112 has a shape that is symmetric with respect to the center line in the major axis direction, and is formed in a box shape with the front side as the opening surface. The front case 111 and the rear case 112 are fitted so that the opening surface of the front case 111 and the opening surface of the rear case 112 face each other, and the antenna case 110 is configured by closing both opening surfaces, and the inside is a storage space. In the storage space of the antenna case 110, for example, the planar antenna 5 according to the fifth embodiment capable of receiving terrestrial digital television broadcasts is stored, and a booster may be stored in the storage space. At the center of the back surface of the rear case 112, a power supply unit 113 having a coaxial terminal for outputting a received signal received by the terrestrial digital antenna stored in the storage space is integrally formed so as to protrude. Further, at the lower part of the back surface of the rear case 112, a mounting portion 114 for mounting the antenna device 100 according to the present invention on a wall surface or the like is integrally formed so as to protrude.

[0045] As shown in FIGS. 25 and 26, the rear case 112 is formed such that a number of first bosses 112a and a number of second bosses 112b stand upright toward the inner surface that serves as a storage space. The first boss 112a has a cylindrical shape that tapers toward the tip, and the second boss 112b is formed in a tapered shape with a cross-shaped cross-section that tapers toward the tip. Inside the rear case 112, a reflector 52' is stored and fixed as shown in FIG. 25. In this case, four first bosses 112a formed at the four corners inside the first boss 112a are inserted into respective four insertion holes 52c formed at the four corners of the reflector 52'. Since the first boss 112a has a tapered cylindrical shape, the reflector 52' is firmly inserted into the first boss 112a so that it does not easily come out. Further, since the bent portions 52b formed on both sides of the reflector 52' are elastically slidably contacted with the inner surfaces on both sides in the longitudinal direction of the rear case 112, the reflector 52' is surely fixed to the inner surface of the rear case 112.

[0046] Note that, in order to store the reflector 52 of the planar antenna 5 of the fifth embodiment in the rear case 112, a reflector 52' obtained by slightly processing the reflector 52 is used. In the reflector 52', insertion holes 52c are formed at the four corners of the planar portion 52a as shown in FIG. 26. Further, the shapes on both sides of the openings A4, A5, and A6 are processed to be the shapes of A4', A5', and A6'. As a result, the reflector 52' is fixed in close proximity to be substantially parallel to the planar inner surface of the rear case 112. In this case, the first boss 112a and the second boss 112b penetrate through the reflector 52' and protrude to the inner surface side. At this time, a predetermined first boss 112a and second boss 112b are inserted and protrude into the openings A1 to A9. In particular, the second boss 112b is inserted into the rhombic opening a1 in the opening A1, and any other boss can be inserted into the rhombic opening a9 in the opening A9. In this way, the first boss 112a and the second boss 112b stand upright beyond the reflector 52', and although not shown, a radiation element 01 is fixed using the first boss 112a and the second boss 112b.

[0047] <Planar Antenna of the Sixth Embodiment of the Present Invention> The planar antenna 6 of the sixth embodiment of the present invention is an antenna with improved gain for receiving terrestrial digital television broadcasts, and the operating frequency band is 470 MHz to 710 MHz. The planar antenna 6 of the sixth embodiment is a planar antenna in which the radiation element 01 in the planar antenna 5 of the fifth embodiment is replaced with a radiation element 02 having a different configuration, and the configuration excluding the radiation element is the same as that of the planar antenna 5 of the fifth embodiment. The configuration of the planar antenna 6 of the sixth embodiment is shown in FIGS. 27 to 29. FIG. 27 is a front view showing the configuration of the planar antenna 6 of the sixth embodiment, FIG. 28 is a rear view showing the configuration of the planar antenna 6 of the sixth embodiment, and FIG. 29 is a front view showing the configuration of the radiation element 02 of the planar antenna 6 of the sixth embodiment. As shown in these figures, the planar antenna 6 of the sixth embodiment includes a radiation element 02 including a first radiation element 20 and a second radiation element 21 formed of a triangular double-loop element, and a reflector 52 disposed rearward at a predetermined interval facing the radiation element 02. The reflector 52 is formed by processing a metal plate into a vertically long rectangle, has a rectangular planar portion facing the entire surface of the radiation element 02, and bent portions 52b bent toward the radiation element 02 side are formed on both sides of the planar portion. The bent portion 52b is composed of a hypotenuse rising obliquely from the side of the planar portion 52a and a vertical side rising vertically from the tip of the hypotenuse. Although it is shown as the reflector 52 in FIGS. 27 and 28, any one of the reflectors 12 to 42 in the planar antenna 1 to the planar antenna 4 of the first embodiment may be used.

[0048] The configuration of the radiation element 02 will be described. The radiation element 02 is composed of a first radiation element 20 and a second radiation element 21 having a shape symmetrical to that of the first radiation element. As shown in FIGS. 27 to 29, the first radiation element 20 has two triangular notches formed vertically on a rectangular metal plate such that the vertices face each other, and trapezoidal notches are formed on the left and right such that they face each other. The upper and lower sides are composed of a wide outer element 20a, a trapezoidal inner element 20b extending from the outer element 20a toward the center, and a thin U-shaped slit 20d formed between the outer element 20a and the inner element 20b. The outer frame is formed by four sides including the upper and lower sides configured as described above and the left and right sides formed by a first power supply element 20c composed of the hypotenuses extending from the ends of the upper and lower sides and triangular elements connected to the hypotenuses. The triangular elements connected to the hypotenuses on the left and right sides that serve as the first power supply element 20c have their bases forming the edges of the left and right sides, respectively, and their vertices facing each other at the center. The hypotenuse extending diagonally downward to the center of the left side is connected to the other vertex of the triangular element forming the left side, and the hypotenuse extending diagonally upward to the center of the left side is connected to the remaining vertex of the triangular element forming the left side. Also, the hypotenuse extending diagonally downward to the center of the right side is connected to the other vertex of the triangular element forming the right side, and the hypotenuse extending diagonally upward to the center of the right side is connected to the remaining vertex of the triangular element forming the right side. A downward triangular loop element is formed by the upper half of the left and right sides configured as described above and the outer element 20a which is the upper side, and an upward triangular loop element is formed by the lower half of the left and right sides configured as described above and the outer element 20a which is the lower side. The first radiation element 20 in the planar antenna 6 of the sixth embodiment is a triangular double-loop element composed of the two triangular loop elements described above, and the opposing vertices of the two opposing triangular loop elements are two power supply points 20e.

[0049] Further, the second radiation element 21 has the same shape as that of the first radiation element 20 and is symmetric thereto. The upper side and the lower side are composed of a wide outer element 21a and a trapezoidal inner element 21b formed inside the outer element 21a, with the central part of the inner element 21b connected to the outer element 21a via a narrow U-shaped slit 21d. The outer frame is composed of four sides, namely, the upper side and the lower side configured as described above, and the left side and the right side composed of a second feeding element 21c formed by a hypotenuse extending from the ends of the upper side and the lower side and a triangular element connected to the hypotenuse. A downward triangular loop element is formed by the upper side and the lower side, the upper half of the left side and the right side which are the second feeding element 21c, and the outer element 21a which is the upper side. An upward triangular loop element is formed by the lower half of the left side and the right side which are the second feeding element 21c and the outer element 21a which is the lower side. The second radiation element 21 in the planar antenna 6 of the sixth embodiment is a triangular double loop element composed of the two triangular loop elements described above, and the opposing vertices of the two opposing triangular loop elements are two feeding points 21e. One end of a feeding line 23 is connected to each of the two feeding points 20e of the first radiation element 20, and the other end of the feeding line 23 is connected to each of the two feeding points 21e of the second radiation element 21. A feeding substrate 24 is provided at approximately the central part of the feeding line 23, a feeding part 25 is formed on the feeding substrate 24, and power is fed from the feeding part 25 to approximately the central part of the two feeding lines 23.

[0050] The feeding part 25 has the same configuration as that shown in FIG. 6. Approximately the central parts of the two feeding lines 23 are connected to the upper surface of the feeding substrate 24 by soldering or the like. Two protrusions are formed approximately at the central parts of the two feeding lines 23 so as to face each other. The shield part of the coaxial cable is soldered to one protrusion of the feeding line 23, and the core wire of the coaxial cable is soldered to the other protrusion of the feeding line 23. The planar antenna 6 of the sixth embodiment is fed by the coaxial cable. The impedance of the feeding part 25 can be adjusted by the protrusions. Further, adjustment plates (not shown) for adjusting the impedance of the feeding part 25 are printed or attached to both sides of the surface of the feeding substrate 24. However, the adjustment plates may be omitted. The configuration of the reflector 52 is as described in the planar antenna 5 of the fifth embodiment, so the description thereof is omitted. However, by making the openings A1 to A9 of the reflector 52 have an optimized number and shape, it becomes possible to improve the reflection characteristics of the reflector 52. Also, the lateral width of the reflector 52 can be reduced, and thereby, since the lateral width of the planar antenna 6 of the sixth embodiment can be reduced, the dimensions of the planar antenna 6 can be miniaturized. Further, since the radiation elements 02 of the planar antenna 6 of the sixth embodiment include two radiation elements, i.e., a first radiation element 20 and a second radiation element 21, which are arranged in the vertical direction, the gain of the planar antenna 6 of the sixth embodiment is improved.

[0051] Regarding the dimensions of each part of the planar antenna 6 of the sixth embodiment of the present invention, the lateral width of the planar antenna 6 of the sixth embodiment is about 230 mm, and the longitudinal length is about 600 mm. As shown in FIGS. 19(a) and (b), the lateral width W2 of the reflector 52 is about 230 mm, the longitudinal length L1 is about 600 mm, the height H1 of the bent portion 52b is about 25 mm, the height H3 of the hypotenuse is about 10 mm, the lateral width W3 of the openings A1 to A9 is about 180 mm, the length L5 of the longest longitudinal part of the openings A1 to A9 is about 69.3 mm, the length L6 of the shortest longitudinal part of the openings A1 to A9 is about 34.6 mm, and the distance W4 between the first peak or valley and the third peak or valley of the zigzag-shaped horizontal lines m1 to m10 is about 140 mm. Also, the width D of the zigzag-shaped horizontal lines m1 to m10 is about 10 mm. The widths of the vertical lines n1 and n2 and the widths of the Y-shaped lines y1 and y2 are the same as the width D of the horizontal lines m1 to m10, which is about 10 mm. The lateral width W5 of the blocking portions S1 and S2 formed at the central parts of the two openings A3 and A7 is about 110 mm. And the widths of the outer edges of the two vertical lines n1 and n2 are approximately the same as the lateral width W5 of the blocking portions S1 and S2, which is about 110 mm. As shown in FIG. 29, the lateral width W1 (the lateral width of the outer elements 20a and 21a) of each of the first radiation element 20 and the second radiation element 21 is about 220 mm, the longitudinal length L2 of each is about 280 mm, the vertical width L8 of the outer elements 20a and 21a is about 50 mm, the length of the long side W7 of the trapezoidal inner elements 20b and 21b is about 168 mm, the length of the short side W8 is about 110.8 mm, the vertical width L9 is about 30 mm, the width L10 of the slits 20d and 21d is about 5 mm, and the distance W9 between the tips is about 50 mm. The lateral width W1 of the radiation element 02 is about 220 mm, the longitudinal length L1 is about 600 mm, and the distance L3 between the first radiation element 20 and the second radiation element 21 arranged in the longitudinal direction is about 40 mm. Also, although not shown, the lateral width of the power supply substrate 24 is about 110 mm, the longitudinal length is about 30 mm, and the distance H2 between the radiation element 02 and the reflector 52 is about 45 mm.

Industrial Applicability

[0052] In the planar antenna and the antenna device according to the embodiments of the present invention described above, the operating frequency band is not limited to 470 MHz to 710 MHz, and other frequency bands may also be used. Also, in the planar antenna 1 of the first embodiment to the planar antenna 4 of the fourth embodiment of the present invention described above, they can be housed in a synthetic resin case having a thin rectangular parallelepiped shape. Further, the radiation elements of the planar antenna 1 of the first embodiment to the planar antenna 4 of the fourth embodiment of the present invention are not limited to the radiation element 01, and the radiation element 02 can be used. Furthermore, in the planar antenna 1 of the first embodiment to the planar antenna 5 of the fifth embodiment of the present invention described above, one wavelength of the center frequency 590 MHz in the operating frequency band of 470 MHz to 710 MHz is approximately 508.4 mm. And when one wavelength of the center frequency of the operating frequency band is defined as 1λ, if the lateral widths W5 of the closing portions S1 and S2 of the reflector 12 to the reflector 52 are set to be approximately 0.08λ to approximately 0.216λ, the antenna characteristics will be improved.

Description of Reference Numerals

[0053] 1 planar antenna, 2 planar antenna, 3 planar antenna, 4 planar antenna, 5 planar antenna, 6 planar antenna, 01 radiating element, 02 radiating element, 10 first radiating element, 10a first feeding element, 10b feeding point, 10c notch, 11 second radiating element, 11a second feeding element, 11b feeding point, 11c notch, 12 reflector, 12a planar portion, 12b bent portion, 13 feeding line, 14 feeding substrate, 15 feeding part, 16 coaxial cable, 17 adjustment plate, 20 first radiating element, 20a outer element, 20b inner element, 20c first feeding element, 20d slit, 20e feeding point, 21 second radiating element, 21a outer element, 21b inner element, 21c second feeding element, 21d slit, 21e feeding point, 22 reflector, 22a planar portion, 22b bent portion, 23 feeding line, 24 feeding substrate, 25 feeding part, 32 reflector, 32a planar portion, 32b bent portion, 42 reflector, 42a planar portion, 42b bent portion, 52 reflector, 52a planar portion, 52b bent portion, 52c insertion hole, 100 antenna device, 110 antenna case, 111 front case, 112 rear case, 112a first boss, 112b second boss, 113 feeding part, 114 mounting part, 200 planar antenna with reflector, 210 front element, 211 rear element, 212 protrusion, 213 feeding point, 214 feeding line, 215 feeding part, 216 rising part, 217a, 217b, 217c gap, A1~A9 opening, S1, S2 closing part

Claims

1. A first radiating element including a loop element formed in a triangular loop shape, A second radiating element including a loop element formed in a triangular loop shape, having a shape symmetrical to the first radiating element and arranged in a vertical direction with respect to the first radiating element, A reflector disposed at a predetermined interval facing the first radiating element and the second radiating element and arranged at the rear, having a planar portion facing the first radiating element and the second radiating element, and bent portions on both sides of the planar portion bent toward the sides of the first radiating element and the second radiating element, and a plurality of openings formed in the planar portion, A planar antenna, characterized in that a vertical line is formed in the vertical direction in the planar portion.

2. Blocking portions for blocking the central portions of the openings are respectively provided in the openings at symmetrical positions, and the vertical line formed in the vertical direction in the planar portion is formed at the central portion of the planar portion. The planar antenna according to claim 1, characterized in that.

3. Blocking portions for blocking the central portions of the openings are respectively provided in the openings at symmetrical positions, and the vertical line formed in the vertical direction in the planar portion is a first vertical line formed in the vertical direction at the upper part of the upper blocking portion and the central part of the lower part of the lower blocking portion, and two second vertical lines formed in the vertical direction between the openings provided with the blocking portions and arranged symmetrically with the width of the lateral width of the blocking portion. The planar antenna according to claim 1, characterized in that.

4. Blocking portions for blocking the central portions of the openings are respectively provided in the openings at symmetrical positions, and the vertical line formed in the vertical direction in the planar portion is two vertical lines arranged symmetrically with the width of the lateral width of the blocking portion. The planar antenna according to claim 1, characterized in that.

5. Blocking portions for blocking the central portions of the openings are respectively provided in the openings at symmetrical positions, and the vertical line formed in the vertical direction in the planar portion is a first vertical line formed in the vertical direction at the central portion of the planar portion and two second vertical lines arranged symmetrically with the width of the lateral width of the blocking portion. The planar antenna according to claim 1, characterized in that.

6. Blocking portions that block the central portions of the openings are respectively provided at symmetric positions of the openings, and the vertical lines formed in the vertical direction on the planar portion are a first vertical line formed in the vertical direction at the upper part of the upper blocking portion and the central part of the lower part of the lower blocking portion, and two second vertical lines formed in the vertical direction between the openings where the blocking portions are symmetrically arranged with the width of the lateral width of the blocking portion, and Y-shaped lines are symmetrically formed at the uppermost part of the plurality of openings and the central part of the opening below it, and at the lowermost part of the plurality of openings and the central part of the opening above it. By forming the Y-shaped lines, another opening is formed in the uppermost and lowermost openings. The planar antenna according to claim 1, characterized in that.

7. The first radiating element and the second radiating element are each a triangular double-loop element, and the vertices of two facing triangles are respectively feeding points, and two first feeding lines connected to each of the feeding points of the first radiating element, and a feeding board to which two second feeding lines connected to each of the feeding points of the second radiating element are connected, and the first feeding line and the second feeding line on the feeding board are fed from a feeding portion. The planar antenna according to any one of claims 1 to 6, characterized in that.

8. The planar antenna according to claim 7, characterized in that an adjustment board for adjusting impedance is formed on the feeding board.

9. In the plurality of openings formed in the planar portion, the horizontal lines above and below the openings are formed in a zigzag shape or a waveform. The planar antenna according to any one of claims 1 to 6, characterized in that.

10. In the plurality of openings formed in the planar portion, the horizontal lines above and below the openings are formed in a zigzag shape or a waveform, and in the upper horizontal line and the lower horizontal line of the opening, the zigzag shape or the waveform is formed in a symmetric shape. The planar antenna according to any one of claims 1 to 6, characterized in that.

11. The planar antenna according to any one of claims 1 to 6, characterized in that it can be housed in a synthetic resin case having a thin rectangular parallelepiped shape.

12. The first radiation element and the second radiation element are each a triangular double-loop element, and each of the triangular double-loop elements includes an outer element forming an upper side and a lower side, a feeding element forming a triangle connecting both ends of the outer element, an inner element formed by extending from the outer element toward the center side, the outer element, the feeding element, and a slit formed between the outer element and the inner element. The planar antenna according to any one of claims 1 to 6, characterized in that it comprises the above.

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