Circularly polarized wave antenna

Abstract

To achieve a wide band circularly polarized wave antenna.SOLUTION: A circularly polarized wave antenna includes a loop element, first to fourth linear elements 111 to 114, fifth to eighth linear elements 121 to 124, and first to fourth connection conductors 41 to 44. The loop element has substantially the same length as a first wavelength corresponding to a first frequency in a frequency band of a radiated radio wave. Each of the first to fourth linear elements 111 to 114 has a length of approximately half of the first wavelength, and has one end connected to a position obtained by equally dividing the loop element into approximately four in a circumferential direction, and the other end serving as a feeding point PP. Each of the fifth to eighth linear elements 121 to 124 has a length of substantially half of a second wavelength corresponding to a second frequency in the frequency band higher than the first frequency, and has one end connected to a position obtained by dividing a circle of the second wavelength into substantially four in the circumferential direction and the other end serving as the feeding point PP.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a circularly polarized antenna that transmits and receives circularly polarized waves. [Background technology]

[0002] Patent Document 1 describes a circularly polarized antenna. The circularly polarized antenna described in Patent Document 1 includes one loop element having a length of approximately one wavelength of the radio waves to be radiated (transmitted and received), and four linear elements. One end of each of the four linear elements is connected to a position that divides the loop element into approximately four equal parts.

[0003] The four linear elements extend in a direction perpendicular to the plane defined by the loop element, and the other ends are formed in a dome shape to cover the loop element. Power is supplied to the other ends of the four linear elements with a phase difference of 90 degrees. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2000 / 69022 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional circularly polarized antennas such as that shown in Patent Document 1, it has not been easy to further widen the bandwidth.

[0006] SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to provide a wideband circularly polarized antenna. [Means for solving the problem]

[0007] The circularly polarized antenna of the present invention includes a loop element, a first, second, third, and fourth linear elements, a fifth, sixth, seventh, and eighth linear elements, and a first, second, third, and fourth connecting conductor. The loop element has a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave. The first, second, third, and fourth linear elements each have a length substantially half the first wavelength, one end of each of which is connected to a position obtained by dividing the loop element into substantially four equal parts in the circumferential direction, and the other end of each of which is a feed point. The fifth, sixth, seventh, and eighth linear elements each have a length substantially half the second wavelength corresponding to a second frequency in the frequency band that is higher than the first frequency, one end of each of which is connected to a position obtained by dividing a circle of the second wavelength into substantially four equal parts in the circumferential direction, and the other end of each of which is a feed point. The first connecting conductor connects one end of the first linear element and one end of the fifth linear element that are adjacent in a direction perpendicular to the tangent of the loop element. The second connecting conductor connects one end of the second linear element and one end of the sixth linear element that are adjacent in a direction perpendicular to the tangent of the loop element. The third connecting conductor connects one end of the third linear element and one end of the seventh linear element that are adjacent in a direction perpendicular to the tangent of the loop element. The fourth connecting conductor connects one end of the fourth linear element and one end of the eighth linear element that are adjacent in a direction perpendicular to the tangent of the loop element.

[0008] In this configuration, the loop element and the first, second, third, and fourth linear elements function as a first antenna for radio waves of the first frequency, and the fifth, sixth, seventh, and eighth linear elements function as a second antenna for radio waves of the second frequency. With the above configuration, the first antenna and the second antenna are coupled as in a staggered tuning method, making it possible to emit radio waves in a frequency band that includes the first and second frequencies.

[0009] Furthermore, since the second antenna is configured not to have a loop element, the effect of the second antenna on the radiation characteristics can be suppressed, thereby making it possible to further flatten the SWR in the frequency band between the first frequency and the second frequency, thereby achieving a wider bandwidth.

[0010] In the circularly polarized antenna of the present invention, the first linear element, the second linear element, the third linear element, and the fourth linear element have portions that extend in the opposite direction to the loop element with respect to the feed point. The extending portions have a bent shape that is recessed in the direction away from each other. This suppresses coupling that is undesirable for a wider bandwidth, thereby achieving a further wider bandwidth.

[0011] In the circularly polarized antenna of the present invention, the first, second, third, and fourth linear elements each include a plurality of sub-linear elements. The plurality of linear elements of the first linear element are connected to positions on either side of a connection point where the first connecting conductor is connected to the loop element. The plurality of linear elements of the second linear element are connected to positions on either side of a connection point where the second connecting conductor is connected to the loop element. The plurality of linear elements of the third linear element are connected to positions on either side of a connection point where the third connecting conductor is connected to the loop element. The plurality of linear elements of the fourth linear element are connected to positions on either side of a connection point where the fourth connecting conductor is connected to the loop element.

[0012] In this configuration, by configuring each of the first, second, third, and fourth linear elements with a plurality of sub-linear elements, it becomes possible to further adjust the band, thereby achieving a wide band.

[0013] The circularly polarized antenna of the present invention includes a loop element, a first, second, third, and fourth linear elements, and a fifth, sixth, seventh, and eighth linear elements. The loop element has a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave. The first, second, third, and fourth linear elements each have a length of approximately half the first wavelength, one end of each of which is connected to a position obtained by dividing the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is a feed point. The fifth, sixth, seventh, and eighth linear elements each have a length of approximately half the second wavelength corresponding to a second frequency in the frequency band that is higher than the first frequency, one end of each of which is connected to a position obtained by dividing the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is a feed point.

[0014] The first, second, third, and fourth linear elements each include a plurality of sub-linear elements. The plurality of linear elements of the first linear element are connected to each of the positions sandwiched between a connection point where the fifth linear element is connected to the loop element. The plurality of linear elements of the second linear element are connected to each of the positions sandwiched between a connection point where the sixth linear element is connected to the loop element. The plurality of linear elements of the third linear element are connected to each of the positions sandwiched between a connection point where the seventh linear element is connected to the loop element. The plurality of linear elements of the fourth linear element are connected to each of the positions sandwiched between a connection point where the eighth linear element is connected to the loop element.

[0015] In this configuration, the loop element and the first, second, third, and fourth linear elements function as a first antenna for radio waves of the first frequency, and the fifth, sixth, seventh, and eighth linear elements function as a second antenna for radio waves of the second frequency. With the above configuration, the first antenna and the second antenna are coupled as in a staggered tuning method, making it possible to emit radio waves in a frequency band that includes the first and second frequencies.

[0016] Furthermore, since the second antenna is configured not to have a loop element, the effect of the second antenna on the radiation characteristics can be suppressed, thereby making it possible to further flatten the SWR in the frequency band between the first frequency and the second frequency, thereby achieving a wider bandwidth.

[0017] The circularly polarized antenna of the present invention includes a reflecting member arranged on the opposite side of the loop element to the direction in which the first, second, third and fourth linear elements and the fifth, sixth, seventh and eighth linear elements extend.

[0018] This configuration makes it possible to realize a more sensitive circularly polarized antenna. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a perspective view of a circularly polarized antenna according to a first embodiment. [Diagram 2] FIG. 2 is a three-orthogonal view of the circularly polarized antenna according to the first embodiment. [Diagram 3] FIG. 3 shows the results of simulating the SWR of the circularly polarized antenna according to the first embodiment and the circularly polarized antenna of the comparative example. [Figure 4] FIG. 4 is a perspective view of a circularly polarized antenna according to the second embodiment. [Diagram 5] FIG. 5 shows the results of simulating the SWR of the circularly polarized antenna according to the second embodiment. [Figure 6] FIG. 6 is a perspective view of a circularly polarized antenna according to the third embodiment. [Figure 7] 7(A) and 7(B) are perspective views showing a part of a circularly polarized antenna according to a third embodiment. [Figure 8] FIG. 8 shows a result of simulating the SWR of the circularly polarized antenna according to the third embodiment. [Figure 9] FIG. 9 is a perspective view of a circularly polarized antenna according to the fourth embodiment. [Figure 10] 10(A) and 10(B) are perspective views showing a part of a circularly polarized antenna according to a fourth embodiment. [Figure 11] FIG. 11 shows a result of simulating the SWR of the circularly polarized antenna according to the fourth embodiment. [Figure 12] FIG. 12 is a perspective view of a circularly polarized antenna according to the fifth embodiment. [Figure 13] FIG. 13 is a perspective view of a circularly polarized antenna according to the sixth embodiment. [Figure 14] FIG. 14 is a three-view diagram of a circularly polarized antenna according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [First embodiment] A circularly polarized antenna according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the circularly polarized antenna according to the first embodiment. FIG. 2 is a three-sided view of the circularly polarized antenna according to the first embodiment. FIG. 2 is a top view, a first side view, and a second side view. Note that the top and side views in each embodiment of the present invention are used for convenience of explanation and do not limit the direction of use. In the following, the case of radiation (wave transmission) will be described as an example, but the circularly polarized antenna 1 can not only transmit waves but also receive waves.

[0021] As shown in Figures 1 and 2, the circularly polarized antenna 1 includes a plurality of linear elements 111-114 (linear element 111, linear element 112, linear element 113, linear element 114), a plurality of linear elements 121-124 (linear element 121, linear element 122, linear element 123, linear element 124), a loop element 12, a plurality of power supply conductors 31-34 (power supply conductor 31, power supply conductor 32, power supply conductor 33, power supply conductor 34), and a plurality of connecting conductors 41-44 (connecting conductor 41, connecting conductor 42, connecting conductor 43, connecting conductor 44).

[0022] The plurality of linear elements 111-114 correspond to the first, second, third, and fourth linear elements, respectively. The plurality of linear elements 121-124 correspond to the fifth, sixth, seventh, and eighth linear elements, respectively. The plurality of connecting conductors 41-44 correspond to the first, second, third, and fourth connecting conductors, respectively.

[0023] The loop element 12 is a linear conductor having a circular ring shape. The length of the loop element 12 is substantially the same as a first wavelength corresponding to a first frequency in the frequency band of radio waves (radiated radio waves) radiated by the circular polarized antenna 1. Here, the term "substantially the same as the first wavelength" refers to a length that includes the same length as the first wavelength and includes a length within an error range in the radiation characteristics of the circular polarized antenna 1. Note that the loop element 12 is not limited to a circular ring shape, and may be a ring shape having a regular polygon (for example, a regular octagon or more).

[0024] Each of the linear elements 111-114 is a linear conductor. Each of the linear elements 111-114 has a length of approximately half the first wavelength. Here, the length of approximately half the first wavelength includes half the first wavelength and is within an error range in the radiation characteristics of the circularly polarized antenna 1.

[0025] One ends of the plurality of linear elements 111-114 are connected to the loop element 12 at positions that divide the loop element 12 into approximately four equal parts in the circumferential direction. Specifically, a connection point 132 between one end of the linear element 112 and the loop element 12 is located at a position that is approximately 1 / 4 of the circumferential direction of the loop element 12 from a connection point 131 between one end of the linear element 111 and the loop element 12. A connection point 133 between one end of the linear element 113 and the loop element 12 is located at a position that is approximately 1 / 4 of the circumferential direction of the loop element 12 from a connection point 132 between one end of the linear element 112 and the loop element 12. A connection point 134 between one end of the linear element 114 and the loop element 12 is located at a position that is approximately 1 / 4 of the circumferential direction of the loop element 12 from a connection point 133 between one end of the linear element 113 and the loop element 12. A connection point 131 between one end of the wire element 111 and the loop element 12 is located at a position approximately ¼ of the circumference of the loop element 12 from a connection point 134 between one end of the wire element 114 and the loop element 12 .

[0026] The multiple linear elements 111-114 extend in a direction perpendicular to the plane (the XY plane in FIGS. 1 and 2) on which the loop element 12 is formed. The multiple linear elements 111-114 extend on the same side of the plane on which the loop element 12 is formed.

[0027] Parts of the other ends of the multiple linear elements 111-114 curve toward the center Oa of the loop element 12 when viewed in a direction (Z-axis direction) perpendicular to the plane (XY plane in FIGS. 1 and 2) on which the loop element 12 is formed. This curvature brings the other end parts of the multiple linear elements 111-114 close to each other.

[0028] The other end of the wire element 111 is connected to a feed point PP (PP1) through a feed conductor 31. The feed conductor 31 also functions as a part of the wire element 111.

[0029] The other end of the wire element 112 is connected to a feed point PP (PP2) through a feed conductor 32. The feed conductor 32 also functions as a part of the wire element 112.

[0030] The other end of the wire element 113 is connected to a feed point PP (PP3) through a feed conductor 33. The feed conductor 33 also functions as a part of the wire element 113.

[0031] The other end of the wire element 114 is connected to a feed point PP (PP4) through a feed conductor 34. The feed conductor 34 also functions as a part of the wire element 114.

[0032] Each of the linear elements 121-124 is a linear conductor. Each of the linear elements 121-124 has a length of approximately half the second wavelength. The second wavelength is a wavelength corresponding to a second frequency that is higher than the first frequency within the frequency band radiated by the circularly polarized antenna 1. The length of approximately half the second wavelength here includes half the second wavelength and is within an error range in the radiation characteristics of the circularly polarized antenna 1.

[0033] One ends of the plurality of wire elements 121-124 are disposed at positions that divide an imaginary circle 22X into approximately four equal parts in the circumferential direction. As indicated by the two-dot chain line in Fig. 1, the imaginary circle 22X is disposed on the inside of the loop element 12 and has a length of the second wavelength.

[0034] Specifically, the position of one end of the linear element 122 on the imaginary circle 22X is approximately 1 / 4 of the circumferential position of the imaginary circle 22X from the position of one end of the linear element 121 on the imaginary circle 22X. The position of one end of the linear element 123 on the imaginary circle 22X is approximately 1 / 4 of the circumferential position of the imaginary circle 22X from the position of one end of the linear element 122 on the imaginary circle 22X. The position of one end of the linear element 124 on the imaginary circle 22X is approximately 1 / 4 of the circumferential position of the imaginary circle 22X from the position of one end of the linear element 123 on the imaginary circle 22X. The position of one end of the linear element 121 on the imaginary circle 22X is approximately 1 / 4 of the circumferential position of the imaginary circle 22X from the position of one end of the linear element 124 on the imaginary circle 22X.

[0035] The position of one end of the linear element 121 on the imaginary circle 22X is based on the connection point 131 at one end of the linear element 111 to the loop element 12, and is located inside the loop element 12 in a direction perpendicular to the tangent to the loop element 12 at the connection point 131.

[0036] The position of one end of the linear element 122 on the imaginary circle 22X is based on the connection point 132 at one end of the linear element 112 to the loop element 12, and is located inside the loop element 12 in a direction perpendicular to the tangent to the loop element 12 at the connection point 132.

[0037] The position of one end of the linear element 123 on the imaginary circle 22X is based on the connection point 133 at one end of the linear element 113 to the loop element 12, and is located inside the loop element 12 in a direction perpendicular to the tangent to the loop element 12 at the connection point 133.

[0038] The position of one end of the linear element 124 on the imaginary circle 22X is based on the connection point 134 at one end of the linear element 114 to the loop element 12, and is located inside the loop element 12 in a direction perpendicular to the tangent to the loop element 12 at the connection point 134.

[0039] The multiple linear elements 121-124 extend in a direction perpendicular to the plane (XY plane in FIGS. 1 and 2) on which the loop element 12 is formed. The multiple linear elements 121-124 extend on the same side of the plane on which the loop element 12 is formed, more specifically, on the same side as the multiple linear elements 111-114.

[0040] The other end portions of the multiple linear elements 121-124 are curved toward the center of the loop element 12 when viewed in a direction (Z-axis direction) perpendicular to the plane (XY plane in FIGS. 1 and 2) on which the loop element 12 is formed. Due to this curvature, the other end portions of the multiple linear elements 121-124 are close to each other.

[0041] The other end of the wire element 121 is connected to a feed point PP (PP1) through a feed conductor 31. The feed conductor 31 also functions as a part of the wire element 121.

[0042] The other end of the wire element 122 is connected to a feed point PP (PP2) through a feed conductor 32. The feed conductor 32 also functions as a part of the wire element 122.

[0043] The other end of the wire element 123 is connected to a feed point PP (PP3) through a feed conductor 33. The feed conductor 33 also functions as a part of the wire element 123.

[0044] The other end of the wire element 124 is connected to a feed point PP (PP4) through a feed conductor 34. The feed conductor 34 also functions as a part of the wire element 124.

[0045] In this shape, the linear elements 111 and 121 run substantially parallel to each other in close proximity. The linear elements 112 and 122 run substantially parallel to each other in close proximity. The linear elements 113 and 123 run substantially parallel to each other in close proximity. The linear elements 114 and 124 run substantially parallel to each other in close proximity.

[0046] The connecting conductor 41 linearly connects one end of the linear element 111 to one end of the linear element 121. The connecting conductor 42 linearly connects one end of the linear element 112 to one end of the linear element 122. The connecting conductor 43 linearly connects one end of the linear element 113 to one end of the linear element 123. The connecting conductor 44 linearly connects one end of the linear element 114 to one end of the linear element 124.

[0047] In this configuration, power with a phase difference of 90 degrees is fed to feed point PP1, feed point PP2, feed point PP3, and feed point PP4 in that order. As a result, a first circularly polarized antenna that mainly receives radio waves of a first frequency is formed by the multiple linear elements 111-114 and loop element 12. A second circularly polarized antenna that receives radio waves of a second frequency is formed by the multiple linear elements 121-124.

[0048] Furthermore, because the elements to which power of the same phase is supplied run nearly parallel to each other in close proximity, the first circularly polarized antenna and the second circularly polarized antenna are coupled as in a staggered tuning system, making it possible to radiate radio waves in a frequency band that includes the first and second high frequencies.

[0049] Furthermore, in the circularly polarized antenna 1, the second antenna does not include a loop element. Specifically, there is no loop element at the position of the imaginary circle 22X. This makes it possible to suppress the influence of the second antenna on the radiation characteristics. This makes it possible to further flatten the SWR in the frequency band between the first frequency and the second frequency, thereby achieving a wider bandwidth.

[0050] Furthermore, the first circularly polarized antenna and the second circularly polarized antenna are connected by a plurality of connecting conductors 41-44, which allows the degree of coupling between the first circularly polarized antenna and the second circularly polarized antenna to be adjusted, thereby achieving a wider bandwidth.

[0051] 3 shows the results of simulating the SWR of the circularly polarized antenna according to the first embodiment and a comparative example of a circularly polarized antenna. The comparative example is a circularly polarized antenna having a loop element arranged on imaginary circle 22X and not including multiple connecting conductors 41-44.

[0052] 3, the circularly polarized antenna 1 has a wider frequency band where the SWR is less than 2.0 and also has a wider frequency band where the SWR is less than 1.5 than the comparative circularly polarized antenna. In this way, the circularly polarized antenna 1 can achieve wideband radiation characteristics.

[0053] [Second embodiment] A circularly polarized antenna according to a second embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a perspective view of the circularly polarized antenna according to the second embodiment.

[0054] 4, the circularly polarized antenna 1A according to the second embodiment differs from the circularly polarized antenna 1 according to the first embodiment in that it includes a plurality of linear elements 111A-114A. Other configurations of the circularly polarized antenna 1A are similar to those of the circularly polarized antenna 1, and a description of similar parts will be omitted.

[0055] The circularly polarized antenna 1A includes a linear element 111A, a linear element 112A, a linear element 113A, and a linear element 114A.

[0056] The wire element 111A has a portion near the other end (the end on the feed point PP1 side) that extends in the opposite direction to the loop element 12 with respect to the feed point PP1. The wire element 111A has a bent shape BT1 in the portion extending in the opposite direction to the loop element 12.

[0057] The wire element 112A has a portion near the other end (the end on the feed point PP2 side) that extends in the opposite direction to the loop element 12 with respect to the feed point PP2. The wire element 112A has a bent shape BT2 in the portion extending in the opposite direction to the loop element 12.

[0058] The wire element 113A has a portion near the other end (the end on the feed point PP3 side) that extends in the opposite direction to the loop element 12 with respect to the feed point PP3. The wire element 113A has a bent shape BT3 in the portion extending in the opposite direction to the loop element 12.

[0059] The wire element 114A has a portion near the other end (the end on the feed point PP4 side) that extends in the opposite direction to the loop element 12 with respect to the feed point PP4. The wire element 114A has a bent shape BT4 in the portion extending in the opposite direction to the loop element 12.

[0060] The bent shapes BT1, BT2, BT3, and BT4 are each recessed in a direction away from the power feed point, based on the end connected to the power feed point. That is, the bent shapes BT1, BT2, BT3, and BT4 are recessed in a direction away from each other.

[0061] With this configuration, the circularly polarized antenna 1A can adjust the radiation characteristics and SWR characteristics to improve the characteristics on the low frequency side while maintaining the coupling of the staggered tuning method.

[0062] Fig. 5 shows the results of simulating the SWR of the circularly polarized antenna according to the second embodiment. As shown in Fig. 5, the circularly polarized antenna 1A can achieve a characteristic that the frequency bands where the SWR is less than 2.0 and the frequency bands where the SWR is less than 1.5 are wider toward the lower frequency side than the circularly polarized antenna 1 according to the first embodiment (see Fig. 3).

[0063] [Third embodiment] A circularly polarized antenna according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 6 is a perspective view of the circularly polarized antenna according to the third embodiment. Fig. 7(A) and Fig. 7(B) are perspective views showing a part of the circularly polarized antenna according to the third embodiment.

[0064] 6, 7(A) and 7(B), the circularly polarized antenna 1B according to the third embodiment differs from the circularly polarized antenna 1 according to the first embodiment in that it includes a plurality of linear elements 111B-114B. Other configurations of the circularly polarized antenna 1B are similar to those of the circularly polarized antenna 1, and a description of similar parts will be omitted.

[0065] The circularly polarized antenna 1B includes a linear element 111B, a linear element 112B, a linear element 113B, and a linear element 114B.

[0066] The linear element 111B includes a sub-linear element 1111 and a sub-linear element 1112. The sub-linear element 1111 and the sub-linear element 1112 have substantially the same shape as the linear element 111 of the above-described embodiment.

[0067] One end of the sub linear element 1111 and one end of the sub linear element 1112 are connected near a connection point 131 of the loop element 12. The connection point of one end of the sub linear element 1111 and the connection point of one end of the sub linear element 1112 are arranged on either side of the connection point 131 in the circumferential direction of the loop element 12. The distance between the connection point of one end of the sub linear element 1111 and the connection point 131 is approximately the same as the distance between the connection point of one end of the sub linear element 1112 and the connection point 131.

[0068] The other end of the secondary linear element 1111 and the other end of the secondary linear element 1112 are connected to each other and are then connected to the feed conductor 31 .

[0069] One end of the sub linear element 1121 and one end of the sub linear element 1122 are connected near a connection point 132 of the loop element 12. The connection point of one end of the sub linear element 1121 and the connection point of one end of the sub linear element 1122 are arranged on either side of the connection point 132 in the circumferential direction of the loop element 12. The distance between the connection point of one end of the sub linear element 1121 and the connection point 132 is approximately the same as the distance between the connection point of one end of the sub linear element 1122 and the connection point 132.

[0070] The other end of the secondary linear element 1121 and the other end of the secondary linear element 1122 are connected to each other and are then connected to the feed conductor 32 .

[0071] One end of the sub linear element 1131 and one end of the sub linear element 1132 are connected near a connection point 133 of the loop element 12. The connection point of one end of the sub linear element 1131 and the connection point of one end of the sub linear element 1132 are arranged on either side of the connection point 133 in the circumferential direction of the loop element 12. The distance between the connection point of one end of the sub linear element 1131 and the connection point 133 is approximately the same as the distance between the connection point of one end of the sub linear element 1132 and the connection point 133.

[0072] The other end of the secondary linear element 1131 and the other end of the secondary linear element 1132 are connected to each other and are then connected to the feed conductor 33 .

[0073] One end of the sub linear element 1141 and one end of the sub linear element 1142 are connected near the connection point 134 of the loop element 12. The connection point of one end of the sub linear element 1141 and the connection point of one end of the sub linear element 1142 are arranged on either side of the connection point 134 in the circumferential direction of the loop element 12. The distance between the connection point of one end of the sub linear element 1141 and the connection point 134 is approximately the same as the distance between the connection point of one end of the sub linear element 1142 and the connection point 134.

[0074] The other end of the secondary linear element 1141 and the other end of the secondary linear element 1142 are connected to each other and are then connected to the feed conductor 34 .

[0075] With this configuration, the circularly polarized antenna 1B can adjust the radiation characteristics and SWR characteristics to further improve the characteristics on the low frequency side and achieve flat characteristics while maintaining the coupling of the staggered tuning method.

[0076] Fig. 8 shows the results of simulating the SWR of the circularly polarized antenna according to the third embodiment. As shown in Fig. 8, the circularly polarized antenna 1B can realize the characteristics that, compared to the circularly polarized antenna 1 of the first embodiment (see Fig. 3), the frequency bands where the SWR is less than 2.0 and the frequency bands where the SWR is less than 1.5 are wider toward the lower frequency side, and further, the bands where the SWR is less than 2.0 and is substantially the same are even wider.

[0077] [Fourth embodiment] A circularly polarized antenna according to a fourth embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a perspective view of the circularly polarized antenna according to the fourth embodiment. Fig. 10(A) and Fig. 10(B) are perspective views showing a part of the circularly polarized antenna according to the fourth embodiment.

[0078] 9, 10(A) and 10(B), the circularly polarized antenna 1C according to the fourth embodiment differs from the circularly polarized antenna 1B according to the third embodiment in that it includes a plurality of linear elements 111C-114C. Other configurations of the circularly polarized antenna 1C are similar to those of the circularly polarized antenna 1B, and a description of similar parts will be omitted.

[0079] Circularly polarized antenna 1C includes linear element 111C, linear element 112C, linear element 113C, and linear element 114C. Circularly polarized antenna 1C does not include the linear elements 121-124 and the connecting conductors 41-44 included in circularly polarized antenna 1B.

[0080] The linear element 111C includes a sub-linear element 1110, a sub-linear element 1111, and a sub-linear element 1112. The sub-linear elements 1111 and 1112 have substantially the same shape as the linear element 111 of the above-described embodiment. The sub-linear element 1110 is shorter than the sub-linear elements 1111 and 1112, and has a length of substantially 1 / 2 the second wavelength.

[0081] One end of the sub-linear element 1110 , one end of the sub-linear element 1111 , and one end of the sub-linear element 1112 are connected to the loop element 12 .

[0082] The connection point between one end of the secondary linear element 1111 and the loop element 12 and the connection point between one end of the secondary linear element 1112 and the loop element 12 are arranged in the circumferential direction of the loop element 12, sandwiching the connection point between one end of the secondary linear element 1110 and the loop element 12.

[0083] The other end of the sub-linear element 1110 , the other end of the sub-linear element 1111 , and the other end of the sub-linear element 1112 are connected to each other and connected to the feed conductor 31 .

[0084] The linear element 112C includes a sub-linear element 1120, a sub-linear element 1121, and a sub-linear element 1122. The sub-linear element 1121 and the sub-linear element 1122 have substantially the same shape as the linear element 112 of the above-described embodiment. The sub-linear element 1120 is shorter than the sub-linear element 1121 and the sub-linear element 1122, and has a length of substantially 1 / 2 the second wavelength.

[0085] One end of the sub-linear element 1120 , one end of the sub-linear element 1121 , and one end of the sub-linear element 1122 are connected to the loop element 12 .

[0086] The connection point between one end of the secondary linear element 1121 and the loop element 12 and the connection point between one end of the secondary linear element 1122 and the loop element 12 are arranged in the circumferential direction of the loop element 12, sandwiching the connection point between one end of the secondary linear element 1120 and the loop element 12.

[0087] The other end of the sub-linear element 1120 , the other end of the sub-linear element 1121 , and the other end of the sub-linear element 1122 are connected to each other and connected to the feed conductor 32 .

[0088] The linear element 113C includes a sub-linear element 1130, a sub-linear element 1131, and a sub-linear element 1132. The sub-linear element 1131 and the sub-linear element 1132 have substantially the same shape as the linear element 113 of the above-described embodiment. The sub-linear element 1130 is shorter than the sub-linear element 1131 and the sub-linear element 1132, and has a length of substantially 1 / 2 the second wavelength.

[0089] One end of the sub-linear element 1130 , one end of the sub-linear element 1131 , and one end of the sub-linear element 1132 are connected to the loop element 12 .

[0090] The connection point between one end of the secondary linear element 1131 and the loop element 12 and the connection point between one end of the secondary linear element 1132 and the loop element 12 are arranged in the circumferential direction of the loop element 12, sandwiching the connection point between one end of the secondary linear element 1130 and the loop element 12.

[0091] The other end of the sub-linear element 1130 , the other end of the sub-linear element 1131 , and the other end of the sub-linear element 1132 are connected to each other and connected to the feed conductor 33 .

[0092] The linear element 114C includes a sub-linear element 1140, a sub-linear element 1141, and a sub-linear element 1142. The sub-linear element 1141 and the sub-linear element 1142 have substantially the same shape as the linear element 114 of the above-described embodiment. The sub-linear element 1140 is shorter than the sub-linear element 1141 and the sub-linear element 1142, and has a length of substantially 1 / 2 the second wavelength.

[0093] One end of the sub-linear element 1140 , one end of the sub-linear element 1141 , and one end of the sub-linear element 1142 are connected to the loop element 12 .

[0094] The connection point between one end of the secondary linear element 1141 and the loop element 12 and the connection point between one end of the secondary linear element 1142 and the loop element 12 are arranged in the circumferential direction of the loop element 12, sandwiching the connection point between one end of the secondary linear element 1140 and the loop element 12.

[0095] The other end of the sub-linear element 1140 , the other end of the sub-linear element 1141 , and the other end of the sub-linear element 1142 are connected to each other and connected to the feed conductor 34 .

[0096] With this configuration, the circularly polarized antenna 1B can maintain the coupling of the staggered tuning method and achieve a wide bandwidth, similar to the circularly polarized antenna 1C.

[0097] Fig. 11 shows the results of simulating the SWR of the circularly polarized antenna according to the fourth embodiment. As shown in Fig. 11, the circularly polarized antenna 1C has a wide frequency band where the SWR is less than 2.0 and a wide frequency band where the SWR is less than 1.5.

[0098] [Fifth embodiment] A circularly polarized antenna according to a fifth embodiment of the present invention will be described with reference to Fig. 12. Fig. 12 is a perspective view of the circularly polarized antenna according to the fifth embodiment.

[0099] 12, the circularly polarized antenna 1D according to the fifth embodiment differs from the circularly polarized antenna 1 according to the first embodiment in that it includes a reflecting member 50. Other configurations of the circularly polarized antenna 1D are similar to those of the circularly polarized antenna 1, and descriptions of similar parts will be omitted.

[0100] The circularly polarized antenna 1D includes a reflecting member 50. The reflecting member 50 is a reflector having a parabolic surface. The reflecting member 50 is disposed on the opposite side of the loop element 12 to the plurality of linear elements 111-114 and 121-124.

[0101] With this configuration, the circularly polarized antenna 1D can be realized as an antenna with higher sensitivity than the circularly polarized antenna 1. The configuration of the reflecting member 50 can also be applied to the above-mentioned circularly polarized antennas 1A, 1B, and 1C.

[0102] [Sixth embodiment] A circularly polarized antenna according to a sixth embodiment of the present invention will be described with reference to the drawings. Fig. 13 is a perspective view of the circularly polarized antenna according to the sixth embodiment. Fig. 14 is a three-sided view of the circularly polarized antenna according to the sixth embodiment.

[0103] 13 and 14, the circularly polarized antenna 1E according to the sixth embodiment differs from the circularly polarized antenna 1 according to the first embodiment in that it uses multiple conductor plates instead of the multiple linear elements used in the circularly polarized antenna 1. Other configurations of the circularly polarized antenna 1E are similar to those of the circularly polarized antenna 1, and a description of similar parts will be omitted.

[0104] The circularly polarized antenna 1E includes a conductor plate 61, a conductor plate 62, a conductor plate 63, and a conductor plate 64. The multiple conductor plates 61, 62, 63, and 64 are flat conductors.

[0105] The outer shape of the conductive plate 61 is similar to the shape formed by the linear elements 111, 121, and the connecting conductor 41 according to the first embodiment.

[0106] The outer shape of the conductive plate 62 is similar to the shape formed by the linear elements 112, 122, and the connecting conductor 42 according to the first embodiment.

[0107] The outer shape of the conductive plate 63 is similar to the shape formed by the linear elements 113, 123, and the connecting conductor 43 according to the first embodiment.

[0108] The outer shape of the conductive plate 64 is similar to the shape formed by the linear elements 114, 124, and the connecting conductor 44 according to the first embodiment.

[0109] With this configuration, the circularly polarized antenna 1E can achieve characteristics similar to those of the circularly polarized antenna 1.

[0110] The configuration using a conductor plate like the circularly polarized antenna 1E can also be applied to the circularly polarized antenna 1A of the second embodiment and the circularly polarized antenna 1D of the fifth embodiment.

[0111] <1> a loop element having a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave; first, second, third and fourth linear elements each having a length of approximately half the first wavelength, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is a power supply point; fifth, sixth, seventh and eighth linear elements, each of which has a length approximately half a second wavelength that is higher than the first frequency and corresponds to a second frequency within the frequency band, one end of each of which is connected to a position that divides a circle of the second wavelength into approximately four equal parts in the circumferential direction, and the other end of each of which is the feeding point; a first connecting conductor connecting one end of a first linear element and one end of a fifth linear element adjacent to each other in a direction perpendicular to a tangent line of the loop element; a second connecting conductor connecting one end of the second linear element and one end of the sixth linear element adjacent to each other in a direction perpendicular to the tangent line of the loop element; a third connecting conductor connecting one end of the third linear element and one end of the seventh linear element adjacent to each other in a direction perpendicular to the tangent line of the loop element; a fourth connecting conductor connecting one end of a fourth linear element and one end of an eighth linear element adjacent to each other in a direction perpendicular to the tangent of the loop element, said fourth connecting conductor connecting one end of the fourth linear element and one end of an eighth linear element adjacent to each other in a direction perpendicular to the tangent of the loop element.

[0112] <2> <1> A circularly polarized antenna comprising: the first linear element, the second linear element, the third linear element, and the fourth linear element each have a portion extending in a direction opposite to the loop element with respect to the power supply point; A circularly polarized antenna, wherein the extending portions have a bent shape that is concave in a direction away from each other.

[0113] <3> <1> or <2> A circularly polarized antenna comprising: each of the first, second, third and fourth linear elements includes a plurality of sub-linear elements; the first linear element is connected to each of the positions on either side of a connection point where the first connecting conductor is connected to the loop element, the second linear element is connected to each of the positions on either side of a connection point where the second connecting conductor is connected to the loop element, the third linear element is connected to each of the positions on either side of a connection point where the third connecting conductor is connected to the loop element, A circularly polarized antenna, wherein the plurality of linear elements of the fourth linear element are connected to respective positions on either side of a connection point where the fourth connecting conductor is connected to the loop element.

[0114] <4> a loop element having a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave; first, second, third and fourth linear elements each having a length of approximately half the first wavelength, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is a power supply point; fifth, sixth, seventh and eighth linear elements, each of which has a length approximately half a second wavelength that is higher than the first frequency and corresponds to a second frequency within the frequency band, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is the feeding point; Equipped with each of the first, second, third and fourth linear elements includes a plurality of sub-linear elements; The first linear element is connected to each of the plurality of linear elements at positions on either side of a connection point at which the fifth linear element is connected to the loop element, The plurality of linear elements of the second linear element are connected to each of the positions sandwiching a connection point where the sixth linear element is connected to the loop element, The third linear element is connected to each of the plurality of linear elements at positions on either side of a connection point at which the seventh linear element is connected to the loop element, A circularly polarized antenna, wherein the plurality of linear elements of the fourth linear element are connected to respective positions on either side of a connection point where the eighth linear element is connected to the loop element.

[0115] <5> <1> ~ <4> A circularly polarized antenna comprising: A circularly polarized antenna comprising a reflecting member arranged on the opposite side of the loop element to a direction in which the first, second, third, and fourth linear elements and the fifth, sixth, seventh, and eighth linear elements extend. [Explanation of symbols]

[0116] 1, 1A, 1B, 1C, 1D: Circularly polarized antennas 12: Loop element 22X: Virtual circle 31-34: Power supply conductor 41-44: Connecting conductor 50: Reflective material 61-64: Conductor plate 111-114, 111A-114A, 111B-114B, 111C-114C: Linear elements 121-124: Linear elements 131, 132, 133, 134: Connection points 1110, 1111, 1112, 1120, 1121, 1122, 1130, 1131, 1132, 1140, 1141, 1142: Minor linear elements BT1, BT2, BT3, BT4: Bent shape Oa:Center PP, PP1, PP2, PP3, PP4: Power supply points

Claims

1. a loop element having a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave; first, second, third and fourth linear elements each having a length of approximately half the first wavelength, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in a circumferential direction, and the other end of each of which is a power supply point; fifth, sixth, seventh and eighth linear elements, each of which has a length that is approximately half a second wavelength that is higher than the first frequency and corresponds to a second frequency within the frequency band, one end of each of which is connected to a position that divides a circle of the second wavelength into approximately four equal parts in the circumferential direction, and the other end of each of which is the feeding point; a first connecting conductor connecting one end of the first linear element and one end of the fifth linear element adjacent to each other in a direction perpendicular to a tangent line of the loop element; a second connecting conductor connecting one end of the second linear element and one end of the sixth linear element adjacent to each other in a direction perpendicular to a tangent line of the loop element; a third connecting conductor connecting one end of the third linear element and one end of the seventh linear element adjacent to each other in a direction perpendicular to a tangent line of the loop element; a fourth connecting conductor connecting one end of the fourth linear element and one end of the eighth linear element adjacent to each other in a direction perpendicular to a tangent line of the loop element; A circularly polarized antenna having

2. 2. The circularly polarized antenna according to claim 1, the first linear element, the second linear element, the third linear element, and the fourth linear element each have a portion extending in a direction opposite to the loop element with respect to the power supply point, The extending portions have a bent shape recessed in a direction away from each other. Circularly polarized antenna.

3. 2. The circularly polarized antenna according to claim 1, each of the first, second, third and fourth linear elements includes a plurality of sub-linear elements; the first linear element is connected to each of the positions on either side of a connection point where the first connecting conductor is connected to the loop element, the second linear element is connected to each of the positions on either side of a connection point where the second connection conductor is connected to the loop element, the third linear element is connected to each of the positions on either side of a connection point at which the third connecting conductor is connected to the loop element, The plurality of linear elements of the fourth linear element are connected to respective positions on either side of a connection point where the fourth connection conductor is connected to the loop element. Circularly polarized antenna.

4. a loop element having a length substantially equal to a first wavelength corresponding to a first frequency in the frequency band of the radiated radio wave; first, second, third and fourth linear elements each having a length of approximately half the first wavelength, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in a circumferential direction, and the other end of each of which is a power supply point; fifth, sixth, seventh and eighth linear elements, each of which has a length that is approximately half a second wavelength that is higher than the first frequency and corresponds to a second frequency within the frequency band, one end of each of which is connected to a position that divides the loop element into approximately four equal parts in the circumferential direction, and the other end of each of which is the feeding point; Equipped with each of the first, second, third and fourth linear elements includes a plurality of sub-linear elements; The first linear element is connected to each of the plurality of linear elements at positions on either side of a connection point at which the fifth linear element is connected to the loop element, The plurality of linear elements of the second linear element are connected to each of the positions sandwiching a connection point where the sixth linear element is connected to the loop element, The third linear element includes a plurality of linear elements connected to each other at positions on either side of a connection point where the seventh linear element is connected to the loop element, The plurality of linear elements of the fourth linear element are connected to each of the positions sandwiching the connection point where the eighth linear element is connected to the loop element. Circularly polarized antenna.

5. 5. A circularly polarized antenna according to claim 1, a reflecting member disposed on the opposite side of the loop element in a direction in which the first, second, third, and fourth linear elements and the fifth, sixth, seventh, and eighth linear elements extend; Circularly polarized antenna.

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