JP7232859B2 - Circularly polarized antenna device - Google Patents

Description

The present invention relates to a circularly polarized wave antenna device, and more particularly to a circularly polarized wave antenna device configured to receive circularly polarized waves using a plurality of linearly polarized wave antenna elements.

A signal from an artificial satellite used in a global positioning system (GPS) is a circularly polarized wave signal, and as a circularly polarized wave antenna device for receiving this signal, a patch antenna using a ceramic or laminated substrate is used. are commonly known. Patch antennas using expensive dielectric materials such as ceramics and laminated substrates are expensive and relatively heavy.

Furthermore, in the recent satellite positioning system (GNSS (Global Navigation Satellite System)), it is possible to receive not only GPS but also signals in multiple frequency bands such as GLONASS and Galileo, so multiband (L1, L2, L5 bands, etc. ) is required. As such a multi-band circularly polarized antenna device, there is known one in which ceramic patch antennas are stacked in multiple stages. However, since the patch antenna is laminated using expensive ceramic materials, the cost is further increased, and the weight is also increased.

Instead of such a patch antenna using expensive and heavy ceramics, there is also known a circularly polarized antenna device configured to be able to receive circularly polarized waves using a plurality of linearly polarized antenna elements (for example, Patent Document 1 ). The antenna device of Patent Document 1 has four inverted F antenna elements arranged point-symmetrically on a ground plane when viewed from above. Parallel feeding is performed using a plurality of phase shifters in order to give a phase difference to each feeding point of these four inverted F antenna elements and realize four-point feeding. Specifically, a 180-degree phase shifter that distributes the signal from the low-noise amplifier to two paths, and a signal with a phase difference of 90 degrees from each of the distributed paths to the two feeding points. A feed circuit using a 90 degree phase shifter that distributes to .

JP 2015-037240 A

Parallel feeding circuits such as those of the prior art required the use of a plurality of phase shifters , resulting in an increase in size. In addition, when trying to mount a low-noise amplifier circuit, which is generally required in a circularly polarized wave antenna device for GNSS, on a circuit board together with a phase shifter , it was difficult to mount on a single-sided board due to the layout.

SUMMARY OF THE INVENTION In view of such circumstances, it is an object of the present invention to provide a circularly polarized antenna device that is inexpensive, compact, and lightweight.

In order to achieve the object of the present invention described above, a circularly polarized wave antenna device according to the present invention includes at least three or more feeding points, a synthesis point for feeding power in series to each feeding point, and a ground layer. and a circularly polarized antenna configured to receive circularly polarized waves having at least three or more linearly polarized antenna elements erected on the circuit board and connected to respective feeding points, A series feed circuit for supplying power from a combining point to each feed point in series, the series feed circuit including a plurality of transmission lines extending between and connecting each feed point in series. and an impedance transformer extending between the feed point and the combining point at the ends of a plurality of transmission lines connected in series, the plurality of transmission lines and the impedance transformer for each linearly polarized antenna element. Each transmission line has a characteristic impedance that is adjusted so that the received signal amplitudes are substantially equal, and the line length of each transmission line is configured so that the phase difference of each linearly polarized antenna element is substantially equal. and a circuit.

Here, each linearly polarized wave antenna element of the circularly polarized wave antenna may be composed of an inverted L-shaped element or an inverted F-shaped element.

Further, each linearly polarized wave antenna element of the circularly polarized wave antenna may be made of a sheet metal element having a line width in a direction perpendicular to the circuit board.

In addition, the circularly polarized antenna has at least three or more linearly polarized antenna elements so as to be able to receive circularly polarized waves in a plurality of frequency bands. may be coaxially arranged.

In addition, the impedance converter of the series feeding circuit, in order from the side farthest from the combining point, for the combined impedance obtained by combining the characteristic impedance of the linearly polarized antenna element connected to each feeding point and the characteristic impedance of the transmission line, It is sufficient if impedance conversion is performed so that matching can be obtained at the synthesis point.

Further, it is sufficient that an amplifier circuit is provided, and the amplifier circuit is arranged in the central portion of the circularly polarized antenna when viewed from the top of the circuit board.

Moreover, the circularly polarized wave antennas arranged coaxially may be molded by insert molding so that the portions other than the feeding terminals thereof are sealed.

Further, in the manufacturing method of the circularly polarized antenna device of the present invention, the linearly polarized antenna element of the first frequency band and the linearly polarized antenna element of the second frequency band are paired as one pair, and the feeding terminals thereof are connected to each other. Prepare four sheet metal elements that are integrally molded so that the linearly polarized wave antenna element of the second frequency band is the first frequency The four sheet metal elements are arranged so as to be inside the linearly polarized wave antenna element of the band, and are inserted so that the parts other than the part integrally molded so that the feeding terminal is connected are sealed. The linearly polarized antenna element for the first frequency band and the linearly polarized antenna element for the second frequency band are electrically connected by molding and cutting the integrally molded portion so that the feed terminal is connected. a circuit board having eight feed points and a ground plane, the molded and electrically isolated linearly polarized antenna element for a first frequency band and the linearly polarized antenna for a second frequency band; It is sufficient to electrically connect each feed terminal of the element to each feed point on the provided circuit board.

The circularly polarized wave antenna device of the present invention has the advantage of being inexpensive, compact and lightweight.

FIG. 1 is a schematic perspective view for explaining a circularly polarized wave antenna device of the present invention. FIG. 2 is a circuit diagram showing a series feeding circuit of the circularly polarized antenna device of the present invention by a lumped constant circuit. FIG. 3 is a graph of frequency characteristics of the series feeding circuit of the circularly polarized antenna device of the present invention designed as shown in FIG. FIG. 4 is a schematic perspective view for explaining a case where the circularly polarized wave antenna device of the present invention has three linearly polarized wave antenna elements. FIG. 5 is a schematic top view for explaining the configuration of the circularly polarized antenna device of the present invention so as to be compatible with circularly polarized waves in a plurality of frequency bands. FIG. 6 is a schematic top view for explaining a specific example of the series feeding circuit of the circularly polarized antenna device of the present invention. FIG. 7 is a schematic perspective view for explaining a manufacturing method when the circularly polarized wave antenna device of the present invention is configured to be compatible with circularly polarized waves in a plurality of frequency bands.

Hereinafter, embodiments for carrying out the present invention will be described together with illustrated examples. FIG. 1 is a schematic perspective view for explaining a circularly polarized wave antenna device of the present invention. As shown in the figure, the circularly polarized wave antenna device of the present invention is mainly composed of a circuit board 10, a circularly polarized wave antenna 20, and a series feeding circuit 30. As shown in FIG. The illustrated circularly polarized antenna device can be used, for example, as a circularly polarized antenna device for L2 band and L5 band of GNSS. Further, the circularly polarized wave antenna device of the present invention can be used for circularly polarized waves, and can be applied to, for example, SDARS (Satellite Digital Audio Radio Services).

The circuit board 10 has a plurality of feed points 11 , 12 , 13 , 14 , a combining point 15 and a ground plane 16 . The circuit board 10 is, for example, a double-sided board, and the ground layer 16 may be provided on the back surface. A ground layer may be provided on the surface side by appropriately patterning the feeding points. In the illustrated example, there are four feeding points, and a first feeding point 11, a second feeding point 12, a third feeding point 13, and a fourth feeding point 14 are arranged clockwise on the circuit board 10. there is Combining point 15 is for feeding these in series. That is, the synthesis point 15 is a portion obtained by synthesizing the feed points in series.

The circularly polarized antenna 20 has a plurality of linearly polarized antenna elements 21 , 22 , 23 and 24 . The linearly polarized antenna elements 21, 22, 23 and 24 are erected on the circuit board 10 and connected to the feeding points 11, 12, 13 and 14, respectively. Circularly polarized wave antenna 20 is configured to be able to receive circularly polarized waves using a plurality of linearly polarized wave antenna elements 21 , 22 , 23 , and 24 . In the illustrated example, the first linearly polarized antenna element 21, the second linearly polarized antenna element 22, the third linearly polarized antenna element 23, and the fourth linearly polarized antenna element 24 are rectangular in top view. are placed in More specifically, a plurality of linearly polarized antenna elements 21, 22, 23, and 24 are arranged point-symmetrically clockwise. Moreover, each of the linearly polarized wave antenna elements 21, 22, 23, and 24 has shown an example in which each is composed of a linear inverted L-shaped element. However, the present invention is not limited to this, and may be configured with, for example, an inverted F-shaped element. Each linearly polarized antenna element constituting the circularly polarized antenna 20 does not necessarily have to be an inverted L-shaped element or an inverted F-shaped element. Any possible element is fine. Also, the linearly polarized wave antenna element is not limited to a linear element, and may be arranged on a circuit board or formed of a sheet metal element, for example.

The series feeding circuit 30 is for feeding the respective feeding points 11, 12, 13 and 14 in series from the combining point 15. FIG. The series feeding circuit 30 has a plurality of transmission lines 31 , 32 , 33 and an impedance converter 34 . A plurality of transmission lines 31, 32, 33 extend between the feeding points and connect the feeding points in series. Specifically, in the illustrated example, the first transmission line 31 extends between the first feeding point 11 and the second feeding point 12, and the second transmission line 32 extends between the second feeding point 12 and the third feeding point. 13 and a third transmission line 33 extends between the third feeding point 13 and the fourth feeding point 14 . These are connected in series to form one transmission line. The impedance converter 34 extends between the feed points at the ends of the plurality of transmission lines connected in series, specifically between the fourth feed point 14 and the combining point 15 . The plurality of transmission lines 31, 32, 33 and the impedance converter 34 each have a characteristic impedance that is adjusted so that the received signal amplitudes of the linearly polarized antenna elements 21, 22, 23, 24 are substantially equal. is configured as Further, the line lengths of the transmission lines 31, 32, 33 are configured so that the phase differences of the linearly polarized antenna elements 21, 22, 23, 24 are substantially equal. That is, when using the four linearly polarized antenna elements 21, 22, 23 and 24, the transmission line should shift the phase by 90 degrees (λ/4). Specifically, the transmission line may be a λ/4 line.

A more specific configuration of the series feeding circuit will be described below using a lumped constant circuit. FIG. 2 is a circuit diagram showing a series feeding circuit of the circularly polarized antenna device of the present invention by a lumped constant circuit. In the figure, the parts denoted by the same reference numerals as those in FIG. 1 represent the same parts. In this example, each linearly polarized antenna element 21, 22, 23, 24 and each transmission line 31, 32, 33 is represented by an LC circuit. Specifically, for example, each linearly polarized antenna element 21, 22, 23, 24 shall have a characteristic impedance of 50Ω. Also, the transmission lines 31, 32, 33 are assumed to shift the phase by 90 degrees. As shown, the first feeding point 11 is connected to a first linearly polarized antenna element 21 represented by an LC circuit. A first transmission line 31 represented by an LC circuit is connected between the first feeding point 11 and the second feeding point 12 . Since the first linearly polarized antenna element 21 having a characteristic impedance of 50Ω is connected to the first feeding point 11, the characteristic impedance of the first transmission line 31 is configured to be 50Ω. At the second feeding point 12, the characteristic impedance of 50 Ω of the first transmission line 31 and the characteristic impedance of 50 Ω of the second linearly polarized antenna element 22 join, resulting in a combined impedance of 25 Ω ((50×50)/(50+50) ). Therefore, the characteristic impedance of the second transmission line 32 is configured to be 25Ω. Similarly, at the third feeding point 13, the characteristic impedance of 25Ω of the second transmission line 32 and the characteristic impedance of 50Ω of the third linearly polarized antenna element 23 join together, resulting in a combined impedance of 16.7Ω ((25×50 )/(25+50)). Therefore, the characteristic impedance of the third transmission line 33 is configured to be 16.7Ω. Further, at the fourth feeding point 14, the characteristic impedance of 16.7Ω of the third transmission line 33 and the characteristic impedance of 50Ω of the fourth linearly polarized antenna element 24 join together, resulting in a combined impedance of 12.5Ω ((16. 7×50)/(16.7+50)). Therefore, the impedance converter 34 may convert the combined impedance of 12.5Ω so that matching can be achieved with 50Ω at the combined point 15 . That is, the impedance converter 34 may be configured to perform impedance conversion of 25Ω (√(12.5×50)). The impedance converter 34 may perform impedance conversion while shifting the phase using a λ/4 line, or may perform only impedance conversion using an LC matching circuit.

The serial feeding circuit of the circularly polarized antenna device of the present invention is configured in this way, so that the received signal amplitudes of the linearly polarized antenna elements 21, 22, 23, and 24 are adjusted to be substantially equal. It will be. Then, the transmission lines 31, 32, 33 enable feeding so that the feeding points 11, 12, 13, 14 have a phase difference of 90 degrees. Thereby, it is configured to be able to receive circularly polarized waves.

FIG. 3 is a graph of frequency characteristics of the series feeding circuit of the circularly polarized antenna device of the present invention designed as shown in FIG. FIG. 3(a) represents the amplitude ratio between the paths, and FIG. 3(b) represents the phase difference between the paths. As can be seen from the frequency characteristics of FIG. 3(a), according to the series feeding circuit of the circularly polarized wave antenna device of the present invention, four feeding points can be synthesized with substantially the same amplitude. Further, as can be seen from the frequency characteristics of FIG. 3(b), according to the series feeding circuit of the circularly polarized wave antenna device of the present invention, four feeding points can be synthesized so as to be approximately equal with a phase difference of approximately 90 degrees. ing.

It should be noted that the specific characteristic impedance values described above are merely examples, and the present invention is not limited to these. Also, for example, even if the characteristic impedance of each linearly polarized antenna element is not 50Ω but different from each other, it is possible to configure an appropriate transmission line and impedance converter by obtaining the combined impedance in the same manner as described above. .

In the examples so far, four linearly polarized antenna elements are used to receive circularly polarized waves. The present invention is not limited to this, and can be configured to receive circularly polarized waves as long as there are three or more linearly polarized antenna elements. That is, at least three or more linearly polarized wave antenna elements are sufficient, and the circuit board may also have three or more feeding points. FIG. 4 is a schematic perspective view for explaining a case where the circularly polarized wave antenna device of the present invention has three linearly polarized wave antenna elements. In the figure, the parts denoted by the same reference numerals as those in FIG. 1 represent the same parts. As shown in FIG. 4, the circuit board 10 has three feed points 11, 12, 13 and a combining point 15. As shown in FIG. Also, three linearly polarized antenna elements 21, 22, 23 are connected to the feed points 11, 12, 13, respectively. Three linearly polarized wave antenna elements 21, 22, and 23 are arranged in a triangular shape when viewed from above so that circularly polarized waves can be received. The linearly polarized wave antenna elements 21, 22, and 23 in the illustrated examples are made of sheet metal elements having a line width in the direction perpendicular to the circuit board 10. FIG. However, the present invention is not limited to this, and linear elements may be used. By providing a linewidth, it becomes possible to adjust the band of the linearly polarized antenna element. Moreover, the linearly polarized wave antenna elements 21, 22, and 23 have shown an example in which the open end side is bent downward in order to secure the element length.

In this example, the series feeding circuit 30 has two transmission lines 31, 32 extending between the feeding points 11, 12, 13 and connecting the feeding points 11, 12, 13 in series. It also has an impedance converter 34 between the third feed point 13 and the combining point 15 at the end of the transmission line. As a result, the transmission lines 31 and 32 have a phase difference of 120 degrees so that the phase differences between the feeding points 11, 12 and 13 are substantially equal, for example, by the same method as described above. It should be configured as follows. Further, it is sufficient to use the transmission lines 31, 32 and the impedance converter 34 so as to have a characteristic impedance such that the received signal amplitudes of the linearly polarized antenna elements 21, 22, 23 are substantially equal. .

The number of elements of the circularly polarized wave antenna device of the present invention is not particularly limited as long as it is configured to receive circularly polarized waves. For example, it may be composed of five linearly polarized wave antenna elements arranged in a pentagonal shape, six linearly polarized wave antenna elements arranged in a hexagonal shape, or the like.

The circularly polarized wave antenna device of the present invention can further be configured to support circularly polarized waves in a plurality of frequency bands. For example, it can be configured to be compatible with GNSS L1, L2, and L5 bands. FIG. 5 is a schematic top view for explaining the configuration of the circularly polarized antenna device of the present invention so as to be compatible with circularly polarized waves in a plurality of frequency bands. In the figure, the parts denoted by the same reference numerals as those in FIG. 1 represent the same parts. As illustrated, in this example, a plurality of circularly polarized antennas are coaxially arranged. That is, the outer first circularly polarized antenna 20a and the inner second circularly polarized antenna 20b are arranged coaxially. Note that the inner circularly polarized antenna has a higher frequency element than the outer one. The first circularly polarized antenna 20a has four linearly polarized antenna elements 21a, 22a, 23a, and 24a, and is configured to be able to receive circularly polarized waves in the L2 and L5 bands, for example. The second circularly polarized antenna 20b has four linearly polarized antenna elements 21b, 22b, 23b, and 24b, and is configured to be able to receive, for example, L1 band circularly polarized waves. Note that another circularly polarized antenna may be arranged coaxially so as to be compatible with another frequency band.

The first circularly polarized antenna 20a and the second circularly polarized antenna 20b are fed in series by a first series feeding circuit 30a and a second series feeding circuit 30b, respectively. Each power supply circuit may be configured in the same manner as the example illustrated above. That is, the circuit board may be provided with eight feeding points 11a-14a and 11b-14b, and each feeding circuit may feed in series. Specifically, the series feeding circuit 30a has a plurality of transmission lines 31a, 32a, 33a and an impedance converter 34a. A plurality of transmission lines 31a, 32a, and 33a extend between the feeding points and connect the feeding points in series. The impedance converter 34a extends between the feeding points at the ends of the plurality of transmission lines connected in series, specifically between the fourth feeding point 14a and the combining point 15a. The plurality of transmission lines 31a, 32a, 33a and the impedance converter 34a each have a characteristic impedance that is adjusted so that the received signal amplitudes of the linearly polarized antenna elements 21a, 22a, 23a, 24a are substantially equal. is configured as Further, the line lengths of the transmission lines 31a, 32a, 33a are configured so that the phase differences of the linearly polarized antenna elements 21a, 22a, 23a, 24a are substantially equal. The first circularly polarized antenna 20a is fed in series by the series feeding circuit 30a configured as described above. Also, the series feeding circuit 30b has a plurality of transmission lines 31b, 32b, 33b and an impedance converter 34b. A plurality of transmission lines 31b, 32b, and 33b extend between the feeding points and connect the feeding points in series. The impedance converter 34b extends between the feeding points at the ends of the plurality of transmission lines connected in series, specifically between the fourth feeding point 14b and the combining point 15b. The plurality of transmission lines 31b, 32b, 33b and the impedance converter 34b each have a characteristic impedance that is adjusted so that the received signal amplitudes of the linearly polarized antenna elements 21b, 22b, 23b, 24b are substantially equal. is configured as The transmission lines 31b, 32b, 33b are configured to have substantially the same phase difference between the linearly polarized antenna elements 21b, 22b, 23b, 24b. The second circularly polarized antenna 20b is fed in series by the series feeding circuit 30b configured as described above.

Since a plurality of circularly polarized antennas can be arranged coaxially in this way, the height does not increase as compared with the case of stacking patch antennas. Furthermore, since there is a space in the center of the circularly polarized wave antenna when viewed from above, it is also possible to arrange an amplifier circuit in this space. That is, as shown in FIG. 5, the amplifier circuit 40 may be arranged in the central portion of the circularly polarized antennas 20a and 20b when viewed from the top of the circuit board 10. As shown in FIG.

It should be noted that, instead of the example in which a plurality of circularly polarized wave antennas are coaxially arranged, even in the case of one circularly polarized wave antenna shown in FIG. 1, the amplifier circuit can be similarly arranged in the central portion.

Also, even in an example in which a plurality of circularly polarized wave antennas are coaxially arranged, the number of linearly polarized wave antenna elements is not particularly limited as long as each circularly polarized wave antenna is configured to be able to receive circularly polarized waves.

In the circularly polarized wave antenna device of the present invention, the linearly polarized wave antenna element does not have to be straight when viewed from above, and may be curved along a circle. Furthermore, the transmission line does not have to be straight when viewed from above, and may be curved along its extension. FIG. 6 is a schematic top view for explaining a specific example of the series feeding circuit of the circularly polarized antenna device of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIG. 1 represent the same parts. This example has two series feeding circuits 30a and 30b in order to be able to handle circularly polarized waves in a plurality of frequency bands. The series feeding circuits 30a, 30b are composed of transmission lines 31a-33a; 31b-33b curved along a circle and impedance converters 34a, 34b. Each transmission line has a line length such that the phase difference is substantially equal. In addition, it has a line width such that it has a characteristic impedance at which the received signal amplitude is approximately the same. Such transmission lines are patterned on the circuit board 10 .

Next, a method for manufacturing the circularly polarized wave antenna device of the present invention will be described with reference to FIG. FIG. 7 is a schematic perspective view for explaining a manufacturing method when the circularly polarized wave antenna device of the present invention is configured to be compatible with circularly polarized waves in a plurality of frequency bands. In the figure, the parts with the same reference numerals as those in FIG. 5 represent the same parts. This manufacturing method can be applied to a circularly polarized wave antenna device in which a plurality of circularly polarized wave antennas are coaxially arranged so as to be compatible with circularly polarized waves in a plurality of frequency bands as shown in FIG.

First, as shown in FIG. 7(a), a sheet metal element 20' is formed. The sheet metal element 20' includes a linearly polarized antenna element 21a (22a, 23a, 24a) for the first circularly polarized antenna 20a on the low frequency side and a linearly polarized antenna element 21a (22a, 23a, 24a) for the second circularly polarized antenna 20b on the high frequency side. The elements 21b (22b, 23b, 24b) are formed as one pair and are integrally formed so that the respective feed terminals 25a, 25b (26a, 26b; 27a, 27b; 28a, 28b) are connected. Four sheet metal elements 20' are prepared.

Next, as shown in FIG. 7(b), the prepared four sheet metal elements 20' are arranged point-symmetrically in a top view, with the linearly polarized wave antenna elements 21b, 22b, 23b, and 24b on the high frequency side being low frequency. are arranged inside the linearly polarized wave antenna elements 21a, 22a, 23a, and 24a on the side. That is, the four sheet metal elements 20' are arranged in a rectangular shape in such a direction that the power supply terminals 25a, 25b (26a, 26b; 27a, 27b; 28a, 28b) face outward. In the illustrated example, an example in which the linearly polarized wave antenna element on the high frequency side is arranged inside the linearly polarized wave antenna element on the low frequency side has been described, but the present invention is not limited to this, and vice versa. Also good. That is, by adding an inductor, a meander, or the like to shorten the electrical length or increase the height, the antenna element on the low-frequency side having the longer electrical length may be placed inside.

The four sheet metal elements 20' arranged in this manner are sealed except for the portions integrally formed so that the power supply terminals 25a and 25b (26a and 26b; 27a and 27b; 28a and 28b) are connected. It is molded by insert molding so as to be fixed. That is, insert molding is performed so that only the power supply terminal portion is exposed.

After the sheet metal element 20' is sealed by insert molding, the integrally molded portion is cut so that the power supply terminals 25a and 25b (26a and 26b; 27a and 27b; 28a and 28b) are connected, thereby reducing the The linearly polarized wave antenna elements 21a, 22a, 23a, 24a on the frequency side and the linearly polarized wave antenna elements 21b, 22b, 23b, 24b on the high frequency side are electrically separated. As a result, the outer first circularly polarized antenna 20a and the inner second circularly polarized antenna 20b are formed.

In this way, by performing insert molding in a state in which the power supply terminals are connected to each other, it is possible to prevent distortion of the sheet metal element during insert molding and during transportation for connection to the circuit board. Easier handling in stages.

Then, as shown in FIG. 7(c), a circuit board 10 having eight feeding points 11a-14a, 11b-14b and a ground layer is prepared. Finally, feed terminals 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, 25a, respectively of the molded and electrically separated linearly polarized antenna elements 21a, 22a, 23a, 24a on the low frequency side and the linearly polarized antenna elements 21b, 22b, 23b, 24b on the high frequency side; 26a, 26b; 27a, 27b; 28a, 28b are electrically connected to respective feed points 11a-14a, 11b-14b on the provided circuit board.

Moreover, it is also possible to appropriately place a wave director, a parasitic element, or the like in the molded upper space.

In the illustrated example, an example in which insert molding is performed in a state in which the power supply terminals are integrally formed so as to be connected has been described, but the present invention is not limited to this. For example, even if the feeding terminal of the sheet metal element is not connected and the linearly polarized wave antenna element on the low frequency side and the linearly polarized wave antenna element on the high frequency side are separated, the sheet metal that makes them one pair Prepare four elements, place them so that the linearly polarized antenna element on the high frequency side is inside the linearly polarized antenna element on the low frequency side, and then perform insert molding so that everything other than the feeding terminal is sealed. It may be molded by That is, a plurality of circularly polarized wave antennas arranged coaxially may be molded by insert molding so that the portions other than the feeding terminals thereof are sealed. Even in a state in which the feeding terminals are separated in this way, the antenna element can be modularized by insert molding, which facilitates handling in the manufacturing stage.

The circularly polarized wave antenna device of the present invention is manufactured in this way, so that even when the circularly polarized wave antennas are coaxially arranged so as to be able to handle circularly polarized waves in a plurality of frequency bands, it can be easily It is manufacturable.

It should be noted that the circularly polarized wave antenna device of the present invention is not limited to the illustrated examples described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

REFERENCE SIGNS LIST 10 circuit board 11 first feeding point 12 second feeding point 13 third feeding point 14 fourth feeding point 15 combining point 16 ground layer 20 circularly polarized antenna 20a first circularly polarized antenna 20b second circularly polarized antenna 20' Sheet metal element 21 1st linearly polarized antenna element 22 2nd linearly polarized antenna element 23 3rd linearly polarized antenna element 24 4th linearly polarized antenna element 25a, 25b feeding terminal 30 series feeding circuit 31 first transmission line 32 th 2 transmission line 33 third transmission line 34 impedance converter 40 amplifier circuit

Claims (8)

A circularly polarized antenna device capable of receiving circularly polarized waves, the circularly polarized antenna device comprising:
a circuit board having at least three or more feeding points, a combining point for feeding power to each feeding point in series, and a ground plane;
a circularly polarized antenna having at least three or more linearly polarized antenna elements erected on a circuit board and connected to respective feeding points, and configured to be able to receive circularly polarized waves;
A series feed circuit for supplying power from a combining point to each feed point in series, the series feed circuit including a plurality of transmission lines extending between and connecting each feed point in series. and an impedance transformer extending between the feed point and the combining point at the ends of a plurality of transmission lines connected in series, the plurality of transmission lines and the impedance transformer for each linearly polarized antenna element. Each transmission line has a characteristic impedance that is adjusted so that the received signal amplitudes are substantially equal, and the line length of each transmission line is configured so that the phase difference of each linearly polarized antenna element is substantially equal. a circuit;
A circularly polarized antenna device comprising: 2. The circularly polarized wave antenna device according to claim 1, wherein each linearly polarized wave antenna element of said circularly polarized wave antenna is composed of an inverted L-shaped element or an inverted F-shaped element. . 3. The circularly polarized wave antenna device according to claim 1, wherein each linearly polarized wave antenna element of the circularly polarized wave antenna is made of a sheet metal element having a line width in a direction perpendicular to the circuit board. A circularly polarized antenna device. 4. The circularly polarized wave antenna device according to claim 1, wherein the circularly polarized wave antenna has at least three or more linearly polarized waves so as to be compatible with circularly polarized waves in a plurality of frequency bands. 1. A circularly polarized wave antenna device comprising a plurality of circularly polarized wave antennas having antenna elements and configured to be able to receive circularly polarized waves arranged coaxially. 5. The circularly polarized wave antenna device according to claim 1, wherein the impedance converter of the series feeding circuit is a linearly polarized wave antenna element connected to each feeding point in order from the side farthest from the combining point. A circularly polarized wave antenna device characterized in that impedance conversion is performed so that matching can be achieved at a synthesis point with respect to a synthesized impedance obtained by synthesizing the characteristic impedance of a transmission line and the characteristic impedance of a transmission line. 6. The circularly polarized wave antenna device according to any one of claims 1 to 5, further comprising an amplifier circuit, wherein the amplifier circuit is arranged at the center of the circularly polarized antenna when viewed from above the circuit board. A circularly polarized antenna device characterized by: 7. The circularly polarized wave antenna device according to any one of claims 4 to 6, wherein the plurality of circularly polarized wave antennas arranged coaxially are molded by insert molding so that the portions other than the feeding terminals thereof are sealed. A circularly polarized antenna device characterized by: A method for manufacturing a circularly polarized wave antenna device according to any one of claims 4 to 7, wherein the method for manufacturing the circularly polarized wave antenna device comprises:
Four sheet metal elements integrally molded so that each pair of linearly polarized wave antenna elements of the first frequency band and linearly polarized wave antenna elements of the second frequency band are connected to each feeder terminal. prepare,
Arrange the prepared four sheet metal elements point symmetrically in a top view so that the linearly polarized antenna element for the second frequency band is inside the linearly polarized antenna element for the first frequency band,
Molding the arranged four sheet metal elements by insert molding so that the parts other than the parts integrally molded so as to connect the power supply terminals are sealed,
The low-frequency side linearly polarized wave antenna element and the high frequency side linearly polarized wave antenna element are electrically separated by cutting the integrally molded part so that the feeding terminal is connected,
providing a circuit board having eight feed points and a ground plane;
The feeding terminals of the molded and electrically separated linearly polarized wave antenna element on the low frequency side and the linearly polarized wave antenna element on the high frequency side are electrically connected to respective feeding points on the provided circuit board. ,
A method of manufacturing a circularly polarized antenna device, characterized by:

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