Compact mobile body

Abstract

The present disclosure relates to a compact mobile body. The compact mobile body is provided with a wireless communication device and a dipole antenna having two antenna elements. The two antenna elements are fixed so as to form an angle that is: equal to or greater than an angle at which a required gain can be ensured; but equal to or less than 180 degrees.

Description

small mobile object

[0001] The present disclosure relates to small vehicles.

[0002] Patent Literature 1 discloses a technology using a drone equipped with a wireless communication device. Thus, there is a demand for a wireless communication device to be equipped on a small mobile object. The small mobile object is, for example, a motorcycle, a small passenger car, or a small flying object such as a drone.

[0003] Furthermore, Patent Document 2 discloses a technology for mounting a wireless communication device using a monopole antenna on a drone. A monopole antenna operates by grounding one end of the antenna, and is therefore smaller than other antennas. Therefore, when mounting a wireless communication device on a small mobile object with limited mounting space, a monopole antenna is often used, particularly for transmitting and receiving radio waves at frequencies such as the HF band.

[0004] Kohei Kawabata; Hiroyuki Arai, “Wind Influence of Air Wire Antenna Suspended from Drone”, 2018 International Symposium on Antennas and Propagation, October 2018.Koki Ito, Katsuyuki Fujii, Yasuyuki Okumura, Masahiro Umehira, “Effect of Unmanned Aerial Vehicles for Electromagnetic Field Measurement on Near Field of “High-frequency-Band Monopole Antennas”, 2023 IEEE 12th Global Conference on Consumer Electronics, October 2023.

[0005] However, because small mobile devices have limited mounting space, wireless communication devices mounted on small mobile devices are often installed near electronic devices that emit electromagnetic noise. This means that the level of noise entering the received signal at the antenna is high. As a result, wireless communication quality using wireless communication devices mounted on small mobile devices is prone to degradation.

[0006] In particular, in order to transmit and receive relatively low-frequency radio waves in HF bands and other communications, a large conductive plate is required as a ground. Monopole antennas mounted on small mobile objects cannot accommodate a large conductive plate in the small mounting space, making it difficult to obtain a stable grounding environment. As a result, wireless communications using monopole antennas have the problem of further deterioration in communication quality.

[0007] In order to solve the above-mentioned problems, the present disclosure aims to provide a small mobile object capable of improving the communication quality of the wireless communication device mounted thereon.

[0008] An aspect of the present disclosure is preferably a small mobile body comprising a wireless communication device and a dipole antenna having two antenna elements, the two antenna elements being fixed at an angle greater than or equal to an angle that ensures the required gain and less than or equal to 180 degrees.

[0009] According to the aspects of the present disclosure, the communication quality of the wireless communication device equipped therewith can be improved.

[0010] FIG. 1 is a diagram showing a small mobile body according to a first embodiment of the present disclosure; FIG. 2 is a block diagram showing a configuration example of a small mobile body according to a first embodiment of the present disclosure; FIG. 3 is a diagram showing details of a small mobile body according to a first embodiment of the present disclosure; FIG. 4 is a diagram showing an example of use of a monopole antenna; FIG. 5 is a diagram showing a small mobile body according to a first comparative example; FIG. 6 is a block diagram showing a configuration example of a small mobile body according to a first comparative example; FIG. 7 is a diagram showing interference with wireless communication of a monopole antenna according to a first comparative example; FIG. 8 is a diagram showing a small mobile body according to a second comparative example; FIG. 9 is a diagram showing a small mobile body according to a third comparative example; FIG. 10 is a diagram showing a small mobile body according to a fourth comparative example.

[0011] Embodiment 1 [Configuration of a Small Mobile Body According to Embodiment 1 of the Present Disclosure] Fig. 1 is a diagram showing a small mobile body according to Embodiment 1 of the present disclosure. In this disclosure, an example in which the small mobile body is a drone is shown, but the present disclosure is not limited to this. In other words, the small mobile body may be a motorcycle, a small passenger car, or a small aerial vehicle including a drone.

[0012] The small vehicle 100 is equipped with a skid 2. The skid 2 is a landing gear, and is a base used when the small vehicle 100 lands.

[0013] A base 4 is installed on the skid 2. Four rotors 6 are connected to the base 4. The rotors 6 are fixed to supports fixed vertically to the base 4 and rotate horizontally relative to the base 4. The rotors 6 levitate the small mobile object 100 by rotating. This motor generates electromagnetic noise.

[0014] A wireless communication device 8 is mounted on the base 4. A dipole antenna 10 is mounted on the wireless communication device 8.

[0015] The dipole antenna 10 has a support 14 fixed perpendicular to the mounting surface, and antenna elements 32a and 32b fixed to the support. The antenna elements 32a and 32b are fixed at an angle between an angle that ensures the required gain and an angle that is 180 degrees or less. It is preferable that the lengths of the antenna elements 32a and 32b are the same to improve radiation efficiency.

[0016] Because the dipole antenna 10 is an ungrounded antenna, it does not require a conductor plate and can perform good wireless communication even in a small installation space where a stable grounding environment cannot be obtained. Therefore, by using the dipole antenna 10, communication quality can be improved even if the wireless communication device 8 is installed near electronic devices such as motors that emit electromagnetic noise.

[0017] 2 is a block diagram showing an example of the configuration of the small moving body according to the first embodiment of the present disclosure, in which the skid 2 and the rotor 6 are omitted.

[0018] The small mobile object 100 includes a base 4. A wireless communication device 8 is fixed on the base 4 using a holder 5. The wireless communication device 8 is connected to a balun 12 via a coaxial cable 7. The balun 12 is an element that converts between a balanced circuit and an unbalanced circuit.

[0019] The balun 12 is connected to the antenna element 38a via the cable 9. The antenna element 38a is connected to the loading coil 34a. The loading coil 34a is connected to the antenna element 36a.

[0020] The balun 12 is also connected to the antenna element 38b via the cable 9. The antenna element 38b is connected to the loading coil 34b. The loading coil 34b is connected to the antenna element 36b.

[0021] The antenna element 38a, the loading coil 34a, and the antenna element 36a constitute an antenna element 32a, which will be described later. It is preferable that the antenna element 38a, the loading coil 34a, and the antenna element 36a are fixed in a straight line.

[0022] The antenna element 38b, the loading coil 34b, and the antenna element 36a constitute an antenna element 32b, which will be described later. It is preferable that the antenna element 38b, the loading coil 34b, and the antenna element 36a are fixed in a straight line.

[0023] Furthermore, the antenna element 32a and the antenna element 32b constitute the dipole antenna 10. The antenna element 32a and the antenna element 32b may be fixed to the balun 12 to form a specific angle, or may be fixed to the holder 5 to form a specific angle.

[0024] Furthermore, a support 14 is fixed onto the base 4 using a holder 5. The support 14 is a jig for stabilizing the antenna element by fixing it to the base 4. A balun 12 is fixed to the support 14 using the holder 5.

[0025] 3 is a diagram illustrating the details of the small vehicle 100 according to the first embodiment of the present disclosure. Here, the configuration of the small vehicle 100 is illustrated in more detail by showing a front view of the small vehicle 100. Note that the skid 2 is omitted here.

[0026] The small moving body 100 includes a base 4. Rotating wings 6 are connected to the base 4. Two rotating wings 6 are shown here. A safety limit 50 is the limit of the area where the rotating wings 6 may come into contact when rotating.

[0027] A wireless communication device 8 is mounted on the base 4. The wireless communication device 8 is connected to a balun 12. The balun 12 is connected to an antenna element 32a having a loading coil 34a. The antenna element 32a has a shorter overall length due to the inclusion of the loading coil 34a.

[0028] The balun 12 is also connected to an antenna element 32b having a loading coil 34b, which reduces the overall length of the antenna element 32b.

[0029] A support 14 is fixed to the base 4. A holder 5 is fixed to the support 14. A balun 12 is fixed to the holder 5.

[0030] The dipole antenna 10 will now be described in more detail. First, the antenna elements 32a and 32b are fixed in an area that does not fall within the safety limit 50. This reduces the risk of the small moving body 100 crashing due to the antenna element 32a or 32b coming into contact with the rotor 6 while the small moving body 100 is flying.

[0031] Furthermore, the antenna elements 32a and 32b are fixed in an area where the center of gravity of the entire small mobile body 100 is lower than the altitude limit 60 that can ensure the flight stability of the small mobile body 100. Specifically, for example, the antenna elements 32a and 32b are fixed in an area where the center of gravity of the entire small mobile body 100 is equal to or lower than the value set as the altitude limit that can ensure the flight stability of the small mobile body 100. This reduces the risk of the flight of the small mobile body 100 becoming unstable.

[0032] Furthermore, the antenna elements 32a and 32b have loading coils 34a and 34b, respectively, which shortens the overall length, thereby further reducing the risk of the flight of the small moving object 100 becoming unstable.

[0033] As described above, the antenna elements 32a and 32b are fixed at an angle between an angle that ensures the required gain and 180 degrees in the region 70 that is outside the safety limit 50 and is equal to or less than the altitude limit 60.

[0034] [Advantages of the Small Mobile Body According to the First Embodiment of the Present Disclosure] Advantages of the small mobile body according to the first embodiment of the present disclosure will be explained by showing a small mobile body according to a comparative example. Figure 4 is a diagram showing an example of use of a monopole antenna. Here, an example of use in which the monopole antenna 20 is mounted on a small passenger car is shown.

[0035] Monopole antennas operate by grounding one end of the antenna, making them smaller than other antennas. For this reason, monopole antennas are often used when installing wireless communication devices in small mobile devices with limited installation space.

[0036] 5 is a diagram showing a small mobile object according to a first comparative example. The small mobile object 500 differs from the small mobile object 100 in that it has a monopole antenna 20 instead of the dipole antenna 10.

[0037] 6 is a block diagram showing an example of the configuration of a small moving body according to a first comparative example, in which the skid 2 and the rotor blades 6 are omitted.

[0038] The small mobile object 500 includes a base 4. A wireless communication device 8 is fixed onto the base 4 using a holder 5. An antenna base 16 is also fixed onto the base 4 using the holder 5. The wireless communication device 8 is connected to the antenna base 16 via a coaxial cable 7.

[0039] A monopole antenna 20 is installed on the antenna base 16. The antenna base 16 is a jig for stabilizing the antenna element by fixing it to the pedestal 4, and performs the same function as the support 14.

[0040] 5 and 6, the small mobile object 500 has a small mounting space, and as a result, the monopole antenna 20 is installed near electronic devices such as motors that generate electromagnetic noise.

[0041] 7 is a diagram showing the operation of transmitting and receiving radio waves on a drone using the monopole antenna according to the first comparative example. With reference to FIG. 7, interference experienced by the monopole antenna 20 according to the first comparative example will be described in detail.

[0042] As described above, the monopole antenna 20 mounted on the small mobile object 500 is installed near electronic devices such as motors that emit electromagnetic noise. The monopole antenna 20 is a grounded antenna that utilizes a mirror image as its operating principle. On a drone without a conductor plate, the drone body functions as a mirror image of the monopole antenna body. However, the drone body is small compared to the size of the required conductor plate, and its operation as a mirror image is unstable, resulting in a weak mirror image function. As a result, this electromagnetic noise interferes with wireless communications of the monopole antenna 20 as a mirror image 30a or 30b of the real image 30 of the monopole antenna 20.

[0043] As a result, there has been a problem that communication quality is easily degraded in wireless communication by the wireless communication device 8 mounted on the small mobile object 500. The present disclosure solves this problem by using a dipole antenna 10.

[0044] 8 is a diagram showing a small mobile object according to a second comparative example. The small mobile object 600 differs from the small mobile object 100 in that it includes a dipole antenna 10a in which two antenna elements are fixed to a support pillar at an angle of 180 degrees in parallel.

[0045] The dipole antenna 10a is a larger antenna than the monopole antenna 20. Therefore, the small mobile body 600 equipped with the dipole antenna 10a has a higher center of gravity than the small mobile body 100, which causes a problem of unstable flight.

[0046] In the small vehicle 100 according to this embodiment, the antenna elements 32a and 32b are fixed in an area 70 that is equal to or less than the altitude limit 60. Furthermore, the antenna elements 32a and 32b each have a loading coil 34a and 34b, thereby shortening the overall length. This configuration lowers the center of gravity, thereby solving the problem of unstable flight.

[0047] 9 is a diagram showing a small mobile body according to a third comparative example. The small mobile body 700 differs from the small mobile body 100 in that a dipole antenna 10b, with two antenna elements fixed parallel to the support 14 at an angle of 180 degrees, is installed on the bottom surface of the base 4.

[0048] The height of the dipole antenna 10b is greater than the height of the skid 2. In other words, the dipole antenna 10b installed on the bottom surface of the base 4 cannot be accommodated inside the skid 2. Therefore, in the small mobile object 700, the dipole antenna 10b interferes with the ground when landing, making landing difficult.

[0049] In the small mobile object 100 according to this embodiment, a dipole antenna 10 is mounted on the wireless communication device 8. This configuration solves the problem of difficulty in landing.

[0050] 10 is a diagram showing a small mobile object according to a fourth comparative example. The small mobile object 800 differs from the small mobile object 100 in that it includes a dipole antenna 10c in which two antenna elements are fixed to a support 14 at an angle of 180 degrees perpendicular to the support 14.

[0051] In the dipole antenna 10c, two antenna elements are close to the drone's rotor 6. Therefore, if the antenna element 32a or 32b comes into contact with the rotor 6 while the small mobile object 100 is flying, there is a problem that the small mobile object 100 may crash.

[0052] In the small moving body 100 according to this embodiment, the antenna elements 32a and 32b are fixed in an area 70 that is outside the safety limit 50. This configuration solves the problem of the small moving body 100 crashing.

[0053] 2 Skid 4 Base 6 Rotor 8 Wireless communication device 10 Dipole antenna 10a Dipole antenna 10b Dipole antenna 10c Dipole antenna 32a Antenna element 32b Antenna element 34a Loading coil 34b Loading coil 36a Antenna element 36b Antenna element 38a Antenna element 38b Antenna element 50 Safety limit 60 Altitude limit 70 Area 100 Small mobile body 500 Small mobile body 600 Small mobile body 700 Small mobile body 800 Small mobile body

Claims

1. A small mobile object equipped with a wireless communication device and a dipole antenna having two antenna elements, the two antenna elements being fixed at an angle between an angle that ensures the required gain and an angle that does not exceed 180 degrees.

2. The small mobile object according to claim 1, further comprising a rotor, wherein the two antenna elements are fixed in an area that does not fall within a safety limit that is the limit of the area where the rotor may come into contact when rotating.

3. A small mobile body as described in claim 1, wherein the two antenna elements are fixed in an area where the center of gravity of the entire small mobile body including the dipole antenna is below a value set as an altitude limit that ensures the flight stability of the small mobile body.

4. The small mobile object according to claim 1, wherein the two antenna elements each have a loading coil.

5. The small mobile object according to claim 1, wherein the two antenna elements have the same length.

6. The small mobile object according to claim 1, wherein the dipole antenna is mounted on the wireless communication device.

7. The small mobile object according to claim 1, which is an aircraft.

8. The small mobile body according to claim 7, further comprising: a skid; a base installed on said skid; and a plurality of rotors connected to said base and rotating horizontally relative to said base 4, wherein said wireless communication device and said dipole antenna are fixed on said base.

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