JP2692242B2 - Vehicle-mounted diversity antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage structure for a motor antenna without losing the characteristics of a vehicle-mounted diversity antenna such as a car telephone antenna.

[Prior art]

Conventionally, as a mobile communication antenna, there is a space diversity antenna in which two antennas are vertically arranged in order to improve reception sensitivity. In recent years, in quasi-microwave communications including car telephones, cars are increasingly used as mobile stations. Also, as disclosed in JP-A-59-97207 and JP-A-60-249403, various diversity receiving systems are considered on the mobile station side as an automobile as a structure for improving the communication quality. Has been.

[Problems to be solved by the invention]

When the diversity antenna is mounted on a vehicle, if the diversity antenna is always projected from the mounted vehicle, it is necessary to remove the antenna, for example, at the time of car washing and garage parking, which is complicated and may be damaged. There is also a risk of theft and intentional damage. The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to be able to be housed inside a vehicle as needed, and the outer diameter of the antenna can be made small so as not to spoil the appearance. Another object of the present invention is to provide a vehicle-mounted diversity antenna that has a good diversity effect by adopting a configuration in which the power feeding unit matches the antenna when unfolded.

[Means for Solving the Problems]

The configuration of the invention for solving the above-mentioned problems is a sleeve antenna arranged in an upper stage, a cylindrical monopole antenna arranged in a lower stage, which accommodates the sleeve antenna by sliding in an electrically insulating state. A double-cylindrical accommodating portion including an inner cylindrical tube of a conductor that slidably accommodates the monopole antenna in an electrically conductive state, and an outer cylindrical tube of a conductor that surrounds the outer side of the inner cylindrical tube coaxially. , A predetermined impedance matching is achieved between the feeder cable for feeding the monopole antenna and the inner cylindrical tube of the accommodating section, which is connected to the sleeve antenna and supplies power to the sleeve antenna, and the outer cylindrical tube of the accommodating section. A through hole is provided at a predetermined position, a central coaxial side of the through hole is connected to the inner cylindrical tube of the housing, and a ground side is connected to the outer cylindrical tube to feed power to the monopole antenna. The disposed racks cable to the antenna, characterized in that an antenna driving device for receiving or the storage unit from the exhibition out the sleeve antenna and the monopole antenna to the receiving unit.

[Action]

The sleeve antenna is arranged on the upper stage and the monopole antenna is arranged on the lower stage.The antenna driving device retracts or pulls out the rack cable arranged on the sleeve antenna to store the sleeve antenna in the internal space of the monopole antenna or the inside. It is projected from the space, and further, it is stored in the storage section provided in the vehicle body together with the monopole antenna or is expanded from the storage section. The storage part has a double-cylindrical structure consisting of a conductor inner tube and an outer tube that always maintain electrical continuity with the monopole antenna.The power supply to the monopole antenna is provided in the outer tube of the storage part. This is performed by connecting the center coaxial side of the feeder cable for feeding to the inner tube from the through hole and connecting the ground side to the outer tube. Therefore, it becomes easy to set the through hole for connecting the central coaxial side of the feeder cable for feeding the monopole antenna to a position where a predetermined impedance matching can be obtained, and the diversity effect is good when the antenna is extended. Become.

【Example】

Hereinafter, the present invention will be described based on specific examples. FIG. 1 (a) is a front view showing the structure of a vehicle-mounted diversity antenna according to the present invention, and FIG. 1 (b) is a first view.
FIG. 1 (a) is an enlarged detail view of the B part, and FIG. 1 (c) is a transverse sectional view taken along the line I-I of FIG. 1 (a). 1 is an upper sleeve antenna, 2 is a lower monopole antenna, and is a vehicle-mounted diversity antenna 10
0 is configured. 3 is a coaxial inner conductor of the sleeve antenna 1, 4 is its radiating part, 5 is its λ / 4 spell top, and the radiating part 4 and λ / 4 spell top 5 form a λ / 2 dipole antenna. Is forming. Here, λ indicates the wavelength of the center frequency of the frequency band for communication. 6 is a coaxial feeder cable 7
And 8 is a resin radome of the sleeve antenna 1. 38 is a cylindrical tube of the monopole antenna 2, its length is as a ground plane of the vehicle body at lambda _1/4-length, the principle of the mirror image, to form a dipole antenna of lambda _1/2. The λ ₁ may be the center frequency of the frequency band for communication or the center frequency of the reception band on the mobile station side. The radome 8 overlaps at the upper end portion 53 of the cylindrical tube 38, and a conductor or resin cylinder 18 is inserted and fixed to the outer circumference of the radome 8 at the overlapping portion.
The outer diameter is slightly smaller than the inner diameter of the cylindrical tube 38, and is set so that it can slide smoothly inside the cylindrical tube 38. Further, the upper end surface of the cylindrical tube 38 is provided with a hole 54 having a diameter slightly larger than the outer diameter of the radome 8 and smaller than the outer diameter of the cylinder 18. Therefore, at the upper end of the cylinder 18, the radome 8 does not protrude from the hole 54 at the upper end of the cylindrical tube 38. As the monopole antenna 2, the cylindrical tube 38 overlaps with the upper end 56 of the housing tube 55 that constitutes the inner tube of the housing, and the conductor cylindrical tube 57 is inserted into the outer circumference of the cylindrical tube 38 at the upper end 56. It is fixed, and its outer diameter is slightly smaller than the inner diameter of the storage tube 55, and is set so as to be slidable smoothly inside the storage tube 55. Further, the upper end surface of the storage pipe 55 is provided with a hole 58 having a diameter slightly larger than the outer diameter of the cylindrical pipe 38 and smaller than the outer diameter of the conductor cylindrical pipe 57. Therefore, at the upper end of the cylindrical pipe 57, the cylindrical pipe 38 does not protrude from the hole 58 at the upper end of the storage pipe 55. Further, a resin antenna top 17 is provided at the upper end of the radome 8, and since the outer diameter of the resin top 17 is larger than the hole 58 at the upper end of the storage tube 55, the antenna top 17 contacts the upper end of the storage tube 55 during storage. The radome 8 does not enter the storage tube 55 any more. Reference numeral 59 denotes a cylindrical tube that surrounds the storage tube 55 coaxially and forms an outer tube of the storage section. The lower end of the cylindrical tube (hereinafter referred to as a choke tube) 59 has a short-circuit surface 69 to electrically connect with the storage tube 55. It is short-circuited. The upper end of the choke pipe 59 is fixed to the upper end of the storage pipe 55 by a resin ring 60, and the upper end of the choke pipe 59 is connected to the vehicle body and grounded. Reference numeral 61 is an insertion mounting hole for the choke tube 59 provided in the vehicle body. Reference numeral 62 denotes a coaxial connector that is an output terminal of a feeder cable 31 for feeding power from the communication device 29 to the monopole antenna 2, its ground side 63 is a choke tube 59, and its central coaxial side 64 is a choke tube 59. It is connected to the storage tube 55 through the through hole provided. An output terminal 68 of the sleeve antenna 1 is connected to the power feeding feeder cable 30 fed from the communication device 29. Coaxial feeder cable 7 for sleeve antenna 1
The rack cable 20 arranged in parallel with the coaxial feeder cable 7 attached to the connection member 6 and the coaxial feeder cable 7 penetrates through the inside of the cylindrical pipe 38 and the storage pipe 55 as the monopole antenna 2 and is sleeved by the rack cable 20. The antenna 1 and the monopole antenna 2 are stored in the storage pipe 55 or the storage pipe.
Exhibition from 55. Reference numeral 65 is a drive unit that constitutes an antenna drive device for pulling in or pulling out the rack cable 20. Driver 65
Although detailed description of the above is omitted, it is basically the same as the drive structure of the current motor antenna for radio. However, a winding unit 66 that winds the rack cable 20 and the coaxial feeder cable 7 on the same axis, and a buffer coaxial feeder cable storage unit that twists when the coaxial feeder cable 7 is wound.
It consists of 67. Next, in order not to lose the characteristics of the vehicle-mounted diversity antenna, the impedance matching condition of the mounting position of the coaxial connector 62 with respect to the coaxial tube composed of the choke tube 59 and the storage tube 55 for the monopole antenna 2 is described. This will be described with reference to FIGS. 2 (a), 2 (b) and 2 (c). Z _A is the antenna impedance viewed from P ₁ , Z _C is the coaxial tube characteristic impedance determined by the inner diameter a of the choke tube 59 and the outer diameter b of the storage tube 55, and Z (L _C −L _P ) is the coaxial connector 62.
Is the impedance in the direction from which the antenna is viewed, and Z (L _P ) is the impedance in the direction from the coaxial connector to the short circuit surface 69. L _C is the length of the choke tube 59, L _P is the distance from the short-circuit face 69 to the coaxial connector 62. Z ₁ is the impedance seen from the coaxial connector 62. ρ is VSWR at the coaxial connector 62. Z ₀ is the characteristic impedance of the feeder cable for feeding from the coaxial connector. Further, X _L is a reactance component for the inductance of the portion connected to the housing tube 55 of the central coaxial side 64 of the coaxial connector 62. From this, if the antenna impedance Z _A is known, the mounting positions of the coaxial tube and the coaxial connector are optimized using the following formula. In the above equation, L _C , L _P , and Z _C that hold ρ ≦ 1.9 may be obtained. Further, according to the experiments conducted by the inventors, the distance L _d between the lower end of the λ / 4 spell top 5 and the upper end of the monopole antenna 2 of the sleeve antenna 1 shown in FIG. ~ 2 mm
Was optimal. Further, the length of the monopole antenna 2 may be (5/8) λ or (6/8) λ. Here, for example, if the length of the monopole antenna 2 is (5/8) λ, the distance between the sleeve antenna 1 and the monopole antenna 2 can be widened to reduce the correlation, and the main beam of the monopole antenna 2 can be reduced. The direction can be suppressed low and the antenna gain is improved. In the above embodiment, the storage pipe 55 and the choke pipe 59 are short-circuited at the lower end, but they may be open.
The principles described in FIGS. 2 (a), 2 (b) and 2 (c) can be similarly applied. Furthermore, the storage pipe 55 and the choke pipe 59 in FIG.
By filling a dielectric material (relative permittivity E _r ) between and,
Overall dimensions Can be made smaller. Further, by using a cable in which the rack cable 20 and the coaxial feeder cable 7 are integrated, a more compact structure can be achieved. Further, the distance L _d between the lower end of the λ / 4 spell top 5 of the sleeve antenna 1 and the upper end of the monopole antenna 2 is L _d.
May be L _d = n · λ.

【The invention's effect】

The present invention relates to an antenna drive device for storing a sleeve antenna arranged in an upper stage and a lower monopole antenna in a storage portion by a rack cable arranged in the sleeve antenna, and extending the storage antenna from the storage portion, a monopole antenna, and Feeder cable for feeding a sleeve antenna that penetrates through the inner space of the inner tube of the storage section and the through hole provided in the outer tube of the storage section is centered coaxially with the inner tube and grounded to the outer tube. It is equipped with a feeder cable for feeding the monopole antenna with the sides connected, and by feeding the monopole antenna from its storage part, the sleeve antenna allows the internal space of the monopole antenna to pass through the rack cable and feed of the sleeve antenna. It can be used through with a feeder cable for use, and the monopole antenna is stored using the inner tube of the storage section. It becomes easy to reduce the outer diameter of the antenna to the extent that there is no problem in terms of appearance when using a vehicle-mounted diversity antenna as a motor antenna, and the connection position of the center coaxial side and the ground side of the feeder cable for feeding the monopole antenna is the housing of the antenna. -It can be set regardless of the expansion, and impedance matching with the monopole antenna can be achieved, so the diversity effect will not deteriorate.

[Brief description of the drawings]

FIG. 1A is a front view showing the configuration of a vehicle-mounted diversity antenna according to a specific embodiment of the present invention. FIG. 1 (b) is an enlarged detailed view of part B in FIG. 1 (a). FIG. 1 (c) is a cross-sectional view taken along the line I-I of FIG. 1 (a). 2 (a), 2 (b) and 2 (c) are explanatory views for determining the optimum mounting position of the coaxial connector with respect to the coaxial tube according to the embodiment. 1 ... Sleeve antenna, 2 ... Monopole antenna 3 ... Coaxial inner conductor, 4 ... Radiating part 5 ... λ / 4 spell top, 6 ... Connection member 7 ... Coaxial feeder cable, 8 ... Radome 20 …… Rack cable, 29 …… Communication device 30,31 …… Feeder cable for power supply 38 …… Cylinder tube, 55 …… Storage tube, 59 …… Choke tube 62 …… Coaxial connector, 65 …… Driving unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 63-42506 (JP, A) JP 60-249403 (JP, A) JP 59-97207 (JP, A)

Claims (1)

(57) [Claims] 1. A sleeve-shaped antenna arranged in an upper stage, a cylindrical monopole antenna arranged in a lower stage and slidably accommodating the sleeve antenna in an electrically insulated state, and the monopole antenna is electrically connected. A double-cylindrical accommodating portion composed of an inner cylindrical tube of a conductor that slides and accommodates in an electrically conductive state, and an outer cylindrical tube of a conductor that surrounds the outer side of the inner cylindrical tube coaxially, the monopole antenna and the A feeder cable for feeding the sleeve antenna by penetrating through the inner space of the inner tubular tube of the housing portion, and a through hole provided at a predetermined position in the outer tubular tube of the housing portion with a predetermined impedance matching. A feeder cable for feeding power to the monopole antenna by connecting a central coaxial side of the through hole to the inner cylindrical tube of the housing and a ground side of the outer cylindrical tube, and the feeder antenna for power supply to the sleeve antenna. The sleeve antenna and the vehicle mounting diversity antenna, characterized in that said monopole antenna and a housing or the antenna driving device for the storage unit from the exhibition issued to the storage unit by Kkukeburu.