JPH0810971Y2 - Feeding structure of rod antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a feed structure for a rod antenna, which is capable of matching adjustment in a feed portion of the rod antenna.

(Prior Art) In recent years, automobile wireless telephones have been rapidly spreading,
As an antenna for this purpose, a two-stage collinear array antenna in which two half-wavelength dipole antennas having a carrier wave of an automobile radio telephone signal of 870 to 940 MHz and one-quarter wavelength dipole antennas are stacked in two stages is generally mounted on the automobile. Then, from the base end portion of the two-stage collinear array antenna, an automobile radio telephone signal is input to and output from the automobile radio telephone via, for example, a 50Ω coaxial cable.

In order to efficiently input the car radio telephone signal received by this rod antenna to the car radio telephone and to efficiently radiate the car radio telephone signal from the antenna, it is necessary to obtain matching between the rod antenna and the coaxial cable. is necessary. Therefore, a power feeding structure is adopted in which the base end side of the rod antenna mounted on the automobile is extended to the inside of the automobile and the coaxial cable is electrically connected to a position where the coaxial cable and the coaxial cable can be aligned.

(Problems to be solved by the invention) By the way, if the frequency of the carrier wave is high as in the case of a car radio telephone signal, the wavelength becomes shorter. Then, a slight deviation in the position where the coaxial cable is electrically connected becomes a large deviation with respect to the wavelength, and it is difficult to obtain the desired matching. Therefore, there has been a strong demand for a feed structure for a rod antenna that can improve the poor yield due to variations in the manufacturing process.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a feed structure for a rod antenna in which the position of the feed point can be adjusted.

(Means for Solving the Problem) In order to achieve the above object, the power feeding structure of the rod antenna of the present invention has a power feeding tube for adjustment, which is electrically connected to a base end side of an antenna rod, at a terminal end side of a power feeding tube. One end of the tube is fitted to be slidable in the axial direction and electrically connected, and a power supply line is electrically connected to the terminal end of the power supply tube for adjustment, and the power supply tube for adjustment is connected to the power supply tube. Fixing means for fixing the adjusting tube to the feeding tube and adjusting the axial position where the adjusting feeding tube is fitted to the feeding tube so that the feeding tube is electrically connected to the antenna rod. In addition, the length up to the position where the power supply line is electrically connected is adjusted to adjust the rod antenna and the power supply line.

Then, while inserting the antenna rod into the power feeding tube, a conductive elastic member is interposed between the power feeding tube and the base end side of the antenna rod, and the antenna rod with respect to the power feeding tube. It may be configured to be movable in the axial direction and electrically connected via the conductive elastic member.

(Operation) Since the adjustment power supply tube electrically connected to the power supply line is slidably fitted into the terminal end of the power supply tube electrically connected to the antenna rod so as to be electrically connected, the adjustment power supply tube By adjusting the position in the mating direction, the length from the position where the antenna rod and the feeding tube are electrically connected to the position where the feeding line is electrically connected is adjusted to achieve matching adjustment, and the dimensional accuracy of parts is improved. And so on,
The feed line may be connected to the position of the antenna rod that has the input impedance that most matches the feed line.

If the antenna rod is inserted into the power feeding tube with the conductive elastic member interposed, the antenna rod can be expanded and contracted.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a vertical cross-sectional view of an embodiment of a feed structure for a rod antenna according to the present invention, FIG. 2 is an enlarged view of a main part of the vertical cross-section of FIG. 1, and FIG. FIG. 4 is a diagram for explaining the electrical characteristics of the antenna of FIG. 4, and FIG. 4 is a diagram showing a change in the standing wave ratio characteristic of the antenna due to the adjustment.

In the figure, the rod antenna is a two-stage collinear array antenna in which a half-wavelength dipole antenna 1, a phase inversion coil 2 and a 1/4 wavelength dipole antenna 3 are stacked. Then, the antenna rod of the 1/4 wavelength dipole antenna 3 in the lower stage is located inside the body 4 of the automobile.
It is extended by 5/12 wavelength. A power supply spring 6 having a barrel-shaped sliding contact portion made of phosphor bronze or the like as a conductive elastic member is fixed to the extended antenna rod 5. Further, the antenna rod 5 is inserted into the feeding tube 7 made of a conductive material, and the sliding contact portion of the feeding spring 6 is brought into close contact with the inner peripheral surface of the feeding tube 7 so as to be slidable. The power supply tube 7 is integrally formed with the cylindrical base member 9 on the outer peripheral portion with the insulating material 8 interposed therebetween. Further, a mounting means (not shown) for mounting on the body 4 of the automobile or the like is appropriately provided on the tip end side of the tubular base member 9, and the tubular base member 9 has a tubular shape on the terminal end side. The power supply base member 10 is inserted. An insulating member 11 having a hole through which the power feeding tube 7 can be inserted is disposed in the power feeding base member 10, and an adjusting power feeding tube 12 made of a conductive material is disposed on the inner periphery of the hole by integral molding. When the power feeding base member 10 is inserted into the tubular base member 9, the tip end side of the power feeding tube 12 for adjustment is slidably fitted to the terminal end side of the power feeding tube 7 and is electrically connected. Further, a claw 13 is cut and raised at the terminal end of the adjusting power supply tube 12, and a coaxial cable 14 as a power supply line is connected to the claw 13. The set screws 15, 15 are screwed into the cylindrical base member 9, and the set screws 15, 15 hold and release the feed base member 10 to position the adjusting feed tube 12 with respect to the feed tube 7. Can be adjusted in the direction of expansion and contraction of the antenna rod 5 and fixed. The wavelength between the tip of the power feeding tube 7 in the fitted state and the cut and raised position of the claw 13 of the power feeding tube 12 for adjustment is about 5/12 wavelength. The electrical connection between the claw 13 and the coaxial cable 14 is an insulating member.
It is integrally covered with 11. Further, the drive cord 16 is connected to the end of the upper and lower antenna pole that extends and contracts through the antenna rod 5.

In this configuration, when the drive cord 16 is extended by a motor (not shown), the upper antenna pole projects from the antenna rod 5 in the antenna extension direction, and then the antenna rod 5 is regulated in the feeding tube 7 by the feeding spring 6. It moves to the tip direction until it reaches the end, and the rod antenna is in the extended state. Further, when the drive cord 16 is wound up, the upper antenna pole is housed in the antenna rod 5, and then the antenna rod 5 is connected to the feeding tube 7
The rod antenna is housed in the car body 4 by being moved in the housing direction.

By the way, in the extended state of the rod antenna as shown in FIG. 3 (a), the current is distributed as shown in FIG. 3 (b) and the voltage is distributed as shown in FIG. 3 (c). And coaxial cable
14 connecting power points from the car body 4 about 5 /
With 12 wavelengths, the rod antenna has an input impedance of about 50Ω.

Therefore, the set screws 15 and 15 are loosened to slide the power feeding base member 10 in the axial direction, and the length of fitting and inserting the adjusting power feeding tube 12 into the power feeding tube 7 is appropriately adjusted by Δl, thereby making the coaxial Matching can be achieved by obtaining an optimum input impedance for the cable 14. FIG. 4 shows a change in the standing wave ratio characteristic due to the adjustment. By adjusting and shifting the standing wave ratio characteristic, different solid line and broken line standing wave ratio characteristics can be obtained.

In the above embodiment, one embodiment of the expandable telescopic rod antenna is shown, but the present invention is not limited to this, and the present invention can be applied to a rod antenna in which the antenna rod 5 is fixed to the feeding tube 7 and cannot be stored. You may apply the electric power feeding structure of. Further, the fixing of the adjusting power supply tube 12 is not limited to the set screws 15 and 15 as in the above-mentioned embodiment, and it goes without saying that any means can be used as long as it can be fixed so as not to shift after the adjustment. Further, the power feeding structure of the rod antenna of the present invention is not limited to the application of the vehicle radio telephone signal to the rod antenna.

(Effects of the Invention) Since the power feeding structure for the rod antenna of the present invention is configured as described above, the following effects are achieved.

By adjusting the position of the feeding point after manufacturing the rod antenna, the length from the position where the antenna rod and the feeding tube are electrically connected to the position where the feeding line is electrically connected can be adjusted for matching adjustment. It is possible to absorb variations in dimensional accuracy, etc., a feeding point is obtained at an optimum input impedance position of the antenna rod, and reliable matching between the rod antenna and the feeding line is obtained. In particular, when applied to a feed structure of a rod antenna used at a high carrier frequency such as a car radio telephone signal, the matching can be greatly improved by a slight adjustment of the adjusting feed tube.

Then, if the antenna rod is inserted by interposing a conductive elastic member in the feeding tube, the antenna rod can be moved in the extension / contraction direction within the feeding tube, which is useful in constructing a retractable rod antenna.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of a feed structure for a rod antenna according to the present invention, FIG. 2 is an enlarged view of a main part of the vertical cross-section of FIG. 1, and FIG. FIG. 4 is a diagram for explaining the electrical characteristics of the antenna of FIG. 4, and FIG. 4 is a diagram showing a change in the standing wave ratio characteristic of the antenna due to the adjustment. 5: Antenna rod, 6: Feed spring, 7: Feed tube, 12: Adjustment feed tube, 13: Claw, 14: Coaxial cable, 15: Set screw.

Claims (2)

[Scope of utility model registration request] 1. An end portion of a power supply tube electrically connected to a base end side of an antenna rod is fitted with one end side of a power supply tube for adjustment so as to be slidable in an axial direction and electrically connected. Then, a power supply line is electrically connected to a terminal end of the power supply tube for adjustment, and fixing means for fixing the power supply tube for adjustment to the power supply tube is provided, and the power supply tube for adjustment is fitted to the power supply tube. By adjusting the axial position to adjust the length from the position where the power feeding tube is electrically connected to the antenna rod to the position where the power feeding line is electrically connected to the adjustment tube, a rod antenna A feed structure for a rod antenna, wherein the feed line is configured to be adjusted and adjusted. 2. The antenna rod is inserted into the feeding tube, and a conductive elastic member is interposed between the feeding tube and the base end side of the antenna rod, and the antenna rod is attached to the feeding tube. 2. It is configured so as to be movable in the axial direction with respect to, and electrically connected via the conductive elastic member.
The feeding structure of the rod antenna described.