JP2004048369A - Composite antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable composite antenna which is constituted by combining a circular polarization antenna with a vertical polarization antenna and is suitably miniaturized and made thin. <P>SOLUTION: A patch antenna 11 being a circular polarization antenna for satellite waves is placed and fixed on a printed circuit board 10, and a power feeding pin 19 is connected to the power feeding line of a coaxial cable 30. A helical conductor 13 of a helical antenna 12 being a vertical polarization antenna for a ground wave is arranged above a central through-hole 11a of the patch antenna 11, and a linear conductor 14 extended to the lower part of the helical conductor 13 is put through the central through-hole 11a, and connected to the power feeding line of a coaxial cable 31. Thus, the heightwise dimension or planar size of the whole composite antenna can be reduced. Also, the relative positional relation of a patch electrode 21 and the helix conductor 13 is made almost uniform along the peripheral direction, so that the collapse of non-directional properties within an azimuth face due to the electromagnetic coupling of the patch antenna 11 and the helical antenna 12 can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite antenna mounted on a mobile body such as an automobile and capable of receiving satellite waves and terrestrial waves.
[0002]
[Prior art]
Circularly polarized waves are mainly used in systems that receive satellite broadcasts in vehicles such as automobiles, but recently, in order to increase the reception probability in blind zones such as behind buildings, similar to direct broadcast waves from geostationary satellites, A satellite broadcasting system that retransmits the contents on the ground has been considered. Conventionally, as an antenna applicable to such a satellite broadcasting system, a composite antenna as shown in FIG. 6 has been proposed.
[0003]
The conventional composite antenna shown in FIG. 6 has a 4-wire wound helical antenna 2 for receiving a circularly polarized wave and a monopole antenna 3 for receiving a vertically polarized terrestrial wave on a printed circuit board 1. Schematically configured. A ground conductor made of copper foil or the like is provided on almost the entire upper surface of the printed circuit board 1, and a microstrip line is provided on the lower surface of the printed circuit board 1. The helical antenna 2 is provided with four helical conductors 5 extending spirally on the outer peripheral surface of a cylindrical block 4 made of a dielectric, and feeds each helical conductor 5 connected to the microstrip line with a phase difference of 90 degrees. It is to do. When the helical antenna 2 is excited, a circularly polarized wave is radiated upward, so that it can function as an antenna for receiving satellite waves. In addition, the monopole antenna 3 raises a linear conductor having a length of about a quarter of the wavelength of a radio wave to be used, and connects the lower end of the conductor to a microstrip line to supply power. When the monopole antenna 3 is excited, omnidirectional vertically polarized radio waves are radiated in a plane parallel to the printed circuit board 1, so that the antenna can function as an antenna for receiving ground waves.
[0004]
[Problems to be solved by the invention]
In the above-described conventional composite antenna, the height of the helical antenna 2 is about 0.55λ, where λ is the wavelength of a radio wave to be used. Therefore, when the operating frequency is, for example, 2.3 GHz (λ = 130 mm), the height is The size is increased up to about 72 mm, and there has been a problem that it is not possible to reduce the thickness suitable for an antenna mounted on a moving body such as an automobile. Further, since such a conventional composite antenna has a structure in which the helical antenna 2 and the monopole antenna 3 are arranged side by side, a large size is required in plan view, it is difficult to reduce the size, and the antennas 2 and 3 are electromagnetically coupled. Therefore, the directivity of the monopole antenna 3 tends to be distorted on the side of the helical antenna 2, and therefore, there is a problem that the reception sensitivity of the terrestrial wave at a specific azimuth angle tends to decrease.
[0005]
The present invention has been made in view of such a situation of the related art, and an object thereof is to provide a highly reliable composite antenna suitable for reduction in size and thickness by combining a circularly polarized antenna and a vertically polarized antenna. Is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, a composite antenna according to the present invention includes a dielectric substrate having a through hole in a central portion, a patch electrode provided on an upper surface, a ground electrode provided on a lower surface, and the dielectric electrode connected to the patch electrode. A patch antenna having a feed pin connected to the first feed line, a printed board on which a ground conductor is provided on the upper surface and the patch antenna is mounted and fixed, and a helix fixed to the printed board and extending spirally A helical antenna in which a conductor is disposed above the through hole and a linear conductor extending downward from the helical conductor is inserted into the through hole and connected to a second feed line, and the patch antenna is excited. The helical antenna is excited to emit a vertically polarized radio wave while radiating a circularly polarized radio wave.
[0007]
In the composite antenna configured as described above, if the patch antenna is excited in the TM11 mode, a circularly polarized wave is radiated upward, so that the patch antenna can function as a circularly polarized wave antenna for satellite waves. In addition, if the helical antenna is excited in the normal mode, omnidirectional vertically polarized radio waves are radiated around in a plane parallel to the printed circuit board, so this helical antenna functions as a terrestrial vertically polarized antenna. Can be done. A helical conductor is placed above the through hole provided in the center of the patch antenna, and a helical antenna is erected using this through hole. It is a compact composite antenna that can receive and requires only a small height or planar size.
[0008]
Also, in this composite antenna, the relative positional relationship between the patch electrode and the helical conductor can be set substantially uniformly along the circumferential direction, so that the antenna in the azimuthal plane due to the electromagnetic coupling between the patch antenna and the helical antenna can be set. It is easy to avoid the loss of directivity, and therefore stable performance with little variation in reception sensitivity depending on the azimuth can be expected. The composite antenna can easily connect the feeder pin of the patch antenna or the linear conductor of the helical antenna to the feeder line on the lower surface side of the printed circuit board.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is an exploded perspective view of a composite antenna according to a first embodiment of the present invention, FIG. 2 is a perspective view of the composite antenna, and FIG. FIG. 4 is a top view of the antenna, and FIG. 4 is a sectional view taken along line AA of FIG.
[0010]
The composite antenna shown in these figures includes a printed circuit board 10 having insertion holes 10a and 10b, a patch antenna 11 for satellite waves mounted and fixed on the printed circuit board 10, and a central through-hole 11a of the patch antenna 11. And a helical conductor 13 disposed above the helical conductor 12 and fixed to the printed circuit board 10.
[0011]
A ground conductor 15 is provided on almost the entire upper surface of the printed circuit board 10, and lands 16 and 17 are provided on the lower surface of the printed circuit board 10. In the printed circuit board 10, the patch antenna 11 is mounted and fixed on the ground conductor 15 via an insulating double-sided tape 18, and the lower end of the feed pin 19 of the patch antenna 11 is inserted into the insertion hole 10a. . The lower end of a linear conductor 14 extending downward from the helix conductor 13 is inserted into the insertion hole 10b of the printed circuit board 10.
[0012]
The patch antenna 11 includes a disk-shaped dielectric substrate 20, a substantially circular patch electrode 21 provided on an upper surface of the dielectric substrate 20, and a ground electrode 22 provided on substantially the entire lower surface of the dielectric substrate 20. And a power supply pin 19 which is soldered to the patch electrode 21 and penetrates the dielectric substrate 20. The power supply pin 19 is supplied with a predetermined high-frequency signal. The patch electrode 21 is a radiating element having a microstrip structure, and notches 21 a (which may be protrusions) serving as degenerate separation elements are provided at two points symmetrically on the outer periphery of the patch electrode 21. The power supply pin 19 selects an appropriate power supply point with matching impedance and is connected to the patch electrode 21. The lower end of the power supply pin 19 is soldered to the power supply line (inner conductor) of the coaxial cable 30 on the land 16 of the printed circuit board 10. Is attached.
[0013]
In the patch antenna 11 having such a configuration, when the size of the patch electrode 21 or the notch 21a is set to an appropriate value and excited in the TM11 mode, a circularly polarized wave is radiated upward. It can function as a wave antenna. The patch antenna 11 has a single feeding point, and is provided with a degenerate separation element such as a notch 21a to provide a 90-degree phase difference between two orthogonal modes having different resonance lengths. is there. The patch antenna 11 has a central through-hole 11a, which is a relief hole for the helical antenna 12, but the center through-hole 11a is for inserting the linear conductor 14, so that the diameter may be extremely small. Since the drilling position is also at the center of the patch electrode 21, the antenna characteristics of the patch antenna 11 are hardly affected by the center through hole 11a.
[0014]
The helical conductor 13 and the linear conductor 14 of the helical antenna 12 are a single wire made of a piano wire, a shape memory alloy, or the like, so that a predetermined high-frequency signal is supplied to the helical conductor 13 via the linear conductor 14. Has become. The helical antenna 12 solders the lower end of the linear conductor 14 to the feed line (inner conductor) of the coaxial cable 31 at the land 17 of the printed circuit board 10 so that the axial direction of the helical conductor 13 is aligned with the ground conductor 15. It is fixed to the printed circuit board 10 in an orthogonal posture. Although not shown, a matching circuit for the helical antenna 12 is provided on the lower surface of the printed circuit board 10.
[0015]
When the helical antenna 12 having such a configuration is excited in the normal mode, an omnidirectional vertically polarized radio wave is surrounded by a plane parallel to the ground conductor 15, similarly to the monopole antenna standing upright with respect to the ground conductor 15. Since radiation is performed, the helical antenna 12 can function as a vertically polarized antenna for terrestrial waves. However, since the helical conductor 13 as a radiating element is wound up in a coil shape, the height of the helical antenna 12 can be less than half the height of a monopole antenna having the same operating frequency.
[0016]
As described above, the composite antenna according to the first embodiment can receive satellite waves by the plate-shaped patch antenna 11, and can receive terrestrial waves by the helical antenna 12 having a small height dimension. Since the helical antenna 12 is erected using the central through hole 11a, the entire device is thin and small in plan. Therefore, this composite antenna is suitable as a small in-vehicle antenna that can receive both terrestrial waves and satellite waves. In this composite antenna, since the relative positional relationship between the patch electrode 21 and the helix conductor 13 is substantially uniform along the circumferential direction, the omni-directionality in the azimuth plane due to the electromagnetic coupling between the patch antenna 11 and the helical antenna 12 is increased. Therefore, stable performance with little variation in reception sensitivity depending on the azimuth can be expected. Since the operation of connecting the power supply pins 19 and the linear conductors 14 to the power supply lines of the coaxial cables 30 and 31 can be easily performed on the lower surface side of the printed circuit board 10, the composite antenna has good assembling workability. .
[0017]
FIG. 5 is a perspective view of a composite antenna according to a second embodiment of the present invention. Reference numeral 25 generally indicates a patch antenna, and portions corresponding to FIG. 2 are denoted by the same reference numerals.
[0018]
The composite antenna shown in FIG. 5 differs from the first embodiment in that the patch antenna 25 is provided with a 90-degree phase difference circuit (not shown) on the printed circuit board 10 side in a two-point feeding system. . In this patch antenna 25, a circular patch electrode 27 is provided on the upper surface of a dielectric substrate 26, and power supply pins 28 and 29 are soldered to two places of the patch electrode 27, and lower end portions of the power supply pins 28 and 29 are provided. Are connected to the 90-degree phase difference circuit. Thereby, two orthogonal modes having phases different from each other by 90 degrees can be excited, so that the patch antenna 25 can function as a circularly polarized antenna for satellite waves, similarly to the patch antenna 11.
[0019]
In each of the above-described embodiments, it is preferable that the composite antenna be covered with a radome (not shown) when the antenna is actually mounted on a moving body such as an automobile. In other words, if the composite antenna is covered with a radome made of a dielectric material, adhesion of dust and the like and collision of flying objects can be prevented without adversely affecting the antenna characteristics, and the life of the composite antenna can be extended.
[0020]
【The invention's effect】
The present invention is implemented in the form described above, and has the following effects.
[0021]
A helical antenna, which is a vertically polarized antenna for terrestrial waves, is erected using a through-hole provided in the center of a patch antenna, which is a circularly polarized antenna for satellite waves. Since the height of the antenna can be small, a composite antenna that can receive satellite waves and terrestrial waves and can be easily reduced in size and thickness can be obtained, and is particularly suitable for use in vehicles. In addition, since this composite antenna can set the relative positional relationship between the patch electrode and the helical conductor almost uniformly along the circumferential direction, the omnidirectional plane in the azimuthal plane caused by the electromagnetic coupling between the patch antenna and the helical antenna It is easy to avoid the loss of sex, and therefore stable performance with little variation in receiving sensitivity depending on the azimuth can be expected.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a composite antenna according to a first embodiment of the present invention.
FIG. 2 is a perspective view of the composite antenna.
FIG. 3 is a top view of the composite antenna.
FIG. 4 is a sectional view taken along line AA of FIG.
FIG. 5 is an exploded perspective view of a composite antenna according to a second embodiment of the present invention.
FIG. 6 is a perspective view of a composite antenna according to a conventional example.
[Explanation of symbols]
Reference Signs List 10 Printed circuit boards 10a, 10b Insert holes 11, 25 Patch antenna 11a Center through hole 12 Helical antenna 13 Helix conductor 14 Linear conductor 15 Ground conductors 19, 28, 29 Feeding pins 20, 26 Dielectric substrates 21, 27 Patch electrodes 21a Cut Chip 22 Ground electrode 30, 31 Coaxial cable

Claims (1)

A patch electrode was provided on the upper surface of a dielectric substrate having a through hole in the center, a ground electrode was provided on the lower surface, and a power supply pin connected to the patch electrode and penetrating the dielectric substrate was connected to a first power supply line. A patch antenna,
A printed circuit board on which the patch antenna is mounted and fixed by providing a ground conductor on the upper surface,
A helical conductor fixed to the printed circuit board and extending spirally was disposed above the through-hole, and a linear conductor extending downward from the helical conductor was inserted into the through-hole and connected to a second power supply line. With a helical antenna,
A composite antenna, wherein the patch antenna is excited to emit circularly polarized radio waves, and the helical antenna is excited to emit vertically polarized radio waves.

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