JP3417732B2 - Planar antenna and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a miniaturized horizontal omnidirectional linearly polarized antenna, and more particularly to a planar antenna suitable for mounting on a PCMCIA card for 2.4 GHz band wireless LAN. It is a thing.

[0002]

2. Description of the Related Art A wireless LAN using a frequency in the 2.4 GHz band is being put into practical use as a kind of communication means, but this uses an antenna to transmit information. As an antenna for this frequency band, a whip antenna is used to obtain omnidirectionality in the horizontal plane with respect to vertically polarized waves.

This whip antenna has a large shape and is limited in mounting method, position, etc. In order to solve this, the present inventor has proposed a dielectric substrate having a through hole in Japanese Patent Application No. 6-276042. The thin flat antenna used is proposed.

FIG. 4 is a front sectional view showing an example of such a planar antenna. A through hole is formed in a dielectric substrate 40, a surface electrode 41 is formed on the front surface, and a ground electrode 42 is formed on the back surface. The radiation electrode 43 is partially formed in the. The surface electrode 41, the radiation electrode 43, and the ground electrode 42 are short-circuited. A metal pin 44 is inserted into the through hole in order to feed power to the impedance matching point of 50Ω in the through hole, and is in contact with the radiation electrode 43 at the impedance matching point.

[0005]

In the above planar antenna, it is necessary to form a partial electrode having a portion where the dielectric is exposed on the wall surface of the through hole, and a metal piece is inserted even when the conductor is applied. Even in such a case, the man-hour will increase.

Further, it is necessary to insert a power feeding pin into the through hole and connect it to an electrode partially formed inside the through hole, which makes it difficult to make a reliable and stable connection. In particular, it is necessary to connect at the impedance matching point, and the deviation of the characteristics is likely to occur.

Further, since the radiation electrode in the through hole serves as a partial electrode, the use efficiency of the through hole portion of the dielectric substrate as a radiation electrode space becomes poor. The efficiency is maximized if the entire inside of the through hole can be used as a radiation electrode.

The present invention solves the above problems,
(EN) A planar antenna which is easy to manufacture, has stable characteristics, and has good radiation efficiency.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above problems by making the radiation electrode formed on the wall surface of the through hole a uniform electrode and supplying power at the lower end thereof.

[0010] That is, the table on the wall surface of the through hole and comprises a dielectric surface electrode of a metal film on the surface of the substrate, the back surface of the metal film by the earth electrode of the dielectric substrate and the dielectric substrate through-hole of
It is equipped with a radiation electrode made of a metal film that is connected to the surface electrode and extends to a predetermined depth from the surface.The radiation electrode and the ground electrode are connected by a reactance in the through hole, and a conductor piece is inserted into the through hole so that the radiation electrode The feeding conductor is connected to the impedance matching point of the radiating electrode by abutting on the lower end.

[0011]

The planar antenna according to the present invention forms a parallel resonance circuit of the capacitance between the surface electrode and the ground electrode, the inductance of the cylindrical conductor in the through hole, and the combined inductance of the reactance. This radiation electrode is formed by grinding the conductor film formed on the entire surface in the through hole, and the conductor film left at that time can be used as reactance.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing an embodiment of the present invention. A through hole (15) is formed in the center of a circular dielectric substrate (10), and a surface electrode (11) is formed around the surface side of the through hole. A ground electrode 12 is formed on the back surface of the dielectric substrate 10. These are formed in a predetermined pattern by printing (application) of a conductor paste and baking.

A radiation electrode 13 is formed on the wall surface of the through hole 15 of the dielectric substrate 10. The radiation electrode 13 is formed on the entire wall surface of the through hole 15. The radiation electrode 13 is an entire surface (uniform) electrode that is connected to the surface electrode 11 and is formed from the surface of the dielectric substrate 10 to a certain depth. Radiation electrode 13 and ground electrode 12
Are connected via a short-circuit conductor 16 formed on the wall surface of the through hole. Therefore, on the ground electrode side of the wall surface of the through hole, there is no electrode other than the short-circuit conductor 16 and a portion where the dielectric is exposed is formed. These conductor films can be formed by applying and baking a conductor paste.

FIG. 2 is a side sectional view showing a state in which a power feeding conductor is inserted at the impedance matching point of the radiation electrode 23, that is, at the lower end of the conductor film in the through hole. The conductor pin 24 is inserted into the through hole in which the radiation electrode 23 is formed, and power is supplied by contacting and connecting with the radiation electrode at the end of the conductor film on the side of the ground electrode. It is preferable that the conductor pin 24 is formed by bending a metal plate so as to elastically contact the wall surface of the through hole. In that state, the planar antenna is completed by bonding and fixing with solder or the like.

As the power feeding means, not only the above direct connection structure but also the conductor pin 34 coated with the dielectric 37 is inserted into the through hole as shown in FIG. You can also do In this case, the dielectric 37
Insertion and fixing can be performed by utilizing the elasticity of the resin or the like.

In the method of manufacturing a planar antenna according to the present invention, the electrodes can be formed by applying a predetermined conductor paste on both surfaces of the dielectric substrate and the inner wall surface of the through hole by a printing method. Alternatively, after forming the conductor film on the entire surface, the conductor film in the through hole may be removed from the ground electrode, that is, the rear surface side of the dielectric substrate by grinding to leave a predetermined conductor pattern. In this case, it is possible to form electrodes and reactances while adjusting the characteristics.

Further, the conductor pin for power feeding may be inserted from the lower side or the upper side. If a flange is formed at the end of the pin, the fixed position can be stabilized. Also, the connection can be secured by soldering.

The short-circuit conductor formed on the same surface as the ground electrode and connecting the radiation electrode and the ground electrode acts equivalently as reactance. The reactance can be adjusted by the length and width of the short-circuit conductor, and thus the impedance matching point can be adjusted.

[0020]

According to the present invention, since the conductor pin for power feeding and the cylindrical entire surface electrode are connected to each other, the assembly is facilitated and the stable characteristics are facilitated.

Further, since the conductor film can be formed on the entire wall surface of the through hole, the conductor film can be easily formed unlike the conventional partial electrode. Further, the entire inside of the through hole can be efficiently used as a space for the radiation electrode.

Further, the electrodes uniformly formed on the wall surface of the through hole are securely connected to the feeding pin, and the center of the feeding pin and the center of the antenna element are made to coincide with each other for mounting regardless of the rotation angle of the element. be able to.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 shows an embodiment in which the pin of the present invention is inserted,
(a) is a side sectional view, (b) is a partial perspective view

3 (a) is a side sectional view and FIG. 3 (b) is a partial perspective view of another embodiment in which the pin of the present invention is inserted.

FIG. 4 is a front sectional view showing a conventional planar antenna.

[Explanation of symbols]

10: Dielectric substrate 11: Surface electrode 12: Ground electrode 13, 23, 33: Radiation electrode 24, 34: Metal pin 15: Through hole 16: Short-circuit conductor 37: Dielectric

Claims (5)

(57) [Claims] 1. A surface electrode made of a metal film on the surface of a dielectric substrate having a through hole, a ground electrode made of a metal film on the back surface of the dielectric substrate, and a surface electrode connected to the wall surface of the through hole of the dielectric substrate. Equipped with a radiation electrode made of a metal film extending to a predetermined depth from the surface, the radiation electrode and the ground electrode are connected by a reactance in the through hole, and a conductor piece is inserted into the through hole to abut the lower end of the radiation electrode. A flat antenna in which a feeding conductor is connected to the impedance matching point of the radiation electrode. 2. The planar antenna according to claim 1, wherein the conductor piece is a molded metal piece and is in direct contact with the radiation electrode. 3. The planar antenna according to claim 1, wherein a portion of the conductor piece inserted into the through hole is covered with a dielectric and is connected to the radiation electrode via a capacitor. 4. The planar antenna according to claim 1, wherein the reactance is a conductor film formed on a wall surface of a through hole connecting the radiation electrode and the ground electrode. 5. After forming a conductor film on the entire wall surface of the through hole, the conductor film in the through hole from the back surface of the dielectric substrate to the position of the impedance matching point is ground, and a part of the conductor film is cut through the through hole. The method for manufacturing a planar antenna according to claim 1, wherein the conductor strip is left in the extending direction of the conductor strip.