JPH0518111U - Micro strip antenna - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] A 50 ohm line is formed from the feeding point to the connection point to achieve impedance matching. [Structure] A conductor 13 connected to a feeding point through a through hole of a dielectric substrate 10 is covered with a dielectric 15, and a conductor film 14 electrically connected to a ground electrode 12 is formed in the through hole of the dielectric substrate 10. . The conductor 13 and the conductor film 14 form a coaxial line. Conductor 13
The outer diameter of the conductor 13 and the inner diameter of the conductor film 14 can be determined to be 50 ohms by setting a predetermined ratio according to the outer diameter of the conductor and the dielectric constant of the dielectric 15.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a microstrip antenna used in a navigation system or the like, and relates to a structure for drawing out a line from a radiation electrode.

[0002]

[Prior Art]

 In a GPS navigation system or the like, a small antenna that receives signals from satellites is required, and the use of a microstrip antenna is being considered as one of them.

In this microstrip antenna, a radiation electrode having a size of ½ of the wavelength to be received is provided on the surface of a dielectric substrate, and a ground electrode is formed on the entire back surface. There are two types of radiation electrodes, square and circular, and the reception frequency is broadened by devising the shape.

FIG. 2 is a front cross-sectional view showing an example of the structure of such a conventional microstrip antenna, showing a mounting structure on a printed circuit board. A radiation electrode 21 is formed on the front surface of the dielectric substrate 20, and a ground electrode 22 is formed on the back surface. The conductor 23 is drawn out from the 50 ohm point of the radiation electrode 21 to the back surface through the through hole formed in the dielectric substrate 20. This conductor is connected to the wiring pattern of the printed board 27 via the connector 26. On the printed circuit board 27, circuit elements for constituting an amplifier, a filter, etc. are mounted.

[0005]

[Problems to be solved by the device]

 In the microstrip antenna, the conductor is connected to the 50 ohm point as described above, but it is desirable to form a 50 ohm line from this point to the connection point on the printed circuit board. However, in the above structure, it is not a 50 ohm system and impedance mismatch occurs. This causes problems such as increased loss.

The present invention provides a structure in which a line of approximately 50 ohms is formed from the radiation electrode to the connection point.

[0007]

[Means for Solving the Problems]

 The present invention solves the above problem by forming a 50 ohm coaxial line in a dielectric substrate. That is, the front surface of the dielectric substrate is equipped with a radiation electrode having a size of half the wavelength and the back surface is provided with a ground electrode, and the conductor is passed through the through hole formed in the dielectric substrate from the radiation electrode feeding point to the back surface. In the microstrip antenna derived from Fig. 2, a conductor film that is electrically connected to the ground electrode is provided in the through hole, a conductor covered with a dielectric is inserted into the through hole, and the tip of the conductor is connected to the radiation electrode. It is characterized by

[0008]

[Action]

 The conductor inserted in the through-hole constitutes a coaxial line with the conductor film in the through-hole. To form.

[0009]

【Example】

 An embodiment 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. The dielectric substrate 10 is Teflon (registered trademark) (ε = 2.3) or other dielectric material and has a dielectric constant (ε _r ) of 20.
When using a material of about 1.5 mm, it can be downsized to about 18 mm square when used in the 1.575 GHz band. In the case of a square, the electrode size is determined by the equation (1) of equation 1. Further, the effective dielectric constant (ε _eff ) becomes the value of the formula (2) of the equation 1 depending on the plate thickness n electrode width w, and ε _eff becomes the value of about 0.6 to 0.9 of ε _r . If Teflon is used, 55mm square is required. A radiation electrode 11 having a size of λ / 2 is formed on the front surface, and a ground electrode 12 is formed on the front surface on the back surface. A line from the feeding point of 50 ohms to the wiring pattern of the printed board 17 is formed by the conductor 13, and the line is a coaxial line.

[0011]

[Equation 1]

A conductor film 14 that does not reach the surface of the dielectric substrate is formed in the through hole, and the conductor film 14 is electrically connected to the ground electrode 12. The conductor 13 is covered with a dielectric 15 such as Teflon, and the conductor 13 is located at the center of the dielectric 15. The tip of the conductor 13 is connected to the radiation electrode 11 by solder or the like, and at this time, it is preferable to solder the through hole so that the solder does not flow into the through hole and the through hole is covered with a thin metal plate or the like.

The back surface of the dielectric substrate 10 can be mounted on the front surface of the printed board 17 as shown in FIG. 1, and can be connected to the ground electrode 12 and the ground wiring pattern. The other end of the conductor 13 may be passed through the through hole of the print substrate 17 and connected to the conductor pattern on the back surface by soldering or the like.

In order to form a 50 ohm line, the outer diameter of the conductor 13 serving as the central conductor, the inner diameter of the conductor film 12 formed in the through hole, and the dielectric constant of the dielectric material 15 interposed therebetween are considered. There is a need to. For example, when Teflon (ε = 2.3) is used, the ratio of the outer diameter of the conductor 13 to the inner diameter of the conductor film 14 may be about 3.6. The general formula for setting to 50 ohms is shown in the following Equation 2.

[0015]

[Equation 2]

In Equation 2, ln is the line length, D is the inner diameter of the conductor formed in the through hole, and d is the outer diameter of the center conductor.

The dielectric to be inserted into the through hole is not limited to the structure in which it is completely inserted into the through hole as shown in FIG. 1, but a part thereof may not be inserted into the dielectric substrate. Further, a brim can be formed at that portion to serve as a stopper when inserting the through hole, and soldering or the like becomes easy.

[0018]

[Effect of the device]

 According to the present invention, since it is possible to connect from the feeding point to the connecting point by the line of 50 ohm system at the feeding point, impedance matching becomes easy and a microstrip antenna with less loss can be obtained.

Further, since it is not necessary to use a connector or the like and the antenna can be mounted on the printed circuit board or the like as it is, it is advantageous in terms of downsizing of the device.

[Brief description of drawings]

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

FIG. 2 is a front sectional view of a conventional example.

[Explanation of symbols]

 10 Dielectric substrate 11 Radiation electrode 12 Ground electrode 13 Conductor 14 Conductor film 15 Dielectric

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyoshi Takano 828 Hinohara, Tamagawa, Hama-gun, Hiki-gun, Saitama Prefecture Toko Co., Ltd. Tamagawa factory

Claims (2)

[Scope of utility model registration request] 1. A dielectric substrate is provided with a radiation electrode having a size of ½ of the wavelength on the front surface and a ground electrode on the back surface, and a conductor is penetrated from a radiation electrode feeding point into a through hole formed in the dielectric substrate. In the microstrip antenna that is led out to the back surface, a conductor film that is electrically connected to the ground electrode is provided in the through hole,
A microstrip antenna characterized in that a conductor covered with a dielectric is inserted into the through hole, and the tip of the conductor is connected to a radiation electrode. 2. The microstrip antenna according to claim 1, wherein a 50 ohm coaxial line is formed by a conductor inserted into the through hole and a conductor film formed in the through hole.