JPH05152831A - Resonance frequency adjustment method for microstrip antenna - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The resonance frequency is adjusted without changing the electrodes. [Structure] A hole 15 is formed on the bottom surface of the dielectric substrate 20 from the side of the ground electrode 12 to reduce the effective dielectric constant of the dielectric substrate 20, or the hole 15 is filled with a dielectric material to reduce the effective dielectric constant. By raising it, the resonance frequency is raised and lowered to perform adjustment. When the effective dielectric constant increases, the resonance frequency decreases,
Conversely, when the effective permittivity decreases, the resonance frequency increases. [Effect] The resonance frequency can be adjusted in both directions of increasing and decreasing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip antenna used in a navigation system or the like, and more particularly to a method of adjusting its resonance frequency.

[0002]

2. Description of the Related Art In a GPS navigation system or the like, a small antenna for receiving a signal from a satellite is required, and use of a microstrip antenna is considered as one of them.

In this microstrip antenna, a radiation electrode having a size of a half of the wavelength of light received is provided on the surface of a dielectric substrate, and a ground electrode is formed on the entire back surface. There are square and circular radiating electrodes, and the band of the receiving frequency is widened by devising the shape.

FIG. 3 is a front sectional view showing an example of the structure of such a conventional microstrip antenna. A radiation electrode 31 is formed on the front surface of the dielectric substrate 30, and a ground electrode 32 is formed on the back surface. From the 50 ohm point of the radiating electrode, the conductor is drawn out by the coaxial line through the through hole. In the case of a rectangular electrode, its dimension L is determined by the equation (1), and the effective permittivity ε _eff that determines it is determined by the equation. Here, f ₀ is the resonance frequency, ε _r is the dielectric constant of the dielectric substrate, C is the speed of light, h is the thickness of the dielectric substrate, and w is the width of the electrode.

[0005]

[Equation 1]

[0006]

When actually manufacturing a microstrip antenna, it is necessary to adjust the frequency. Generally, the work of fitting the electrodes is performed by cutting the electrodes. However, it is difficult to finely adjust the frequency, which is a major factor in the increase in man-hours.

The present invention makes it possible to easily adjust the resonance frequency of the microstrip antenna and to provide an adjustment method capable of increasing or decreasing the frequency.

[0008]

The present invention solves the above problems by forming holes in the bottom surface of a dielectric substrate and filling the holes with a dielectric.

That is, in the resonance frequency adjusting method of the microstrip antenna, in which the radiation electrode having a size of ½ of the wavelength is provided on the front surface of the dielectric substrate and the ground electrode is provided on the back surface, the ground electrode is provided on the back surface of the dielectric substrate. By forming a hole extending inside the dielectric substrate, the effective permittivity with respect to the permittivity of the dielectric substrate is lowered, thereby increasing the resonance frequency.

Further, the surface of the dielectric substrate has a half wavelength
In a resonance frequency adjusting method for a microstrip antenna having a radiation electrode having a size of 5 mm and a ground electrode on the back surface, a hole extending from the ground electrode to the inside of the dielectric substrate is formed on the back surface of the dielectric substrate, and the hole is filled with the dielectric material. Is characterized by increasing the effective permittivity with respect to the permittivity of the dielectric substrate, thereby lowering the resonance frequency.

[0011]

[Function] By forming a hole for removal of the dielectric and filling it with a dielectric, the effective dielectric constant (ε _eff above) of the dielectric substrate is changed, and the resonance frequency is maintained without changing the electrode. Is adjusted in both directions.

[0012]

1 is a front sectional view showing an embodiment of the present invention. A radiation electrode 11 is formed on the front surface of a dielectric substrate 10, and a ground electrode 12 is formed on the back surface. The bottom surface of the dielectric substrate 10 has holes 15 extending from the ground electrode 12 into the dielectric substrate.
Are formed. Although the structure in which the ground electrode 12 side of the dielectric substrate 10 is mounted on the ground panel 17 is shown, it may be mounted on the ground pattern of the circuit board.

When the effective permittivity of the dielectric substrate 10 decreases due to the formation of the holes 15, the resonance frequency due to the electrodes of the same size increases according to the above formula. Therefore, set the size of the radiation electrode in advance below the resonance frequency,
The resonance frequency can be adjusted by controlling the diameter and the depth of the hole 15.

The holes can be formed by cutting the dielectric substrate with a router. The effective permittivity can be controlled by controlling its position, diameter and depth.

FIG. 2 is a front sectional view showing another embodiment of the present invention. The radiation electrode 21 and the ground electrode 22 are formed on the dielectric substrate 20, and the holes are formed on the bottom surface of the dielectric substrate as described above, but the holes are filled with the dielectric 26.
Like the above, it is mounted on the earth panel 27.

When the effective dielectric constant of the dielectric substrate 20 is increased by filling the dielectric 26, the resonance frequency due to the electrodes of the same size is reduced from the above formula. Therefore, the resonance frequency can be adjusted by forming the size and depth of the hole so as to be set lower than the resonance frequency in advance and controlling the filling amount of the dielectric 26.

By providing a plurality of holes or filling them with a dielectric, the adjustment range can be expanded. However, if too many numbers are provided or too large holes are formed, problems with respect to strength will occur, so it is desirable to keep them to a minimum.

A microstrip antenna of 1500 MHz band having a 20 mm square radiating electrode formed on a 30 mm square, 6 mm thick dielectric substrate with a dielectric constant of 21 has a hole with a diameter of 3 mm and a depth of 3 mm at the center of the radiating electrode. And formed at a position corresponding to the center of each side. A ground plate was placed on this back surface to close the hole. At this time, the resonance frequency changed from 1500MHz to 1550MHz.

When these holes were filled with a dielectric material having a dielectric constant of 80 and closed with the same ground plate, the frequency changed from 1550 MHz to 1470 MHz.

[0020]

According to the present invention, the resonance frequency can be easily adjusted without touching the electrodes. Moreover, since the electrodes are not shaved, fine adjustment and readjustment are facilitated, and not only the number of steps can be reduced but also the yield can be improved. In addition, since a hole can be formed directly below the radiation electrode, the range of adjustment of the effective dielectric constant can be widened.

Further, it is possible to make adjustments in both the raising direction and the lowering direction, and it becomes easy to deal with variations in element characteristics.

[Brief description of drawings]

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

FIG. 2 is a front sectional view showing another embodiment of the present invention.

FIG. 3 is a front sectional view showing a conventional example.

[Explanation of symbols]

 10, 20, 30: Dielectric substrate 11, 21, 31: Radiation electrode 12, 22, 32: Ground electrode 15: Hole 26: Dielectric

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[Procedure amendment]

[Submission date] June 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

When the effective permittivity of the dielectric substrate 10 decreases due to the formation of the holes 15, the resonance frequency at the electrodes of the same size increases from the above formula. Therefore, the resonance frequency can be adjusted by setting the size of the radiation electrode so as to be lower than the predetermined resonance frequency and controlling the diameter and the depth of the hole 15.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

When the effective dielectric constant of the dielectric substrate 20 is increased by filling the dielectric 26, the resonance frequency at the electrodes of the same size is reduced from the above equation. Therefore, by setting the size and depth of the hole so as to be higher than the predetermined resonance frequency and controlling the filling amount of the dielectric 26,
The resonance frequency can be matched.

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

Claims (2)

[Claims] 1. A method for adjusting a resonance frequency of a microstrip antenna, comprising a radiation electrode having a size of ½ of a wavelength on a front surface of a dielectric substrate and a ground electrode on a back surface of the dielectric substrate. A resonance frequency adjusting method for a microstrip antenna, comprising forming a hole extending inside a dielectric substrate to reduce the effective permittivity with respect to the permittivity of the dielectric substrate, thereby increasing the resonance frequency. 2. A resonance frequency adjusting method for a microstrip antenna, comprising a radiation electrode having a size of ½ of a wavelength on the front surface of a dielectric substrate and a ground electrode on the back surface, and a method of adjusting the resonance frequency from the ground electrode to the back surface of the dielectric substrate. By forming a hole extending inside the dielectric substrate and filling the hole with a dielectric, the effective permittivity with respect to the permittivity of the dielectric substrate is increased, thereby lowering the resonance frequency. Resonance frequency adjustment method.