JP2000201008A - Microstrip line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a dielectric loss, and to improve Q characteristics as resonating elements by forming notched parts in prescribed shapes at the prescribed positions of an insulating substrate along the both side edges of the longitudinal direction of a band-shaped conductor provided on the insulating substrate. SOLUTION: Insulating notched parts 3 are formed along both side edge faces 2a of a band-shaped conductor 2 formed on an insulating substrate 1 in the neighborhood of antinodes for maximizing the current density of standing waves generated in the longitudinal direction when high frequency currents flow in the conductor 2 so that an insulator loss can be effectively reduced. Also, when length L1 of the conductor 2 is 1/2 of the wavelength of the current standing waves, and the both edges are opened, the central part is set as the antinode point, and the notched parts 3 are formed in the neighborhood of the central part. Length L2 of the notched part 3 is set so as to be almost 1/2 of length between the central part and one edge part of the conductor 2 so that the range of about 50% of the maximum current density can be covered. Also, the depth of the notched part 3 is set so as to be the width of the notched part 3 or more so that the effect can be made higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip line used for, for example, a resonance element of a voltage controlled oscillator.

[0002]

2. Description of the Related Art A conventional microstrip line is shown in FIG.
It will be described according to. The microstrip line is used, for example, as a resonance element of an oscillation circuit, and includes a strip-shaped conductor 22 provided on an upper surface of an insulating substrate 21. One end 22a of the conductor 22 is opened or short-circuited, and the other end 22b is connected to an oscillation circuit (not shown).

[0005] Here, a voltage / current standing wave is generated on the line of the conductor 22. Since the phase of the current standing wave and the phase of the voltage standing wave are shifted from each other by π / 4, the current standing wave is an antinode at the node of the voltage standing wave, that is, the current density is the largest. The current standing wave becomes a node at the antinode of the voltage standing wave.

[0004] In addition, a microstrip line is used as a resonance element between a node and an antinode, depending on the phase relationship between the voltage standing wave and the current standing wave, to be dielectric or capacitive.

[0005]

When a high-frequency current is applied to the conductor 22, the high-frequency current becomes highest in the surface layer of the conductor 22 due to the skin effect. Further, since the high-frequency current flows through the conductor 22 as a current standing wave, the current density is highest at the antinode. That is, the conductor 22
And the current density is highest at the antinode of the current standing wave.

Here, the flow of the high-frequency current flowing through the conductor 22 is hindered by the dielectric loss caused by the insulating substrate 21, and is particularly affected by the dielectric loss at the antinode where the current density is high. For this reason, a high-frequency current is most difficult to flow particularly at an antinode of a high current density. As a result, there is a problem that a large Q as a resonance element cannot be obtained.

An object of the present invention is to solve this problem. An object of the present invention is to reduce a dielectric loss caused when a high-frequency current is applied to a microstrip line and to increase Q as a resonance element. is there.

[0008]

As a first means for solving the above-mentioned problem, a strip-shaped conductor provided on an upper surface of an insulating substrate is provided, and the insulating substrate is formed along both longitudinal ends of the conductor. The configuration was such that an insulator lacking portion formed by cutting out was provided.

[0009] As a second solution, the insulator lacking portion is formed near the antinode of the current standing wave generated in the conductor.

[0010] Further, as a third solution, a configuration is adopted in which the length in the longitudinal direction of the lacking portion of the edge is １ ／ of the length between the antinode and the node at the wavelength of the current standing wave. did.

Further, as a fourth solution, the insulator lacking portion is constituted by a groove, and the depth of the groove is made substantially equal to or greater than the width of the insulator lacking portion.

[0015] As a fifth solution, the insulator lacking portion is formed as a hole penetrating the insulator.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A microstrip line according to the present invention will be described with reference to FIGS. Here, FIG. 1 shows a top view of the first embodiment of the present invention, FIG. 2 also shows a top view of the second embodiment, FIG. 3 shows the same of the third embodiment, and FIG. FIG. 5 is a sectional view taken along line 5-5 of FIGS. 1 to 4, and FIG. 6 is a sectional view of another essential part of FIGS.

First, in FIGS. 1 to 4, the microstrip line of the present invention comprises a strip-shaped conductor 2 provided on the upper surface of an insulating substrate 1 having a ground conductor 1a (see FIGS. 5 and 6) on the lower surface. ing. An insulator lacking portion 3 is formed by cutting out the insulating substrate 1 along the whole or a part of both side ends 2 a in the longitudinal direction of the conductor 2.
The conductor 2 has one end 2b open or short-circuited, and the other end 2c connected to an oscillation circuit (not shown).

Here, when a high-frequency current flows through the conductor 2,
An electromagnetic field is generated around the conductor 2. However, since the insulator lacking portion 3 is provided along both side ends 2a of the conductor 2, the dielectric loss at that portion is reduced, so that the electromagnetic field easily flows. ,
As a result, a high-frequency current flowing through the conductor 2 easily flows, and thus Q as a resonance element increases.

Here, a voltage / current standing wave is generated on the line of the conductor 2 in the longitudinal direction, and the current density becomes maximum at the antinode of the current standing wave. 3
Is also effective near this antinode. For example, as shown in FIG. 1, when the length L1 of the conductor 2 is の (half wavelength) of the wavelength λ of the current standing wave and both ends are open, the central portion 2d of the conductor 2 Since this becomes the antinode of the standing wave, the effect can be obtained by providing the insulator lacking portion 3 near the central portion 2d. In this case, as shown in FIG. 2, the length L2 of the insulator lacking portion 3 in the longitudinal direction is equal to the antinode of the current standing wave at the center 2d of the conductor 2 as described above. It is formed to be approximately 1/2 of the length between 2d and one end 2b of the conductor 2 and approximately 1/2 of the length between the center 2d of the conductor 2 and the other end 2c of the conductor 2. That is, by forming the length L2 of the insulator lacking portion 3 in the longitudinal direction to be approximately half the length L1 of the conductor 2 in the longitudinal direction, the range of about 50% of the maximum current density can be reduced. Since the cover is provided, more effects can be obtained.

For example, as shown in FIG.
Is 1/4 of the wavelength λ of the current standing wave and one end 2b of the conductor 2 is opened, the current standing wave becomes an antinode of the current standing wave at the one end 2b of the conductor 2. Therefore, the effect can be obtained if the insulator lacking portion 3 is provided near the one end 2c of the conductor 2. In this case, as shown in FIG. 4, the length L4 of the insulator lacking portion 3 in the longitudinal direction is changed to the length L of the conductor 2 in the longitudinal direction.
More effect can be obtained by setting the ratio to approximately 1/2 of 3. When one end 2b of the conductor 2 is short-circuited, the other end 2c of the conductor 2 becomes an antinode of the current standing wave. By forming the insulator lacking portion 3 as described above, an effect can be obtained.

The insulator lacking portion 3 forms a hole having a bottom 3a as shown in FIG. It is desirable that the depth D of the insulator lacking portion 3 be equal to or greater than the width W of the insulator lacking portion 3. By setting the depth D of the insulator lacking portion 3 in this manner, dielectric loss due to an electromagnetic field generated when a high-frequency current flows through the conductor 2 is reduced. The insulator lacking portion 3 is formed by a hole having the depth D as described above, but may be formed by a through hole having no bottom 3a as shown in FIG. The effect can be obtained.

[0019]

As described above, the first solution of the present invention is to form a strip-shaped conductor provided on the upper surface of an insulating substrate and cut off the insulating substrate along both longitudinal ends of the conductor. By adopting the configuration with the formed insulator missing part,
In the vicinity of the antinode of the current standing wave having a high current density, there is no insulating substrate that causes dielectric loss, so that dielectric loss does not occur, and as a result, high-frequency current flows easily. Therefore, Q can be made large.

Further, as a second solution of the present invention, the insulator lacking portion is formed near the antinode of the current standing wave generated in the conductor, so that the current density is the highest. Since there is no insulating substrate near the antinode of the standing wave, dielectric loss does not occur, and as a result, a high-frequency current flows easily. Therefore, Q can be made large.

As a third solution of the present invention, the length in the longitudinal direction of the edge-missing portion is set to 1/2 of the length between the antinode and the node at the wavelength of the current standing wave. With this configuration, there is no insulating base near the antinode of the current standing wave having a high current density, and no dielectric loss occurs.As a result, high-frequency current is reduced. Easy to flow. Therefore, Q can be made large.

Further, as a fourth solution of the present invention, the insulator lacking portion is constituted by a groove, and the depth of the groove is substantially equal to or greater than the width of the insulator lacking portion. Since a range of about 50% of the maximum current density is covered, a high-frequency current flows more easily.

Further, as a fifth solution of the present invention, since the insulator lacking portion is formed as a hole penetrating the insulator, the dielectric loss can be more greatly attenuated. Current flows more easily.

[Brief description of the drawings]

FIG. 1 is a top view of a first embodiment of a microstrip line of the present invention.

FIG. 2 is a top view of a second embodiment of the microstrip line of the present invention.

FIG. 3 is a top view of a third embodiment of the microstrip line of the present invention.

FIG. 4 is a top view of a fourth embodiment of the microstrip line of the present invention.

FIG. 5 is a cross-sectional view of a main part of a part 5-5 in FIGS. 1 to 4 of the present invention.

FIG. 6 is a sectional view of another essential part of FIGS. 1 to 4 of the present invention.

FIG. 7 is a top view of a conventional microstrip line.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating board 2 Conductor 2a Both ends in the longitudinal direction of a conductor 2b One end of a conductor 2c The other end of a conductor 2d Position of λ / 4 from one end of a conductor in the longitudinal direction of a conductor 3 Insulated part 3a Bottom part

Claims (5)

[Claims] 1. An insulator lacking portion formed of a strip-shaped conductor provided on an upper surface of an insulating substrate and formed by cutting the insulating substrate along both longitudinal ends of the conductor. Microstrip line. 2. The microstrip line according to claim 1, wherein the insulator lacking portion is formed near an antinode of a current standing wave generated in the conductor. 3. The method according to claim 1, wherein the length of the insulator-deficient portion in the longitudinal direction is の of the length between the antinode and the node at the wavelength of the current standing wave. The microstrip line according to claim 1 or 2. 4. The insulator lacking portion is formed by a groove, and the depth of the groove is substantially equal to or greater than the width of the insulator lacking portion. Microstrip line. 5. The microstrip line according to claim 1, wherein the insulator lacking portion is a hole penetrating the insulator.