JP2004014834A - Microwave circuit with printed resistor - Google Patents

Abstract

An object of the present invention is to provide a printed resistance circuit which is excellent in environment resistance and has a small resistance change due to a deviation from a strip line when used for an antenna requiring environment resistance such as a mobile satellite communication antenna.
In a microwave circuit with a printed resistor, a substrate, a plurality of circuit surfaces provided on and inside the substrate, and a high-frequency line portion for transmitting a high-frequency signal provided on the circuit surface on the substrate surface are provided. A printed resistor provided on a circuit surface inside the substrate, and a through hole for conducting the high-frequency line and the printed resistor.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-frequency circuit used in a communication device or the like, and more particularly to a microwave circuit with a printed resistor having a resistor in the circuit.
[0002]
[Prior art]
Conventionally, there has been a microwave circuit with a printed resistor of this type as shown in FIG. FIG. 6 shows an example of a conventional microwave circuit with a printed resistor disclosed in JP-A-5-199022, which has a function of a power distribution / combination circuit.
[0003]
In this figure, 2 is a dielectric substrate, 3 is a microstrip line, and 4 is a printed resistor. This power distribution / combination circuit is generally referred to as a Wilkinson distributor that is connected in multiple stages to distribute and combine high-frequency power.
[0004]
FIG. 7 is an enlarged view of a strip line and a printed resistor of the isolation resistor of the Wilkinson distributor shown in FIG. In FIG. 7, 3 is a high-frequency strip line, 4 is a printed resistor section, and 6a is a land, which is formed in the same layer. The land 6a is formed wider than the line width of the high-frequency strip line 3.
[0005]
Next, the operation of this conventional microwave circuit with a printed resistor will be described. First, second, and third terminals P1, P2, and P3 for inputting and outputting a high-frequency signal are formed on a side surface of the dielectric substrate 2. A transmission line composed of the microstrip line 3 is formed between these terminals, and an input signal is distributed or combined between the first terminal P1 and the second and third terminals P2 and P3 to be output. In order to ensure isolation between the distributed terminals P2 and P3, a printed resistor section 4 having a resistance component is provided between the second and third terminals. For example, the printed resistor can be processed into a desired size by etching a resistive film formed on a dielectric substrate, or a resistive film having a desired size can be formed by silk screen printing or the like.
[0006]
As shown in this figure, in the conventional microwave circuit with a printed resistor, the microstrip line 3 and the printed resistor section 4 are formed on the same surface of the dielectric substrate 2. In general, the printed resistor is formed by printing a material exhibiting resistance characteristics on a dielectric substrate separately from the conductor of the microstrip line. Therefore, a thin, small-sized microwave circuit having excellent high-frequency characteristics can be obtained.
[0007]
[Problems to be solved by the invention]
However, when the above-described power distribution / combination circuit is used for a mobile satellite communication antenna or the like, there is a possibility that a microstrip line formed on the same surface and a printing resistor portion are printed with a deviation. In the Wilkinson distributor, the isolation characteristic is degraded due to the deviation of the resistance value of the printed resistance portion from a desired value. In the worst case, there is a possibility that the conductor of the strip line and the printed resistance portion may be formed without being in contact with each other. In this case, for example, there is a problem that the radiation characteristics of the antenna device are greatly deteriorated.
[0008]
In order to solve the problem of the displacement between the microstrip line and the printed resistor, a wide land can be provided at the connection between the microstrip line and the printed resistor as shown in FIG. There is a problem that the transmission performance is deteriorated as described later.
[0009]
In addition, when the power distribution / combination circuit as described above is used under conditions where environmental resistance is required, such as in an aircraft, since the power distribution / combination circuit is formed on the same surface as the microstrip line, it is susceptible to moisture and the resistance value changes. There is a problem. It is also possible to protect the printed resistance portion by coating it with a resin. However, in the case of a suspended line described later, there is a small gap with the ground conductor, and it is difficult to perform manual coating. There is. In addition, since there are generally a plurality of such printed resistor portions in the high-frequency circuit, there is a problem that the operation becomes complicated.
[0010]
The present invention has been made in order to solve the above problems, and when used in an antenna requiring environmental resistance such as a mobile satellite communication antenna, the present invention has excellent environmental resistance and is not compatible with a strip line. It is an object of the present invention to obtain a printed resistance circuit having a small resistance change due to displacement.
[0011]
[Means for Solving the Problems]
A microwave circuit with a printed resistor according to the first aspect of the present invention transmits a substrate, a plurality of circuit surfaces provided on and inside the substrate, and a high-frequency signal provided on the circuit surface on the substrate surface. A high-frequency line portion, a printed resistance portion provided on a circuit surface inside the substrate, and a through-hole for conducting the high-frequency line portion and the printed resistance portion.
[0012]
In a microwave circuit with a printed resistor according to a second aspect of the present invention, the printed resistor and the through hole are connected via a land provided on a circuit surface inside the substrate.
[0013]
In the microwave circuit with a printed resistor according to the third aspect of the present invention, the outer dimensions of the land are formed to be smaller than the width of the printed resistor portion.
[0014]
Further, the microwave circuit with a printed resistor according to the invention according to claim 4 is characterized in that the specific frequency f0 of the high-frequency signal transmitted through the high-frequency line, the inductive component L determined by the physical size of the through hole, and the physical size of the land. The determined capacitive component C has a through hole and a land having physical dimensions satisfying a relationship of f0 = 1 / (2π (LC) ^1/2 ).
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, a microwave circuit with a printed resistor according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a cross-sectional configuration of a microwave circuit with a printed resistor according to Embodiment 1 of the present invention. In the drawings, the same reference numerals indicate the same or corresponding parts. In this figure, 1 is a ground conductor, 2 is a dielectric substrate and has a multilayer structure having an inner layer (in the case of this figure, an inner layer is provided between a first dielectric plate and a second dielectric plate). Reference numeral 3 denotes a high-frequency strip line, 4 denotes a printed resistor portion provided in an inner layer, 5 denotes a through hole, and 6 denotes a land (connection portion between the through hole and the printed resistor portion) provided in the inner layer. Conductor is used as material.
[0016]
Next, the operation of the microwave circuit with the printed resistor according to the first embodiment of the present invention will be described. Here, the high-frequency strip line is described as a suspended line (a high-frequency transmission line having a structure in which a dielectric substrate 2 is surrounded by a ground conductor 1 as shown in the figure). However, other high-frequency strip lines such as a triplate line operate. And the effect is the same. Such a high-frequency strip line can be applied to various functional elements in addition to the Wilkinson distributor shown in the conventional example. The suspended line is formed by sandwiching a dielectric substrate 2 between ground conductors 1 and forming a high-frequency strip line on the dielectric substrate 2.
[0017]
FIG. 1 shows, for example, a cross section of an isolation resistor portion of a Wilkinson distributor. In the case where the isolation resistor of the Wilkinson distributor is formed by a printed resistor, in the first embodiment of the present invention, the printed resistor portion is different from the high-frequency strip line formed on the substrate surface (the inner layer of the dielectric substrate 2). Formed. The printed resistor portions and the high-frequency strip lines formed in the different layers are electrically connected via a through hole 5 for electrically connecting the layers and a land 6 made of a conductor.
[0018]
The microwave circuit with the printed resistor according to the first embodiment of the present invention is configured as described above, and the printed resistor portion is provided in the inner layer of the dielectric substrate. For this reason, the printed resistance portion is less directly affected by the external environment, is not affected by temperature and humidity, and can secure a stable resistance value and obtain stable high-frequency characteristics.
[0019]
In addition, since there is no difference from the basic configuration of a conventional microwave circuit with a printed resistor, it can be easily realized even on a build-up board or the like. FIG. 2 shows a configuration in which Embodiment 1 of the present invention is applied to a multilayer build-up substrate. In the figure, reference numeral 11 denotes a core portion of the build-up board, and 12 denotes a build-up portion which is stacked (built up) on both sides so as to scissor the core portion. The core portion and the build-up portion have a configuration of a single dielectric plate or a multilayer configuration in which a plurality of dielectric plates are stacked. In FIG. 2, the core portion is constituted by three dielectric plates, and the upper and lower build-up portions are constituted by two dielectric plates. The entire build-up substrate has a configuration having six inner layers.
[0020]
The core portion has through holes penetrating all layers. This is for forming a through hole after laminating a plurality of dielectric plates. Each single dielectric plate of the build-up portion has a through-hole at a position different from the through-hole of the core portion. Therefore, when the build-up portions are stacked on the core portion, the positions of the through holes may not overlap. In other words, in a build-up board, only a through-hole can be provided on a normal multilayer board, but the position of the through-hole can be set freely, which can provide flexibility in the circuit design of the board. It becomes possible. In FIG. 2, a print resistor section 4 is provided on the inner layer (the surface of the inner layer 1) of the build-up section. The strip line on the surface of the build-up board is connected to the printed resistor section 4 through the through hole c, and further connected to the strip line in the core section through the through hole d. As described above, it is possible to form an inner layer of the print resistor section even in the build-up board.
[0021]
Embodiment 2 FIG.
FIG. 3 is a diagram showing a configuration of a microwave circuit with a printed resistor according to Embodiment 2 of the present invention. In the figure, reference numeral 4 denotes a printed resistor portion, 5 denotes a through hole, and 6 denotes a land, which has the same structure as that of the first embodiment. It is configured as follows. The outer dimension L of the land 6 on the side of the print resistor section 4 is formed smaller than the width W of the print resistor section 4. That is, L <W. The other configuration is the same as that of the first embodiment, and the description is omitted.
[0022]
The microwave circuit with the printed resistor according to the second embodiment of the present invention is configured as described above. That is, the width of the print resistor section 4 is formed larger than the outer shape of the land 6. Therefore, in addition to the effect of the microwave circuit with the printed resistor according to the first embodiment, the mutual positions of the strip line 3 and the printed resistor portion 4 formed in different layers are slightly shifted during the screen printing or etching process. However, it is unlikely that the lands 6 are formed to extend beyond the width of the print resistor section 4. Therefore, there is no change from the desired resistance value due to the physical shift between the high-frequency line and the printed resistance portion, and stable characteristics can be obtained as the resistance element.
[0023]
Embodiment 3 FIG.
FIG. 4 is a diagram showing a configuration and a principle of a microwave circuit with a printed resistor according to Embodiment 3 of the present invention.
[0024]
First, the basic operation of the microwave circuit with a printed resistor will be described. Regarding the transmission performance of the high-frequency circuit, it is particularly necessary to improve the reflection characteristics. Possible causes of the deterioration of the reflection characteristics include one caused by a difference in characteristic impedance of the line due to physical discontinuity of the line, and one caused by generation of a floating reactance component (capacitive or inductive) peculiar to high frequency.
[0025]
For example, in FIG. 7 shown in the above prior art, the land 6a is made wider than the line width of the high frequency strip line 3 in order to alleviate the problem of the shift between the high frequency strip line and the printed resistance portion. The values of the characteristic impedance and the printed resistance of the high-frequency strip line are determined by the design, but the widths of the strip line and the printed resistance generally do not match due to the dielectric properties and dimensions of the substrate used or the specific resistance (sheet resistance value) of the printed resistance. There are cases. Therefore, the lines having different widths (in FIG. 7, the strip line 3 and the land 6a) are connected as shown in FIG. 7, and the reflection is caused by the difference in characteristic impedance or the capacitive component generated in the connected wide strip line. There is a problem that characteristics are deteriorated.
[0026]
However, in the microwave circuit with a printed resistor according to the third embodiment of the present invention, as shown in FIG. 4A, the printed resistor portion is formed in a layer different from the high-frequency strip line, and the printed resistor portion and the high-frequency strip line It is configured to be connected via a through hole and a land made of a conductor for electrically connecting the interlayers therebetween. This configuration can be modeled and represented by an equivalent circuit in FIG. L1 and L2 are inductive inductance components generated by the through holes a and b, respectively. C1 and C2 are capacitive capacitance components generated by the lands a and b, respectively. R is a resistor, which corresponds to a print resistor section.
[0027]
At this time, for example, a capacitive capacitance component C due to a circular land formed on the printed resistor portion side and an inductive inductance component L generated by a through hole that electrically conducts between thin wire layers are canceled out at a desired frequency f0. For example, by designing so that f0 = 1 / (2 * π * √LC), it is possible to cancel the reactance at the connection portion and obtain a good reflection characteristic. When the element is used within a certain frequency band, for example, the frequency f0 is a frequency within that frequency band, and a particularly desirable frequency is the center frequency of the band. When L and C are determined so as to satisfy the above relationship, the physical dimensions of the corresponding through hole and land can be determined. In this case, the physical dimensions of the through hole and the land cannot be freely set because of the constraint of the above relational expression. For example, as shown in FIG. 5, the outer diameter of the circular through hole is smaller than the width of the high frequency strip line. May be larger.
[0028]
Since the microwave circuit with the printed resistor according to the third embodiment of the present invention is configured as described above, in addition to the effects of the microwave circuit with the printed resistor according to the first and second embodiments, the reactance at the connection part is also increased. And a microwave circuit with a printed resistor having good reflection characteristics can be obtained.
[0029]
【The invention's effect】
Since the microwave circuit with a printed resistor of the present invention is configured as described above, it has an effect of being excellent in environmental resistance and optimizing transmission performance.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a microwave circuit with a printed resistor according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration when the first embodiment of the present invention is applied to a multilayer build-up board.
FIG. 3 is a diagram showing a configuration of a microwave circuit with a printed resistor according to a second embodiment of the present invention.
FIG. 4 is a diagram illustrating a configuration and a principle of a microwave circuit with a printed resistor according to a third embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a microwave circuit with a printed resistor according to a third embodiment of the present invention.
FIG. 6 is a diagram showing a pattern example of a conventional microwave circuit with a print resistor.
FIG. 7 is a diagram illustrating a configuration of a conventional microwave circuit with a printed resistor.
[Explanation of symbols]
1 ground conductor, 2 dielectric substrate, 3 high frequency strip line, 4 printed resistor section, 5 through hole, 6, 6a land, 11 core section, 12 build-up section.

Claims (4)

A substrate, a plurality of circuit surfaces provided on the surface and inside of the substrate, a high-frequency line portion for transmitting a high-frequency signal provided on the circuit surface of the substrate, and a print provided on the circuit surface inside the substrate; A microwave circuit with a printed resistor, comprising: a resistor section; and a through hole for conducting the high-frequency line section and the printed resistor section. 2. The microwave circuit with a printed resistor according to claim 1, wherein the printed resistor and the through-hole are connected via a land provided on a circuit surface inside the substrate. The microwave circuit with a printed resistor according to claim 2, wherein an outer dimension of the land is formed smaller than a width of the printed resistor section. The specific frequency f0 of the high-frequency signal transmitted through the high-frequency line, the inductive component L determined by the physical size of the through hole, and the capacitive component C determined by the physical size of the land are f0 = 1 / (2π (LC) ^{1 3. The} microwave circuit with a printed resistor according to claim 2, further comprising a through hole and a land having physical dimensions satisfying the following relationship:

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