JP3267864B2 - Lumped constant circulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lumped constant type circulator which is a non-reciprocal microwave element using a ferrimagnetic material.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as ICs and transistors, multilayer chip capacitors, multilayer chip inductors,
With the miniaturization of electronic components such as chip resistors, the size and thickness of microwave devices on which these are mounted are rapidly progressing. In such a movement, there is a demand for downsizing and slimming of a lumped-constant circulator / isolator, which is an extremely important non-reciprocal element in configuring a microwave device. In order to meet the needs of the market and reduce the size of the lumped-constant circulator / isolator, there has been a problem that the insertion loss inevitably increases, and at the same time, the reflection loss and the reverse loss deteriorate. In particular, the deterioration of the reflection loss and the increase of the insertion loss directly affect the life of the battery when considered in a microwave portable device such as a mobile phone, which is not preferable. In addition, the deterioration of the backward loss impairs the function of the original circulator / isolator, and leads to an increase in intermodulation distortion (IM) of microwave equipment.

FIG. 8 is a schematic sectional view of the structure of a lumped-constant circulator. 1a, 1b and 1c are three sets of central conductors arranged on the ferrimagnetic material 2. One of the center conductors serves as input / output terminals T1, T2, and T3, and the other is connected to the common unit 3, and in this case, is grounded to a ground conductor. 4
Is an insulating sheet provided so that each central conductor does not short-circuit at the intersection. C is a load capacitance, which determines the operating frequency of the circulator. To realize a circulator operation with a desired impedance, an external magnetic field 5 is applied to the ferrimagnetic material. In addition, a resistor Ro is connected between the T3 terminal and the common unit 3 as shown in the figure to make it an isolator.

Heretofore, the insertion loss of the lumped-constant circulator is such as the magnetic loss (ΔH) of the garnet which is the ferrimagnetic material 2, the loss (copper loss) of the center conductor 1, the dielectric loss (tan δ) of the load capacitance C, and the like. It is believed to be. However, it was not clear how these actually relate to each other to determine the actual increase in insertion loss and the deterioration of reflection loss and reverse loss. The present invention relates to an optimum magnetic field adjustment method discovered by performing a detailed calculation in a case where the above-described loss factor exists, based on the basic principle of a lumped constant circulator.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for adjusting an optimum magnetic field for exhibiting the limit performance of a circulator, which has been discovered in view of the above-mentioned problems of the prior art and which has been found from the basic principle of a lumped-constant circulator. It is.

[0006]

A lumped-constant circulator according to the present invention comprises: a ferrimagnetic body to which a DC magnetic field is applied; three sets of central conductors arranged in proximity to the ferrimagnetic body and intersecting each other; In a configuration in which one of the center conductors is an input / output terminal and the other is connected to a common part in all three sets, and a configuration in which a load capacitance is arranged between one and the other of the center conductors, When a resistor is connected between the two and the common part, and the insertion loss between the remaining two input and output terminals, the reverse loss, and the reflection loss of each terminal are measured by a measurement system having the same internal impedance, the reflection loss is The magnetic field is adjusted to the set magnetic field so as to increase (improve) when the magnetic field is stronger than the set magnetic field and to increase (improve) the reverse loss when the magnetic field is weaker than the set magnetic field. Further, it is characterized in that the resistor is built in and has a function as an isolator.

[0007]

According to the adjusting method of the present invention,
It is possible to maintain an optimal state in which the reflection loss and the reverse loss are balanced, and to configure a high-performance lumped-constant circulator.

An object of the present invention is a method for adjusting an external magnetic field of a lumped constant type circulator. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG.
In a lossless lumped constant type circulator in the MHz band, a microwave is incident from a T1 terminal, and a T2 terminal and a T
FIG. 9 is a diagram illustrating frequency characteristics of S-parameters when outputs are measured at three terminals, calculated using a circuit simulator. At the center frequency represented by the normalized frequency 1, the return loss (S1
Both 1) and the backward loss (S31) become infinite, and the insertion loss (S21) becomes 0. It becomes a so-called ideal circulator. As shown in the figure, the S parameter deviates from the ideal state whether the frequency is higher or lower.

FIG. 2 is a graph showing frequency characteristics of S parameters calculated taking into account the resistance R of the center conductor. As R increases, both S11 and S31 deteriorate. Further, the frequency at which each loss becomes maximum also shifts to the low frequency side in S11 and shifts to the high frequency side in S31. The insertion loss (S21) increases rapidly as R increases. FIG. 3 shows that in FIG.
The frequency characteristic of the S parameter when the external magnetic field is changed is assumed to be 0.2 [Ω]. External magnetic field is normalized magnetic field σo
Is represented by Based on this, the low magnetic field side is indicated by a number below the decimal point, and the high magnetic field side is indicated by a number greater than 1.
As can be seen from this figure, S11 is improved on the high magnetic field side, and S31 is improved on the low magnetic field side. When there is a loss due to R, the optimum states of S11 and S31 cannot be realized at the same frequency in principle.

FIG. 4 is a diagram showing frequency characteristics of S parameters calculated taking into account the loss coefficient tan δ of the load capacitance C.
As tan δ increases, both S11 and S31 deteriorate. Further, the frequency at which each loss is maximized hardly changes. S21 increases rapidly with an increase in tan δ.

FIG. 5 shows the frequency characteristics of the S parameters when the external magnetic field is changed with tan δ = 0.01 in FIG. The external magnetic field is represented by a normalized magnetic field σo. Based on this, the low magnetic field side is indicated by a number below the decimal point, and the high magnetic field side is indicated by a number greater than 1. As in FIG.
11 is improved on the high magnetic field side, and S31 is improved on the low magnetic field side. Even when there is a loss due to tan δ as in the case of R, the optimum states of S11 and S31 cannot be realized at the same frequency.

FIG. 6 is a graph showing frequency characteristics of S-parameters calculated in consideration of the garnet loss coefficient ΔH. Δ
As H increases, both S11 and S31 deteriorate. Further, the frequency at which each loss becomes maximum also shifts to the high frequency side in S11 and shifts to the low frequency side in S31. S21 increases as ΔH increases.

FIG. 7 shows a case where ΔH = 40 [Oe] in FIG.
6 shows the frequency characteristics of S parameters when the external magnetic field is changed. The external magnetic field is represented by a normalized magnetic field σo.
Based on this, the low magnetic field side is indicated by a number below the decimal point, and the high magnetic field side is indicated by a number greater than 1. As can be seen from this figure, S11 is improved on the high magnetic field side, and S31 is improved on the low magnetic field side. Thus, even when there is a loss due to ΔH, the optimum states of S11 and S31 cannot be realized at the same frequency.

When these results are summarized, the insertion loss (S21) naturally increases when losses such as the resistance R of the center conductor, the tan δ of the load capacitance C, and the ΔH of the garnet are introduced. At the same time, reflection loss (S11) and reverse loss (S11)
31) also deteriorates. In order to improve this, the external magnetic field is changed. In any case, the reflection loss (S1
1) is improved when the magnetic field is increased, and the reverse loss (S
31) is improved when the magnetic field is weakened. If there is any loss, there is no external magnetic field that satisfies both simultaneously.

The most desirable point is to set an external magnetic field between the two. That is, it is the most efficient to operate the circulator with the operating magnetic field determined assuming no loss. However, as a practical matter, it is impossible to realize a lossless lumped constant circulator. Therefore, as a practical matter, setting the external magnetic field such that the reflection loss is improved when the magnetic field is strengthened and the reverse loss is improved when the magnetic field is weakened is close to the operating magnetic field of the lossless lumped constant type circulator. Will be. As is clear from the above description, it has been found that the above-described magnetic field setting is most preferable in order to minimize the deterioration of the reflection loss and the reverse loss due to the increase of the loss coefficient.

Although the above description is about a circulator, the same can be said for an isolator configuration in which a resistor is connected between the T3 terminal and the common portion and the resistor is built in. When the output of the T1 terminal is measured by inputting a microwave from the T2 terminal, the backward loss S21 is equal to the above-described S3.
It is equivalent to 1. Therefore, it can be easily understood by a person skilled in the art that the magnetic field adjustment method of the present invention can be applied to an isolator.

[0017]

By using the magnetic field adjustment method of the present invention, a high-performance lumped-constant circulator can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing frequency characteristics of S parameters of a lossless lumped constant type circulator.

FIG. 2 is a diagram showing frequency characteristics of S parameters when a resistance R of a center conductor is considered.

FIG. 3 is a diagram illustrating frequency characteristics of S parameters when a normalized magnetic field is changed with R = 0.2 [Ω], and is a diagram illustrating the principle of the present invention.

FIG. 4 is a diagram showing frequency characteristics of S parameters when tan δ of a load capacitance C is considered.

FIG. 5 is a diagram illustrating frequency characteristics of S parameters when a normalized magnetic field is changed with tan δ = 0.01, illustrating the principle of the present invention.

FIG. 6 shows S in consideration of a garnet loss coefficient ΔH.
The figure which shows the frequency characteristic of a parameter.

FIG. 7 is a diagram showing the frequency characteristics of S parameters when the normalized magnetic field is changed with ΔH = 40 [Oe], showing the principle of the present invention.

FIG. 8 is a schematic structural sectional view of a lumped-constant circulator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Center conductor 2 Ferrimagnetic material 3 Common part 4 Insulating sheet 5 External magnetic field C Load capacitance Ro resistance

──────────────────────────────────────────────────続 き Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01P 1/32 H01P 1/383 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A ferrimagnetic body to which a DC magnetic field has been applied, three sets of center conductors arranged in proximity to each other and intersecting each other, one of the center conductors serving as an input / output terminal, and the other serving as an input / output terminal. In a lumped-constant circulator having a configuration in which a pair is connected to a common part and a load capacitance is arranged between one and the other of the center conductors, a resistor is connected between one of the input / output terminals and the common part. When the insertion loss between the remaining two input / output terminals, the reverse loss, and the reflection loss of each terminal are measured by a measurement system having the same internal impedance, the reflection loss increases when the magnetic field is stronger than the set magnetic field. The magnetic field applied to the ferrimagnetic material is adjusted to the set magnetic field so that the reverse loss increases (improves) when the magnetic field is weaker than the set magnetic field. Constant type Circulator. 2. The lumped-constant circulator according to claim 1, wherein the circulator includes the resistor and has a function as an isolator.