JP2012010153A - Variable phase shifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable phase shifter that has a simpler structure than before and also has a large phase shift amount, and is compact and superior in high-frequency characteristics.SOLUTION: The variable phase shifter has transmission lines 101, 102 including a first dielectric substrate 10 and a signal path 11 formed on an upper surface 10b of the first dielectric substrate 10 and propagating signals. The transmission lines 101, 102 comprise a first transmission line 101 having a second dielectric substrate 20 arranged over the signal line 11; and a second transmission line 102 having a different-dielectric-constant part 23 that has a dielectric constant different from that of the second dielectric substrate 20, arranged over the signal line 11, and differing in effective dielectric constant from the first transmission line 101. The second dielectric substrate 20 and the different-dielectric-constant part 23 are arranged movably along the upper surface 10b of the first dielectric substrate 10, and the transmission line length ratio of the first transmission line 101 and the second transmission line 102 of the transmission lines 101, 102 is varied by the movement.

Description

  The present invention relates to a variable phase shifter, and more particularly to a variable phase shifter having a large phase variable amount.

  As a method for continuously varying the phase, a method in which the length of the transmission line is changed is stable in performance, and is generally used in many cases.

  For example, a variable phase shifter (for example, see Patent Document 1) provided with a mechanism for changing the length of a coaxial transmission line, or a variable phase shifter (for example, Patent Document 2) provided with a mechanism for changing the length of a microstrip line. Is known).

  As shown in FIG. 9A, the conventional variable phase shifter disclosed in Patent Document 1 includes input / output connectors 61 and 62, and a fixed transmission line 63 connected to the input / output connectors 61 and 62. The movable transmission line 64 is slidable with respect to the fixed transmission line 63. The transmission lines 63 and 64 accommodated in the conductive case 65 are fitted into each other in a pipe shape and are electrically connected.

  By moving the movable transmission line 64, the entire length of the transmission lines 63 and 64 can be made variable, whereby the transmission line length between the input / output connectors 61 and 62 changes, and the phase is continuously changed. Can be made variable.

  Further, a conventional variable phase shifter as disclosed in Patent Document 2 includes two microstrip lines 72 and 73 formed on a first substrate 71, as shown in FIG. A coupled microstrip line 75 formed on the substrate 74.

  The second substrate 74 faces the first substrate 71 such that the surface on which the coupled microstrip line 75 is formed and the surface on which the two microstrip lines 72 and 73 of the first substrate 71 are opposed. And slidable. At this time, one end of the coupled microstrip line 75 is in direct contact with and electrically connected to the input side microstrip line 72, and the other end of the second substrate 74 is in direct contact with the output side microstrip line 73. Installed to be electrically connected.

  Then, by sliding the second substrate 74 on which the coupled microstrip line 75 is formed, the transmission line length between the input port Pi and the output port Po is changed to change the phase.

JP-A-11-163608 JP 2009-147442 A

  However, the conventional variable phase shifter disclosed in Patent Document 1 has a complicated driving mechanism for changing the transmission line length and requires that the movable transmission line be configured in a straight line. The larger the variable amount, the larger the size including the drive mechanism. Further, in order to stably change the transmission line length, there is a problem that the processing accuracy of the parts to be used is required and the cost becomes high.

  Further, in the conventional variable phase shifter as disclosed in Patent Document 2, it is difficult to accurately perform pattern matching between the microstrip lines formed on the two opposing substrates, and the movable part is shortened. In order to implement measures such as performing / moving the movable part in a straight line / widening the line width of the movable part as necessary, it is necessary to sacrifice phase variable amount / miniaturization / transmission line characteristics.

  The present invention has been made to solve such a conventional problem, and provides a variable phase shifter having a simpler structure, a larger amount of phase variable than that of the prior art, a small size, and excellent high-frequency characteristics. Objective.

In order to solve the above-mentioned problems, a variable phase shifter according to claim 1 of the present invention is a first dielectric substrate and a signal line formed on one surface of the first dielectric substrate to propagate a signal. The transmission line includes: a first transmission line in which a second dielectric substrate is disposed above the signal line; and the second dielectric substrate above the signal line. A second transmission line having an effective dielectric constant different from that of the first transmission line, wherein the second dielectric substrate and the different dielectric constant part are arranged. Is arranged so as to be movable along the one surface of the first dielectric substrate, and the movement allows the transmission line length ratio of the first transmission line and the second transmission line to be variable in the transmission line. The propagation speed of the signal in the transmission line changes, and the signal It has a structure of outputting by varying the phase.
With this configuration, it is possible to realize a variable phase shifter that has a simpler structure, a smaller size, and a larger phase variable amount than the conventional one.

The variable phase shifter according to claim 2 of the present invention has a configuration in which the signal line is formed in a meandering shape. The variable phase shifter according to claim 3 of the present invention has a configuration in which the signal line is formed in an arc shape having a center of curvature on a predetermined axis.
With these configurations, the length of the transmission line can be increased without increasing the outer shape, so that further miniaturization can be realized and an increase in the phase variable amount can be realized. Note that it is difficult to form the signal line in a meandering manner with a conventional structure in which the transmission line length is variable (movable parts are combined).

The variable phase shifter according to claim 4 of the present invention has a configuration in which a ground conductor is provided at a predetermined position above the different dielectric constant portion so that the characteristic impedance of the transmission line becomes a desired value. .
With this configuration, since the characteristic impedance when the different dielectric constant portion is above the signal line can be deviated from the characteristic impedance when the second dielectric substrate is above, deterioration in frequency characteristics can be eliminated ( Because a mechanism for correcting characteristic impedance is provided by providing a ground conductor at a predetermined position above the different dielectric constant portion), a variable phase shifter excellent in high frequency characteristics can be realized.

The variable phase shifter according to claim 5 of the present invention has a configuration in which the different dielectric constant portion is formed of an air layer or a dielectric member.
Making the different dielectric constant portion an air layer only requires a hollow portion in the second dielectric substrate, and a variable phase shifter can be realized with a small number of components. In addition, the air layer has a low dielectric constant, and a large difference in effective dielectric constant between the first transmission line and the second transmission line can be obtained.
In the invention according to claim 4, since the dielectric member is a dielectric member, since a dielectric material can be interposed between the ground conductor and the signal line, the contact between the ground conductor and the signal line is less likely to occur. There is an effect that it becomes a structure.

In the variable phase shifter according to a sixth aspect of the present invention, the transmission line is a coplanar wave guide or a grounded coplanar wave guide.
Compared to the case where the transmission line is configured by a microstrip line, this configuration has a good group delay characteristic at the high-frequency part even if the different dielectric constant part is an air layer. Can be realized. In addition, in the transmission line of a coplanar wave guide or a grounded coplanar wave guide, even when the distance between the signal line and the grounding conductor pattern is narrow, this structure is a structure in which the transmission line length of the conventional technology is variable (movable parts are matched). Since it is not, it is easily realizable.

  The present invention has a simpler structure than the conventional one and is excellent in miniaturization. Furthermore, the present invention provides a variable phase shifter that can be easily made into a structure excellent in high-frequency characteristics, has a large phase variable amount, is small, and has excellent high-frequency characteristics.

1 is an exploded perspective view showing a configuration of a variable phase shifter according to the present invention. The top view which shows the structural example of the transmission line with which the variable phase shifter which concerns on this invention is equipped. The top view which shows the rotated state of the 2nd dielectric substrate and variable dielectric constant part with which the variable phase shifter which concerns on this invention is equipped AA 'line sectional view and BB' line sectional view of FIG. AA '' line sectional view and BB '' line sectional view of FIG. Graph showing simulation results of reflection characteristic S ₁₁ , transmission characteristic S _21, and group delay characteristic T _g when the second dielectric substrate is disposed on the signal line Graph showing simulation results of reflection characteristics S ₁₁ , transmission characteristics S _21, and group delay characteristics T _g when an air layer is disposed above the signal line (no upper ground conductor) Graph showing simulation results of reflection characteristic S ₁₁ , transmission characteristic S _21, and group delay characteristic T _g when an air layer is disposed above the signal line (with an upper ground conductor) Top view showing the configuration of a conventional variable phase shifter

  Embodiments of a variable phase shifter according to the present invention will be described below with reference to the drawings.

  1 is an exploded perspective view showing a configuration of a variable phase shifter according to the present embodiment, FIGS. 2 and 3 are top views, and FIG. 4 is a cross-sectional view along line AA ′ and a cross-sectional view along line BB ′ in FIG. 5B and 5B are a cross-sectional view taken along line AA ″ and a cross-sectional view taken along line BB ″ in FIG. For the sake of explanation, the dimensional ratio of each component on each drawing does not necessarily match the actual dimensional ratio.

  That is, as shown in FIGS. 1 and 4, the variable phase shifter of the present embodiment includes a cylindrical casing 50, a first dielectric substrate 10 housed in the casing 50, and a first dielectric substrate. 10, the second dielectric substrate 20 disposed on the upper surface 10 b side, the first ground conductor 30 disposed on the upper surface 20 b side of the second dielectric substrate 20, and the lower surface 10 a of the first dielectric substrate 10. And a second ground conductor 40 disposed on the side (the second ground conductor 40 is not shown in FIG. 1).

  The first ground conductor 30 has a rotation shaft 32, and the rotation shaft 32 is provided at the center portion of each of the first dielectric substrate 10, the second dielectric substrate 20, and the second ground conductor 40. A shaft hole to be inserted is formed. The housing 50 is formed with a bearing that rotatably holds the rotary shaft 32. A groove 32a is formed at the upper end of the rotary shaft 32 so that it can be connected to a driving means (not shown) for supplying rotational force. The first ground conductor 30 is rotated integrally with the second dielectric substrate 20 around the rotation shaft 32.

  As shown in FIG. 2A, the upper surface 10b of the first dielectric substrate 10 has a signal line pattern 11 that is an arc-shaped signal line, and a circle that is concentrically arranged on both sides of the signal line pattern 11. Ground conductor patterns 12a and 12b, which are arc-shaped ground conductors, are formed. The signal line pattern 11, the ground conductor patterns 12 a and 12 b, and the different dielectric constant portion 23 are all formed in an arc shape having a center of curvature on the rotation shaft 32. Signals are input to and output from the signal line pattern 11 through the connectors 50 a and 50 b of the housing 50. In FIG. 2, the first ground conductor 30 and the second dielectric substrate 20 are not shown.

  As shown in FIGS. 4 and 5, the second ground conductor 40 and the ground conductor patterns 12 a and 12 b are electrically connected by a plurality of through holes 13 penetrating the first dielectric substrate 10. Thus, a grounded coplanar wave guide (transmission lines 101 and 102) is formed. The inner wall surface of the through hole 13 is plated with metal in order to electrically connect the second ground conductor 40 and the ground conductor patterns 12a and 12b.

  As shown in FIG. 2B, the transmission lines 101 and 102 include a meandering signal line pattern 11 and meandering ground conductor patterns 12 a and 12 b arranged on both sides of the signal line pattern 11. A grounded coplanar wave guide may be included.

  As shown in FIGS. 1 and 4, the second dielectric substrate 20 and the first ground conductor 30 are sequentially disposed above the first dielectric substrate 10. The lower surface 20 a of the second dielectric substrate 20 can come into contact with the signal line pattern 11. The second dielectric substrate 20 includes a cavity 21, and the first ground conductor 30 includes a protrusion 31 that fits into the cavity 21. The protrusion 31 functions as a ground conductor in a transmission line to be described later (hereinafter referred to as a ground conductor 31).

  As shown in FIG. 5B, the front end surface 31 a of the ground conductor 31 is a predetermined distance Δ (the thickness of the second dielectric substrate 20 and the ground conductor 31 with respect to the upper surface 10 b of the first dielectric substrate 10. Are opposed to each other. As a result, an air layer 23 (hereinafter also referred to as a different dielectric constant portion 23) as a different dielectric constant portion is formed in a region sandwiched between the first dielectric substrate 10 and the ground conductor 31 in the cavity portion 21. It is like that. The second dielectric substrate 20 and the different dielectric constant portion 23 are movably disposed along the upper surface 10 b of the first dielectric substrate 10. The different dielectric constant portion 23 may be made of a dielectric member having a dielectric constant different from that of the second dielectric substrate 20 instead of the air layer.

  The lateral dimension (direction intersecting with the signal line direction) of the different dielectric constant portion 23 is set to be narrow, and even when a load is applied from above and below, the peripheral regions 24 and 25 of the cavity portion 21 shown in FIG. It plays a role, and has a structure that stably maintains the distance between the signal line pattern 11 and the front end surface 31 a of the ground conductor 31. Further, at least one of the peripheral regions 24 and 25 may be made of a conductor or an insulator. This conductor may be made of the same material as the first ground conductor 30 or the second ground conductor 40.

  As described above, the first dielectric substrate 10, the second dielectric substrate 20, the air layer 23, and the ground conductor 31 are arranged around the signal line pattern 11. A transmission line having a predetermined effective dielectric constant is configured by the dielectric constants of these portions around the signal line pattern 11. The transmission line includes a first transmission line 101 including a first dielectric substrate 10 and a second dielectric substrate 20 around the signal line pattern 11 shown in FIG. 4A, and FIG. And the second transmission line 102 including the air layer 23 and the ground conductor 31, and the first transmission line 101 and the second transmission line 102 are connected along the signal propagation direction. It has become.

  FIG. 3 shows that the second dielectric substrate 20 and the cavity portion 21 are provided in the second dielectric substrate 20 above the signal line pattern 11 formed on the upper surface 10 b of the first dielectric substrate 10. It is the top view which showed a mode that the different dielectric constant part 23 (air layer in this figure) formed rotated about the rotating shaft 32 together. In FIG. 3, the first ground conductor 30 is not shown.

  For example, the second dielectric substrate 20 is arranged as shown in FIGS. 3A to 3C with respect to the fixed first dielectric substrate 10. In FIG. 3A, the second dielectric substrate 20 is in contact with the signal line pattern 11 so as to cover the signal line pattern 11 on the upper surface 10b of the first dielectric substrate 10 as much as possible. FIG. 3C shows a state in which the transmission line length of the transmission line 101 is maximized (state 1: a state in which the ratio of the first transmission line 101 is maximized), and FIG. a state in which the transmission line length of the second transmission line 102 is maximized (state 3: a state in which the ratio of the second transmission line 102 is maximized); FIG. 3B shows a state between the state 1 and the state 3 (state 2: a state in which the first transmission line 101 and the second transmission line 102 are mixed).

  As described above, both the second dielectric substrate 20 and the different dielectric constant portion 23 are rotated about the rotation axis 32, whereby the transmission line length of the first transmission line 101 and the second transmission line 102 are increased. Since the ratio of the transmission line length is continuously varied and the effective dielectric constant of the transmission line between the connectors 50a and 50b changes, the propagation speed of the signal in the transmission line changes. Therefore, the signal input to the signal line pattern 11 is output with its phase changed.

  However, simply changing the effective dielectric constant of the transmission line changes the characteristic impedance of the transmission line. As a result, there is a problem that impedance mismatch occurs with an external device (not shown) connected via the connectors 50a and 50b.

  Therefore, in the variable phase shifter of the present embodiment, the transmission line characteristic impedance in the state 1 is designed to match a desired characteristic impedance (for example, 50Ω), and the transmission line length of the second transmission line 102 is set. Even in the state 3 in which the maximum is set, the thickness Δ of the different dielectric constant portion 23 is set so that the characteristic impedance of the transmission line matches the desired characteristic impedance, and the ground conductor 31 is close to the signal line pattern 11. I am letting.

FIGS. 6 to 8 show the results of simulation of the reflection characteristics (S ₁₁ ), transmission characteristics (S ₂₁ ), and group delay characteristics (T _g ) of the variable phase shifter of this embodiment.

6 shows a case where the second dielectric substrate 20 is arranged above the signal line pattern 11 (corresponding to the state 1 shown in FIG. 3A), and FIG. 7 shows an air layer above the signal line pattern 11. When the ground conductor 31 is removed, FIG. 8 shows the reflection characteristic S when the air layer and the ground conductor 31 are disposed above the signal line pattern 11 (corresponding to the state 3 shown in FIG. 3C). ₁₁ shows simulation results of (a), transmission characteristics S ₂₁ (b), and group delay characteristics T _g (c).

The simulation conditions in FIGS. 6 to 8 are as follows.
First dielectric substrate 10: dielectric constant 2.17, length 5 mm, width 1.4 mm, thickness 0.5 mm (FIGS. 6 to 8)
Second dielectric substrate 20: dielectric constant 6.15, length 5 mm, width 1.4 mm, thickness 1.0 mm (FIG. 6)
Different dielectric constant portion 23: air layer, length 5 mm, width 1.4 mm, thickness 1.0 mm (FIG. 7), 100 μm (FIG. 8)

That is, the following can be understood from the simulation results shown in FIGS.
When the second dielectric substrate 20 is above the first dielectric substrate 10, the high frequency characteristics are good, and the upper limit of the operating frequency range is about 30 GHz (FIG. 6).
-When there is an air layer above the first dielectric substrate 10 and there is no ground conductor 31 (the thickness of the air layer is 1.0 mm), the high frequency characteristics are poor, and the upper limit of the operating frequency range is about several GHz ( FIG. 7).
When the first dielectric substrate 10 has an air layer and the ground conductor 31 (the thickness of the air layer is 100 μm), the high frequency characteristics are improved, and the upper limit of the operating frequency range is about 30 GHz (FIG. 8). ).
The maximum phase variable amount at a transmission line length of 5 mm is about 14 ps over a wide frequency range up to about 30 GHz (from comparison between FIG. 6C and FIG. 8C).

  Therefore, even when the phase variable amount is required to be 100 ps, the transmission line length only needs to be about 35 mm. With the structure shown in FIG. 1 (with the ground conductor 31), the operating frequency range can be expanded to about 30 GHz. The outer dimensions can be considerably reduced to about 30 mm in diameter. This is about 1/3 the size of the conventional structure (Patent Document 1). In addition, the conventional structure (Patent Document 2) can achieve the same size, but it is quite difficult to make a structure that can use the operating frequency range up to about 30 GHz. The degree is the upper limit.

  It is possible to widen the operating frequency range up to about 40 GHz by adjusting the transmission line conditions and the above-mentioned distance Δ, etc., and further reducing the external dimensions by meandering the signal line pattern 11. Is possible.

  In the above description, the transmission line of the variable phase shifter of the present embodiment is a grounded coplanar wave guide. However, a coplanar wave guide, a microstrip, or the like may be used as the transmission line. Further, in the above description, the transmission line is configured by the first transmission line 101 and the second transmission line 102. However, the present invention is not limited to this, and for example, a third transmission line may be provided. .

10 First dielectric substrate 10a Lower surface 10b Upper surface (one surface)
11 Signal line pattern (Signal line)
12a, 12b Grounding conductor pattern 13 Through hole 20 Second dielectric substrate 20a Lower surface 20b Upper surface 21 Hollow portion 23 Air layer (different dielectric constant portion)
24, 25 Peripheral region 30 First ground conductor 31 Protrusion (ground conductor)
31a Tip surface 32 Rotating axis (predetermined axis)
32a groove 40 second ground conductor 50 housing 50a, 50b connector 101 first transmission line 102 second transmission line

Claims (6)

A transmission line including a first dielectric substrate and a signal line formed on one surface of the first dielectric substrate for propagating a signal;
The transmission line has a first transmission line in which a second dielectric substrate is disposed above the signal line, and a different dielectric constant portion having a dielectric constant different from that of the second dielectric substrate is disposed above the signal line. A second transmission line having an effective dielectric constant different from that of the first transmission line,
The second dielectric substrate and the different dielectric constant portion are arranged to be movable along the one surface of the first dielectric substrate,
By changing the transmission path length ratio of the first transmission line and the second transmission line in the transmission line by the movement, the propagation speed of the signal in the transmission line changes, and the phase of the signal is variable. A variable phase shifter characterized in that the output is performed.   The variable phase shifter according to claim 1, wherein the signal line is formed in a meandering shape.   The variable phase shifter according to claim 1, wherein the signal line is formed in an arc shape having a center of curvature on a predetermined axis.   4. The ground conductor is provided at a predetermined position above the different dielectric constant portion so that the characteristic impedance of the transmission line becomes a desired value. 5. Variable phase shifter.   The variable phase shifter according to any one of claims 1 to 4, wherein the different dielectric constant portion is formed of an air layer or a dielectric member.   The variable phase shifter according to any one of claims 1 to 5, wherein the transmission line is a coplanar wave guide or a grounded coplanar wave guide.

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