JP5355354B2 - Diode limiter, diode limiter device, and radar device - Google Patents

Description

  The present invention relates to a diode limiter that limits the maximum power of a high-frequency signal.

  As shown in FIG. 1, the radar apparatus guides a high-frequency signal output from the magnetron 1 to an antenna 3 via a circulator 2 and emits it to the outside. The echo signal from the outside is received by the antenna 3 and guided to the reception module 5 that performs signal processing on the echo signal received through the circulator 2 and the limiter 4. The limiter 4 is provided in order to prevent a high-power high-frequency signal from being input to the receiving module 5.

  Conventionally, as a limiter, a diode limiter as shown in Patent Documents 1 and 2 is used. The diode limiters disclosed in Patent Documents 1 and 2 reflect the input power when the high-frequency high-frequency signal is input and the diode is turned on to change the coupling characteristics.

JP-A-63-206001 JP 2008-306308 A

  However, since diodes have large variations in characteristics such as withstand voltage, it is difficult to realize stable limiting characteristics as a diode limiter. In particular, when a semi-coaxial resonant circuit as shown in Patent Documents 1 and 2 is used, there are cases where the design parameters for structurally adjusting the characteristics of the resonant circuit are few and desired limiting characteristics cannot be obtained. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide a diode limiter that can provide a more stable limiting characteristic than conventional ones.

The diode limiter of the present invention includes a first resonance window , a second resonance window , a resonator, a center conductor, and a diode. The first resonance window is connected to the input waveguide to introduce electromagnetic waves. The second resonance window is connected to an output waveguide to derive the electromagnetic wave. The resonator is disposed in a direction perpendicular to the traveling direction of the electromagnetic wave introduced from the first resonance window , the first cavity portion disposed between the first resonance window and the second resonance window , A second cavity that is spatially connected to the cavity. The center conductor is disposed in the first cavity and the second cavity, and a diode is connected thereto. The diode limiter of the present invention is characterized in that the cross-sectional area of the cross section perpendicular to the central conductor of the second cavity is different from the cross-sectional area of the cross section perpendicular to the central conductor of the first cavity.

  For example, when the cross-sectional shapes of the first cavity portion and the second cavity portion are circular, the cross-sectional shape (coaxial outer diameter) corresponds to the impedance when viewed as a transmission line on an equivalent circuit. When changed, the impedance of the transmission line changes, and the impedance as the resonance circuit can be freely adjusted. In particular, when the cross-sectional shape is uniform as in the prior art, it is considered that there is one transmission line on the equivalent circuit, so even if this cross-sectional shape is changed, the impedance as a resonant circuit does not change greatly. If a portion having a different cross-sectional shape is provided as in the present invention, it is considered that there are a plurality of transmission lines, and the impedance adjustment range as a resonance circuit can be expanded as compared with the conventional case. As a result, the tolerance to variations in the characteristics of the diode is greater than in the prior art, and stable limiting characteristics can be obtained.

A plurality of diode limiters may be spatially connected to each other in the electromagnetic wave traveling direction. In this case, each diode limiter is connected to each other via the first resonance window and the second resonance window . In order to adjust the coupling characteristics of the plurality of diode limiters, the cross-sectional area of the first resonance window or the second resonance window may be adjusted. In order to change the cross-sectional area, for example, a screw can be projected toward the inside of the coupling window, and the protruding length of the screw can be changed.

  According to the present invention, it is possible to realize a diode limiter that can obtain a more stable limiting characteristic than conventional ones.

It is a block diagram which shows the structure of a radar apparatus. It is a permeation | transmission perspective view which shows the structure of the diode limiter concerning 1st Embodiment. It is sectional drawing which shows the structure of the diode limiter which concerns on 1st Embodiment. FIG. 4A is an equivalent circuit diagram of a conventional resonance circuit and the resonance circuit of the present invention, and FIG. 4B shows the impedance change of the resonance circuit when the impedance of the transmission line is changed. FIG. 5 (A) and 5 (B) are diagrams comparing leakage power in PIN diodes of different lots, and FIG. 5 (C) is a diagram illustrating leakage power when coaxial outer diameters are different. . It is the figure which showed the impedance of the conventional resonant circuit and the impedance of the resonant circuit of this invention on the Smith chart. It is a permeation | transmission perspective view which shows the structure of the diode limiter which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the diode limiter which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the diode limiter which concerns on a modification.

<< First Embodiment >>
FIG. 2 is a transparent perspective view of the diode limiter according to the first embodiment. 3A is a longitudinal sectional view of the central portion of the diode limiter according to the first embodiment, and FIG. 3B and FIG. 3C are horizontal sectional views of the central portion (A−). (A sectional view and BB sectional view). In this embodiment, the radio wave traveling direction is the Z direction, the right side in the radio wave traveling direction is the X direction, and the upper side is the Y direction.

  The diode limiter 7 shown in FIG. 2 is arranged between the circulator and the receiving module, similarly to the limiter 4 shown in FIG. The diode limiter 7 is composed of a rectangular parallelepiped conductor portion 13, and the conductor portion 13 includes a resonance window (input coupling window) 11 that is an electromagnetic wave introduction portion connected to an input-side waveguide, and an output-side waveguide. A resonance window (output coupling window) 12 which is an electromagnetic wave derivation unit connected to the tube is provided.

  The resonance window 11 and the resonance window 12 have a shape in which the side surface of the conductor portion 13 is opened in a rectangular shape (a shape in which a side parallel to the center conductor described later is shorter than a side in a direction perpendicular to the center conductor). However, the opening shape is not limited to this example. The resonance window 11 and the resonance window 12 are connected to a cavity (resonator) 10 formed of a cylindrical cavity provided in the conductor portion 13. The resonance window 11 and the resonance window 12 are respectively provided with an introduction portion adjustment screw 18 and a lead-out portion adjustment screw 19 that protrude toward the inside of the resonance window (in the Y direction). When the projecting lengths of the introduction part adjusting screw 18 and the lead-out part adjusting screw 19 are changed, the frequency characteristics of the resonance window 11 and the resonance window 12 can be changed, and matching with the waveguides on the input and output sides, respectively. (Functions as an input coupling window adjustment unit and an output coupling window adjustment unit). Note that the protruding direction is not limited to the direction shown in FIGS. Moreover, the aspect which protrudes from both sides may be sufficient as a screw.

  The cavity 10 is provided with a post (center conductor) 15 protruding in the Y direction from the lower inner wall 13A of the conductor portion 13. A PIN diode 16 is joined to the upper end portion of the post 15, and the upper end of the PIN diode 16 is connected to the upper inner wall of the conductor portion 13. As described above, the diode limiter 7 forms a semi-coaxial resonance circuit by the coaxially arranged cavity 10, the post 15, and the PIN diode 16, and the inside of the conductor portion 13 conducts radio waves from the resonance window 11 to the resonance window 12. Functions as a wave guide. The PIN diode may be connected between the lower end of the post 15 and the lower inner wall 13A of the cavity 10.

  When a high power pulse is input into the cavity 10 through the resonance window 11, a voltage is applied between the post 15 and the conductor portion 13 to turn on the PIN diode 16. When the PIN diode 16 is turned on and a current flows, the characteristics of the resonance circuit are greatly changed, so that a mismatch with the input side occurs and the input power is reflected. Thus, the diode limiter 7 limits the maximum power of the high frequency signal.

  The cavity 10 has a two-stage cylindrical shape whose diameter changes stepwise. That is, it has a shape in which two cylindrical cavities are provided in the Y direction. The coaxial outer diameter of the upper cavity is φ1, and the coaxial outer diameter of the lower cavity is φ2. The length L in the vertical direction of the cavity 10 corresponds to the resonance length as the resonance circuit, and is about 16 mm when the frequency is 9.4 GHz, for example. The length L can be adjusted by changing the height of the lower inner wall 13A in the Y direction. The lower inner wall 13A meshes with the conductor portion 13 and the post 15 with screws, and functions as a bottom surface position adjusting portion by rotating the lower inner wall 13A.

  As shown in the equivalent circuit diagram of FIG. 4B, the coaxial outer diameters φ1 and φ2 correspond to the impedances Z1 and Z2 when viewed as transmission lines in the resonance circuit. By changing the coaxial outer diameters φ1 and φ2, the impedances Z1 and Z2 of the transmission line change, and the impedance as the resonance circuit can be adjusted.

  In general, PIN diodes have large variations in characteristics such as withstand voltage, and leakage power to the output side varies from lot to lot. For example, as shown in FIG. 5A, in a certain diode A, the withstand voltage is close to the standard value, and the leakage power decreases with a certain amount of input power (for example, the leakage power is about 7 dBm when the input power is 20 dBm). However, as shown in FIG. 5B, the other diodes B have a withstand voltage higher than the standard value, and an almost linear output is generated even at high input power (for example, input power). However, the leakage power is close to 30 dBm even at 30 dBm).

  However, in the diode limiter 7 of this embodiment, the impedances Z1 and Z2 can be adjusted by adjusting the coaxial outer diameters φ1 and φ2, and the leakage power can be controlled as shown in FIG. it can. In the example of FIG. 5C, changes in leakage power are shown when the coaxial outer diameter φ1 is changed to 19, 20, and 21 mm, respectively. For example, when the coaxial outer diameter φ1 is changed by 1 mm at an input power of 30 dB, the leakage power changes by about 4 dBm. Therefore, even when the characteristics of the diode vary, stable limiting characteristics can be obtained.

  In particular, when the coaxial outer diameter is uniform as in the conventional diode limiter, as shown in FIG. 4 (A), it is considered that there is one transmission line on the equivalent circuit. As shown in FIG. 4, even if the impedance Z1 is changed by changing the coaxial outer diameter, the input impedance Zin in the resonance circuit does not change greatly, but if the coaxial outer diameter is changed stepwise as in the present invention, Since it is considered that there are a plurality of transmission lines on the equivalent circuit as shown in FIG. 5B, the adjustment range of the input impedance Zin can be expanded as compared with the conventional case as shown in FIG.

  Such a difference in impedance change will be described with reference to the Smith chart of FIG. In the case of a resonant circuit with a uniform coaxial outer diameter as in the past, even if the impedance Z1 of the transmission line is changed by changing the coaxial outer diameter, the impedance cannot be greatly shaken as seen on the Smith chart, The impedance as a resonance circuit does not change greatly (see the black dot in the left column of the figure). On the other hand, in the resonant circuit of the present invention, since the number of transmission lines increases as a plurality of impedance changing elements, only changing one of the plurality of transmission lines (impedance Z2 in the example in the figure). The impedance as a resonance circuit can be greatly changed as seen on the Smith chart, and the impedance as the resonance circuit can be greatly changed (the matching with the input / output side is adjusted by the introduction portion adjusting screw 18 and the lead portion adjusting screw 19). Is possible).

  Therefore, with the resonance circuit of the present invention, the impedances Z1 and Z2 of the transmission line are kept low so that the current flows easily when the diode is turned on, but the impedance as the resonance circuit is turned on with a desired power. Can be adjusted. As a result, the tolerance to variations in the characteristics of the diode is greater than in the prior art, and stable limiting characteristics can be obtained.

<< Second Embodiment >>
FIG. 7 is a transparent perspective view of the diode limiter according to the second embodiment. FIG. 8A is a longitudinal sectional view of the central portion of the diode limiter according to the second embodiment, and FIG. 8B is a transverse sectional view (AA sectional view) of the central portion. Also in the second embodiment, the radio wave traveling direction is the Z direction, the right side in the radio wave traveling direction is the X direction, and the upper side is the Y direction. In addition, about the structure which is common in 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The diode limiter 8 is arranged between the circulator and the receiving module, like the diode limiter 7. The diode limiter 8 includes a rectangular parallelepiped conductor portion 53. The resonance window 11 on the input side of the diode limiter 8 is connected to a cavity 50 </ b> A formed of a cylindrical cavity provided in the conductor portion 53. The output-side resonance window 12 is connected to a cavity 50 </ b> B formed of a cylindrical cavity provided in the conductor portion 53. The cavity 50A and the cavity 50B are connected in the vicinity of the center of the conductor portion 53, and the cross section (longitudinal cross section) of the coupling window 57, which is the connection location, is rectangular. That is, the diode limiter shown in the first embodiment is connected in a plurality of spaces, and is connected via the input coupling window and the output coupling window of each diode limiter. . The coupling window 57 is provided with a screw 57 that protrudes inward (in the Y direction). Changing the protruding length of the screw 57 can change the cross-sectional area of the coupling window 57, and the coupling characteristics of the two cavities 50A and 50B can be adjusted.

  The cavity 50A is provided with a post 55A protruding in the Y direction from the lower inner wall 53A of the conductor portion 53. A PIN diode 56A is joined to the upper end portion of the post 55A, and the upper end of the PIN diode 56A is connected to the upper inner wall of the conductor portion 53. Similarly, the cavity 50B is provided with a post 55B protruding in the Y direction from the lower inner wall 53B of the conductor portion 53. A PIN diode 56B is joined to the upper end portion of the post 55B, and the upper end of the PIN diode 56B is connected to the upper inner wall of the conductor portion 53. The length LA in the vertical direction of the cavity 50A and the length LB in the vertical direction of the cavity 50B correspond to the resonance length as the resonance circuit, respectively, and each length is the lower inner wall as in the first embodiment. Adjustment is possible by changing the height of 53A or 53B in the Y direction.

  The cavity 50A and the cavity 50B have a two-stage cylindrical shape whose diameter changes stepwise. The coaxial outer diameter of the upper cavity portion of the cavity 50A is φ3, and the coaxial outer diameter of the lower cavity portion is φ4. The coaxial outer diameter of the upper cavity portion of the cavity 50B is φ5, and the coaxial outer diameter of the lower cavity portion is φ6. The coaxial outer diameter φ3 and the coaxial outer diameter φ5 are different outer diameters, and the coaxial outer diameter φ4 and the coaxial outer diameter φ6 are also different outer diameters.

  That is, the configurations of the cavity 50A and the cavity 50B are basically the same as those of the cavity 10 shown in the first embodiment, but the cavity 50A and the cavity 50B have different inner diameters (coaxial outer diameters). Yes. This is to absorb variations in characteristics of the PIN diodes used in the respective resonance circuits. In other words, the coaxial outer diameter differs depending on the characteristics of each PIN diode.

  In this way, by connecting two semi-coaxial resonant circuits with different cavity inner diameters in series and providing a coupling characteristic adjusting screw in the coupling window, the parameters for adjusting the characteristics of the resonant circuit further increase. The limiting characteristics can be adjusted in a wider range.

<Modification>
FIG. 9 is a cross-sectional view showing the structure of a diode limiter according to a modification. In addition, about the structure which is common in 2nd Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted. The cavity 70A and the cavity 70B of the diode limiter 9 shown in the same figure are those in which the shape of the upper cavity is a rectangular parallelepiped instead of the cylindrical cavity 50A and cavity 50B shown in the second embodiment. is there. Thus, the shape of the cavity is not limited to a cylinder, and various modifications are possible.

  In each of the above examples, the example in which the coaxial outer diameter changes stepwise is shown. However, an aspect in which the coaxial outer diameter gradually changes along the central axis may be used. Further, even when the step changes, the configuration is not limited to two steps, and the coaxial outer diameter may be changed in multiple steps.

DESCRIPTION OF SYMBOLS 10 ... Cavity 11 ... Resonance window 12 ... Resonance window 13 ... Conductor part 13A ... Lower inner wall 15 ... Post 16 ... PIN diode 18 ... Introduction part adjustment screw 19 ... Derived part adjustment screw

Claims (17)

A first resonance window connected to the input waveguide and introduced with electromagnetic waves;
A second resonance window connected to an output waveguide and from which the electromagnetic wave is derived;
A first cavity disposed between the first resonance window and the second resonance window; and the first cavity disposed in a direction perpendicular to a traveling direction of the electromagnetic wave introduced from the electromagnetic wave introduction section. And a resonator having a second cavity spatially connected to each other,
A central conductor disposed in the first cavity and the second cavity;
A diode disposed in connection with the central conductor;
A diode limiter comprising:
The diode limiter characterized in that a cross-sectional area of a cross section of the second cavity portion perpendicular to the central conductor is different from a cross-sectional area of the cross section of the first cavity portion perpendicular to the central conductor. The diode limiter according to claim 1, wherein
The first cavity and the second cavity have a cylindrical shape having a common central axis,
The diode limiter, wherein the central conductor is disposed on the central axis. The diode limiter according to claim 2, wherein
A diode limiter characterized in that an inner diameter of the second cavity is smaller than an inner diameter of the first cavity. The diode limiter according to claim 1 or 2,
The diode limiter according to claim 2, wherein the second cavity has a step-like change in cross section in the vertical direction. The diode limiter according to claim 1 or 2,
The diode limiter according to claim 2, wherein the second cavity has a cross-sectional area that gradually changes in the vertical direction. The diode limiter according to any one of claims 1 to 5,
The diode limiter, wherein the first resonance window includes an input coupling window adjustment unit for adjusting a cross-sectional area of the first resonance window . The diode limiter according to claim 6.
The first resonance window has a rectangular shape perpendicular to the electromagnetic wave introduction direction, and a side parallel to the central conductor is shorter than a side perpendicular to the central conductor. Characteristic diode limiter. The diode limiter according to claim 6 or 7,
The first resonance window protrudes toward the inner wall of the first resonance window, and has an introduction portion adjusting screw with an adjustable protrusion length.   9. The diode limiter according to claim 8, wherein a protruding length of the introduction portion adjusting screw is adjustable in a direction parallel to the center conductor. The diode limiter according to any one of claims 1 to 9,
The diode limiter, wherein the second resonance window includes an output coupling window adjustment unit that adjusts a cross-sectional area of the second resonance window . The diode limiter according to claim 10,
The diode limiter, wherein the second resonance window protrudes toward an inner wall of the second resonance window and has a lead-out portion adjusting screw whose protrusion length can be adjusted.   12. The diode limiter according to claim 11, wherein a protruding length of the lead-out portion adjusting screw is adjustable in a direction parallel to the center conductor. The diode limiter according to any one of claims 1 to 12,
The diode limiter, wherein the second cavity portion includes a bottom surface position adjusting portion that adjusts a distance of a bottom surface opposite to the first cavity portion with respect to the first cavity portion. The diode limiter according to claim 13.
The diode limiter is characterized in that the diode is disposed inside the first cavity. A plurality of diode limiters according to any one of claims 1 to 14,
The diode limiter device, wherein the diode limiters are arranged spatially connected to each other in the traveling direction. The diode limiter device according to claim 15,
The diode limiter device, wherein the diode limiters are spatially connected to each other via the first resonance window and the second resonance window . A magnetron that generates electromagnetic waves,
An antenna for emitting an electromagnetic wave generated by the magnetron and receiving an echo signal;
A radar apparatus including a signal processing unit that performs signal processing on a received echo signal,
Between the signal processing unit and the antenna,
A radar apparatus comprising the diode limiter according to any one of claims 1 to 14 or the diode limiter apparatus according to claim 15 or 16.

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