JP4814211B2 - Harmonic suppression resonator, harmonic propagation blocking filter, harmonic suppression oscillator and microwave transmitter - Google Patents

Description

  The present invention relates to a harmonic suppression resonator that suppresses harmonic components other than the fundamental frequency in a circuit that handles high-frequency signals, a harmonic propagation blocking filter including the harmonic suppression filter, a harmonic suppression oscillator, a microwave transmitter, and the like. The present invention relates to a wave suppression high frequency device.

  From the viewpoint of effective use of radio resources, regulations and recommendations are made in various high-frequency devices so that unnecessary radiation does not occur in a frequency band far from the use frequency band.

  For example, Patent Document 1 discloses that unnecessary radiation contained in a radio wave radiated from a radar that handles high power is suppressed.

  A magnetron is used as a transmission pipe of a marine radar. This magnetron basically oscillates in a π mode and generates a microwave having a fundamental frequency, but at the same time, a frequency component (double frequency component) of a π-1 mode which is an oscillation mode of a second harmonic of the fundamental frequency. ) Occurs as unnecessary radiation. In Patent Document 1, in order to suppress this unnecessary radiation, a spurious suppression filter (LPF) is provided in a coaxial tube on the central axis of the rotary joint using a rotary joint of the pedestal portion.

In general, in a high-frequency device using a waveguide as a transmission line, a waveguide type resonator is installed as a filter in order to propagate only the fundamental wave component.
JP 2007-81856 A

  However, in the configuration using the low-pass filter as disclosed in Patent Document 1, although the harmonic component can be suppressed over a relatively wide frequency band from the fundamental frequency band to the high frequency band, the fundamental frequency There is a problem that the attenuation characteristic from the band to the high band is not steep, and the effect of suppressing the second harmonic of the core is low.

Further, in the configuration including the waveguide type resonator as a filter, for example, a waveguide type filter that resonates in a TE ^{□ 101} mode (hereinafter simply referred to as “TE101 mode”) of a rectangular waveguide is provided. In this case, not only the fundamental wave is transmitted, but also the second harmonic is transmitted because it resonates in the TE ^{□ 202} mode (hereinafter simply referred to as the TE202 mode). For this reason, the waveguide filter cannot be used as a harmonic propagation blocking filter. This will be described next with reference to FIG.

  FIG. 1 is a diagram showing a configuration of a conventional waveguide resonator having no harmonic suppression function. FIG. 1A is an external perspective view thereof. Basically, the rectangular waveguide is cut into a square shape so that the front and rear openings are closed with a conductor.

  FIG. 1B schematically shows the electromagnetic field distribution of the fundamental wave. FIG. 1C schematically shows the configuration of the electromagnetic field distribution of the second harmonic. Here, the solid arrows indicate the electric field lines at a certain moment, the dot marks, and the cross marks indicate the directions of the magnetic fields, and the distribution of the electromagnetic field intensity.

  Since the waveguide resonator that resonates in the TE101 mode resonates in the TE202 mode as described above, the second harmonic when the TE101 mode is the fundamental wave cannot be suppressed.

  Accordingly, an object of the present invention is to provide a harmonic suppression resonator having a high harmonic suppression effect and a harmonic suppression high-frequency device including the same.

In order to solve the above-described problems, the present invention is configured as follows.
(1) A harmonic suppression resonator according to the present invention is a waveguide type resonator having a resonance region in which a fundamental wave resonates in a TE mode.
It is a cutoff region with respect to the fundamental wave, and is formed by a dimension that becomes a propagation region with respect to n-th harmonics to be suppressed [n is an integer of 2 or more], and the center is from the center in the longitudinal direction of the E plane of the resonance region. An additional area is provided at a shifted position .

With this configuration, since the additional region does not affect the fundamental wave, the resonance frequency of the fundamental wave is not changed, but the resonance frequency of the nth harmonic is lowered. Therefore, the nth harmonic (nth multiplied wave) to be suppressed does not resonate with the resonance frequency of the nth harmonic (nth harmonic) of the resonator. In other words, it acts as a harmonic suppression resonator that resonates with respect to the fundamental wave but does not resonate with respect to the suppression harmonic.
Moreover, this makes it easy for the standing wave of the nth harmonic to stand in the additional region, and the harmonic suppression effect is enhanced.

(2) The resonance region is a substantially rectangular waveguide resonator in which the fundamental wave resonates in the TE mode.
The additional region has a shape in which the E surface of the substantially rectangular waveguide resonator is projected, and the width along the longitudinal direction of the E surface is equal to or less than ½ wavelength of the fundamental wave and 1 of the nth harmonic. / 2 wavelength or more, and the depth is other than the m / 2 wavelength of the n-th order harmonic [m is an integer of 1 or more].

  According to this configuration, the nth-order harmonic to be suppressed can be effectively suppressed, and unnecessary harmonics can be greatly suppressed.

(3) The depth of the additional region is particularly approximately (1 + 2 m) / 4 wavelength [m is an integer of 0 or more] of the nth-order harmonic.
According to this configuration, the nth-order harmonic to be suppressed can be most effectively suppressed, and unnecessary harmonics can be greatly suppressed. In addition, the size of the additional region can be kept small, and the overall size is not increased.

( 4 ) A harmonic propagation blocking filter according to the present invention includes a harmonic suppression resonator having the above-described configuration and an input / output unit that introduces and derives a propagation signal from the resonance region.

  Providing this harmonic propagation blocking filter in the middle of the waveguide, for example, prevents the propagation of nth harmonics to be suppressed.

( 5 ) A harmonic suppression oscillator according to the present invention includes the harmonic suppression resonator having any one of the above-described configurations and an active circuit coupled to the harmonic suppression resonator and oscillating at a fundamental frequency.

  Thereby, a harmonic suppression oscillator having a high C / N ratio in which harmonic components are suppressed can be configured.

( 6 ) A microwave transmitter according to the present invention includes the harmonic propagation blocking filter in a propagation path between a magnetron that oscillates a fundamental wave in a π mode and an antenna.

  With this configuration, the π-1 mode harmonic component generated from the magnetron is blocked by the harmonic propagation blocking filter, so that unnecessary radiation is suppressed.

  According to the present invention, the resonator that resonates at the fundamental frequency and suppresses the predetermined harmonic frequency without resonating, the filter that prevents the propagation of unnecessary harmonics, and the oscillation of unnecessary frequency components are suppressed. An oscillator and a microwave transmitter that suppresses unnecessary harmonic radiation can be obtained.

<< First Embodiment >>
FIG. 2 is a perspective view showing a basic configuration of the harmonic suppression resonator according to the first embodiment and an example of an electromagnetic field distribution in each mode.

  As shown in FIG. 2A, the harmonic suppression resonator 101 includes a resonance region 21 and an additional region 22 protruding from a part thereof. In the figure, the surface indicated by E is the E surface, and the surface indicated by H is the H surface. This resonator can also be called a cavity resonator having an additional space inside.

  The additional region 22 has a shape in which the E surface of the resonance region 21 partially protrudes, and the width along the longitudinal direction of the E surface of the resonance region 21 is not more than ½ wavelength of the fundamental wave. And a length of which is approximately 1/4 wavelength of the nth-order harmonic.

When the frequency of the fundamental wave is 9.4 GHz, the dimensions of each part in the figure are as follows.
a: 22.9 mm
b: 5 mm
c: 20 mm
d: 5 mm
e: 10 mm
FIG. 2B shows the electromagnetic field distribution of the fundamental wave, and FIG. 2C shows the electromagnetic field distribution of the second harmonic mode (pseudo TE202 mode). Since the additional region 22 is a cutoff region for the fundamental wave, as shown in FIG. 2B, the resonance frequency of the fundamental wave hardly changes even if the additional region 22 exists. On the other hand, as shown in FIG. 2 (C), the second harmonic enters the additional region 22 and thus acts as a resonance region including the additional region 22. As a result, the effective resonance space of the second harmonic is expanded, and the resonance frequency of the second harmonic is lower than that in the case where the additional region 22 is not provided. Therefore, there is no resonance at the frequency of the second harmonic (a frequency twice the fundamental frequency).

  As shown in FIG. 2D, if the depth of the additional region 23 protruding from the resonance region 21 is ½ wavelength of the second harmonic, a standing wave as shown in FIG. It occurs and resonates at twice the frequency of the fundamental wave. Therefore, it is important to appropriately determine the depth dimension d of the additional region. If this dimension d is set to approximately ¼ wavelength of the second harmonic, the amount of shift of the resonance frequency of the second harmonic to the low band is maximized, and the suppression effect of the second harmonic is most enhanced accordingly.

  FIG. 3 shows an example in which the additional region 24 with respect to the resonance region 21 is temporarily formed so that the center of the additional region 24 is in the longitudinal direction along the longitudinal direction of the E plane. In this case, as shown in FIG. 3B, the standing wave of the second harmonic cannot sufficiently enter the additional region 24, and the effective resonance space is not expanded. Therefore, the effect of lowering the resonance frequency of the second harmonic is small.

  Therefore, the additional region 24 is arranged such that the center of the additional region 24 is shifted from the central position in the length direction along the longitudinal direction of the E plane.

<< Second Embodiment >>
FIG. 4 is a perspective view showing a configuration of a harmonic propagation blocking filter according to the second embodiment. Here, only the space where the electromagnetic field distribution occurs is extracted and shown. In FIG. 4, the harmonic propagation blocking filter 201 includes three resonance regions 21a, 21b, and 21c, and additional regions 22a and 22c are provided for the resonance regions 21a and 21c, respectively. In addition, input / output spaces 31a and 31c are provided, and a coupling window 33aa is provided between the input / output space 31a and the resonance region 21a. Similarly, a coupling window 33cc is provided between the input / output space 31c and the resonance region 21c. A coupling window 33ab is provided between the resonance regions 21a and 21b, and a coupling window 33bc is provided between 21b and 21c.

  In this way, a three-stage resonator filter is formed in which three resonators including three resonance regions 21a, 21b, and 21c and additional regions 22a and 22c are sequentially coupled. This filter acts as a band pass filter having a function of passing the band of the fundamental frequency and blocking the second harmonic.

<< Third Embodiment >>
FIG. 5 is a perspective view of the main part of the harmonic wave propagation blocking filter according to the third embodiment, and FIG. 6 is an exploded plan view of its components.
The harmonic propagation blocking filter 202 is basically composed of two metal blocks 41 and 43 and a partition plate 42 between them.

  FIG. 6A is a plan view of the first metal block 41, and the resonance regions 51a and 51b are formed by forming concave portions having a constant depth. An additional region 52b is provided in the resonance region 51b. A coupling window 33ab is formed between the two resonance regions 51a and 51b. Further, a coupling window 33aa that extends backward in the figure is formed in the resonance region 51a.

  In the second metal block 43, resonance regions 51c and 51d, an additional region 52c, and coupling windows 33cd and 33dd are formed in a mirror-symmetric relationship with the metal block 41, respectively.

  The partition plate 42 is a metal plate sandwiched between the resonance region forming surfaces of the metal blocks 41 and 43, and opens a coupling window 33bc that communicates the resonance regions 51b-51c.

  FIG. 5A shows a resonance region formed by superposing the three members shown in FIG. Here, input / output spaces 32a and 32d connected to the coupling windows 33aa and 33dd are provided. This is the end of the rectangular waveguide.

  With this structure, the input / output space 32a → coupling window 33aa → resonance region 51a → coupling window 33ab → (resonance region 51b, additional region 52b) → coupling window 33bc → (resonance region 51c, additional region 52c) → coupling window. Electromagnetic waves propagate along the path of 33cd → resonance region 51d → coupling window 33dd → input / output space 32d.

  FIG. 5B shows a double wave standing wave generated in the resonance region as a concentration distribution. Thus, a part of the second harmonic is also generated in the additional regions 52b and 52c, and the resonance frequency thereof is lower than twice the fundamental frequency.

  This filter is composed of a four-stage resonator in which four resonators are coupled in order, and a second-order harmonic is formed by a resonator portion including the resonance region 51b and the additional region 52b, and a resonator portion including the resonance region 51c and the additional region 52c. Wave resonance is blocked.

  In this way, it acts as a band pass filter having a function of passing the fundamental frequency band and blocking the second harmonic.

FIG. 7 is a diagram showing frequency characteristics when the harmonic wave propagation blocking filter shown in FIGS. 5 and 6 and its additional region are not provided.
FIG. 7A is a characteristic diagram of the high-frequency propagation blocking filter according to the third embodiment, and FIG. 7B is a characteristic chart of a filter that does not include the additional regions 52b and 52c as a comparative example. In both cases, the fundamental frequency is 9.4 GHz, but when there is no harmonic blocking function, passbands are generated in approximately 13.8 GHz and 18.8 GHz bands as shown in FIG. On the other hand, the harmonic propagation blocking filter according to the third embodiment has a large insertion loss of 18.8 GHz as shown by a circle in FIG. I understand.

<< Fourth Embodiment >>
FIG. 8 is a horizontal sectional view showing the configuration of the harmonic suppression resonator according to the fourth embodiment. The harmonic suppression resonator 102 includes a resonance region 21 and an additional region 22 similar to those shown in the first embodiment. The resonance region 21 and the additional region 22 are formed in a metal block, and a waveguide portion 40 is formed in the metal block, and a coupling window is provided between a predetermined portion of the waveguide portion 40 and the resonance region 21. 33 is provided.

  With such a configuration, the electromagnetic wave propagating through the waveguide section 40 is coupled to the resonator including the resonance region 21 and the additional region 22 through the coupling window 33. The fundamental wave is coupled with this resonator and is substantially totally reflected. On the other hand, since the second harmonic is not coupled with the harmonic suppression resonator 102, it passes through the waveguide section 40 as it is. In this way, a desired fundamental wave can be trapped and used as a circuit that transmits the second harmonic.

<< Fifth Embodiment >>
FIG. 9 is a circuit diagram of a harmonic suppression oscillator according to the fifth embodiment. The harmonic suppression oscillator 301 includes a transmission line 61 with one end terminated without reflection, a harmonic suppression resonator 103 coupled thereto, an active element Q as a negative resistance element coupled with a signal propagating through the transmission path 61, and a stub. 62 and 63 are provided.

  With such a configuration, it functions as a band reflection type oscillation circuit. Since the harmonic suppression resonator 103 is a harmonic suppression resonator that resonates at the fundamental frequency and does not resonate at the second harmonic frequency, it does not resonate at the second harmonic frequency, and a second harmonic component is generated. An oscillation signal having a high C / N ratio can be obtained. Note that the harmonic suppression resonator 102 has a mode that resonates at the second harmonic, but the harmonic suppression resonator 103 is coupled to the transmission path 61 at a position that satisfies the oscillation condition at the fundamental frequency. The resonance condition of the harmonic wave does not satisfy the oscillation condition, and as a result, the resonance frequency component of the double wave does not occur.

  When the transmission path 61 is formed of a waveguide, the harmonic suppression resonator 102 shown in the fourth embodiment can be used as the harmonic suppression resonator 103.

<< Sixth Embodiment >>
FIG. 10 is a circuit diagram of a harmonic suppression resonator according to the sixth embodiment. This harmonic suppression resonator includes a circular resonance region 71 and an additional region 72. In each of the embodiments described above, the resonance region of the fundamental wave has a substantially rectangular parallelepiped shape. However, as shown in FIG. 10, the resonance region of the fundamental wave may have a cylindrical shape. Since the resonance mode of the fundamental wave in the resonance region 71 is the TM ^{○ 010} mode and the resonance mode of the second harmonic is the TM ^{○ 210} mode, the operation and effect of the additional region 72 are the same as those shown in FIG. is there.

<< Seventh Embodiment >>
FIG. 11 is a block diagram showing a configuration of a radar as an example of a microwave transmitter according to the seventh embodiment. The high-frequency circuit section of the radar includes a magnetron 2 that oscillates microwaves, a drive circuit 1 that drives the pulses, a circulator 3 that propagates the oscillation signal of the magnetron 2 in the subsequent direction, a terminator 4, and harmonics that suppress second harmonics. Wave propagation blocking filter 202, a circulator 6 that propagates a transmission signal to the rotary joint side, a circulator 6 that propagates a reception signal to the reception circuit side, a rotary joint 7, an antenna 8, and a restriction that prevents the power of the transmission signal from entering the reception circuit side A limiter circuit 9 and a receiving circuit 10 are provided.

  When the drive circuit 1 drives the magnetron 2 in a pulsed manner, a pulsed microwave signal of 9.4 GHz is output, and the air passes through the path of the circulator 3 → the harmonic propagation blocking filter 202 → the circulator 6 → the rotary joint 7 → the antenna 8. Radiated. Further, the signal reflected by the target is received by the antenna 8 and is received through the path of the rotary joint 7 → the circulator 6 → the limiter circuit 9 → the receiving circuit 10.

  In this way, when the transmission signal passes through the harmonic propagation blocking filter 202, the second harmonic is blocked, so that unnecessary radiation of the second harmonic from the antenna 8 is suppressed. Since the harmonic propagation blocking filter 202 is provided after the circulator 3, the second harmonic is effective not only for the magnetron 2 but also for the circulator 3.

  Since the second harmonic wave reflected without passing through the harmonic wave propagation blocking filter 202 is consumed by the terminator 4 via the circulator 3, there is no adverse effect on the magnetron 2.

  In each of the embodiments described above, the resonance region of the fundamental wave is configured by a cavity resonator. However, the resonance region does not need to be air, and is filled with a solid dielectric. Also good. Further, the “waveguide resonator” of the present invention, which may be configured by forming an electrode film on the outer surface of the dielectric block, includes such a configuration.

It is a figure which shows the example of a structure of the conventional waveguide type resonator, and electromagnetic field distribution of a fundamental wave mode and a 2nd harmonic mode. It is a figure which shows the example of the structure of the harmonic suppression resonator which concerns on 1st Embodiment, and the electromagnetic field distribution of each mode. It is a figure which shows the example of the formation position of the additional area | region of a harmonic suppression resonator. It is a perspective view of the principal part of the harmonic propagation blocking filter according to the second embodiment. It is a figure which shows the example of the perspective view and electromagnetic field distribution of the principal part of the harmonic propagation blocking filter which concerns on 3rd Embodiment. It is a top view of the component of the same harmonic propagation prevention filter. It is a figure which shows the frequency characteristic of the same harmonic propagation blocking filter. It is a horizontal sectional view showing the composition of the harmonic suppression resonator concerning a 4th embodiment. It is a circuit diagram of the harmonic suppression oscillator which concerns on 5th Embodiment. It is a figure which shows the structure of the harmonic suppression resonator which concerns on 6th Embodiment. It is a block diagram which shows the structure of the radar which concerns on 7th Embodiment.

Explanation of symbols

11-waveguide resonator 21-resonance region 21a-21c-resonance region 22,23,24-addition region 31,32-input / output space 33-coupling window 40-waveguide portion 41,43-metal block 42-partition plate 51,71-resonance region 52,72-addition region 101,102,103-harmonic suppression resonator 201,202-harmonic propagation blocking filter 301-harmonic suppression oscillator

Claims (7)

In a waveguide type resonator having a resonance region where the fundamental wave resonates in the TE mode,
It is a cutoff region with respect to the fundamental wave, and is formed by a dimension that becomes a propagation region with respect to n-th harmonics to be suppressed [n is an integer of 2 or more], and the center is from the center in the longitudinal direction of the E plane of the resonance region. harmonic suppression resonator comprising the additional area which is disposed in a position displaced. The resonance region is a substantially rectangular waveguide resonator in which the fundamental wave resonates in the TE mode.
The additional region has a shape in which the E surface of the substantially rectangular waveguide resonator is projected, and the width along the longitudinal direction of the E surface is equal to or less than ½ wavelength of the fundamental wave and 1 of the nth harmonic. 2. The harmonic suppression resonator according to claim 1, wherein the harmonic suppression resonator has a length other than m / 2 wavelengths [m is an integer equal to or greater than 1].   The harmonic suppression resonator according to claim 2, wherein the depth of the additional region is approximately (1 + 2 m) / 4 wavelength [m is an integer of 0 or more] of the nth-order harmonic. A harmonic suppression resonator according to any one of claims 1 to 3 harmonic propagation blocking filter having input and output portions for introducing and derives the propagation signal to the resonance region. A harmonic suppression resonator according to any one of claims 1 to 3 harmonic suppression oscillator coupled to the harmonic suppression resonator provided with, an active circuit which oscillates at a frequency of the fundamental wave. A microwave transmitter comprising a magnetron that oscillates the fundamental wave in a π mode and an antenna, and comprising the harmonic propagation blocking filter according to claim 4 in a propagation path between the magnetron and the antenna.   A microwave transmitter according to claim 6;
  A radar apparatus comprising: a receiving circuit that receives a signal reflected by a target from a microwave radiated from the antenna.

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