JP4301722B2 - Transmitter with built-in reception band noise suppression filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmitter in a communication device for a microwave band and a millimeter wave band in which a transmitter / receiver is integrated, and more particularly, to an improvement in a function of suppressing noise and spurious applied to a receiver.
[0002]
[Prior art]
Conventionally, as this type of apparatus in which a transceiver is integrated, for example, a transmission / reception antenna system for satellite communication using a broadcast satellite or a communication satellite can be cited.
In such a transmission / reception antenna system, a first stage circuit of a receiving unit that performs amplification and frequency conversion of a received signal and a final stage circuit that constitutes a part of the transmitter and performs final amplification of the transmission signal are parabolic units for satellite communication. It is configured to be integrated with an antenna, a feed horn, a connecting waveguide, and the like.
In such a transmission / reception antenna system, there is a system in which transmission / reception is performed at the same time. In such a transmission / reception antenna system, the transmission / reception circuit as described above is in close proximity due to a demand for miniaturization of the entire transmission / reception antenna system. Therefore, even if the transmission wave band and the reception wave band are separated from each other, it is difficult to avoid the influence of the transmission wave on the reception circuit. Therefore, a device is devised to suppress and prevent the influence of the transmission wave on the reception circuit. Various methods have been used in the past.
[0003]
As a conventional measure for suppressing and preventing the influence of the transmission wave on the reception circuit, for example, in the final circuit of the transmitter provided in the antenna system, the frequency component in the reception band of the transmission wave is attenuated. There is a method of providing a band-pass filter or a high-pass filter using a microstrip line.
There is also a method for suppressing or preventing the influence of the transmission wave in the reception band by connecting a so-called waveguide bandpass filter to the final circuit of the transmitter.
Furthermore, the final stage circuit of the transmitter described above is provided integrally with the waveguide coaxial converter, but this waveguide coaxial converter is provided with a plurality of so-called screws so as to prevent the band of the reactive element type. It is also possible to construct a filter.
[0004]
[Problems to be solved by the invention]
However, in the case of configuring a filter using the above-described microstrip line, when the reception band is wide and close to the transmission band, power loss in the transmission band due to the filter occurs. Therefore, there is a problem that transmission level compensation is required.
Further, in the configuration in which a waveguide bandpass filter is newly attached, there is a problem that the device price increases as the number of parts of the device increases.
Furthermore, in the case of constructing a reactance element type filter using screws, in addition to an increase in the device price accompanying an increase in the number of parts, there is a need for adjustment work to obtain a desired filter characteristic. There's a problem.
[0005]
The present invention has been made in view of the above circumstances, and has a reception band noise suppression filter built-in transmission that can suppress and prevent the occurrence of spurious and noise due to a transmission wave in the reception band with a simpler configuration than conventional ones. The machine is provided.
Another object of the present invention is to reduce noise, spurious and the like due to a transmission wave in a wide reception band even when the reception band is wide and close to the transmission band. It is an object of the present invention to provide a transmitter with a reception band noise suppression filter that can be prevented.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a transmitter with a built-in reception band noise suppression filter according to the present invention includes:
A circuit board on which a circuit for amplifying a transmission wave at the final stage is formed and a waveguide part are integrally attached, and the transmission wave output from the circuit board by the waveguide part propagates through the waveguide. In a transmitter that is configured to be converted into a mode and output from the waveguide unit and integrated with a receiver,
The waveguide section, while formed by a tapered waveguide and the cutoff frequency of the reception band frequency, the opening of the waveguide section, Ri name by fixing a metallic filter plate,
The metal filter plate has a first predetermined length in the vertical direction from the upper left corner of the filter opening and a second predetermined length along the wide side in the filter opening that coincides with the opening of the waveguide portion. A first adjustment piece formed respectively;
The first adjustment piece is formed from a corner facing the diagonal direction of the filter opening to a third predetermined length in the vertical direction and a fourth predetermined length along the wide side. A second adjusting piece is provided,
A capacitive first window is between the first adjustment piece and the wide piece of the filter opening facing the first adjustment piece,
A capacitive second window is between the second adjustment piece and the wide piece of the filter opening facing the second adjustment piece,
Inductive third windows are respectively formed between the first adjustment piece and the second adjustment piece ,
While allowing blocking passage of a signal of the reception frequency band is made to allow the passage of a low loss of the transmitted wave outside the reception frequency band.
[0007]
In the above configuration, since the metal filter plate having desired filter characteristics is provided at the opening of the waveguide portion, spurious and noise due to the transmission wave in the reception band can be generated with a simple configuration as compared with the prior art. It can be suppressed and prevented.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a first configuration example of the transmitter with built-in reception band noise suppression filter in the embodiment of the present invention will be described with reference to FIGS. 1 to 3.
The transmitter with a built-in reception band noise suppression filter is suitable for use as a transmitter / receiver antenna system for satellite communication, for example, and is formed integrally with the waveguide unit 1 and the waveguide unit 1. The main body 2 and the transmission circuit board 3 are roughly divided (see FIG. 1). In FIG. 1, the metal filter plate 9 and the transmission circuit board 3 are schematically shown, and show the state of the cut surface of the waveguide portion 1 and the housing portion 2. is not.
[0009]
The waveguide section 1 is formed in a so-called known / known coaxial waveguide converter. That is, the waveguide section 1 is formed so that one opening 4 and the short-circuit surface 5 face each other in the traveling direction of electromagnetic waves (the direction of the white arrow in FIG. 1), and one wide surface (FIG. 1). In FIG. 1, probes 6 are provided at appropriate positions on the front and back sides of the paper (see FIG. 1). The probe 6 is formed on a transmission circuit board 3 having one end side located inside the waveguide section 1 and the other end attached to the planar portions of the waveguide section 1 and the casing section 2. The transmission signal applied to the probe 6 from the transmission circuit board 3 is converted into a propagation mode suitable for propagation in the waveguide section 1. It has become so.
[0010]
Further, the waveguide section 1 in the embodiment of the present invention has an inner surface (a surface facing the surface on which the probe 6 is provided) inclined surface 7 from the position of the short-circuit surface 5 to the vicinity of the opening 4. A tapered waveguide having a characteristic as a high-pass filter is formed (see FIG. 1). Accordingly, the waveguide section 1 has an angle θ between the horizontal direction (when the probe 6 is viewed in FIG. 1 so that the probe 6 is along the vertical direction and the horizontal direction on the paper surface) and the inclined surface 7 and the vertical direction (front and back direction on the paper surface) and the side wall. By appropriately selecting the angle θ ′ (draft angle) (not shown) and the distance L between the probe 6 and a metal filter plate 9 to be described later, it has a wide band attenuation characteristic and a wide band transmission band pass characteristic. (Specific examples of characteristics will be described later).
[0011]
From the short-circuit surface 5 side of the waveguide section 1, the casing section 2 extends in the direction opposite to the opening section 4, and extends from a part of the waveguide section 1 to the casing section 2. The transmission circuit board 3 is disposed on the surface (see FIG. 1).
The transmission circuit board 3 is a final-stage amplifier circuit that finally amplifies a microwave (or millimeter wave) transmission wave, and a microstrip line (not shown) with a microwave power transistor (or millimeter wave power transistor) 8 as a center. Z).
[0012]
On the other hand, the periphery of the opening 4 of the waveguide portion 1 is a flange 1a, and a metal filter plate 9 is fixed (see FIG. 1). The method for fixing the metal filter plate 9 can be arbitrarily selected from various methods such as screwing and caulking, and need not be limited to a specific fixing method.
A feed horn (not shown) is connected to the waveguide section 1 with the metal filter plate 9 interposed therebetween, and the waveguide section 1 transmits the transmission mode converted into the propagation mode in the waveguide. A transmission wave from the trusted circuit board 3 passes through the metal filter plate 9 and is guided to an antenna (not shown) through the feed horn.
[0013]
The metal filter plate 9 is made of, for example, a metal plate having a thickness t of about 1 mm, and the planar shape thereof is the opening 4 of the waveguide portion 1 as shown in FIG. The first adjustment piece 11 is provided in the filter opening 10 formed in the matching shape and size to form the capacitive first window 13, and the second adjustment piece 12 is provided to provide the capacitive second. In addition, an inductive third window 15 is formed between the first adjustment piece 11 and the second adjustment piece 12. FIG. 2 shows a planar shape when the metal filter plate 9 is viewed from the direction opposite to the transmission wave propagation direction (see the white arrow in FIG. 1). In FIG. 2, a rectangular shape represented by a partial dotted line and a partial solid line indicates the planar shape of the filter opening 10 before the first and second adjustment pieces 11 and 12 are formed.
In the embodiment of the present invention, the first adjustment piece 11 is provided at one corner of the filter opening 10, specifically, from the upper left corner to the vertical direction (the vertical direction in FIG. 2), in other words, the filter A (cm) as a first predetermined length along a side perpendicular to the wide side of the opening 10 (side in the left-right direction in FIG. 2), and b (cm) as a second predetermined length along the wide side. It is formed in a rectangle having a length.
[0014]
In addition, the second adjustment piece 12 is formed in the vertical direction from the corner at which the first adjustment piece 11 is formed and the opposite corner of the filter opening 10 in the diagonal direction, that is, the lower right corner of the filter opening 10. It is formed in a rectangle having a third predetermined length c (cm) and a fourth predetermined length d (cm) along the wide side. Therefore, the first window 13 has a width (horizontal direction in FIG. 2) of b (cm), and a height (vertical direction in FIG. 2) is the length of the filter opening 10 in the vertical direction. If the thickness is f (cm), it has a size of (f−a) cm.
On the other hand, the second window 14 has a width of d (cm) and a height of (fc) cm. Assuming that the lateral width of the filter opening 10 is g (cm), the third window 15 has a width of {g− (b + d)} cm and a height of f (cm). It has become.
[0015]
By providing the metal filter plate 9 having such a shape so as to be orthogonal to the propagation direction of the electromagnetic wave, the portion of the first window 13 is equivalent to the first capacitor C1 with respect to the electromagnetic wave. The portion of the second window 14 acts as a second capacitor C2 equivalent to electromagnetic waves, and the portion of the third window 15 acts as a first coil L1 equivalent to electromagnetic waves, respectively. (See FIG. 3).
The first and second capacitors C1 and C2 and the first coil L1 are equivalent to being connected in parallel to the propagation path of the electromagnetic wave. By appropriately selecting these values, the first and second capacitors C1 and C2 and the first coil L1 are equivalent. The parallel connection circuit of the capacitors C1 and C2 and the first coil L1 serves as a filter that allows electromagnetic waves in a predetermined frequency band to pass through with low loss and attenuates electromagnetic waves outside the predetermined frequency band. It will be.
In order to make the metal filter plate 9 have a pass characteristic with respect to a desired frequency band and an attenuation characteristic outside a predetermined frequency band as described above, specifically, the symbols a to b shown in FIG. What is necessary is just to select the dimension of each part shown by d suitably. The metal filter plate 9 is preferably manufactured by punching or etching. In such a manufacturing method, stable manufacturing can be realized while relatively maintaining the accuracy of the finished dimensions, so that it can be manufactured at low cost. The characteristics of the metal filter plate 9 as a filter are almost determined by the dimensional accuracy and the mounting accuracy. In the manufacturing process using the manufacturing method as described above, the mechanical dimensional accuracy at the time of finishing is managed. This is very convenient because it also manages the variation in filter characteristics.
[0016]
Next, the operation of the transmitter with built-in reception band noise suppression filter in the embodiment of the present invention having the above configuration will be described. First, power is applied to the circuit in the transmission circuit board 3, and the transmission circuit board 3 is illustrated. The transmitted wave amplified in the final stage amplification circuit that is not applied is applied to the probe 6 and converted from the propagation mode in the final stage amplification circuit to a propagation mode suitable for propagation in the waveguide, thereby transforming the waveguide section 1 into the metal filter plate. Propagate in the direction of 9. Since the inside of the waveguide portion 1 up to the metal filter plate 9 is a tapered waveguide, this portion acts as a so-called high-pass filter, and the transmitted wave to propagate is this portion, A frequency component lower than the original transmission frequency band is removed to some extent. Then, the metal filter plate 9 is reached. Here, the frequency component outside the transmission frequency band is further removed and input to a feed horn (not shown) connected to the waveguide portion 1 so as to sandwich the metal filter plate 9. It will be. Therefore, a transmission wave from which noise and spurious components that affect the receiver are sufficiently removed is input to the feed horn.
[0017]
FIG. 5 is a characteristic diagram showing an example of the pass characteristic of the waveguide section 1 of the transmitter with a built-in reception band noise suppression filter having the above-mentioned configuration. The horizontal axis indicates the frequency (GHz) and the vertical axis indicates the attenuation (dB). Also, in the figure, the section between the white triangle marker with the number 1 and the white triangle marker with the number 2 is the transmission frequency band (in FIG. 5, “Tx band”). On the other hand, the section between the white triangle marker with the numeral 3 and the white triangle marker with the numeral 4 is the reception frequency band ("Rx band" in FIG. 5). Notation).
A characteristic line represented by a solid line in FIG. 3 indicates the metal filter plate 9 from the position of the output end of the final stage amplifier circuit formed on the transmission circuit board 3, that is, the connection point (not shown) with the probe 6. It shows the frequency change of the insertion loss that occurs before passing through. According to this characteristic line, a slight amount of attenuation (approximately −1 to −2 dB) is obtained for a signal in the transmission frequency band, whereas a sufficiently large attenuation is obtained for a signal in the reception frequency band. The amount of the signal (approximately -33 to -52 dB) is shown, and the signal of the frequency component that affects the receiver is surely blocked, while the desired transmission wave is guided without unnecessary attenuation. It can be confirmed that the wave tube unit 1 outputs to a feed horn (not shown).
[0018]
In FIG. 5, a characteristic line represented by a two-dot chain line indicates a metal filter plate from an output end of the final stage amplifier circuit formed on the transmission circuit board 3, that is, a connection point (not shown) with the probe 6. The frequency characteristic of the loss (reflection loss) which arises in the transmission wave which passes the metal filter board 9 by the reflected wave which arises while passing 9 is shown.
According to this characteristic line, the reflection loss in the transmission frequency band is sufficiently small (approximately −15 to −18 dB), and the transmission wave is output from the waveguide section 1 without being subjected to unnecessary attenuation. Can be confirmed.
[0019]
Next, a second configuration example will be described with reference to FIG. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, different points will be mainly described.
First, in this second configuration example, other parts such as the waveguide section 1 (see FIG. 1) other than the metal filter plate 9A are the same as those shown in FIG.
Therefore, in the second configuration example, the configuration of the metal filter plate 9A different from the configuration shown in FIG. 1 will be mainly described.
The metal filter plate 9A in the second configuration example is obtained by further forming a fourth window 16 on the metal filter plate 9 having the configuration shown in FIG.
That is, the first adjustment piece 11A of the metal filter plate 9A has a fifth predetermined length a ′ (cm) in the vertical direction from the upper left corner of the filter opening 10 and a sixth predetermined length along the wide side. (B'-e) The rectangular fourth window 16 having a width e (cm) is formed so as to be formed.
The basic position and shape of the second adjustment piece 12 are the same as those shown in FIG. 2. In this second configuration example, the height c ′ (cm) and the lateral width d are the same. ′ (Cm) (see FIG. 4).
[0020]
In the metal filter plate 9A having such a shape, the fourth window 16 has both capacitive and inductive characteristics. Therefore, the portion of the fourth window 16 is resistant to electromagnetic waves. Equivalently, it acts as a parallel circuit of the third capacitor C3 and the second coil L2.
The parallel circuit of the third capacitor C3 and the second coil L2 is connected in series with the first capacitor C1 (see FIG. 3) that is equivalently formed in the first window 13 portion. The equivalent state is obtained, and further, this is equivalent to the case where the first coil L1 and the second capacitor C2 are connected in parallel to the series circuit portion.
Eventually, the metal filter plate 9A allows electromagnetic waves in a predetermined frequency band to pass through with low loss by appropriately selecting the values of the first and second coils L1 and L2 and the first to third capacitors C1 to C3. On the other hand, the function as a filter for attenuating electromagnetic waves outside this predetermined frequency band is the same as the metal filter plate 9 described above.
In order for the metal filter plate 9A to have a pass characteristic with respect to a desired frequency band and an attenuation characteristic outside a predetermined frequency band as described above, specifically, the code a ′ shown in FIG. What is necessary is just to select suitably the dimension of each part shown by -d 'and e.
[0021]
In the embodiment of the invention described above, the waveguide section 1 is described as being formed as a tapered waveguide. However, the reception frequency band is particularly wide and close to the transmission frequency band. In such a case, coupled with the action of the metal filter plate 9 (9A), the generation of spurious and noise due to the transmission wave in the reception frequency band is sufficiently suppressed without causing unnecessary power loss of the transmission wave. In order to prevent this, it is preferable to use a tapered waveguide. However, when the reception band and the transmission band are relatively separated from each other, the waveguide section 1 does not necessarily need to be a tapered waveguide. In this case, the metal filter plate 9 (9A) alone is sufficient as a normal linear waveguide.
[0022]
【The invention's effect】
As described above, according to the present invention, the metal filter plate having the desired filter characteristics is provided at the output portion of the waveguide. It is possible to suppress and prevent the occurrence of spurious and noise due to the above.
In particular, when the reception frequency band is lower than the transmission frequency band and covers a wide band, the waveguide section is a tapered waveguide having a high-pass filter characteristic with the reception frequency band being a cutoff frequency. Combined with the filter characteristics of the metal filter plate, there is a low loss, and it is possible to more reliably suppress and prevent the occurrence of spurious and noise due to the transmission wave in the reception band.
In addition, by using a metal filter plate, it is necessary to secure a new installation space with low loss compared to the case where a filter is formed on a circuit board by a microstrip line, and for the installation. Therefore, the transmitter can be easily downsized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram including a partial cross section showing a configuration of a transmitter with a built-in reception band noise suppression filter in an embodiment of the present invention.
FIG. 2 is a front view of a metal filter plate in a first configuration example.
FIG. 3 is an explanatory diagram for explaining the function of the metal filter plate shown in FIG. 2;
FIG. 4 is a front view of a metal filter plate in a second configuration example.
FIG. 5 is a characteristic diagram illustrating a pass characteristic of a transmitter with a built-in reception band noise suppression filter according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Waveguide part 2 ... Housing | casing part 3 ... Circuit board 6 for transmission ... Probe 8 ... Power transistor 9 for microwaves ... Metal filter board (1st structural example)
9A ... Metal filter plate (second configuration example)
11 ... 1st adjustment piece (1st structural example)
11A ... 1st adjustment piece (2nd structural example)
12 ... 2nd adjustment piece 13 ... 1st window 14 ... 2nd window 15 ... 3rd window 16 ... 4th window

Claims (2)

A circuit board on which a circuit for amplifying a transmission wave at the final stage is formed and a waveguide part are integrally attached, and the transmission wave output from the circuit board by the waveguide part propagates through the waveguide. In a transmitter that is configured to be converted into a mode and output from the waveguide unit and integrated with a receiver,
The waveguide section, while formed by a tapered waveguide and the cutoff frequency of the reception band frequency, the opening of the waveguide section, Ri name by fixing a metallic filter plate,
The metal filter plate has a first predetermined length in the vertical direction from the upper left corner of the filter opening and a second predetermined length along the wide side in the filter opening that coincides with the opening of the waveguide portion. A first adjustment piece formed respectively;
The first adjustment piece is formed from a corner facing the diagonal direction of the filter opening to a third predetermined length in the vertical direction and a fourth predetermined length along the wide side. A second adjusting piece is provided,
A capacitive first window is between the first adjustment piece and the wide piece of the filter opening facing the first adjustment piece,
A capacitive second window is between the second adjustment piece and the wide piece of the filter opening facing the second adjustment piece,
Inductive third windows are respectively formed between the first adjustment piece and the second adjustment piece ,
While allowing blocking passage of a signal of the reception frequency band, the reception band noise suppression filter built transmitter characterized by being obtained by allowing the passage of a low loss of the transmitted wave outside the reception frequency band. The metal filter plate has a fifth predetermined length in the vertical direction from the upper left corner of the filter opening and a sixth predetermined length along the wide side at the filter opening coincident with the opening of the waveguide portion. The first adjustment piece is provided with a predetermined width so that the windows each have are formed,
A second predetermined length formed from the upper left corner of the filter opening and the diagonally opposite corner of the filter opening to a third predetermined length in the vertical direction and a fourth predetermined length along the wide side. the adjusting pieces and receive band noise suppression filter built transmitter of claim 1 Symbol mounting, characterized by comprising provided.

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