JP2002158510A - Transmitter with built-in reception band noise suppressing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress and prevent the generation of sprious or noise caused by transmitting waves within a receiving band having a simple configuration. SOLUTION: A casing part 2 is extended on the opposite side of an opening part 4 of a waveguide part 1, a circuit board 3 for transmitting is located on the surface of these waveguide part 1 and the casing part 2, and transmitting waves outputted from the circuit board 3 for transmitting are converted to the propagation mode of the waveguide part 1 via probe 6, while a metal filter plate 9, having attenuation characteristics within a receiving frequency band, is fixed on the opening part 4, so that the sprious or noise components within the receiving frequency band contained in transmitted waves to be passed can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter in a communication device for a microwave band or 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 signals given to a receiver. Etc.

[0002]

2. Description of the Related Art Conventionally, as a device of this type in which a transmitter / receiver is integrally incorporated, for example, a transmitting / receiving antenna system for satellite communication using a broadcasting satellite or a communication satellite can be mentioned. 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 last-stage circuit that forms a part of a transmitter and performs final amplification of a transmitted signal include a parabola for satellite communication. This is a configuration provided integrally with an antenna, a feed horn, a connection waveguide, and the like. Among such transmission / reception antenna systems, there is a type in which transmission / reception is performed at the same time. In such a system, the transmission / reception circuit as described above is extremely close due to a demand for miniaturization of the whole transmission / reception antenna system. It is difficult to avoid the influence of the transmission wave on the reception circuit even if the transmission wave band and the reception wave band are far apart. Conventionally, various types have been used.

[0003] As a conventional measure for suppressing or preventing such an influence of a transmission wave on a receiving circuit, for example, a final stage circuit of a transmitter provided in an antenna system attenuates a frequency component in a reception band of the transmission wave. There is a method of providing a band-pass filter or a high-pass filter using a microstrip line for the purpose. There is also a method of connecting a so-called waveguide bandpass filter to the final stage circuit of the transmitter to suppress or prevent the influence of the transmission wave in the reception band. Furthermore, the final stage circuit of the above-described transmitter is provided integrally with the waveguide coaxial converter. However, a plurality of so-called screws are provided in the waveguide coaxial converter to provide a reactive element type band rejection device. It is also conceivable to configure a filter.

[0004]

However, in the case where a filter is formed using the above-mentioned microstrip line, if the receiving band is wide and close to the transmitting band, the filter is not used. There is a problem that power loss occurs in the transmission band, and transmission level compensation is required. Further, in a configuration in which a waveguide bandpass filter is newly attached, there is a problem in that the number of parts of the device increases and the price of the device increases. Further, in the case of using a screw to form a reactive element type filter, in addition to an increase in the device price due to an increase in the number of parts, it is necessary to perform an adjustment operation to obtain a desired filter characteristic. There's a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has a simple configuration as compared with the related art, and is capable of suppressing and preventing spurious and noise generation due to a transmission wave in a reception band. A transmitter with a built-in filter is provided. Another object of the present invention is that even when the reception band is wide and close to the transmission band,
An object of the present invention is to provide a transmitter with a built-in reception band noise suppression filter which has low loss and can suppress and prevent noise and spurious due to a transmission wave in a wide reception band.

[0006]

In order to achieve the above object, a transmitter with a built-in reception band noise suppression filter according to the present invention comprises a circuit board on which a circuit for amplifying a transmission wave at a final stage is formed; A waveguide section is integrally attached, and the transmission section output from the circuit board is converted into a propagation mode of the waveguide by the waveguide section and output from the waveguide section. In a transmitter integrated with a receiver, a metal filter plate formed to have an attenuation characteristic in a reception frequency band is fixed to an opening of the waveguide section.

In the above configuration, a metal filter plate having a desired filter characteristic is provided in the opening of the waveguide, so that spurious and noise due to a transmission wave in a reception band can be obtained with a simpler configuration than in the related art. Can be suppressed and prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. The members, arrangements, and the like described below do not limit the present invention, and can be variously modified within the scope of the present invention. First, a first configuration example of a transmitter with a built-in reception band noise suppression filter according to an 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, for example, a transmission / reception antenna system for satellite communication, and includes a waveguide section 1 and the waveguide section 1.
And a transmission circuit board 3 (see FIG. 1). In FIG. 1, the metal filter plate 9 and the circuit board 3 for transmission are schematically shown.
It does not show a state of the waveguide section 1 and the housing section 2 on a cut surface.

The waveguide section 1 is formed in a so-called well-known and well-known coaxial waveguide converter. That is, the waveguide portion 1 is formed such that one opening 4 and the short-circuit surface 5 are opposed to each other in the traveling direction of the electromagnetic wave (the direction of the outlined arrow in FIG. 1), and one wide surface (FIG. 1). The probe 6 is provided at an appropriate position on the front side of the paper surface (see FIG. 1). One end of the probe 6 is located inside the waveguide portion 1, and the other end is formed on the transmission circuit board 3 attached to the planar portion of the waveguide portion 1 and the housing 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 unit 1. It has become so.

Further, the waveguide section 1 according to the embodiment of the present invention has one internal surface (the surface facing the surface on which the probe 6 is provided) extending from the position of the short-circuit surface 5 to the vicinity of the opening 4. A tapered waveguide formed on the inclined surface 7 and having characteristics as a high-pass filter (see FIG. 1).
Therefore, the waveguide section 1 is formed by an angle θ between the horizontal direction (the horizontal direction on the paper when viewing FIG. 1 so that the probe 6 is along the vertical direction) and the inclined surface 7 and the vertical direction (the front and back directions on the paper) and the side wall. By appropriately selecting the size of an angle θ ′ (draft) (not shown) to be formed and the distance L between the probe 6 and a metal filter plate 9 described later, a broadband attenuation characteristic and a wideband transmission bandpass characteristic can be obtained. (Specific characteristic examples will be described later).

From the short-circuit surface 5 side of the waveguide section 1, the housing section 2
Extend in a direction opposite to the opening 4, and
The transmission circuit board 3 is disposed on the surface of the housing 2 from a part of the housing 2 (see FIG. 1).
The transmission circuit board 3 includes a microstrip line (not shown) including a microwave power transistor (or millimeter-wave power transistor) 8 as a final-stage amplifier circuit that finally amplifies a microwave (or millimeter-wave) transmission wave. ).

On the other hand, the periphery of the opening 4 of the waveguide section 1 is a flange 1a to which a metal filter plate 9 is fixed (see FIG. 1). The method of fixing the metal filter plate 9 can be arbitrarily selected, such as screwing or caulking, and is not limited to a specific fixing method. Then, a feed horn (not shown) is connected to the waveguide unit 1 with the metal filter plate 9 interposed therebetween, and the waveguide unit 1 converts the transmission horn into a propagation mode in the waveguide. A transmission wave from the credit circuit board 3 passes through the metal filter plate 9 and is guided to an antenna (not shown) via the feed horn.

The metal filter plate 9 has a thickness t, for example.
Is formed using a metal plate having a size of about 1 mm, and has a planar shape that matches the shape and size of the opening 4 of the waveguide section 1 as shown in FIG. The first adjustment piece 11 is provided in the portion 10 to provide the capacitive first window 1.
3 and a second adjusting piece 12 is provided to form a capacitive second window 14, and an inductive third window is provided between the first adjusting piece 11 and the second adjusting piece 12. The window 15 is formed. 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, the rectangular shape represented by a partly dotted line and a partly solid line corresponds to the first and second adjustment pieces 11 and 1.
2 shows a plan shape of the filter opening 10 before forming the filter opening 2. In the embodiment of the present invention, the first adjustment piece 11 is provided at one corner of the filter opening 10, specifically, in the vertical direction (up and down direction in FIG. 2) from the upper left corner, in other words, the filter The wide side of the opening 10 (FIG. 2)
Along the side perpendicular to the left and right sides of the drawing).
Are formed in a rectangular shape having a length of a (cm) as the predetermined length and a length of b (cm) as the second predetermined length along the wide side.

The second adjustment piece 12 is formed from a corner opposite to the corner where the first adjustment piece 11 is formed in the diagonal direction of the filter opening 10, that is, from the lower right corner of the filter opening 10. C (cm) as a third predetermined length in the longitudinal direction,
It is formed in a rectangle having a length of d (cm) as the fourth predetermined length along the wide side. Therefore, the first window 13 has a width (b-cm in FIG. 2) of b (cm) and a height (up-down direction in FIG. 2) of a length of the filter opening 10 in the vertical direction. Assuming that the height is f (cm), it has a size of (fa) cm. On the other hand, the second window 14
Has a width of d (cm) and a height of (fc) cm. If the 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 what it has.

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 window with respect to the electromagnetic wave. As the capacitor C1, the portion of the second window 14 is equivalent to a second capacitor C2 for electromagnetic waves, and the portion of the third window 15 is equivalent to the first coil L1 for electromagnetic waves. , Respectively (see FIG. 3). These 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, and by appropriately selecting these values, the first and second capacitors C1 and C2 are selected. The second parallel connection circuit of the capacitors C1 and C2 and the first coil L1 functions as a filter that allows electromagnetic waves in a predetermined frequency band to pass with low loss and attenuates electromagnetic waves outside the predetermined frequency band. It is what becomes.
In order for the metal filter plate 9 to have a pass characteristic for a desired frequency band and an attenuation characteristic outside a predetermined frequency band as described above, specifically, reference numerals a to a 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 maintaining relatively accurate finished dimensions, so that manufacturing can be performed at low cost. The characteristics of the metal filter plate 9 as a filter are almost determined by dimensional accuracy and mounting accuracy.
In the manufacturing process using the manufacturing method as described above, managing the mechanical dimensional accuracy at the time of finishing is also very convenient because it also manages the dispersion of the filter characteristics.

Next, the operation of the transmitter with a built-in reception band noise suppression filter according to 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 wave amplified by the last-stage amplifier circuit 3 (not shown) is applied to the probe 6, and is converted from the propagation mode in the last-stage amplifier circuit to a propagation mode suitable for propagation in the waveguide, and The light propagates in the direction of the metal filter plate 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 transmission wave is Frequency components lower than the original transmission frequency band are removed to some extent. Then, the signal reaches the metal filter plate 9, where the frequency component outside the transmission frequency band is further removed, and is input to a feed horn (not shown) connected to the waveguide unit 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.

FIG. 5 is a characteristic diagram showing an example of the pass characteristic of the waveguide unit 1 of the transmitter with a built-in reception band noise suppression filter in the above configuration. In the figure, the horizontal axis represents the frequency (GHz),
The vertical axis indicates the attenuation (dB). In the same 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, "T
x band), and the interval between the white triangle marker with the number 3 and the white triangle marker with the number 4 is the reception frequency band (in FIG. 5, " Rx band ”). And
In the figure, a characteristic line represented by a solid line passes through the metal filter plate 9 from the output terminal of the final-stage amplifier circuit formed on the transmission circuit board 3, that is, the position of the connection point (not shown) with the probe 6. This shows a change in the frequency of the insertion loss that occurs until the insertion. According to this characteristic line, the signal in the transmission frequency band has a slight attenuation (approximately -1 to -2 dB), whereas the signal in the reception frequency band has a sufficiently large attenuation. Amount (approximately -33 to -52 dB)
And the transmission of a signal having a frequency component that affects the receiver is reliably prevented, while the desired transmission wave is transmitted from the waveguide unit 1 to the feed horn (not shown) without receiving unnecessary attenuation. It can be confirmed that it is output.

In FIG. 5, a characteristic line represented by a two-dot chain line is an output terminal of the final stage amplifier circuit formed on the transmission circuit board 3, that is, a connection point with the probe 6 (not shown).
3 shows frequency characteristics of a loss (reflection loss) generated in a transmission wave passing through the metal filter plate 9 due to a reflected wave generated while passing through the metal filter plate 9. According to this characteristic line, the reflection loss in the transmission frequency band is sufficiently small (about -15 to -18 dB), and the transmission wave is output from the waveguide unit 1 without undergoing unnecessary attenuation. Can be confirmed.

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 will be omitted. Hereinafter, different points will be mainly described. First, in the second configuration example, it is assumed that other parts such as the waveguide unit 1 (see FIG. 1) other than the metal filter plate 9A are the same as the configuration shown in FIG. Therefore, in the second configuration example, the configuration of the metal filter plate 9A that is different from the configuration shown in FIG. 1 will be mainly described. The metal filter plate 9A in the second configuration example is the same as the metal filter plate 9 having the configuration shown in FIG.
In addition, a fourth window 16 is further formed. That is, the first adjustment piece 11A of this metal filter plate 9A
Is a fourth rectangular predetermined length a '(cm) as the fifth predetermined length in the vertical direction from the upper left corner of the filter opening 10 and a (b'-e) cm as the sixth predetermined length along the wide side. It is provided with a width e (cm) so that the window 16 is formed. The second adjustment piece 12 has a basic position,
The shape is the same as that shown in FIG. 2, and in this second configuration example, the height c ′ (cm) and the width d ′
(Cm) (see FIG. 4).

The metal filter plate 9 having such a shape
4A, the fourth window 16 has both capacitive and inductive properties, and therefore, the portion of the fourth window 16 is equivalent to the third capacitor C3 and the third capacitor C3 with respect to electromagnetic waves. The second coil L2 functions as a parallel circuit. Then, the third capacitor C3 and the second
The parallel circuit of the coil L2 of the first capacitor C1 (see FIG. 3) is equivalently formed in the first window 13 portion.
, And a state equivalent to connecting the first coil L1 and the second capacitor C2 in parallel to the series circuit portion. As a result, the metal filter plate 9A allows electromagnetic waves in a predetermined frequency band to pass 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 the predetermined frequency band is the same as that of the metal filter plate 9 described above. In order for the metal filter plate 9A to have the pass characteristic in the desired frequency band and the attenuation characteristic outside the predetermined frequency band as described above, specifically, the reference symbol a ′ shown in FIG. The dimensions of each part indicated by d to e may be appropriately selected.

In the embodiment of the present invention described above, the waveguide section 1 has been described as being formed as a tapered waveguide. In particular, the reception frequency band is wide and the transmission frequency band is limited. In the case of close proximity,
In combination with the operation 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, the waveguide unit 1 does not necessarily need to be a tapered waveguide. In this case, a metal filter plate 9 (9A) alone is sufficient as a normal linear waveguide.

[0022]

As described above, according to the present invention,
Since a metal filter plate having desired filter characteristics is provided at the output portion of the waveguide, it is possible to suppress and prevent the generation of spurious and noise due to the transmission wave in the reception band with a simple configuration, unlike the related art. It has the effect of being able to do so. In particular, when the reception frequency band is lower than the transmission frequency band and extends over a wide band, the waveguide section may be a tapered waveguide having a high-pass filter characteristic with the reception frequency band as a cutoff frequency. Low loss combined with the filter characteristics of the metal filter plate, and
This has the effect that spurious and noise generation due to transmission waves in the reception band can be more reliably suppressed and prevented. Also, by using a metal filter plate, it is necessary to secure a new large installation space with a lower loss compared with a case where a filter is formed on a circuit board by a microstrip line. Therefore, there is an effect that the size of the transmitter can be easily reduced.

[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 according to an embodiment of the present invention.

FIG. 2 is a front view of a metal filter plate in the first configuration example.

FIG. 3 is an explanatory diagram for explaining a 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 showing pass characteristics of the transmitter with a built-in reception band noise suppression filter according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Waveguide part 2 ... Housing part 3 ... Transmission circuit board 6 ... Probe 8 ... Microwave power transistor 9 ... Metal filter plate (1st example of structure) 9A ... Metal filter plate (2nd example of structure) 11) First adjustment piece (first configuration example) 11A ... First adjustment piece (second configuration example) 12 ... Second adjustment piece 13 ... First window 14 ... Second window 15 ... 3rd window 16… 4th window

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 1/50 H04B 1/50

Claims (4)

[Claims] 1. A circuit board on which a circuit for amplifying a transmission wave at a final stage is formed, and a waveguide portion are integrally attached.
A transmitter configured such that a transmission wave output from the circuit board is converted into a propagation mode of a waveguide by the waveguide unit and output from the waveguide unit, and is integrated with a receiver 3. The transmitter with a built-in reception band noise suppression filter, wherein a metal filter plate formed to have an attenuation characteristic in a reception frequency band is fixed to an opening of the waveguide section. 2. The transmitter with a built-in reception band noise suppression filter according to claim 1, wherein the waveguide section is formed in a tapered waveguide having a cutoff frequency at the reception band frequency. 3. The metal filter plate has a first predetermined length along a wide side extending vertically from an upper left corner of the filter opening to a filter opening corresponding to the opening of the waveguide section. A third predetermined length in the longitudinal direction from a first adjustment piece formed to a predetermined length of 2 and a corner diagonally opposite to the corner where the first adjustment piece is formed and the diagonal direction of the filter opening. 3. A built-in reception band noise suppression filter according to claim 1, wherein a second adjustment piece formed at a fourth predetermined length is provided along the long side and the wide side, respectively. Transmitter. 4. The metal filter plate has a fifth predetermined length along a wide side extending vertically from an upper left corner of the filter opening to a filter opening corresponding to the opening of the waveguide section. A first adjustment piece having a predetermined width is provided so as to form a window having a predetermined length of 6, and an upper left corner of the filter opening is opposed to a diagonal direction of the filter opening. A third predetermined length in the vertical direction from the corner
3. The transmitter with a built-in reception band noise suppression filter according to claim 1, wherein a second adjustment piece is formed at a fourth predetermined length along the wide side. .