JPS6150522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric drop-in filter that can be incorporated into a module of a microwave integrated circuit.

In microwave communication equipment, the high frequency parts of receivers and transmitters are equipped with isolators, filters, mixers,
It is composed of microwave devices such as amplifiers, but conventionally, these devices are individually assembled into cases, and after each adjustment and inspection is completed, a waveguide or a waveguide is connected between the cases of each device. The method used was to connect via coax. However, this method has the disadvantage that it takes up extra space, which limits the overall size reduction. In contrast, recently, microwave integrated circuits (hereinafter referred to as MICs) have been used in mixers, amplifiers, etc.
By applying the isolator as a drop-in isolator to the MIC board and connecting each unit with ribbons, etc., the entire high-frequency circuit can be integrated as one module, making it smaller and cheaper. Development is underway to achieve this goal. In this case, if each unit has a wider band, an advantage can be obtained that the overall characteristics can be obtained without adjustment when the units are connected with a ribbon or the like.

By the way, as a filter used in addition to the mixer, amplifier, and isolator mentioned above, incorporating a semi-coaxial filter made of a conventional resonant element such as a round bar as part of a module will only increase the number of cutting and processing steps. Therefore, it is difficult to connect to the MIC board, making it unsuitable as a MIC module device. Also, as another conventional example,
Stripline filters in which patterns of resonant elements and coupling elements are formed on a dielectric substrate by vapor deposition or etching have the drawbacks of low attenuation constant Q ₀ and large insertion loss.

On the other hand, recent progress has been made in the development of dielectric resonators using dielectrics with high relative permittivity, and it has become possible to obtain filters with high Q ₀ and good frequency stability. This filter can be configured simply by placing it on the MIC board, so it is becoming widely used as the most suitable filter for modularizing microwave devices. However, since this filter has an electromagnetic field component leaking from the resonator to the outside, it is necessary to shield it, and as can be seen from the cross-sectional structure of FIG. 1, conventionally this filter was used inside a case. In the figure, 101 is a case, 102 is a dielectric resonator, 1
03 is a rexolite stand that supports the resonator 102,
104 is an input/output connecting rod. Furthermore, 105 is a fine adjustment screw for varying the resonant frequency of the dielectric resonator 102, and metal, a dielectric rod, or the like is used. When using a dielectric filter configured in this way in a microwave module,
Instead of an input/output connector, a method must be used, such as providing a pin and connecting the pin and the board with a ribbon. However, in this method, the advantages of using a dielectric resonator are not fully utilized, as there is not much difference from the case of using the above-mentioned semi-coaxial filter. In addition, when connecting units using ribbons, there is no problem at low frequencies where the deterioration of VSWR is small, but as the frequency increases, the deterioration of VSWR when connecting with ribbons cannot be ignored. In particular, devices such as filters that are strongly affected by the VSWR of input/output lines have the disadvantage that the filters that have been adjusted individually must be readjusted by connecting them with a ribbon.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to drop it into a part of a modularized MIC circuit, and to
To provide an economical dielectric drop-in filter which can be easily ribbon-connected to input/output lines on a dielectric substrate, has no uneven adjustment, has high performance, and is economical.

A plurality of dielectric resonant elements are arranged in at least a part of a module case provided to cover the dielectric substrate in a state where electromagnetic field leakage is shielded,
Further, adjusting screws for adjusting the resonant frequencies of these dielectric resonant elements are provided at positions corresponding to the dielectric resonant elements of the dielectric substrate, thereby forming a band filter, and forming a band filter on the dielectric substrate. The dielectric film of the band filter is grounded to shield the lid of the band filter, and the dielectric film around the adjustment screw corresponding to the input/output side dielectric resonant element of the band filter is partially removed. A dielectric drop-in filter is obtained in which an output coupling line is formed.

Next, a dielectric drop-in filter according to the present invention will be explained in detail with reference to the drawings.

FIGS. 2a and 2b show the structure of an embodiment according to the invention in a top view and a side sectional view taken along the line AA', respectively. In the figure, 1 is a hollow dielectric resonator, 2 is a dielectric rod for adjusting the dielectric resonator 1, and this dielectric rod 2 is connected to the dielectric resonator 1.
Frequency adjustment can be performed by inserting it into the hollow part of. 3 is a rexolite adjustment screw for supporting and movable the dielectric rod 2, 4a and 4b are dielectric supports for supporting the dielectric resonators, and 5 is a dielectric substrate for the stripline. 6 is
A case for the MIC module, 6a is a groove for shielding the resonator 1 opened in the case 6, 7 is a dielectric substrate 5
while fixing the dielectric film 5a on the dielectric substrate.
This is a ground plate that also serves as a presser spring to ground.
In this way, the bandpass filter is constructed by arranging a plurality of dielectric resonators 1, and is dropped into the shielding groove 6a provided in the module case 6, and the input/output side is connected to the dielectric substrate 5. It is coupled to the bandpass filter by input/output lines 5b, 5c provided above.

In the above configuration, input/output line 5
The degree of coupling between the dielectric resonator 1 and the dielectric resonator 1 is determined by the degree of coupling between the dielectric resonator 1 and the dielectric resonator 1, as shown in the partial top view and the side sectional view taken from the line BB' in FIG. 3a, b, and c. A preferable value can be selected by adjusting the electrical angle θ of the arcuate joint portion of the input/output stripline coupled to the input/output stripline and the distance h between the input/output stripline and the resonator. If this relationship is shown experimentally, it will be as shown in FIG. 4, for example. In this figure, the degree of coupling on the vertical axis represents Qext=g ₀ g ₁ /ω. Here, g ₀ and g ₁ are the element values of the basic LPF,
ω is Δf/f ₀ (Δf: 3 dB band, f ₀ : center frequency). Further, the electrical angle θ on the horizontal axis represents θ=2πl/λ. In addition, the input/output lines 5b, 5c
As shown in FIG. 3B, the arcuate joint portion is formed by reducing the diameter of the through hole in the dielectric substrate 5 and forming a strip line with the dielectric film on the substrate. In this case, the dielectric support 4b
is divided into two, 4b ₁ and 4b ₂ . Alternatively, as shown in FIG. 3c, an arc-shaped thin conductor piece can be inserted into the intermediate layer of the integrally formed dielectric support 4b.

Further, the degree of coupling between the resonators can be selected to obtain preferable filter characteristics from the experimental results shown in FIG. 5, for example, based on the spacing d between the resonators shown in FIG. 3a. In this figure, the degree of connectivity on the vertical axis
Kij is It is.

In the above embodiment, it is possible to adjust using the adjustment screw 3 etc. while dropping it into the shielding groove 6a provided in a part of the MIC module, and the input/output lines 5b and 5c are Since it is etched onto the dielectric substrate that serves as the lid of the dielectric filter, it is easy to connect with other MIC devices and there is little leakage to the outside. In addition, since the impedance of the input and output lines can also be adjusted, unlike the conventional type, the filter can be readjusted to eliminate mismatches in the connection lines that occur after connecting the adjusted filter to other devices. There is no such need.

Incidentally, FIG. 6 shows an example in which the drop-in filter according to the present invention is applied to an RF head of a microwave receiver. Figure a is a perspective view showing the external structure, and figure b is a circuit block diagram of the RF head.
In this figure, the RF input signal is amplified by a FET amplifier 11, passes through a drop-in isolator 12, and enters a dielectric drop-in filter 13.
The output of drop-in filter 13 enters mixer 15 through drop-in isolator 14. On the other hand, the output of the local oscillator 16 is applied to the mixer 15 as a local oscillator input. According to this structure,
Since the input to the IF output of the FET amplifier 11 can be connected directly with a ribbon or the like within one case without using an input/output connector, it is possible to significantly reduce costs and downsize. Also,
The dielectric drop-in filter 13 is adjusted by detecting the reflected output from the filter 13 from the terminal of the dummy 12a of the input drop-in isolator 12,
This can be done by adjusting so that the reflected output is minimized.

As is clear from the above description, according to the present invention, a filter can be dropped into a part of a modular MIC circuit and used by connecting the input/output lines on the board with a ribbon. ,
There is no performance deterioration due to connection with other units,
It is easy to adjust, compact, high-performance, and economical, and has great effects when applied to modular MIC circuits as a dielectric drop-in filter.

[Brief explanation of the drawing]

1A and 1B are vertical and cross-sectional views, respectively, of a conventional dielectric filter; FIGS. 2A and 2B are a top view and a side sectional view taken along line AA' of the structure of an embodiment according to the present invention; FIGS. Figures a, b and c
are a partial top view showing the input/output side in FIG. 2 and a side sectional view taken along line BB', FIG. 4 is a characteristic diagram showing changes in the degree of coupling on the input/output side in the example, and FIG. 5 is a diagram showing the results of the implementation. FIGS. 6a and 6b are perspective views of the external structure of an example in which the drop-in filter according to the present invention is applied to the RF head of a microwave receiver, and FIGS. FIG. 3 is a circuit block diagram of the RF head. In the figure, 1 is a dielectric resonator, 2 is a dielectric rod for changing the resonant frequency, 3 is a dielectric adjustment screw, 4a, 4
b, 4b ₁ , 4b ₂ are dielectric supports, 5 is a dielectric substrate, 5a is a dielectric film on the substrate 5, 5b, 5c are input/output lines, 6 is a case of the MIC module, 6a is a shielding groove, 7 is a This is a ground plate that also serves as a presser spring.

Claims (1)

[Claims] 1 A plurality of dielectric resonant elements are arranged in at least a part of the module case provided so as to cover the dielectric substrate, with electromagnetic field leakage shielded, and the resonance of these dielectric resonant elements is A band filter is formed by providing adjustment screws for adjusting the frequency at positions corresponding to the dielectric resonant elements of the dielectric substrate, and the dielectric film on the dielectric substrate is grounded to adjust the band filter. A dielectric film formed by shielding the lid of the filter and further removing partially the conductive film around the adjustment screw corresponding to the input/output side dielectric resonant element of the band filter to form an input/output coupling line. Body drop in filter.