RU2371840C2 - Method for tuning of multilink band filters - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention is intended for fine tuning of multilink band filters (hereinafter referred to as filters) of radio electronic devices of microwave and in compliance with the specified requirements. Result is achieved by tuning of filter by specific points of frequency dependence of transfer coefficient (maximum point (7) - in regulation of links, point of maximum slope (6) - in tuning of resonators) at partial connections of filter into measuring track of device, which make it possible to simultaneously control both frequency of resonator tuning and links size. At the same time calculation is simplified for variation of resonator tuning frequency and links size. Method makes it possible to tune two and more filters with the same parametres. It is not required to make any absorbers, accessories for shorting, devices for energy drain.

EFFECT: lower labour intensiveness of tuning process.

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Description

The invention relates to radio engineering and is intended to configure multi-link bandpass filters (hereinafter referred to as filters) of microwave electronic devices.

There is a method of tuning band-pass filters (see USSR author's certificate No. 1427441, published September 30, 88), according to which each resonator is tuned to the resonant frequency f ₀ with simultaneous detuning of neighboring resonators using absorbers, while tuning is carried out to the maximum of the past Microwave signal.

This tuning method is technically very complicated, since it requires the manufacture of special absorbers and devices for their input into the resonators, a special device for removing energy from the tunable filter resonator together with a special measuring device. Moreover, even a weak connection between the tuned resonator and a special device for energy removal leads to a decrease in the Q factor of this resonator and a decrease in the accuracy of tuning to the maximum signal (especially for narrow-band filters). Also, this method does not allow to determine the measure of change of the coupling coefficients between the resonators, which reduces the accuracy and quality of the settings. In addition, this method assumes the presence of such tuning elements that provide both an increase and a decrease in the frequency of tuning of the filter cavity, which is unacceptable, for example, for a ceramic filter, in which any change in the tuning element only leads to an increase in the frequency of tuning of the resonator and / or reduction of coefficients communication.

There is another way to configure bandpass filters (see US patent No. 5004992, published 2.04.91), according to which, after preliminary calculation, a filter is made on the basis of a ceramic block of a slightly higher height than is required by calculation. Then the filter parameters are measured and the necessary value for reducing the height of the ceramic block from the side of its base is calculated.

This tuning method involves the use of precision equipment for machining a ceramic block, manufacturing filter topology elements. After adjusting the filter, it is necessary to restore the metallization of the base of the ceramic block by burning silver-containing paste. Metallization recovery is a long, several days, process in which the filter is subjected to repeated exposure to a temperature of about 800 ° C. At the same time, the properties of ceramics and the filter topology change slightly, which leads to an error in the filter settings. The accuracy of setting the coupling coefficients is determined by the accuracy of manufacturing the elements of the filter topology and, in accordance with this patent, is not subject to adjustment, which reduces the accuracy and quality of the settings.

The closest adopted for the prototype to the proposed tuning method is the tuning method for the application for the invention of the Russian Federation No. 96117066, published January 10, 1999.

This method consists in tuning all the filter resonators to the center frequency, as well as in adjusting the connections between the resonators and the connections of the extreme resonators with the generator and the load in accordance with the calculated values of the coupling coefficients. In this case, the frequency dependences of both the phase of the reflection coefficient from the input of the filter, which has a greater steepness in the frequency response, and the module of the reflection coefficient, are measured.

In accordance with this method, the filter tuning includes two stages: the first stage is the tuning of the resonators, the second stage is the calculation and adjustment of the links. The stages are carried out separately: when calculating and adjusting the bonds, it is necessary to upset the neighboring resonators, which leads to the appearance of alternating cycles of the mentioned stages. Accordingly, the tuning elements must provide both an increase and a decrease in the frequency of the filter cavity and / or coupling coefficients, which is unacceptable for a ceramic filter. In addition, it is necessary to carry out laborious measurement processes for each individual resonator of the bandwidth at a level of minus 3 dB to calculate the coupling coefficients, and then the reverse calculation for their practical implementation. When adjusting the filter for non-tuned resonators, it is necessary to provide devices for shorting them.

The technical objectives of the present invention are: to simplify and reduce the complexity of the tuning process, ensuring high-precision tuning of a single filter, including a ceramic one, and providing tuning of two or more filters with the same parameters.

A method for tuning multilink bandpass filters is proposed, which consists in tuning filter resonators, adjusting the connections between the resonators and the connections of the extreme resonators with the generator and the load in accordance with the calculated values, measuring the frequency response with greater steepness, measuring the frequency dependence of the reflection coefficient module, DIFFERENT in that tuning of the resonators (except for the central one) and adjustment of the bonds in accordance with the calculated or experimental values are performed according to dots on the frequency dependence of the transmission coefficient with partial filter connections in the instrument’s measuring path, the central resonator is tuned according to the frequency dependence of the reflection coefficient module when the filter is fully turned on, and when two or more filters with the same parameters are configured, the first tuned filter is used as a filter sample, which measures the parameters of the above characteristic points with the subsequent transfer of the measured parameters to custom filters.

The technical result is achieved by tuning the filter at characteristic points of the frequency dependence of the transmission coefficient with partial inclusion of the filter in the measuring path of the device, which allows you to simultaneously control both the tuning frequency of the resonators and the magnitude of the bonds. At the same time, the calculation of changes in the resonator tuning frequency and coupling magnitude is simplified. It is not necessary to manufacture any absorbers, devices for shorting, devices for energy removal, since the filter itself, when partially turned on, is a sensor of the necessary signals.

The implementation of the tuning method (using an example of a third-order ceramic filter) is illustrated by drawings, where Fig. 1 shows a ceramic band-pass filter, Fig. 2 shows the frequency dependence of the transmission coefficient (AFC) of the filter when it is partially turned on between the central resonator and the contact pad, and figure 3 shows the frequency response of the filter when it is partially turned on between the extreme resonator and the contact pad.

To measure the frequency response and the coefficient of reflection coefficient (CO), a panoramic meter of transmission and reflection coefficients was used.

The filter (figure 1) is a ceramic block 1, five faces of which are metallized. Metallized holes with electrically connected pads on the sixth face form the resonators: extreme resonators 2, the central resonator 3. On the same face are the contact pads 4 for connecting the generator and the load. The extreme resonators 2, the central resonator 3, the contact pads 4 are separated from each other and from the lateral metallization by the dielectric gap 5.

On the frequency response of the filter (figure 2) there are two characteristic points:

- point 6 - the point of maximum frequency response steepness;

- point 7 - the maximum frequency response point.

On the frequency response of the filter (figure 3), a characteristic point 8 is highlighted - the maximum frequency response point.

The values of the frequency and transmission coefficient at characteristic points of the frequency response can be determined by calculation or measured experimentally. The tuning of the filter resonators consists in resizing the areas of the resonators 2, 3 from the side of the side metallization. The adjustment of the bonds consists in changing the dimensions of the dielectric gaps between the pads of the resonators 2, 3, between the pads of the resonators 2 and the contact pads 4.

The sequence of operations when implementing the configuration method is illustrated by the following examples.

Example 1: Configuring a single filter

The filter is configured as follows:

- when the filter is partially turned on, the frequency dependence of the transmission coefficient is measured between the left extreme resonator 2 and the left contact pad 4 (generator / load). A characteristic point is isolated on the frequency response in accordance with FIG. 3 and the value of the transmission coefficient is measured in this position. The connection of the left end resonator with the generator / load is controlled by changing the size of the dielectric gap between the left end resonator 2 and the left contact pad 4 in accordance with the calculated or experimental value. The right extreme resonator 2 and the right contact pad 4 (load / generator) are included in the measuring circuit of the device, the adjustment is repeated to establish the same connection of the right extreme resonator with the load / generator;

- when the filter is partially turned on, the frequency dependence of the transmission coefficient is measured between the central resonator 3 and the left contact pad 4. On the frequency response distinguish characteristic points in accordance with figure 2. The frequency value at point 6 adjusts the frequency of the rightmost resonator by changing the size of its area in accordance with the calculated or experimental value. The value of the transfer coefficient at point 7 controls the relationship between the central and leftmost resonator by changing the size of the dielectric gap between them in accordance with the calculated or experimental value. The central resonator 3 and the right contact pad 4 are included in the measuring circuit of the device. The frequency of the leftmost resonator is tuned by resizing its pad. Regulate the connection between the central and rightmost resonator by changing the size of the dielectric gap between them;

- when the filter is fully turned on in the measurement mode of the QoS module, the frequency dependence of the QoS module is measured. The frequency of the central resonator is adjusted so that the equilibrium waveform of the frequency dependence of the KO module is observed.

Example 2: Setting up two or more filters with the same parameters

The filter is configured as follows:

- when the filter sample is partially turned on, the frequency dependence of the transmission coefficient is measured between the left (or right) extreme resonator 2 and the left (or right) contact pad 4. A characteristic point is isolated on the frequency response in accordance with FIG. 3 and the transmission coefficient value is measured in this position;

- when the filter sample is partially turned on, the frequency dependence of the transmission coefficient is measured between the central resonator 3 and the left (or right) contact pad 4. Characteristic points are distinguished on the frequency response in accordance with FIG. 2 and the frequency value is measured at point 6, the value of the transmission coefficient at point 7;

- with the appropriate partial inclusion of the tunable filter, the frequency of the extreme resonators is adjusted, the connections of the central with the extreme resonators, of the extreme resonators with the generator / load are adjusted in accordance with the measured values of the filter sample (see example 1);

- when the filter is fully turned on in the measurement mode of the QoS module, the frequency dependence of the QoS module is measured. The frequency of the central resonator is adjusted so that the equilibrium waveform of the frequency dependence of the KO module is observed.

Thus, the proposed tuning method allows you to set the required tuning frequency of the resonators and adjust the necessary connections between the resonators, between the extreme resonators and the load / generator, which ensures high-precision tuning of the filter, including the ceramic one. The calculation of changes in the frequency of tuning of the resonators and the magnitude of the bonds is significantly simplified; no absorbers, shorting devices, and devices for removing energy are required to be manufactured, since the filter itself, when partially turned on, is a sensor of the necessary signals, which ensures simplicity and low laboriousness of the tuning process. The proposed method also allows you to configure two or more filters with the same parameters.

Claims (1)

The method of tuning multilink bandpass filters, which consists in tuning the filter resonators, adjusting the connections between the resonators and the connections of the extreme resonators with the generator and the load in accordance with the calculated values, measuring the frequency response with greater steepness, measuring the frequency dependence of the reflection coefficient module, characterized in that the setting resonators (except the central one) and the adjustment of the bonds in accordance with the calculated or experimental values is performed by characteristic in the frequency dependence of the transmission coefficient (the maximum point - when adjusting the connections, the maximum steepness - when adjusting the resonators) with partial inclusion of the filter in the measuring path of the device, one contact of which is connected to the input / output of the filter, and the second contact is sequentially from the extreme to the central resonator, the central resonator is tuned according to the frequency dependence of the reflection coefficient module when the filter is fully turned on, and when setting up two or more filters with the same parameters and the first tuned filter is used as a filter sample, in which the parameters of the above characteristic points are measured, followed by the transfer of the measured parameters to the tunable filters.

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