RU2498464C2 - Band-rejection filter - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: band-rejection filter consists of high-Q ceramic resonators and contains the main current-carrying conductor located at one side of dielectric substrate while at its other side there are sections of strip conductors having connection through the face with the main current-carrying conductor and galvanic coupling with ceramic resonators. At that location of spurious rejection band depends on thickness of dielectric substrate.

EFFECT: obtaining high slope ration for rejection band at frequency F0 and shifting spurious rejection band further than 3F0.

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Description

The invention relates to techniques for microwave frequencies and is intended for selection of a microwave signal.

Known bandpass microwave filter US patent US patent No. US 4.983.938, consisting of dielectric coaxial short-circuited resonators with inductors connected in parallel, mounted on a dielectric plate, and mounted on it with a screw. Resonators are interconnected by a concentrated communication capacitance. A coaxial resonator with inductance forms a parallel oscillatory circuit, the frequency of which is changed by means of a screw.

Such a band-stop filter has a relatively gentle characteristic in the region of transition from the barrier to transmission due to losses in coupling capacitors and inductances of the resonant circuit.

The closest analogous combination of essential features is a monolithic ceramic filter with a barrier strip [patent No. US 4.983.938], taken as a prototype containing a dielectric substrate, on the surface of which ceramic resonators are installed, which are connected to the transmission line through the end capacitance, while between the resonators is equal to λ / 4. The resonance frequency setting of the fence loops is selected in such a way as to suppress at the desired frequency P0 (notch frequency). This type of band-stop filter is used if high slope characteristics are not required in the area of transition from the band to the bandwidth. The disadvantage of the prototype is that it has a parasitic obstacle at a frequency close to 2F0.

The aim of the invention is to achieve high slope characteristics in the field of transition from the obstacle to the passband, as well as expanding the passband of the band-stop filter by moving the parasitic obstacle band to a frequency further than 3F0.

To achieve this goal, a band-stop filter consisting of high-quality ceramic resonators is proposed.

According to the invention, the proposed band-stop filter contains a main current-carrying conductor located on one side of the dielectric substrate, on the second surface of which there are segments of strip conductors having a face connection with the main current-carrying conductor and which are galvanically coupled to ceramic resonators, and the location of the parasitic barrier strip depends on the thickness of the dielectric substrate.

The difference between the claimed device and the prototype lies in the fact that the main current-carrying conductor located on one side of the dielectric substrate, on the second surface of which there are segments of strip conductors having a face connection with the main current-carrying conductor and which are galvanic, are introduced into the proposed band-stop filter. connection with ceramic resonators, and the location of the spurious strip of the fence depends on the thickness of the dielectric substrate.

The combination of distinctive features and properties of the proposed band-stop filter in the available literature is not found, therefore, it meets the criteria of novelty and inventive step.

Figure 1, 2 conventionally shows the design of the band-stop filter, figure 3 shows the measured amplitude-frequency characteristic (AFC).

The band-stop filter contains a current-carrying conductor 1 (Fig. 1) located on a dielectric substrate 2 (Fig. 1), on the reverse side of which there are segments of strip conductors 4 (Fig. 2), which are galvanically connected to high-quality ceramic resonators 3 (Fig. .1) forming a fencing strip with a center frequency F0. The thickness of the dielectric substrate determines the position of the spurious strip of the fence, with a center frequency of more than F0.

The notch filter works as follows:

The current-carrying conductor 1 (Fig. 1) is connected through segments of strip conductors 4 (Fig. 2) with a resonator 3 (Fig. 1) having an inductive resistance at the resonance frequency.

The capacitive coupling of each strip conductor 4 together with the inductive resistance of the corresponding ceramic resonator 3 forms a sequential oscillatory circuit having a low resistance at the resonance frequency compared to the wave resistance of the current-carrying line, which leads to reflection of the signal at this frequency in the connection section of the resonator. The quality factor of the ceramic resonator 3 and the structural capacitor is significant, which allows to obtain a high steepness of the transition characteristic in the region of transition from the obstacle to the passband. Figure 3 shows the measured frequency response of the proposed band-stop filter, from which it can be seen that the amplitude characteristic at the lower and upper frequencies of the boom has a large steepness in the transition region, and the stray band of the fence is moved beyond the third harmonic of the boom band F0.

Claims (1)

A band-stop filter, consisting of high-quality ceramic resonators, characterized in that it contains a main current-carrying conductor located on one side of the dielectric substrate, on the second surface of which there are segments of strip conductors that are face-connected to the main current-carrying conductor and which are galvanically connected to ceramic resonators, and the location of the spurious strip of the fence depends on the thickness of the dielectric substrate.

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