RU2460207C2 - Band microwave filter - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: band microwave filter comprises U-shaped electromagnetically joined sections of microstrio lines opened at both ends with a permanent distance between sections of microstrip lines at the length of a communication area, to their extreme sections an input and an output lines are connected accordingly, at the same time side sections of odd U-shaped microstrip lines are arranged as irregular with the width of conductors, reducing from the edges of a communication area to the centre, and side sections of even U-shaped microstrip lines are arranged in the form of elements of identical width along the length of the communication area.

EFFECT: increased selectivity of filtration.

2 dwg

Description

The present invention relates to electronics and can be used for selection in microwave paths.

Known microwave bandpass filter [1], consisting of regular U-shaped electromagnetically connected segments of microstrip lines, open at both ends, with a constant distance between segments of microstrip lines along the length of the communication area, the input and output lines are connected to the extreme of the segments, respectively.

This filter is the closest analogue to the proposed device and is selected as a prototype. The disadvantage of this filter is the deterioration of selectivity in the delay band due to the presence of secondary passband at frequencies that are multiples of the doubled center frequency.

The objective of the invention is to improve the selectivity of the filter by suppressing side bandwidths.

The problem is solved in that in the known scheme of a microwave bandpass filter, consisting of regular U-shaped electromagnetically connected segments of microstrip lines, open at both ends, with a constant distance between them along the length of the communication region, to the extreme segments of which the input and output lines are connected, respectively , the lateral segments of the odd U-shaped microstrip lines are irregular with the width of the conductors decreasing from the edges of the communication region to the center, and the lateral segments of the even U-shaped microstrip skock lines are made in the form of elements of the same width along the length of the communication area.

Comparative analysis shows that the claimed technical solution differs from the prototype in that the lateral segments of the odd U-shaped microstrip lines are irregular with the width of the conductors decreasing from the edges of the communication region to the center, and the lateral segments of the even U-shaped microstrip lines are made in the form of elements of the same widths along the length of the bond area.

When comparing the claimed technical solution not only with the prototype, but also with other well-known technical solutions in science and technology, no solutions were found that have similar characteristics.

The figure 1 shows the electrical circuit of the proposed device. The device consists of U-shaped microstrip lines, open at both ends, with a constant distance between segments of microstrip lines along the length of the communication area. The lateral segments of the odd U-shaped microstrip lines 1 are made irregular with the width of the conductors decreasing from the edges of the communication region to the center, and the lateral segments of the even U-shaped microstrip lines 2 are made in the form of elements of the same width along the length of the communication region. The input 3 and output 4 lines are connected to the extreme segments.

The device operates as follows.

The working frequency signal through the input line 3 is fed to a system of interconnected microstrip U-shaped resonators 1 and 2, each of which is made on the segments of the line open at its ends, and then through line 4 it is fed to the output terminals of the filter. In general, as shown in [1], such a system forms a strip chain. In this case, the amplitude-frequency characteristic of this circuit forms secondary passbands, the average frequencies of which are multiples of the main, operating filter frequency. This is due to the fact that the input impedance of each of the resonators has alternating maxima and minima of its real, imaginary parts and module, as shown in [2]. The case considered in [2] is characterized by constant, frequency independent secondary parameters of the line — its wave impedance ρ and propagation constant γ.

In the proposed filter embodiment, the width of the conductors of the lines forming the odd resonators varies along the length of the line, this leads to the fact that the parameters ρ and γ will depend on the length of the line forming the strip resonator, and, therefore, on the frequency.

The electromagnetic analysis of the proposed filter, the results of which are shown in figure 2, confirms the correctness of the proposed solution.

Thus, the proposed filter circuit allows the design of selective microwave devices, providing high requirements for attenuation in the delay band.

Information sources

1. Lancaster M.J., Jia-Sheng Hong. Microstrip Filters for RF / Microwave Applications. John Wiley & Sons, mc., 2001 .-- 471 p.

2. Beletsky A.F. Fundamentals of the theory of linear electrical circuits. - M.: Communication, 1967. - 608 p.

Claims (1)

A microwave bandpass filter containing U-shaped electromagnetically coupled segments of microstrip lines, open at both ends with a constant distance between them along the length of the communication region, input and output lines are connected to the last of the segments, respectively, characterized in that the side segments of the odd U-shaped microstrip the lines are irregular with a width of conductors decreasing from the edges of the communication region to the center, and the side segments of even U-shaped microstrip lines are made in the form of elements the same width along the length of the communication area.

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