RU2785067C1 - Uhf filter of upper frequencies - Google Patents

Abstract

FIELD: ultra-high frequency equipment.

SUBSTANCE: invention relates to ultra-high frequency equipment; it can be used in selective paths of receiving and transmitting systems. UHF filter of upper frequencies contains dielectric substrate, one surface of which is fully metallized and serves as a grounded base, and on the other surface, segments of a strip conductor are located, twisted in the form of a “pin”, connected to the grounded base through perpendicularly docked extended segment of the strip conductor. On dielectric substrate, a U-shape twisted strip conductor is located, from both sides of which a pair of segments of unidirectional strip conductors are located, interconnected by a short segment.

EFFECT: improvement of frequency-selective properties of a structure.

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Description

The invention relates to microwave technology and can be used in selective paths of receiving and transmitting systems.

A high-pass microstrip filter is known (Utility Model Patent RF No. 154063, N01R 1/203, N01R 1/205), containing a dielectric substrate, one surface of which is completely metallized and serves as a grounded base, and on the other surface there is a rectangular strip metal conductor, which one of its wide edges is connected to the screen, and the external transmission lines are connected to its narrow edges from opposite sides.

The filter is made on a substrate with a dielectric constant ε=80 and a thickness of 1 mm; the substrate is placed in a metal housing-screen, while the height of the upper wall of the screen above the surface of the substrate is 5 mm. The internal dimensions of the body - 27×5×6 mm ³ . The cutoff frequency of the microstrip high-pass filter (Fig. 4) is ~2.6 GHz, up to a frequency of 7 GHz, a passband is observed on its amplitude-frequency characteristic.

The disadvantage of the described microstrip high-pass filter is not wide enough bandwidth and low steepness of the slope of the frequency response, as well as low manufacturability.

The closest in terms of essential features is a microstrip high-pass filter (Patent for the invention of the Russian Federation No. 2670366, H01R 1/203), containing a dielectric substrate, one surface of which is completely metallized and serves as a grounded base, and on the other surface there is a strip metal conductor, the segments of which are folded in the form of a "hairpin" along the axis of symmetry and in the central part are connected to the grounded base, through a perpendicularly joined extended segment of the strip conductor. The increase in the steepness of the slope of the frequency response of the filter is carried out by increasing the number n of strip conductors, joined to each other in the form of a meander line, where n=2, 3, 4…

The filter n=3 (Fig. 3) is made on a ceramic substrate TBNS with a dielectric constant ε=80. The construction used a substrate with dimensions of 12.32×7.44×1.00 mm ³ . The cutoff frequency (Fig. 4) of the filter ƒ _with =2 GHz, the filter bandwidth formed by 11 resonances, is observed on the frequency response up to 7.9 GHz.

The disadvantage of the described microstrip high-pass filter is an insufficiently wide passband, a relatively gentle slope of the frequency response, and relatively weak power suppression at the stopband frequencies.

The objective of the invention is to improve the frequency-selective properties of the design.

This task is achieved by the fact that in the microwave high-pass filter containing a dielectric substrate, one surface of which is completely metallized and serves as a grounded base, and on the other surface there are segments of a strip conductor, rolled up in the form of a "hairpin", connected to a grounded base, through a perpendicularly docked an extended segment of a strip conductor, according to the technical solution, a U-shaped strip conductor is placed on a dielectric substrate, on both sides of which there are a pair of segments of codirectional strip conductors connected to each other by a short segment, and the electromagnetic interaction of the three resonators leads to the appearance of an attenuation pole power on the amplitude-frequency characteristic.

The technical result of the invention is the improvement of the frequency-selective properties of the structure, in particular, the expansion of the bandwidth of the structure, the increase in the steepness of the slope of its frequency response, as well as the increase in power suppression at the frequencies of the stop band, due to the inventive arrangement of strip conductors on a dielectric substrate.

The invention is illustrated by drawings: Fig. 1 shows a microwave high-pass filter device, FIG. 2 - its amplitude-frequency characteristic (S ₂₁ , S ₁₁ ).

The inventive microwave high-pass filter (Fig. 1) contains a dielectric substrate (1), one surface of which is completely metallized and serves as a grounded base, and on the other surface there is a U-shaped strip conductor folded with three extended ones (the length is several times greater than the width) segments (11) and (12), on both sides of which there are segments of a strip conductor (2) - (4) and (7) - (9) rolled up in the form of a "hairpin", and segments (2), (4), (7), (9) are extended, and segments (3) and (8) are almost square. At the same time, all segments rolled up in the form of a "stud" are connected to the grounded base through a perpendicularly joined extended segment of the strip conductor (5) or (10). In each pair of co-directional conductors located both to the left of the U-shaped strip conductor and to the right, segments of the strip conductor (2)-(5) and (6)-(10) are interconnected by a short segment of the strip conductor (6), whose length must be greater than its width.

Let's analyze the principle of operation of the microwave high-pass filter. Located (Fig. 1) on a dielectric substrate (1), coiled strip conductors, when applied to the input (13) of the electromagnetic signal structure, perform the function of three microstrip multimode resonators. The five lowest oscillation modes, both from the input and output resonators with segments (2)-(10) of the strip conductor, are involved in the formation of the filter passband. From a resonator with a U-shaped strip conductor formed by segments (11)-(12), two lowest oscillation modes participate in the formation of the filter passband. Thus, the order of the microwave high-pass filter is twelfth.

By varying the length and width of segments (2)-(12) of the strip conductors of three resonators, the gaps between their segments (9) and (11), as well as the vertical displacement of the conductors of adjacent resonators relative to each other, it is possible to correct their natural frequencies, which allows you to adjust the band transmission of the inventive microwave high-pass filter with the maximum allowable level of reflection loss in it S ₁₁ ≤-14 dB.

An example of a microwave high-pass filter (Fig. 1). The construction used a substrate with dimensions of 18.35×13.80×1.00 mm ³ with dielectric constant ε=9.8 (microwave material - polycor). The indents from the edges of the substrate to the segments (2) and (12) are equal to the thickness of the substrate h=1 mm. The cutoff frequency of the proposed filter (curves 1 in Fig. 2), as well as the cutoff frequency of the prototype filter (curve 2 in Fig. 2) is fixed ƒ _c =2.00 GHz. The bandwidth of the inventive filter, measured at the level of -3 dB from the level of minimum loss at its frequencies L _min =0.35 dB, is in the frequency range of 2.00-8.14 GHz, and the bandwidth of the prototype filter, measured similarly - in the frequency range of 2.00-7.97 GHz , i.e. has a shorter length. In addition, compared with the prototype filter, the inventive filter due to the power attenuation pole on the amplitude-frequency characteristic has a steeper slope of the frequency response, as well as stronger power suppression in the stop band.

Structural parameters of the filter, and in particular the length and width of the conductor segments - (2): 5.10×1.21 mm ² , (3): 0.70×0.68 mm ² , (4): 5.20×1.14 mm ² , (5): 4.50×0.30 mm ² , (6): 1.22×0.40 mm ² , (7): 5.20×0.92 mm 2 , (8): 0.74×0.70 ^{mm 2 ,} (9): 6.70×0.18 mm ² , (10): 4.50×0.78 mm ² , (11): 7.30×0.21 mm ² , (12): 3.69×0.50 mm ² . The gaps between the segments (9) and (11) of the strip conductors are 0.03 mm, the distance between the segments (5) and (10) is 4.26 mm.

Thus, the inventive microwave high-pass filter has better frequency-selective properties: it has a steeper slope in the frequency response, greater power suppression in the stopband, and a wider bandwidth.

Claims (1)

A high-frequency microwave filter containing a dielectric substrate, one surface of which is completely metallized and serves as a grounded base, and on the other surface there are segments of a strip conductor rolled up in the form of a “hairpin” connected to the grounded base through a perpendicularly joined extended segment of a strip conductor, characterized in that that a U-shaped strip conductor is placed on a dielectric substrate, on both sides of which there are a pair of segments of codirectional strip conductors connected to each other by a short segment, and the electromagnetic interaction of the three resonators leads to the appearance of a power attenuation pole on the amplitude-frequency characteristic.

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