RU2017280C1 - Microstrip band-pass filter - Google Patents

Abstract

FIELD: SHF equipment. SUBSTANCE: microstrip band-pass filter includes dielectric backing which one side carries grounding base and the other one - half-wave stepped conductors intercoupled electromagnetically, some of them are inter coupled in pairs over entire length. They are connected by means of extreme steps with adjacent half-wave stepped conductors or with external path. EFFECT: facilitated manufacture, improved operational characteristics. 2 cl, 1 dwg

Description

 The invention relates to microwave technology.

 Known microstrip pole-passing filter containing half-wave segments of microstrip lines, open at both ends and parallel to each other with a shift of half their length [1]. The disadvantages of this filter are low loss of locking and low selectivity.

The closest analogue is a microstrip bandpass filter containing pairs of half-wave step resonators [2]. Microstrip resonators of each pair are electromagnetically interconnected along the entire length. Each pair of resonators by two non-adjacent extreme sections of both resonators is electromagnetically coupled to adjacent pairs or to an external path. The coupling coefficient of the resonators of such a pair vanishes at a frequency F _p located between the frequencies of the first and second resonances of the microstrip resonators. This leads to the fact that on the amplitude-frequency characteristic of the filter at a frequency F _p a damping pole is formed. The frequency of the attenuation pole F _{p is} controlled by a change in the gaps between the extreme and between the middle steps of the pair resonators, which allows one to achieve high filter selectivity at the high-frequency edge of the passband.

 The disadvantages of the filter are the low loss of locking the filter in its low-frequency delay band and low selectivity at the low-frequency edge of the pass band. They are associated with the absence of a damping pole below the frequency of the first resonance of the resonators.

 The aim of the invention is to increase the loss of locking the filter in its low-frequency delay band, as well as increasing selectivity at the low-frequency edge of the filter passband.

 This goal is achieved by the fact that in a microstrip bandpass filter containing a dielectric substrate, on one side of which there is a grounding base, and on the other side there are half-wave conductors electromagnetically coupled to each other, and the first and last are connected to the external path, one of the half-wave conductors are made stepwise and pairwise connected along the entire length and extreme steps - with adjacent half-wave conductors, half-wave step conductors at least one a pair of half-wave graded conductors connected over the entire length respectively associated with adjacent conductors or external half-wave path adjacent stages.

 In addition, the half-wave step conductors of at least one indicated pair of half-wave step conductors connected along the entire length have a gap between the extreme steps connected only to each other, less than the gap between their extreme steps.

 The drawing shows half-wave conductors of a microstrip bandpass filter.

 The microstrip bandpass filter contains a dielectric substrate, on one side of which there is a grounding base, and on the other half-wave step conductors 1-6 located in pairs are placed. The conductors 1 are located opposite the conductor 2, the conductor 3 is opposite the conductor 4, the conductor 5 is opposite the conductor 6. The gaps between the conductors 1 and 2, 3 and 4, 5 and 6 are not constant along their length. They are smaller for the extreme steps of conductors and larger for medium ones.

 The pair of conductors 3 and 4 is offset relative to the pair of conductors 1 and 2 so that the conductors 2 and 3 interact electromagnetically with only the last steps. The pair of conductors 5 and 6 is offset relative to the pair of conductors 3 and 4 so that the conductors 4 and 5 interact electromagnetically also only in the extreme steps. Moreover, the extreme stage of the conductor 4, interacting with the conductor 5, is located opposite the extreme stage of the conductor 3, interacting with the conductor 2.

 The filter made in this way is connected to the external path by two points, one of which is located at the extreme stage of conductor 1, closest to conductor 3, and the other at the extreme stage of conductor 6, farthest from conductor 4.

 In addition, the gap between the extreme steps of the conductor 1 and 2, not connected with other conductors or the external path, is less than the gaps between the other steps. Similarly, the gap between the extreme steps of conductors 3 and 4, not connected with other conductors, is less than the gaps between the other steps.

 Such a filter has two pairs of step conductors, each of which is electromagnetically coupled to adjacent conductors by two adjacent extreme steps of both conductors or connected to an external path. The first such pair is formed by conductors 1 and 2, and the second pair is formed by conductors 3 and 4. As for the third pair of conductors 5 and 6, it is connected to an adjacent conductor 4 and the external path by two non-adjacent extreme steps of both of its conductors.

 Microstrip bandpass filter operates as follows.

 The microwave signal in the passband sequentially passes through the half-wave step resonators 1-6, and in the obstacle band it is reflected from the first of them. The presence in the filter of two pairs of stepped resonators, each of which is connected by adjacent extreme steps to other resonators or connected to an external path, provides two attenuation poles at the low-frequency edge of the amplitude-frequency characteristic, which results in an increase in barrier losses in the low-frequency delay band. The position of each pole can be controlled by the gap between the extreme steps and the gap between the middle steps of the resonators of the corresponding pair. As close as possible, the attenuation pole approaches the low-frequency edge of the passband, when the gap between the extreme steps of the resonators in a pair that are not connected to other resonators or the external path is smaller than the gaps between the other steps. This improves selectivity at the low-frequency edge of the passband.

 The presence of the third pair of step resonators 5 and 6, which is electromagnetically connected to the resonator by one extreme stage of the resonator 5 and connected to the external path by the extreme stage of the resonator 6, provides, as in the prototype, the attenuation pole at the high-frequency edge of the amplitude-frequency characteristic, supporting thereby high selectivity at the high-frequency edge of the passband.

Claims (2)

 1. MICROBAND STRIP-PASS FILTER containing a dielectric substrate, on one side of which there is a grounding base, and on the other side are half-wave conductors electromagnetically coupled to each other, and the first and last are connected to the external path, while one of the half-wave conductors is made stepwise and pairwise interconnected along the entire length and extreme steps - with adjacent half-wave conductors, characterized in that, in order to increase the loss of blocking in the low-frequency field the retention axis, half-wave step conductors of at least one pair of half-wave step conductors connected along the entire length are connected respectively to adjacent half-wave conductors or an external path to adjacent steps.  2. The filter according to claim 1, characterized in that, in order to increase selectivity at the low-frequency edge of the passband, the half-wave stepped conductors of at least one pair of half-wave stepped conductors connected along the entire length have a gap between the extreme steps connected only between by itself, less than the gap between their other extreme steps.

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