RU2640968C1 - Strip resonator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: strip resonator contains two dielectric substrates suspended between the shields of the housing, on both surfaces of which strip metal conductors are electromagnetically connected. Between the substrates there is a thin metal film short-circuited from all sides along the perimeter to the housing, the thickness of which is less than the skin layer in the metal at the working frequency of the resonator.

EFFECT: rarefaction of the natural frequency spectrum of the strip resonator and the increase in the length of the filter barrier band on its basis.

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Description

The invention relates to techniques for high and ultra-high frequencies and is intended to create frequency-selective devices, for example, band-pass filters.

A known design of strip resonators on a suspended substrate, used to create band-pass filters [D.L. Matei, L. Young, E.M.T. Jones // Microwave filters matching circuits and communication circuits. T. 1. - M .: Communication, 1971. - 439 p.]. Resonators are formed by half-wave segments of strip lines, open at both ends. The strip conductors of the resonators are in a continuous dielectric environment at equal distances from the lower and upper surfaces of the screen. The disadvantages of such resonators and filters based on them are the large size at the frequencies of decimeter and meter wavelengths and the close location of the frequency of the second - spurious resonance (resonance of the second vibrational mode) to the frequency of the first - working vibrational mode.

The closest analogous combination of essential features is a strip resonator [m. RF №99248, IPC ⁷ Н01Р 7, publ. 11/10/2010, Bull. No. 31 (Prototype)]. The resonator contains two dielectric substrates suspended between the screens of the housing, on both surfaces of which are applied stripe metal conductors, electromagnetically coupled to each other and having the shape of a rectangle. A resonator of this design and a filter based on it have a significantly shorter length of strip conductors compared to the first analogue, and therefore smaller dimensions of the substrate. This allows you to design miniature strip filters at lower frequencies. The disadvantage of such a resonator, as well as that of the first analogue, is the close arrangement of the resonance of the second, the parasitic vibration mode, to the filter passband, which does not allow the design of filters with a wide obstacle band on its basis.

The technical result of the invention is the rarefaction of the spectrum of natural frequencies of the strip resonator and an increase in the length of the obstacle band of filters based on it.

This technical result is achieved in that in a strip resonator containing two dielectric substrates suspended between the screens of the housing, on both surfaces of which are strip metal conductors, electromagnetically coupled to each other, are applied, a new metal film is located between these substrates, the thickness of which at the operating frequency of the resonator is less than the thickness of the skin layer in the metal of the film.

The differences of the claimed device from the closest analogue are that between the substrates there is a continuous metal film, the thickness of which at the operating frequency of the resonator is less than the thickness of the skin layer in the metal of the film. These differences allow us to conclude that the proposed technical solution meets the criterion of "novelty." Signs that distinguish the claimed technical solution from the prototype are not identified in other technical solutions when studying this and related areas of technology and, therefore, provide the claimed solution with the criterion of "inventive step".

The invention is illustrated by drawings: FIG. 1 - the design of the proposed strip resonator, FIG. 2 - design of a second-order bandpass filter based on a pair of the claimed resonators; FIG. 3 - amplitude-frequency characteristics (AFC) of losses due to the passage of two-link bandpass filters based on the inventive resonator and resonator prototype.

The inventive device (Fig. 1) contains two dielectric substrates 1 suspended between the screens of the housing 3, on both surfaces of which are applied strip metal conductors of the resonators 2, electromagnetically coupled to each other and having the shape of, for example, a rectangle. Between the substrates is a thin metal film 4, shorted on all sides along the perimeter to the body, the thickness of which is less than the skin layer in the metal of the film at the operating frequency of the resonator.

, где σ - удельная проводимость металла, μ - относительная магнитная проницаемость ω-частота. Этот факт лежит в основе работы заявляемого резонатора.It is known that a high-frequency current penetrates into a metal to a certain depth, called the skin layer, which depends on the electrophysical parameters of the material and frequency:

where σ is the specific conductivity of the metal, μ is the relative magnetic permeability ω-frequency. This fact underlies the operation of the inventive resonator.

The inventive strip resonator operates as follows. The film thickness between the substrates in the claimed design is chosen so that at the lowest operating resonance frequency of the structure it is less than the skin layer, therefore, the magnetic field at the operating frequency will penetrate through the film to a distance sufficient to ensure the interaction of the resonator conductors. At the same time, at higher vibrational frequencies, the film thickness becomes comparable and greater than the depth of the skin layer in the metal. Therefore, the interaction of the resonators at the frequencies of higher vibration modes is significantly reduced.

Based on the inventive resonator, a second-order bandpass filter was designed and manufactured (Fig. 2). In FIG. 3 in a wide frequency band shows the amplitude-frequency characteristics of the filter based on the inventive resonator (solid line) and the prototype resonator (dashed line). The design parameters of the resonators in both filters were identical: the dielectric constant of the substrates ε = 80 with their thickness h _d = 0.25 mm, the length of the strip conductors of the resonators 12 mm, their width 2 mm, the distance between the substrates in the resonator h _s = 2 mm, the distance from the top and the lower screen of the housing to the surface of the substrates N _a = 5 mm The inventive resonator used a metal film deposited on a thin dielectric substrate and shorted around the perimeter to the walls of the housing. The film thickness t = 100 nm at the lowest resonant frequency of the claimed design ƒ ₁ ≈ 0.28 GHz was significantly less than the thickness of the skin layer in copper, which is about 1 μm at this frequency. The central frequency of the passband of the filters was ƒ ₀ ≈0.28 GHz, the relative width of the passband of the filters at a level of -3 dB was Δƒ / ƒ ₀ ≈3% at a distance between the resonators S = 4 mm.

It can be seen that the use of the inventive resonator allows not only to expand the barrier band, but also to increase the level of attenuation in it. So if in the prototype filter the length of the obstacle band at the level of -40 dB is about 27ƒ ₀ (ƒ ₀ is the central frequency of the passband), then in the inventive filter, the obstacle band at the level of -50 dB extends to a frequency of at least 140ƒ ₀ .

Thus, the use of the inventive design in band-pass filters allows you to get much more extended strip barriers compared to filters based on traditional designs.

Claims (1)

A strip resonator containing two dielectric substrates suspended between the shields of the housing, on both surfaces of which are applied stripe metal conductors electromagnetically coupled to each other, characterized in that a continuous metal film is located between these substrates, the thickness of which is less than the thickness of the skin layer at the operating frequency of the resonator in metal film.

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