RU2440645C1 - Microstrip protective device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: microstrip protective device is related to ultrahigh frequency equipment and is designed for protection of radio receiving devices, in particular, receivers of radiolocating stations against exposure of electromagnetic oscillations of high capacity. It comprises a dielectric substrate, on one side of which there is a metal layer applied, being a grounded base, and on the second side there are metal strip conductors of input and output resonators applied and joined to each other in an electromagnetic manner, besides, their configuration and distance between them are selected so that at the central frequency of the device working strip their communication ratio is close to zero. In the pass mode the communication between these resonators is carried out via a line made of three sections, two of which are made of normal metal, and one - from high-temperature superconductor (HTSC), besides, the total electric length of this line is resonant at the working frequency of the device or close to it.

EFFECT: expansion of working frequencies band and reduced threshold of actuation.

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Description

The invention relates to techniques for microwave frequencies and is intended to protect radio receivers, in particular radar receivers from exposure to electromagnetic waves of high power.

Known microstrip protective device [ABKozyrev. The effect of fast switching of superconducting films and the possibility of its use in microwave microelectronics. Soros Educational Journal, vol. 8, No. 1, 2004, pp. 93-100], containing a dielectric substrate, on one side of which a film of a material having high-temperature superconductivity (HTSC) is applied, which is a grounded base, and strip conductors are applied to the second , also from HTSC material, forming microstrip resonators, interconnected electromagnetically. Since the loss of the microwave signal in such films in the superconducting state is very small, the transmission coefficient in the passband of the device is close to unity. Under the influence of a powerful electromagnetic pulse, HTSC films change from a superconducting state to a normal state with a high resistance, as a result, the amplitude-frequency characteristic of the device changes, providing a weakening of the output signal compared to the input.

The disadvantage of this protective device is the low maximum permissible power of microwave oscillations, with which it can work without failure. This is due to the insufficiently large value of the surface resistance of a film of a material having high-temperature superconductivity in the normal state. As a result of calculations, this leads to almost complete absorption of the energy of the received electromagnetic wave in the form of heat by the microstrip resonators, which causes the destruction of the strip conductors of the resonators when the input power of the device exceeds the maximum permissible.

A microstrip protective device is also known [B.A. Belyaev, N.A. Drokin., A.A. Lexikov, AM Sergeants, M. A. Konov, V. N. Khakhalkin, Yu. V. Shapotkovsky, RF patent No. 2340046 publ. 11/27/2008, Bull. No. 33], containing a dielectric substrate, on one side of which a metal layer is applied, which is a grounding base, and on the second side are metal strip conductors of two resonators, electromagnetically interconnected, between the strip conductors of the resonators on the surface of the substrate or above these conductors without galvanic contact a film of material having high-temperature superconductivity is located with them, while the resonators are made so that the electric and magnetic bonds and between mutually compensated at the central frequency of the working band device at a normal state of said film. In this device, the passband is formed due to the violation of the mutual compensation of the electrical and magnetic coupling of the resonators with a film of a high-temperature superconductor. Under the action of a powerful electromagnetic pulse, the film goes into a normal state, as a result of which mutual compensation of the mentioned bonds is restored, and the device goes into a “locked” state, which is characterized by a higher level of reflection of microwave power from its input compared to the first analogue, which increases permissible microwave power, with which it can work without failure.

The disadvantage of this protective device is that to ensure that it has wide, more than 1%, relative operating frequency bands, it is necessary to use a relatively large area film of a high-temperature superconductor, and, as a result, lower bias currents are required to lower the threshold for this film.

The closest in combination of essential features is a microstrip protective device [B.A. Belyaev, A.A. Lexikov, A.M. Serzhantov, I.V. Govorun, RF patent No. 2395872, publ. 07/27/2010, Bull. No. 21], characterized in that the film of a material having high-temperature superconductivity is made in the form of a closed strip conductor, for example, in the form of a frame, through which electromagnetic coupling between the resonators is carried out, which forms the passband of the device. Under the influence of a powerful electromagnetic pulse, the superconductor goes into a normal state with high resistance, so that the transmission coefficient of the device drops sharply, and it goes into a "locked" state. This device has a lower threshold in comparison with the second analogue, which depends on the width of the strip conductor forming the frame: the narrower it is, the lower the threshold. However, with a decrease in the width of this strip conductor, the coupling between the resonators also decreases, which leads to a narrowing of the passband of the device. In addition, the relative bandwidth of such a device decreases with an increase in its operating frequency, since the surface resistance of HTSC films increases with frequency.

The technical result when using the invention is to increase the relative bandwidth of the operating frequencies of the device and lower the threshold.

The specified technical result is achieved by the fact that in the inventive microstrip protective device containing a dielectric substrate, on one side of which a metal layer is applied, which is a grounding base, and on the second there are metal strip conductors of two resonators, connected electromagnetically between each other, on or above the surface of the substrate without galvanic contact with the conductors of the resonators is a strip conductor of a material having high temperature superconductivity, and the aforementioned resonators are configured such that the electrical and magnetic connection therebetween mutually compensated at the central frequency of the working band device at a normal state of said strip conductor, new is that the strip conductor of the high temperature superconductor is connected to the strip conductors made of a normal metal. Moreover, the total electrical length of the line formed by these conductors is resonant at or close to the operating frequency of the device.

Differences from the closest analogue are that the connection between two resonators, the electrical and magnetic interaction between which are mutually compensated, is actually carried out using the third resonator, which includes a strip conductor from a high-temperature superconductor, and its natural frequency is equal to or close to the working device frequency.

The invention is illustrated by drawings, which depict:

- Fig.1, 2 and 3 - design options for a protective device;

- Figure 4 - frequency characteristics of the transmission coefficient of a particular implementation of the device, demonstrating its operability, for two states of a film strip conductor from HTSC - superconducting and normal.

The proposed protective device comprises a dielectric substrate 1 (Figs. 1, 2, 3), on one side of which a metal layer 2 is applied, which is a grounded base, and on the second, strip metal conductors of two resonators 3 are applied, having a configuration providing mutual compensation of magnetic and electrical communication between them at the operating frequency of the device [B.A. Belyaev, AM Sergeants. Investigation of the coupling coefficients of hairpin resonators. "Radio engineering and electronics", t. 49, No. 1, 2004, S. 1-9]. In other words, there is no direct connection between the input and output resonators. Also on the same side of the substrate there is a line consisting of segments made of high-temperature superconductor 4 and normal metal 5, 6, and the total electric line length (segments 4, 5 and 6) is selected so that at the operating frequency of the device in it the resonance was excited, and the position of its section 4 was such that it was at the maximum of the high-frequency current at the resonant frequency. Thus, the strip conductors 4, 5 and 6 form a composite resonator, and in its structure the inventive device is a three-link microstrip filter. The configuration of the strip conductors 4, 5 and 6 and the gap between them and the strip conductors of the resonators 3 are selected from the conditions of the required bandwidth of the device in the open state and the level of signal suppression in the "locked". The specified composite resonator (line) can be made on a separate substrate and suspended above the resonators 3, its configuration and position relative to the resonators 3 are selected from the same conditions.

The device has two operating modes. In the first of them, the transmission mode, when the strip conductor 4 is in the superconducting state and its resistance is small, the high-frequency electromagnetic fields of the input resonator induce high-frequency currents in the composite resonator, which, in turn, generate high-frequency electromagnetic fields that induce high-frequency currents in the output resonator. Due to this, a connection is made between the resonators 3, and a passband of the device is formed. As a result, the device in this mode operates as a 3-link bandpass filter with low insertion loss, the bandwidth of which is determined by the magnitude of the coupling of the resonators 3 with the composite resonator. In the second mode, locked, when the strip conductor 4 is in normal condition, its resistance is high, and the quality factor of the resonator, of which it is included, decreases so much that it loses its resonance properties, so that the connection through it between the resonators 3 is broken. Since there is no direct interaction between these resonators (their configuration and the distance between them is such that there is mutual compensation of electric and magnetic interactions), it is obvious that in this case almost all the power is reflected from the input of the device.

The device operates as follows. At temperatures below the phase transition of the HTSC material to the superconducting state and low signal power levels at the input of the device, the current density induced in the strip conductor 4 does not exceed the critical value, and its resistance is small. In this case, the composite resonator provides a sufficient amount of coupling between the resonators 3, due to which the device operates in the bandpass filter mode with low insertion loss. When the power at the input of the device increases to a threshold density of the high-frequency current induced in the composite resonator and flowing through the strip conductor 4, it exceeds the critical value for HTSC, the resistance of the strip conductor 4 jumps by several orders of magnitude due to its transition to the normal state, and the resonator Q factor also decreases . As a result, the transmission coefficient of the device in the operating frequency band decreases by several orders of magnitude, and this is mainly due to the fact that almost all microwave power is reflected from the input.

Figure 4 shows the amplitude-frequency characteristics of the layout of the device for two modes of operation: a band-pass filter (solid line) and locked (dots) made in accordance with Figure 3. The device was made on a sapphire substrate 0.5 mm thick. The strip conductors of the resonators 3 had a width of 1.6 mm, and the “pins” formed by them were 11.3 × 8 mm in size. The distance between the resonators 3 was 3.2 mm. Strip conductors 5 and 6 had a width of 0.2 mm and a length of 12.3 mm. Strip conductor 4 had a width of 0.5 mm and a length of 6.6 mm.

Due to the fact that the connection between the resonators in the transmission mode is mainly capacitive in the claimed device, its value, and with it the relative bandwidth, grow, in contrast to the prototype, with an operating frequency. Since the HTSC strip conductor is located in the region of the maximum high-frequency resonator current, it goes into a normal state, and at the same time the device switches to the “locked” mode, with lower, compared with the prototype, values of the power supplied to the input of the protection device. In addition, with a decrease in the width of this conductor, the current density at the operating frequencies increases in it: using this circumstance, you can set the threshold of the device without the use of bias current or magnetic field. In this case, there will be no decrease in the magnitude of the coupling between the resonators, which determines the relative bandwidth of the device.

Claims (1)

A microstrip protective device containing a dielectric substrate, on one side of which a grounded base is applied, and on the second there are strip conductors of two resonators connected electromagnetically, while the grounded base and resonator conductors are made of metal, and on the surface of the substrate or above it without galvanic contact a strip conductor made of a material having high-temperature superconductivity is located with the conductors of the resonators; s with the possibility of mutual compensation of electrical and magnetic coupling between them at the central frequency of the working strip of the device in the normal state of the specified strip conductor, characterized in that the strip conductor of a high-temperature superconductor is connected to the strips of conductors made of normal metal, and the total electrical length of the line formed these conductors, is resonant at the operating frequency of the device or close to it.

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