CN101150216A - Electrically Tuned HTS Filters - Google Patents

Abstract

An electrically tuned high temperature superconducting filter. Including the shielding box, the substrate and the resonator made of superconducting film on it, the screw rod inserted and fixed on the upper cover of the shielding box and the electric variable capacitance diode installed at the lower end, the electric variable capacitance The diodes are located above each resonator and close to the resonators, and the lead wires of the varactor diodes are drawn out from the screw for external control voltage. The capacitance value of the electric variable capacitance diode can be changed in a wide range, so the present invention has a wide tuning range, and is voltage tuning, and its tuning speed is fast. The screw is fixed on the upper cover, and the structure is stable, which avoids the problem that the tuning screw is not easy to fix and easy to loosen in the mechanically tuned high temperature superconducting filter. This type of electronically tuned filter is easy to adjust, has good repeatability and stable state, and overcomes the technical defects of mechanically tuned superconducting filters. In addition, this type of electronically tuned filter also has the characteristics of simple processing.

Description

Electrically Tuned HTS Filters

[Technical Field]: The present invention belongs to the field of electronic technology, and in particular relates to an electrically tuned high-temperature superconducting filter, which is a microwave passive device.

[Background Technology]: Tunable microwave filters have important application value in the field of communication and radar technology. This is because: (1) changes in processing errors and working environment parameters will cause the center frequency of the filter to drift, and the performance will be affected. This requires the filter to be tunable to a certain extent; (2) Some special uses, especially military applications, require microwave filters to work at different frequencies, and microwave filters are required to have rapid frequency tunability .

Due to its extremely low insertion loss, high out-of-band suppression and excellent sideband characteristics, high-temperature superconducting filters have broad application prospects in mobile communications, satellite communications, and military electronics. At present, the tuning of high temperature superconducting filters mainly adopts the method of mechanical tuning. In order not to be affected by factors such as working environment and electromagnetic compatibility, high temperature superconducting filters are packaged in metal shielding boxes. The basic principle of mechanically tuning the HTS filter is to use a metal or dielectric tuning screw 11 to pass through the upper cover of the shielding box 12 and insert it above the HTS resonator 14 on the substrate 13 , as shown in FIG. 1 . The insertion of the screw changes the electric field distribution above the high-temperature superconducting resonator, which is equivalent to adding an additional capacitance in the equivalent circuit of the high-temperature superconducting resonator, so that the resonant frequency of the resonator can be adjusted. Its tuning range is controlled by the depth of tuning screw insertion.

Mechanically tuned HTS filters have several technical difficulties or drawbacks. First, the tuning screw is easy to loosen during the normal temperature-refrigeration thermal cycle, and its position is easy to change, so that the performance of the high-temperature superconducting filter will change; It is not easy to adjust under certain conditions, and the tuning range is very limited; third, the mechanical tuning speed is very slow, and a special refrigeration device for tuning is required.

On the basis of improving the technology of the mechanically tuned high-temperature superconducting filter, the invention discloses a technical solution of the electrically tuned superconducting filter, which solves the defects of the prior art.

[Content of the invention]: The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art, and provide an electrically tunable high-temperature superconducting filter, which has the characteristics of fast tuning, large tuning range, and good stability.

The electrically tuned high temperature superconducting filter provided by the present invention comprises a shielding box, a substrate at the bottom of the shielding box and a resonator made of a superconducting thin film thereon; The upper cover of the shielding box is inserted and fixed on the upper cover of the shielding box. Each electric variable capacitance diode is located above each resonator of the filter and is close to the resonator. The lead wire of the variable capacitance diode is drawn out by a screw for external control voltage. This electrically tunable high temperature superconducting filter is based on the structure of the traditional high temperature superconducting filter, adding an electrically tunable varactor diode located in the electric field above each resonator, and its position is fixed by a screw fixed on the upper cover of the shielding box.

The material of the screw can be metal or dielectric. The screw rod is fixed on the upper cover of the shielding box through the perforation, and the fixing method can be riveting, welding, nut fixing or screw locking.

The screw is a hollow screw, and the two lead wires of the electric variable capacitance diode are drawn out from the screw. It is also possible to have one lead lead out from the screw and the other welded to the screw and grounded.

Advantage and positive effect of the present invention:

(1) Since the capacitance of the electric tuning varactor has a wide variation value, this kind of electric tuning high temperature superconducting filter has a wide tuning range, and it is voltage tuning, and its tuning speed is fast; (2) this kind of The screw rod of the electric tuning filter is welded or riveted on the upper cover of the filter shielding box, the structure is stable, and the technical defect that the tuning screw rod is not easy to fix and easy to loosen in the mechanically tuned high temperature superconducting filter is avoided. (3) This type of electronically tuned filter is easy to adjust, has good repeatability and stable state, and overcomes the technical defects of mechanically tuned superconducting filters. In addition, this type of electronically tuned filter also has the characteristics of simple processing.

[Description of drawings]:

Fig. 1 is the schematic diagram (side view) of existing mechanically tuned high-temperature superconducting filter; 11 is the tuning screw, 12 is the shielding box, 13 is the substrate of high-temperature superconducting filter, and 14 is the high-temperature superconducting on the substrate Resonators (i.e. microstrip resonators made of high temperature superconducting thin films).

Fig. 2 is the schematic diagram (side view) of electric tuning high-temperature superconducting filter disclosed by the present invention; 21 is shielding box, and 22 is the substrate of high-temperature superconducting filter, and 23 is the resonator on the substrate, and 24 is screw rod , 25 is the variable capacitance diode for electric regulation, and 26 is the lead wire of the variable capacitance diode for electric regulation.

Fig. 3 is the schematic diagram (side view) of the electrically tuned high temperature superconducting filter of another structure disclosed by the present invention with the number of series being 4; 31 is an electrically tuned varactor diode, and 32 is the substrate of the superconducting filter; 33 is the distance between the electric variable capacitance diode and the resonator, and 34 is the lead wire welded on the screw rod.

Fig. 4 is the schematic diagram (top view) of the high-temperature superconducting circuit of the electrically tuned high-temperature superconducting filter disclosed by the present invention; 41 is a semi-lumped microstrip resonator in the superconducting circuit, and 42 is a superconducting The input microstrip in the conductive circuit, 43 is the output microstrip in the superconducting circuit, and 44 is the position of the varactor at the open end of the resonator.

【Detailed ways】:

Example 1:

As shown in Figure 2, the basic structure of the present invention includes a shielding box 21, a substrate 22 at the bottom of the shielding box and a resonator 23 on the substrate, a screw 24 inserted by the upper cover of the shielding box and fixed on the upper cover of the shielding box And the electric adjustable variable capacitance diode 25 that is fixed on the screw rod lower end. The varactor diode is located above the resonator and is close to the resonator, and the lead wire 26 of the varactor diode is drawn out from the screw rod for external control voltage; each resonator top of the filter 23 includes such a screw rod and a variable capacitance diode. diode. In the structure of this electrically tuned high temperature superconducting filter, the upper cover of the shielding box is fixed on the top of each resonator by a screw and is close to the electric tuning varactor diode of the resonator. Each varactor diode is located in the electric field above the resonator. , which is equivalent to adding an additional capacitor in the equivalent circuit of the resonator, and adjusting the voltage across the varactor diode can change the specific capacitance value, thereby achieving the purpose of adjusting the resonant frequency of each resonator.

The material of the screw contained in the structure of the above-mentioned electrically tuned high-temperature superconducting filter is metal or dielectric, and the screw is inserted through a hole in the upper cover of the shielding box, and is fixed on the upper cover of the shielding box. The fixing method is as follows: Welded, riveted or locked with nuts.

The electric tuning varactor diode contained in the structure of the above-mentioned electric tuning high temperature superconducting filter is fixed on the lower end of the screw by welding or bonding; the two lead wires of the varactor diode can be drawn out from the screw rod (see Figure 2 ), or only one lead out, and the other is welded on the screw for grounding (see Figure 3).

Example 2:

As shown in FIG. 3 , the basic structure of the electrically tuned high-temperature superconducting filter provided by this embodiment is the same as that of Embodiment 1, the only difference being that a lead wire 34 of the electric tuned variable capacitance diode 31 is welded on the screw for grounding.

The material of the substrate 32 of the superconducting circuit filter of the above-mentioned filter is 0.5mm thick LaAlO3 single crystal; 41. The input microstrip 42 and the output microstrip 43 are formed, and the graphic size is 26mm×18mm. As shown in FIG. 4, the varactor diodes are located above the opening ends 44 of each resonator, as shown in the dotted line box in the figure.

The shielding box of the filter mentioned above is an oxygen-free copper square box with a thickness of 4mm. The external dimensions are 34mm long x 26mm wide x 15mm high, and the thickness of the top cover of the box is 5mm; the filter port is connected by an SMA microwave connector.

The screw rod of the filter mentioned above is tubular, with an inner diameter of 1.8mm and an outer diameter of 3mm;

The material is brass, and the length is 11 mm; the screw rod is inserted through the hole in the upper cover of the shielding box, and fixed on the upper cover of the shielding box with indium welding.

The electric adjustable varactor diode in the above-mentioned filter is welded to the lower end of the screw with indium, and the distance 33 between the lower end surface of the varactor and the superconducting resonator is less than 1 mm to ensure that it can be in the electric field of the resonator; One lead wire of the tube is led out from the screw rod, and the other lead wire 34 is soldered to the screw rod with indium to form a ground.

Claims (4)

1. An electrically tuned high-temperature superconducting filter, comprising a shielding box, a substrate at the bottom of the shielding box and a resonator made of superconducting thin film on the substrate, characterized in that its lower end is equipped with an electric tuning variable capacitance diode The screw is inserted into the upper cover of the shielding box and fixed on the upper cover of the shielding box. Each electric variable capacitance diode is located above each resonator of the filter and is close to the resonator. The leads of the variable capacitance diodes are drawn out from the screw for external connection. control voltage. 2. The electrically tunable high temperature superconducting filter according to claim 1, characterized in that the material of the screw is metal or dielectric. 3. The electrically tunable high temperature superconducting filter according to claim 1 or 2, characterized in that the screw is a hollow screw, and the two lead wires of the electric tuning varactor are drawn out from the screw. 4. The electrically-tunable high-temperature superconducting filter according to claim 1 or 2, wherein the screw is a hollow screw, one lead wire of the electric-tuning varactor is drawn from the screw, and the other is welded on the screw. on and ground.

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