Three minutes to understand the composition of high-temperature superconducting filters

High temperature superconducting filters require deep cooling because of their low operating temperatures. Therefore, there are many peripheral components and the structure is complicated. Mainly includes high-temperature superconducting filter amplification circuit, depth refrigeration system, precision control system, vacuum insulation system in four parts, as shown in Figure 1.

The high-temperature superconducting filter amplifier circuit is the core part of the system, including the HTS filter and the low-temperature low-noise amplifier (LNA). The filter microstrip circuit is made of high-temperature superconducting thin film materials, and the working temperature is at liquid nitrogen temperature. In the area (77K), the low noise amplifier is also placed in the low temperature region to reduce system noise. The deep refrigeration system provides a high temperature superconducting filter with a low temperature working environment for realizing superconducting characteristics. A commonly used Stirling refrigerator or a pulse tube refrigerator is another key component of the system.

The vacuum heat insulation system separates the superconducting filter amplification circuit working in the liquid nitrogen temperature zone from the external room temperature environment to reduce the heat transfer between the two as much as possible. The maintenance of the vacuum degree will directly affect the state of the refrigerator, affect the super The stability of the waveguide filter system.

The precise control system is a real-time test of the actual operating temperature of the HTS filter amplifying circuit. It can issue instructions to the refrigeration system at any time to keep the temperature in the cold area constant. At the same time, the relevant parameters of the system are monitored and pre-warned.

Compared with traditional filters, HTS filters have obvious performance advantages. The selection of excellent conventional filters produced abroad and superconducting filters manufactured by Tianjin Haitai Superconductor Co., Ltd. are compared, as shown in Figure 2.

It can be seen that the advantages of superconducting filters are mainly reflected in two aspects:

(1) Very low insertion loss (less than 0.2dB), coupled with a low-temperature low-noise amplifier, the noise coefficient of the superconducting filter system is about 0.7dB, which is improved compared to the conventional 2~3dB system noise figure. A lot.

(2) Excellent tape edge steepness characteristics, superconducting filter can produce a nearly rectangular frequency response curve, if used in the presence of adjacent-frequency interference in the environment, can give full play to the advantages of superconducting filter, as shown in Figure 2 As shown, the conventional filter has very limited suppression of interfering signals, and the superconducting filter can completely suppress the interfering signal.

In practical applications, the degree of improvement of the performance of the superconducting filter is directly determined by these two aspects. The improvement of the noise of the superconducting filter system can be directly reflected, regardless of the external wireless environment of the device; it can be improved by suppressing the interference signal. The equipment performance depends on the actual interference status. The more serious the interference, the more obvious the advantages of the superconducting filter. If there is no interference signal, the edge steepness advantage of the superconducting filter will be difficult to realize. Tests have been done abroad, without interference, the system improvement is only 1 ~ 2dB, for strong interference environment, superconducting filter can improve the system more than 10 dB, and even several tens of dB.

At present, a great deal of work has been done at home and abroad for the application of superconducting filters in mobile communication systems. After installing superconducting filters at the base station, the noise coefficient of the receiving system can be effectively reduced, and the anti-jamming capability of the system can be improved. The advantages are as follows:

(1) Reducing the transmission power of mobile phones: The superconducting filter can reduce the noise figure of the base station reception system, improve the base station reception sensitivity, reduce the transmission power of the mobile phone, reduce the harm to the human body from mobile phone radiation, and prolong the battery life of the mobile phone.

(2) Enlarging base station coverage and saving construction investment: The increase of system receiving sensitivity can expand the base station coverage and reduce the number of base stations. Under the condition that the system noise is improved by 3dB, the base station coverage can be increased by 20%, and the coverage area is increased. 40%.

(3) Improve call quality and increase base station capacity: The application of superconducting filters can improve call quality, reduce call drop rate, increase connection rate, and increase data transmission rate, while allowing base stations to accommodate more users.

(4) Make full use of frequency resources: The characteristics of the special sidebands of the superconducting filter are steep and well-out-of-band suppression. Without increasing other equipment, the guard band width can be reduced and the available bandwidth can be increased. .

(5) To provide effective solutions for some special places: In places where cultural relics protection units, tourist attractions, etc. are not suitable for building base stations, coverage can be increased by applying superconducting filters near the base stations, and in addition, people will be aware of environmental issues. The enhancement is also a good solution to the problem of building base stations in residential areas. The research status of HTS filters is based on the requirements of mobile communications, radar, satellite communications, navigation, electronic countermeasures, astronomical observations, digital television, and other systems. Many types have been developed in the United States, China, Britain, and Japan. Different uses of superconducting filters.

In the field of mobile communications, the European Union proposed a research plan for a high-temperature superconducting filter (SUCOM) mobile communication system (SUCOM) in 1996 to design a superconducting filter system that meets the WCDMA requirements of the third generation of mobile communication standards. The United States completed the grid-connected operation test of the superconducting filter in the base station 2000 years ago. Tests on the urban TDMA mobile communication system showed that the superconducting filter increased the capacity of the base station during the peak period by 80%; and the strong radio frequency interference in the CDMA base station. At the same time, the superconducting filter can still greatly increase the coverage area of ​​the base station; Coiaductus and Japan KDD and Hitachi completed the application experiment of the superconducting filter in the 3G system, proving the coverage, capacity, bit error rate, anti-jamming and mobile phone power. There have been significant improvements in such areas. Toshiba Corporation of Japan designed a high-temperature superconducting filter for digital terrestrial TV relay stations in 2004 and successfully tested it in Japan Broadcasting Corporation's equipment.

The field of military equipment has always been an important driving force for the development of superconducting filters. In terms of space applications, the US Navy took the lead in conducting the High Temperature Superconducting Space Experiment Project (HTSSE) and completed the first two phases of testing in 2000; NASA listed the cryogenic receiver front end as a key technology for achieving the strategic goals of the 21st century. For spatial data transmission. In terms of radar and guidance, STI Corporation of the United States has developed a filter bank containing 32 superconducting band-rejection filters, which can achieve fast transitions from 8.5 GHz to 10.5 GHz and play an important role in airborne early-warning radars. The superconducting digital instantaneous frequency measurement receiver system developed by the US company Conductus is specially designed for the radar systems of the Air Force ALR-74 and Navy AN/WLR-11 early warning receivers; the US Naval Experimental Institute is working on superconducting filters and cryogenics. Low-noise amplifiers are used in shipboard Doppler radars to enhance the ability to identify small targets in ocean clutter and monitor looming surface missiles. In the field of radio astronomy, the Netherlands developed a superconducting bandstop filter to solve the serious interference of Russian navigation satellites on the Westerbork radio astronomy telescope; the superconducting filter developed by the University of Birmingham for radio astronomy receivers effectively controls the conventional filtering. The television signal on both sides of the observation window that cannot be eliminated by the instrument interferes. In 2004, when the European Mars landing device was launched, the radio astronomy receiving system of the superconducting filter was enabled.

Lead Free Piezoelectric Elements

The Co-Al Co-doped Barium Titanate Lead-free Piezoelectric Ceramics was successfully developed by Yuhai company through repeated experiments. By Researching the influence of Co-Al Co-doping on the structure and properties of Barium Titanate-based piezoelectric ceramics, the formulation and preparation technology of Barium Titanate-based piezoelectric ceramics were optimized. Yuhai`s BaTiO3 was prepared by conventional solid-phase sintering method, with the piezoelectric constant d33 (>170pC/N), dielectric loss tgδ≤0.5% and mechanical coupling coefficient Kp≥0.34.

Barium titanate lead-free piezoelectric ceramics are important basic materials for the development of modern science and technology, which was widely used in the manufacture of ultrasonic transducers, underwater acoustic transducers, electroacoustic transducers, ceramic filters, ceramic transformers, ceramic frequency discriminators, high voltage generators, infrared detectors, surface acoustic wave devices, electro-optic devices, ignition and detonation devices, and piezoelectric gyroscope and so on.

Application: military, ocean, fishery, scientific research, mine detection, daily life and other fields.

China Patent of Yuhai company`s BaTiO3

Chinese Patent No.: ZL 2011 1 0126758.6

Name: Lead-free Barium Titanate Piezoelectric Material with Addition of Cobalt and Aluminum

Piezo Element,Piezo Ceramic Elements,Piezoelectric Ceramic,Pzt Tubes

Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com