High-isolation high-temperature superconductive diplexer and design method thereof

Abstract

The invention belongs to the technical field of microwave communication, and specifically relates to a high-temperature superconductive diplexer. The technical scheme of the high-isolation high-temperature superconductive diplexer is that two filter channels are respectively arranged at the left and right sides of a common port, and form a T-shaped structure together with the common port, and are mutually connected with each other through a microstrip line; the filter channels, the common port and the microstrip line are processed on an upper layer (1) of a substrate (2); an lower layer of the substrate (2) is a ground layer (3); the substrate (2) is made of magnesium oxide MgO material, or lanthanum aluminate LaAlO3 material and sapphire material; the dielectric constant of the substrate (2) is set as 9.7, and the thickness of the substrate (2) is set as 0.5mm; and both the upper layer (1) and the ground layer (3) are yttrium barium copper oxygen (YBCO) superconductive films. The high-isolation high-temperature superconductive diplexer and the design method thereof can effectively improve the isolation and avoid discontinuity of the microstrip line because of spot welding connection so as to enable the impedance characteristic of a transmission line after preparation to be identical to the design. Therefore, a diplexer with high performance can be obtained.

Description

technical field [0001] The invention belongs to the technical field of microwave communication, and in particular relates to a high-temperature superconducting duplexer. Background technique [0002] High-temperature superconducting filters have the advantages of low insertion loss, high band edge steepness and good out-of-band suppression, which can effectively improve the sensitivity and anti-interference ability of the system, so they are widely used in the fields of mobile communication, radio astronomy and radar detection. As multi-channel communication and frequency hopping communication systems tend to be miniaturized and integrated, superconducting filter technology shows important application value. [0003] A duplexer is a frequency divider consisting of two filters of different frequencies connected in parallel or in series. Split into two narrow-band signal outputs. The trend of wireless communication systems is developing toward miniaturization and integration...

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Problems solved by technology

[0004] Isolation has always been one of the most important indicators of duplexers. Improving isolation can effectively prevent signal crosstalk between two channels. Literature [1] C.Feng, X.B.Guo, X.P.Zhang, X.X.Lu, B.Wei, W.Chen, Y.Zhang, Q.R.Li, Z.J.Ying, B.S.Cao, Design and performance of a compact superconducting duplexer at VHF-band, Physica C: Superconductivity.470(2010)1959-1961 designed a VHF band superconducting duplexer In this method, the two-channel filters are packaged in two shielding boxes, and then a metal partition is added between the two channels for isolation, and connected by spot welding, which effectively improves the isolation between the channels. This is the most widely used method of improving isolation. The advantage of this method is that it can make the structure of the duplexer more compact. The disadvantage is that the substrate needs to be cut and then connected by spot welding, which greatly increases the complexity of the process. Moreover, spot welding will produce matching impedance discontinuity, and the performance of the prepared multiplexer is prone to deterioration, especially at higher frequencies, such as in the X-band, the performance deterioration caused by matching impedance discontinuity is more obvious

Therefore, most of the existing X-band duplexer designs are based on literature [2] X.Shang, Y.Wang, W.Xia, and M.J.Lancaster, Novel multiplexer topologies based on all-resonator structures, IEEE Trans.Microw. The method in Theory Technol.61(2013) 3838-3845 uses a resonant cavity as a resonator, but this will lead to a larger size structure

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