With the rapid development of the communication industry, ushered in the fifth generation of mobile communication network era, that is, the 5g era, because 5g communication needs a higher working frequency band, and the cte of ceramic dielectric filter is close to zero, has the characteristics of high dielectric constant and low loss, can reduce the volume of the traditional cavity filter, so the demand for ceramic dielectric filter increases sharply. But the ceramic medium filter production yield is low, the use of the process is unstable, the cost is high, can not respond to the needs of The Times and customers.

1. The utility model relates to the technical field of filter, in particular to a ceramic medium filter.

2. As a device for filtering and selecting signal waves, filter is an indispensable part of communication system, especially in the construction of base station.

3. With the continuous development of modern communication technology, especially with the development of 5g large-scale antenna integration technology, the requirements for filters are getting higher and higher. Due to the miniaturization and high q value, the application of traditional metal-cavity waveguide filter is increasingly limited. The ceramic dielectric filter because the ceramic material itself can be adjusted to control the dielectric constant, high q value, as well as the material temperature drift characteristics, stable performance, high power, low loss, small volume, with high out-of-band suppression, a wide range of temperature application, with a variety of forms of structure and output interface characteristics, has received more and more attention.

4. The electromagnetic principle of the ceramic dielectric filter is the same as that of the traditional metal cavity waveguide filter, the difference is that the ceramic dielectric filter uses functional ceramics as the medium, and the traditional metal cavity waveguide filter uses air as the medium, the dielectric constant of functional ceramics is different from that of air.

5. Traditional metal cavity waveguide filter automatic welding efficiency is low, high cost; As a new type of waveguide filter, ceramic dielectric filter is a structure that can be installed on pcb board. It can be installed by automatic patch welding process, so the installation efficiency is high and the production cost can be reduced.

6. The ceramic dielectric filter in the prior art usually has a plurality of resonators with parallel symmetric Settings; The structure of resonator is various. By adjusting the size and depth of each cavity hole to adjust the frequency; A groove is used to adjust the coupling quantity of adjacent resonators. Two transmission zeros are realized by coupling several cavities on one side through any groove form.

7. The above structure has the following problems:

8. First, the left and right transmission zeros realized by the above structure are symmetric, which can only be applied to the filter with low requirement of near-end suppression out of band and relatively symmetric suppression out of band; For the performance of the filter with high near-end suppression, more requirement of zero points, and asymmetric transmission of zero points from left to right, such as high left and low right zero points, low left and high right zero points, the existing structure cannot meet the requirements.

9. Second, the cross-coupling between the cross-resonators cannot be realized, resulting in the failure to achieve the transmission zero with stronger coupling.