Adjustable electromagnetic hybrid coupling filter

Abstract

The invention discloses an adjustable electromagnetic hybrid coupling filter comprising a cavity and resonant columns. The resonant columns are fixed in the cavity and resonant frequencies generated by the resonant columns can be adjusted. A capacitive coupling structure and an inductive coupling structure are arranged between each two adjacent resonance columns, wherein capacitive coupling capacity of the capacitive coupling structure and the inductive coupling capacity of the inductive coupling structure can be adjusted. On the basis of coexistence of the two coupling structures, an electromagnetic hybrid coupling structure is formed. A compensation structure connects two resonant columns not adjacent to each other to generate capacitive and / or inductive coupling between the resonant columns not adjacent to each other. Therefore, the location of the passband near-end transmission zero point is adjusted in a large range and thus the distance to the bandpass is reduced, so that the near-end out-of-band rejection is improved and the in-band echo and inversion loss index are enhanced.

Description

technical field [0001] The invention relates to an electromagnetic hybrid coupling filter, in particular to an adjustable electromagnetic hybrid coupling filter capable of correcting the transmission zero point position. Background technique [0002] The electromagnetic hybrid coupling technology refers to the method of using the electrical coupling and magnetic coupling existing on the coupling path between adjacent resonators to generate transmission zeros to improve the out-of-band rejection of the filter. Theoretically, an N-order filter can have at most N-1 sets of electromagnetic hybrid couplings, resulting in N-1 transmission zeros, much more than N-order filters designed with cross-coupling technology or source-load coupling technology. [0003] The frequency of the transmission zero point of the existing electromagnetic hybrid structure is related to the frequency of its adjacent resonator. When the passband of the filter is wide, it is difficult to concentrate the ...

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Problems solved by technology

However, the above-mentioned patented technology still has the following defects: 1. Large volume; 2. Both capacitive coupling and resonance frequency are related to the height of the resonant column, so it is difficult to tune separately; 3. Some dimensions are sensitive and require high processing accuracy

[0005] Another patent application number is CN200810027449.1, which discloses a controllable electromagnetic hybrid coupling coaxial cavity filter. The coaxial cavity filter with only the main coupling path realizes the elliptic function filtering characteristics, but it has the following defects: 1. The resonant column needs capacitive loading to reduce the frequency, and the volume is large; 2. The use of a dielectric substrate deteriorates the intermodulation index of the system; 3. The coupling component is installed on the top of the resonant column, which is not easy to adjust

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