Dielectric wave filter

Abstract

The invention provides a dielectric filter comprising a dielectric block having two through bores, an outer conductor covering an outer peripheral surface of the block and one end face of the block, an inner conductor covering an inner periphery of the block, and a pair of input and output electrodes formed on the surface of the block, the other end face of the block being in the form of an open end face having no conductor layer. The pair of input and output electrodes are opposed to each other on one plane, and a dielectric block exposing portion having no conductor layer thereon is formed between the two electrodes. The block is provided in the other end face thereof with one groove dividing the open end face, and an inner surface defining the groove is provided with a conductor layer joined to the outer conductor.

Description

technical field [0001] The present invention relates to a dielectric filter equipped in a mobile communication device or the like, which determines a frequency-pass characteristic suitable for a signal frequency band to be processed. Background technique [0002] In recent years, in mobile communication devices such as mobile phones, multi-bands and good frequency characteristics in a wide range of frequency bands have been pursued along with multi-functionalization. It is known that such a mobile communication device uses a dielectric filter to transmit and receive signals in a frequency band of, for example, several hundred MHz to several GHz. FIG. 7 shows the structure of a dielectric filter used in an existing mobile communication device (see Japanese Laid-Open Patent Publication No. Hei 7-254806). [0003] As shown in Figure 7, on the dielectric block (1) of rectangular parallelepiped shape that is made of dielectric material such as ceramics, offer 2 through holes (2)...

AI Technical Summary

Problems solved by technology

[0008] However, in the conventional dielectric filter shown in FIG. 7, the attenuation pole on the low-frequency side is changed by changing the external dimensions of the dielectric block, the arrangement of the large-diameter hole portion and the small-diameter hole portion of the through-hole, etc. The position (frequency) of b1 can be adjusted to a certain extent, but it is difficult to perform the same adjustment on the attenuation pole c1 on the high frequency side. In the manufacturing process, changing the shape of the through hole of the dielectric block is indeed a very complicated problem.

[0009] With the multifunctionalization of communication equipment in recent years, although the attenuation characteristics in the high frequency band outside the pass band are also important, in the existing dielectric filters, such as Figure 8 As shown, the harmonic e1 generated in the high-frequency region (near 5 GHz) corresponding to about three times the passband a1 cannot be attenuated sufficiently, and there is a problem that the filter characteristics deteriorate significantly.

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