JPH04332202A - Distribution factor type bisected dielectric resonance unit - Google Patents

Abstract

PURPOSE:To shorten a resonator length by using a distribution factor type filter by cascade-connecting resonators formed an electric conductor layer as an electrode on a dielectric block in which the length of a resonator is divided into two. CONSTITUTION:A first dielectric block 10 comprises a surface all of which is a grounding side open end face, an exposed open end face located opposite to the former surface, and a surface, on which an original dielectric surface is left slightly connectrically with a through-hole 40, including an outer peripheral surface covered entirely with an electric conductor layer 11. A second dielectric block 20, which overlaps with the above-mentioned through-hole, has an electric conductor layer connected successively to the exposed open end face and the inner peripheral wall of the through-hole. Resonator length is derived from the ratio of (length L of 1st dielectric block 10+length H of 2nd dielectric block 20) to the length K of lambda/4 coaxial hollow resonator.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a resonator unit optimal as a distributed parameter filter for high frequencies, which is made by cascade-connecting resonators each having a conductive layer formed on a dielectric block divided into two as electrodes. This paper proposes a two-part structure that can reduce the dielectric length.

0002

[Prior Art] Distributed constant filters, which have been put into practical use in the ultra-high frequency region above the UHF band, are being used as built-in components due to the demand for further miniaturization of communication devices, particularly mobile phones, in which they are incorporated. There is a need to further reduce its dimensions.

Generally, in order to reduce the external dimensions of the above-mentioned constant distribution type filter, it is necessary to reduce the dimensions of the dielectric block 1 constituting the resonator as shown in FIG. With corresponding frequency correction, the interval t between the capacitive electrodes 2 is narrowed in order to increase the capacitance between the electrodes in the center conductor section. However, as a result, the rate of change in the electrode spacing increases due to temperature changes, mechanical vibrations, etc., resulting in a drawback that the resonant frequency of the resonator fluctuates.

[0004] As a preventive measure against the above-mentioned drawbacks, there is an idea to confine the lines of electric force in the dielectric by providing a conductor layer 4 outside the dielectric block in order to suppress the decrease in dielectric constant. If it is formed on the entire surface of the dielectric,
If interstage coupling between cascaded resonators cannot be achieved and the distance between the dielectrics is changed, assembly and adjustment work in a narrow space becomes difficult, and the man-hours for manufacturing and testing increase dramatically. There are drawbacks, such as unavoidable instability due to frequency characteristics.

[0005]

[Problems with the Prior Art] All of the above-mentioned conventional technologies employ a method of increasing electrode capacitance using a conductor formed on a dielectric material, or a structure in which electric lines of force are confined by external electrodes of the dielectric material, so they can be miniaturized. The demand for directional characteristics and the man-hours required for manufacturing and testing conflict with each other, and there is a problem in that not only the sharpness Q of the resonance characteristic deteriorates, but also the resonator length cannot be reduced.

[0006]

[Means for Solving the Problems] However, in order to solve the above-mentioned conventional drawbacks, the present invention divides a dielectric block into two in the resonator length direction so as to obtain a low resonant frequency and increase the shortening ratio. By doing so, each conductor layer is used as a capacitive electrode to reduce the size of the entire resonator.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained below in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a dielectric resonator unit according to the present invention, and (A) of the same figure shows the second dielectric block 20 (
B) represents the first dielectric blocks 10, each block has a through hole 40 in the center, and the first dielectric has a conductive layer 12 on the inner circumferential wall of the through hole and the outer circumferential wall surface. A conductor layer 11 is formed concentrically with the through hole on the bottom surface and the exposed open end surface, and over the entire area where the dielectric material remains. The second dielectric block has a conductive layer formed on the exposed end face and the through hole, and has a resonant frequency f of the entire length (thickness) L of the conductive layer and the resonator length H of the first dielectric block. The length is selected such that the ratio of the resonator length K of a general λ/4 coaxial cavity resonator to the resonator length K, that is, the shortening rate α=(L+H)/K is minimized. Note that α is a value that changes depending on the structure of the transmission line, the distribution of the electromagnetic field, etc., and can be considered to be approximately inversely proportional to the square root of the effective dielectric constant.

FIG. 2 is a longitudinal cross-sectional view in the resonator length direction along the center line of the through hole in FIG. The ratio is determined at the point where α is the minimum. Furthermore, by changing the dielectric constant of each of the dielectric blocks described above, a resonator with suppressed harmonics can be manufactured, for example.

Next, Table 1 shows the resonator length K of a conventional general λ/4 coaxial cavity resonator using air with a dielectric constant of 1.0 as the dielectric material, and the resonator length K of the first and second dielectric materials of the present invention. Regarding the reduction rate α of the total length of each block length H and L, the band frequency (
The second dielectric block length was measured with only the conductor layer (metal electrode) facing the exposed open end surface of the first dielectric block with air in between. It is something.

[0010] When ceramics are used as each dielectric block, since the dielectric constant is 9 to 10, the second
The value of the length L of the dielectric block is 9 to 10 times the stated value, and if an equivalent dielectric block is constructed with an adhesive layer containing a dielectric substance, the outer surface of the first dielectric block A capacitive element can be formed using the conductive layer provided on the substrate as one electrode.

Therefore, in the case of a resonator using ceramic as a dielectric, the minimum value of α of 44.4 when the permittivity is 1 in Table 1 above does not exceed at least 50% even if it changes slightly; There is no change in the overall trend with respect to the shortening rate based on the difference in dielectric constant.

0012

[Table 1]

[0013]

Effects of the Invention As described above, the present invention uses a conductive layer formed on the outer surface of the first and second dielectric blocks that divide the capacitive resonance action into two in the resonator length direction, as a counter electrode. They are coupled capacitively, and by determining the resonator length from the ratio of the normal λ/4 coaxial cavity resonator length to the band frequency of the filter used, resonance can be achieved with the maximum resonant capacity. As a whole, the reduction rate of the resonator length can be reduced to at least 50 to 75%, which greatly contributes to miniaturization.

[0014] Furthermore, there is no need for means for inter-electrode adjustment, etc.
The design becomes easy, the device can be completed with almost no adjustment, the man-hours for mass production and measurement are significantly reduced, and economical efficiency is also satisfied.

[Brief explanation of drawings]

FIG. 1 (A) is an exploded perspective view of a first dielectric block and (B) is an exploded perspective view of a second dielectric block.

FIG. 2 is a vertical sectional side view of FIGS. 1A and 1B.

FIG. 3 is a longitudinal side view of a conventional dielectric resonator.

[Explanation of symbols]

10 First dielectric block 2
0 second dielectric block 30
Dielectric 40 Through holes 11, 12 Conductor layer

Claims (1)

[Claims] Claim 1: A cascade connection in multiple stages, comprising a λ/4 length columnar dielectric block having a through hole in the center, and a conductive layer provided on at least the entire outer circumferential surface of the block, excluding a part thereof, and on the inner circumferential wall of the through hole. In a distributed constant type filter using a resonator grounded as a resonator, the entire ground side open end face of the dielectric block and the outer peripheral surface are included, leaving a small amount of dielectric material concentric with the through hole of the exposed open end face facing the dielectric block. a first dielectric block having a conductive layer formed thereon; and a conductive layer that overlaps the first dielectric block with the through hole and is connected to the entire exposed open end surface of the first dielectric block and the inner circumferential wall of the through hole. and a second dielectric block formed, and the total length of each dielectric block is set to a length determined by the ratio of the normal λ/4 coaxial cavity resonator length to the resonant frequency. Dielectric resonant unit of distributed constant type two-division method.