KR101315878B1 - Dual mode dielectric resonator filter - Google Patents

Abstract

PURPOSE: A duplex mode dielectric resonator filter is provided to improve the degree of integration by reducing overall volume and size. CONSTITUTION: Housing forms two or more cavities. At least one tuning rod (300) adjusts the frequency of a duplex mode. A coupling loop (400) controls the amount of electrostatic coupling. A conductor plate (500) has a diameter smaller than the diameter of the dielectric resonator. An input connector and an output connector are connected to the cavity, respectively.

Description

Dual mode dielectric resonator filter

The present invention relates to a dielectric resonator filter, and more particularly, by reducing the number of cavities by half through a dual mode dielectric resonator, it is possible to reduce the size of the filter and to improve the quality factor and the insertion loss. It is a dual-mode dielectric resonator filter that has a wide bandwidth and can be manufactured in various forms regardless of a specific shape.

The rapid growth of wireless mobile communication service is increasing the demand for various communication devices. RF components constituting a wireless transmission / reception system of a communication device used for wireless mobile communication include an antenna, a power amplifier, a duplexer, a band pass filter, a directional coupler, and a power divider / synthesizer.

Among them, the band pass filter passes the input and output signals through the RF and microwave system with low loss value, removes the parts other than the pass band, and prevents the noise radiation that impedes the adjacent communication channel. High frequency selectivity is required to suppress and receive only the desired signal.

Among the band pass filters, a component used in a base station or a repeater is mainly used as a cavity filter using aluminum or a dielectric resonator filter using a dielectric resonator having a large dielectric constant.

In particular, the dielectric resonator filter has a very small conductor loss because most of the electromagnetic fields are trapped inside the dielectric due to the high dielectric constant of the dielectric resonator. Therefore, a higher quality factor (Q) value can be obtained than a cavity filter, and a filter having stability against temperature can be manufactured due to the high temperature stability of the dielectric resonator.

In addition, since it is relatively small compared to other filters operating in the same frequency band, it is also suitable for miniaturization and light weight, which are required in recent years, and it is possible to implement a dual mode by forming various modes.

Meanwhile, the dielectric resonator filter can be classified into TM (Transverse Magnetic) mode, TEM (Transverse ElectroMagnetic) mode, and TE (Transverse Electric) mode according to its structure. US Patent No. 7,106,152 and the like.

Since the TM mode resonator has a higher Q value than the conventional TEM mode resonator (cavity filter structure), the TM mode resonator filter has an improved Q characteristic of about 40% at the same size. It can be designed in a very small size, and has the advantage of designing a filter with low insertion loss and excellent attenuation at the same size.

Referring to FIGS. 1 and 2, in the conventional dual-pole four-pole dielectric resonator filter structure, a disk-shaped dielectric resonator 12 is formed at the center of the cavity of the conductor housing 10. It is fixedly installed by the same other dielectric support 13, respectively.

The cavity 11 is partitioned by a partition in which a window of a predetermined size is formed to continuously form the coupling between the dielectric resonators 12, and the coupling screw 15 is finely adjusted in the window so as to finely adjust the amount of coupling. ) Is installed through the cover.

In addition, a tuning groove may be formed at an upper end of the dielectric resonator 12, and a tuning screw 14 for finely adjusting the resonance frequency is installed on the cover 16 corresponding to the groove along with the fixing nut. do.

In addition, both sides of the housing 10 are equipped with an input connector 18 for inputting a frequency from the outside and an output connector 19 for outputting the filtered frequency therein, and the input connector 18 is provided with an input feed loop. Connected and the output connector 19 is connected to the output feed loop. The input feed loop delivers the signal coming from the input connector 18 to the first dielectric resonator 12-1, and the output feed loop is the last dielectric. It serves to transfer the signal from the resonator (12-4) to the output connector (19).

The conventional dual-mode dielectric resonator filter can reduce the number of dielectric resonators and the number of cavities by half compared to the single mode method in which the volume of the dielectric resonator becomes large in inverse proportion to frequency, thereby miniaturizing and reducing the filter weight. There are advantages to it.

That is, the single mode method generates only one resonator effect in one dielectric resonator, whereas in the dual mode method, two resonator effects can be obtained in one dielectric resonator.

However, due to the structural characteristics of fixing the dielectric support 13 in the cavity 11 of the housing, there is a limitation in mechanically reducing its volume and size, and there is a limit to miniaturization while keeping the insertion loss small.

In addition, conventionally, the mode between the cavities is coupled to the X, Y axis direction with respect to the center of the cavity, each of the tuning screw for adjusting the resonance frequency and the coupling screw for adjusting the amount of electrostatic coupling is located on the X, Y axis In the case of manufacturing a filter having three or more cavities, it is possible to arrange only in the form of 'ㄹ' or 'V' and cannot arrange them in a line. Therefore, various communication system modules mounted in the enclosure of the radio relay device and the space of the enclosure There are many restrictions on the efficiency, and as a result, there is a problem of increasing the overall volume and size of the radio relay device.

In addition, the conventional dielectric resonator filter suppresses the generation of unwanted waves by adjusting the amount of coupling between dielectric resonators mounted in each cavity according to the size of the window. In order to realize wideband characteristics, spurious Or an abnormal signal such as a notch is generated.

Meanwhile, the RRH (Remote radio head), which is widely applied to a wireless communication system, is composed of two transmission paths and two reception paths. The RRH is a filter that separates transmission and reception signals. It is a filter that separates the transmission and reception signals. It consists of a housing including heat dissipation fins for dissipating heat generated by a power amplifier for accommodating and amplifying a signal.

In addition, the enclosure is divided into two compartments, the upper and the lower, and the duplexer for separating the transmission and reception signals is located at the bottom, and all the above-mentioned modules except the duplexer is located at the top to increase the overall volume and size. The only reason for placing the duplexer in the lower part of the enclosure is mainly because of its size and volume.

Currently commercially available duplexers consist of a transmission filter and a reception filter as a single module. Generally, a cavity filter or a TE mode dielectric filter is widely used in an RRH. In addition, the filter is composed of at least five or more resonators in each transmission and reception path, and each resonator is generally designed to have a quality factor of 3000 or more to satisfy the insertion loss required by the system. The volume is inevitably very large, and for this reason, there is a problem in that the entire lower part of the enclosure is used.

In general, the size of the cavity filter is determined by the size of the coaxial resonator structure, and the quality factor is related to the resonator structure by the following equation.

Where a is the resonator diameter, b is the cavity diameter, and δ is the skin depth.

Republic of Korea Patent Publication No. 10-0631450 (2006.10.04.) Republic of Korea Patent Publication No. 10-0783860 (2007.12.10.) Republic of Korea Patent Publication No. 10-0737618 (2007.07.10.) Republic of Korea Patent Publication No. 10-0390351 (2003.07.10.) Republic of Korea Patent Publication No. 10-2011-0054899 (2011.05.25.) Republic of Korea Patent Publication No. 10-2009-0109445 (2009.10.20.) Republic of Korea Patent Publication No. 10-2011-0074290 (2011.06.30.)

Do-Young Park, A Study on Electromagnetic Distribution Characteristics of Dielectric Resonators and Implementation of Dual-Mode Bandpass Filter (Master's Thesis, Sogang University, 2003). Kim, Ju-Young and 3 others, A Study on the Characteristics of Cylindrical Dielectric Resonator Filter (Korean Society of Electronics Engineers, Vol.25 No.1, 2002). A Study on the Design of Dielectric Resonator Bandpass Filter Considering Temperature and Stability (M.S. Thesis, Soonchunhyang University, 2003).

Accordingly, the inventors of the present invention can achieve miniaturization by reducing the number of cavities in half through a dual mode dielectric resonator, with a wide bandwidth, with an emphasis on solving the above-described problems and problems, and easy to arrange and arrange in the housing of the filter. The present invention was invented during the intensive study to develop a new type of dual mode dielectric resonator filter.

Accordingly, it is an object of the present invention to provide a dielectric resonator filter which can be manufactured in various forms without being bound to a specific form.

It is another object of the present invention to provide a dielectric resonator filter that can reduce the volume and size of an outline.

In order to achieve the object as described above, an embodiment of the present invention, the housing is formed with at least two or more cavities, the cylindrical bottom surface is attached to the bottom surface of the cavity of the housing, respectively, on the outer periphery of the central axis A dielectric resonator having a magnetic field wall surface cut parallel to and inducing mode coupling between the cavities, at least one tuning rod installed in the cavities of the housing to adjust the frequency of the dual mode, and magnetic field wall surfaces of the dielectric resonator. A coupling loop mounted on a wall between the cavities of the housing so as to face any one of the housings and controlling an amount of electrostatic coupling, a disk-shaped conductor plate attached to an upper surface of the dielectric resonator and having a diameter smaller than that of the cylinder; Magnetic field facing the coupling loop among magnetic field walls of the dielectric resonator Face to face the other wall surface magnetic field adjacent to the fitted to the housing to provide a double mode dielectric resonator filter including a respectively connected to the input and output connectors and the cavity.

As a result, the present invention can reduce the size of the cavities by halving the number of cavities through the dual mode dielectric resonator in the implementation of the dielectric resonator filter, as well as facilitating the electrostatic coupling between the cavities and deteriorating the characteristics of the filter and the specific shape. It can be manufactured in various forms without any particular concern, thus improving the ease and generality of the work according to the installation of the filter.

In another embodiment of the present invention, the cavity may be rectangular in cross section, and the magnetic field wall of the dielectric resonator may be disposed to face the rectangular cavity edge.

In another embodiment of the present invention, the conductor plate may be formed with at least one electric field wall surface that is cut parallel to its central axis at the outer circumference of the disc shape to induce a dual mode coupling.

In another embodiment of the present invention, the dielectric resonator is formed with at least one tuning hole for dual mode coupling parallel to the central axis between the magnetic field walls, the coaxial with the tuning hole The tuning rods can be positioned.

In another embodiment of the present invention, a positioning protrusion which is inserted and coupled to correspond to the tuning hole may be formed on the bottom surface of the cavity of the housing.

In another embodiment of the present invention, the tuning rods may be installed at positions facing each other of the magnetic field wall except for the magnetic field wall facing the input and output connectors of the magnetic field walls of the dielectric resonator.

According to the present invention having the above-described problem solving means and configurations, the magnetic field wall is formed on all four outer peripheries of the cylindrical dielectric resonator, and the electrostatic coupling between the cavities is facilitated by mounting the magnetic wall in a 45 degree direction with respect to the central axis of the cavity. In addition, it is possible to manufacture in various forms without deteriorating the characteristics of the filter and the specific form, thereby improving the ease of operation and generality according to the installation of the filter.

In addition, not only reduces the overall volume and size of the wireless relay device for mounting the filter, but also improves the degree of integration by maximizing the space efficiency of the arrangement and enclosures of various communication system modules mounted in the wireless relay device, thereby miniaturizing the wireless relay device. In addition to weight reduction and slimming, cost reduction can be achieved.

In addition, the dual-mode coupling and resonant frequency can be adjusted through the conductor plate, so that a filter of several bands can be manufactured using one type of dual-mode dielectric medium.

1 and 2 is an exemplary view showing an example of a dielectric resonator filter according to the prior art,
3 is a plan view showing a dielectric resonator filter according to an embodiment of the present invention;
4 is a cross-sectional view showing a dielectric resonator filter according to an embodiment of the present invention;
5 is a block diagram showing a dielectric resonator according to an embodiment of the present invention;
6 is an equivalent circuit diagram of a dielectric resonator filter according to an embodiment of the present invention;
7 is a graph showing changes in frequency and Q value according to the size of a conductor plate of a dielectric resonator filter according to an embodiment of the present invention;
8 is a graph illustrating insertion loss among resonance characteristics of a dielectric resonator filter according to an exemplary embodiment of the present invention;
9 is a graph obtained by analyzing a resonance frequency of a dielectric resonator filter according to an embodiment of the present invention through three-dimensional electromagnetic field analysis;
10 is a graph obtained by a three-dimensional electromagnetic field analysis of the resonant frequency of the dielectric resonator filter according to the prior art,

Hereinafter, embodiments according to the present invention will be described more specifically with reference to the accompanying drawings.

Prior to this, the following terms are defined in consideration of the functions of the present invention, and it is to be understood that these are construed in accordance with the technical idea of the present invention and interpreted in a way that is commonly or generally recognized in the technical field.

In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

The accompanying drawings are exaggerated or simplified to illustrate and explain the structure and operation of the present invention in order to facilitate understanding and clarity, and it should be understood that each component does not exactly coincide with the actual size.

3 and 4 show a dielectric resonator filter according to an embodiment of the present invention, Figure 5 shows a dielectric resonator according to an embodiment of the present invention.

3 to 5, the dielectric resonator filter according to the embodiment of the present invention is largely the housing 100, the dielectric resonator 200, the tuning rod 300, the coupling loop 400, the conductor plate ( 500), and input and output connectors 600, 700.

The housing 100 is formed of a conductor having at least two or more cavities 110 having a predetermined shape, the interior of which is divided by a partition at predetermined intervals, and the interior may be silver plated to stabilize electrical performance and maximize conductivity. .

In addition, a positioning protrusion 120 may be formed on the bottom surface of the cavity 110 of the housing to be inserted and coupled to the tuning hole 220 of the dielectric resonator 200 in order to accurately set the mounting position of the dielectric resonator 200. have.

Here, the shape of the cavity 110 is formed in the shape of a cube or a cylinder having isosymmetry such as a rectangular cavity or a circular cavity.

In addition, the housing 100 may include a cover for opening and closing the opening surface. In this case, the housing 100 and its cover may be coupled to each other by forming a plurality of screw holes at corresponding positions, and may be fixed by soldering or adhesive.

The dielectric resonator 200 has a lower surface attached to the bottom surface of the cavity 110 of the housing, and are sequentially connected to each other. The magnetic field wall 210 that induces mode coupling between the cavities 110 on the outer circumferential periphery of the cylindrical shape is the same. It is formed by cutting parallel to an imaginary central axis.

The magnetic field wall surface 210 of the dielectric resonator is disposed to face the corner of the cavity 110 so as not to face the magnetic field wall surface of another adjacent dielectric resonator when the cavity 110 of the housing is rectangular.

That is, as shown in the equivalent circuit diagram of FIG. 6, the magnetic field wall surface 210 of the dielectric resonator is perpendicular to each other in the cavity 110 of the housing in two modes, and the two modes have an angle of 45 degrees from the X and Y axes. Two resonant modes arranged to be excited and neighboring each other may be successively coupled.

Here, the electric field formed in the dielectric resonator 200 has a field formed on two magnetic field walls facing each other among the four magnetic field walls 210 orthogonal to each other, and forms a secondary resonance mode in a direction perpendicular to the resonance mode thus formed. Dual mode is formed.

The magnetic field wall 210 of the dielectric resonator has at least two dual mode coupling tuning holes 220 formed in parallel with the central axis thereof, and on the same axis as the tuning hole 220, a tuning rod ( 300) is located.

That is, the tuning holes 220 are formed to allow mode coupling between the dual modes that are independent of each other and orthogonally occur in the dielectric resonator 200, and to adjust the amount of coupling.

In this case, when the tuning holes 220 are formed at four positions from the central axis, the strength of the mode coupling varies according to the distance away from the center of the dielectric resonator 200, and thus the distance falling from the center may be changed according to the passband of the filter. But they are formed symmetrically to each other.

Further, any one of the four tuning holes 220 or two tuning holes opposing diagonally from the center of the dielectric resonator 200 are selected, and the tuning rods 300 are inserted into each of them, and then the center axis direction thereof is inserted. Moving the position to adjust the amount of coupling between two mutually independent modes occurring in the dielectric resonator 200.

A thin film may be coated on the bottom surface of the dielectric resonator 200 with silver or copper, and then soldered to the bottom surface of the cavity 110 of the housing.

That is, it is very important to assemble the lower surface of the dielectric resonator 200 in close contact with the bottom surface of the cavity 110 of the housing for smooth heat dissipation. It may not be applicable to the product, and if the dielectric bolt is used, the loss of the resonator is maintained, but the breakage caused by vibration occurs easily, and if the conductor bolt is used, the reliability of fixing is secured, but the loss of the resonator may be reduced and unnecessary spurious may be caused. Can be.

The fixing hole 230 may be formed on the central axis of the dielectric resonator 200. In this case, since the electric field is zero in the fixing hole 230, a dielectric or conductor bolt is inserted. It can also be fixed to the bottom surface of the cavity 110 of the housing, and can remove other unnecessary spurious modes.

The tuning rod 300 is made of a conductor, a dielectric, or the like, and is installed through the housing 100 in at least one of the cavities 110 of the housing to finely adjust the resonance frequency of the dual mode.

That is, the tuning rod 300 is located at positions facing the magnetic field wall 210 except for the magnetic field wall 210 facing the input and output connectors 600 and 700 among the magnetic field wall 210 of the dielectric resonator. Is installed.

In addition, the tuning rod 300 is installed at the same position as the tuning hole 220 of the dielectric resonator or located outside the dielectric resonator 200 on the same axis as the tuning hole 220 to finely adjust the coupling amount between the dual modes. Done.

Here, the tuning rod 300 may be provided in the form of a tuning screw to move up and down on the bottom surface of the cavity 110 of the housing.

The coupling loop 400 adjusts the amount of electrostatic coupling between the dielectric resonators 200 so as to face any one of the magnetic field walls 210 of the dielectric resonator so as to suppress the generation of the unwanted wave. It is mounted on the wall between the 110.

Here, the coupling loop 400 and the tuning rod 300 may be inserted into the cavity 110 according to the rotation of the lower surface of the housing 100 so that the length of the coupling loop 400 and the tuning rod 300 may be adjusted to reduce the convenience and time required for mounting. have.

That is, the coupling loop 400 is positioned to face any one of the magnetic field walls 210 of the dielectric resonator so as to couple and pass only the single mode at the time of coupling between the cavity 110 resonating in the dual mode. In this case, the coupling amount may be adjusted by adjusting the size and spacing with the dielectric resonator 200.

The conductor plate 500 is formed in a disc shape having a diameter smaller than that of the dielectric resonator 200 and attached to the upper surface of the dielectric resonator 200.

In addition, the conductive plate 500 may be formed with at least one electric field wall surface 510 cut parallel to its central axis at an outer circumference thereof to induce a dual mode coupling.

Here, the air layer is formed between the conductor plate 500 and the cavity 110 of the housing by a gap having a predetermined interval.

In addition, the coupling bandwidth between the dual modes formed in the single resonator is determined according to the partial cutting shape of the conductor plate 500 and the position of the tuning hole 220 for the dual mode coupling.

The input connector 600 is mounted to the housing 100 to face another magnetic field wall adjacent to the magnetic field wall facing the coupling loop 400 among the magnetic field walls 210 of the dielectric resonator to input a frequency from the outside. Connected to the cavity 110, the output connector 700 is adjacent to the magnetic field wall facing the coupling loop 400 of the magnetic field walls 210 of the dielectric resonator to output the filtered frequency therein. It is mounted on the housing 100 to face the cavity 110 is connected to the cavity 110.

That is, when the cross-sectional shape of the cavity 110 is rectangular, the input and output connectors 600 and 700 are disposed on the corners of the cavity 110.

In addition, the input and output connectors 600 and 700 are connected to the input and output feed loops 610 and 710, and the input feed loop 610 receives the signal coming from the input connector 600 in the first dielectric resonator 200. ), And the output feed loop 710 receives the filtered signal from the last dielectric resonator 200 through the cavity 110 and transmits the filtered signal to the outside through the output connector 700. That is, the input and output feed loops 610 and 710 are connected to the input and output connectors 600 and 700 in the cavity 110 of the housing and induce electromagnetic waves input and output to pass only signals of a desired band. .

The dielectric resonator filter according to the exemplary embodiment of the present invention configured as described above may be arranged in a rectangular shape instead of a square structure in plan view as in the related art. As a result, the planar structure, which is an important design matter of the filter, can be freely designed without being bound to a specific shape, and thus the design of size and shape can be easily performed.

In particular, when applied to a wireless communication system having an enclosure structure such as RRH, not only the space below the enclosure can be used more efficiently, but also the RRH component modules other than the filter module can be easily disposed at the bottom of the enclosure. The volume and size can be greatly improved.

7 is a graph measuring changes in frequency and Q value according to the size of a conductor plate of a dielectric resonator filter according to an exemplary embodiment of the present invention. Here, the X axis represents a Q value and the Y axis represents a frequency (MHz).

Referring to FIG. 7, in Comparative Example 1 in which the diameter of the dielectric resonator 200 and the diameter of the conductor plate 500 are the same, the frequency is lowered but the Q value is lowered. That is, the size of the cavity 110 can be minimized, but the loss increases, making it difficult to commercialize.

On the other hand, the embodiment of the present invention in which the diameter of the conductive plate 500 is smaller than the diameter of the dielectric resonator 200 is relatively high, the setting is easy, and the size of the cavity 110 may be optimized.

On the other hand, Comparative Example 2 is for the case where the conductor plate 500 is not attached to the dielectric resonator 200. In this case, the frequency increases and the Q value increases, but the size of the dielectric resonator 200 is very large. It is difficult to minimize the size of 110.

8 is a graph illustrating insertion loss among resonance characteristics of a dielectric resonator filter according to an exemplary embodiment of the present invention. Here, the X axis represents frequency (GHz) and the Y axis represents loss (dB).

That is, it can be seen that the insertion loss is improved in the dielectric resonator filter according to the embodiment of the present invention.

9 and 10 are graphs showing values obtained by analyzing a resonance frequency of a dielectric resonator filter according to an exemplary embodiment of the present invention and a conventional technique through three-dimensional electromagnetic field simulations.

That is, in the case of the conventional dielectric resonator filter, the coupling bandwidth has a large correlation with the window width between the cavities connecting the two dielectric resonators, and has a bandwidth of about 30 MHz.

On the other hand, in the case of the dielectric resonator filter according to an embodiment of the present invention, the coupling bandwidth can be widened up to about 100 MHz, thereby reducing the size of the dielectric resonator filter having the same bandwidth by at least 50%.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments or constructions. Various changes and substitutions may be made without departing from the spirit and scope of the invention. It will be apparent to those skilled in the art that changes may be made in the embodiments without departing from the spirit and scope of the invention. Accordingly, it is intended that the present invention cover the modifications and applications of this invention provided they come within the scope of the appended claims and their equivalents.

100: housing 110: cavity
120: positioning projection 200: dielectric resonator
210: magnetic field wall 220: tuning hole
230: fixing hole 300: tuning rod
400: coupling loop 500: conductor plate
510: electric wall 530: fixing hole
600: input connector 610: input feed loop
700: output connector 710: output feed loop

Claims (6)

A housing in which at least two cavities are formed;
A dielectric resonator having a lower surface attached to the bottom surface of the cavity of the housing and having a magnetic field wall surface which is cut parallel to its central axis on a cylindrical outer periphery to induce mode coupling between the cavities;
At least one tuning rod installed in the cavities of the housing to adjust the frequency of the dual mode;
A coupling loop mounted on a wall between the cavities of the housing so as to face any one of the magnetic field walls of the dielectric resonator to adjust the amount of electrostatic coupling;
A disk-shaped conductor plate attached to an upper surface of the dielectric resonator and having a diameter smaller than that of the dielectric resonator;
An input and an output connector mounted on the housing so as to face another magnetic wall wall adjacent to the magnetic wall wall facing the coupling loop among the magnetic wall walls of the dielectric resonator;
Including;
The dielectric resonator may have at least two dual mode coupling tuning holes penetrated in parallel with the central axis between the magnetic field walls, and the tuning rod is positioned on the same axis as the tuning hole. Mode dielectric resonator filter.
The method of claim 1,
And wherein the cavity is rectangular in cross section and the magnetic wall surface of the dielectric resonator is disposed to face the cavity edge of the quadrangle.
The method of claim 1,
And the conductor plate has at least one electric field wall surface that is cut parallel to its central axis at an outer periphery of a disc shape and induces a dual mode coupling.
delete The method of claim 1,
And a positioning protrusion inserted into and coupled to the tuning hole on the bottom surface of the cavity of the housing.
The method of claim 1,
And the tuning rods are disposed at positions facing each other of the magnetic field walls except for the magnetic field walls facing the input and output connectors of the magnetic field walls of the dielectric resonator.

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