KR20030013605A - A device of cavity band rejection filter - Google Patents

Abstract

PURPOSE: A cavity band rejection filter is provided to improve reliability of the cavity band rejection filter by reducing an insertion loss and improving a standing-wave ratio in the cavity band rejection filter. CONSTITUTION: A cover portion is formed with a central line(90), a dielectric body(110), a plurality of holes(70), a control bar(80), and a waveguide(100). The central line(90) is used for transmitting an RF signal. The central line(90) is formed in the inside of the waveguide(100) fixed by the dielectric body(110). The control bar(80) is inserted into the holes(70). An upper plate(15) and a lower plate(17) are combined with the third screw(7). An open stub is adhered toward a cavity(40). An N type terminal(20) is fixed by a cover portion and the forth screw(8). The N type terminal(20) is electrically connected to the central line(90). A plurality of cavities(40) is formed on a main body portion. A cavity resonator(50) is fixed to the cavity(40) by the first screw.

Description

Cavity bandstop filter {A DEVICE OF CAVITY BAND REJECTION FILTER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity band rejection filter used in a base station of a mobile communication system, and more particularly, to effectively reduce signal interference between base stations having adjacent or overlapping assigned frequencies. .

In a mobile communication system, a base transceiver station (BTS) transmits and receives data or signals for communication wirelessly by using a frequency of an allocated band with a corresponding mobile terminal.

Many mobile communication service providers transmit and receive using frequencies of similar or adjacent bands, and the base stations of each service provider are often installed in geographically adjacent locations due to the design characteristics of the base stations.

As the modern society is gradually transformed into the structure of the information society, individuals and organizations rapidly expand their communication desire to communicate with anyone anytime, anywhere, and provide low-cost, high-quality and various communication services to satisfy such communication needs. It is continually developing for this purpose.

According to the above trend, even in the same region or the same service provider, mobile communication services of various methods coexist, that is, for example, the mobile station of the base station and Europe using a code division multiplex (CDMA), which has been commercialized for the first time in the world, in Korea. A base station using a Global System for Mobile communication (GSM) method, which is a communication method, may coexist.

Although each of the mobile communication service methods are different frequency bands used, for example, the reception band frequency of the GSM method is 890 MHz to 915 MHz, and the CDMA system transmission band frequency is 869 MHz to 894 MHz, and thus the CDMA system. The signal corresponding to the frequency of the 890 MHz to 894 MHz band of the will have the same effect as communication failure by mutual interference.

In such a case, a communication failure occurs regardless of whether each base station is geographically adjacent or using the same base station.

Accordingly, the CDMA base station and the GSM base station may be subjected to interference caused by their respective assigned frequency bands or mutual influences with frequency signals of adjacent band widths, and a plurality of harmonics or spurious signals. It is necessary to block or suppress the transmission and reception, and the band rejection filter which performs the above function is a band rejection filter.

Bandstop filters are designed in several ways. As an example, when the frequency band is in the range of 1 MHz to 100 MHz, it is designed and manufactured using Lumped R, L, C elements, and helical when the frequency band is in the range of 30 MHz to 800 MHz. Design and manufacture using resonators.

In addition, when the frequency band is in the range of 800 MHz to 10,000 MHz and the band rejection band is narrow to the range of 0.5% to 5% of the filter center frequency, a coaxial resonator is mainly used. In the case of 5% to 20% of the center frequency of the filter, a band stop filter is mainly designed and manufactured using a strip line.

In addition to the above, there is a use of a circulator or isolator and a dielectric resonator. The dielectric resonator uses a ceramic dielectric, which is expensive, and the use of a circulator or isolator is inserted. Since there is a problem such as an increase in loss (Insertion Loss), the present invention relates to a cavity resonant bandstop filter which is relatively inexpensive and easy to manufacture.

The band-stop filter according to the prior art, for example, in the case of the US LORCH company or K & L company, the insertion loss (Insertion Loss) is about 1.0 dB, in another example, domestic ACE company or In the case of KMW, the insertion loss is about 0.7 to 0.8 dB, which is relatively large.

In addition, since the magnitude of the voltage standing wave ratio (VSWR) of the bandstop filter according to the related art is high, about 1.5 to 1.7, it is difficult to use, in particular, to use in a CDMA base station. There is a difficult problem.

It is an object of the present invention to reduce the insertion loss of a band stop filter, to provide a high performance and reliable cavity type band stop filter having excellent measured input / output standing wave ratio characteristics and stable to temperature and vibration changes.

The present invention devised to achieve the above object, in the high-frequency band-stop filter; A lid part configured to form a waveguide in which a center line for transmitting a high frequency signal is fixed by a dielectric; A plurality of N-type terminals which are integrally formed by the lid and the screw and connected to the center line to input and output signals; A plurality of cavities of the same size are formed, and the center bottom surface of each cavity has a feature in which the cavity resonators are respectively fixed by first screws.

1 is a stereoscopic perspective view of a cavity-type bandstop filter according to the present invention;

2 is a front tomographic configuration diagram of a cavity type band stop filter according to the present invention,

Figure 3 is a cross-sectional configuration of the cavity type band stop filter according to the present invention,

4 is a real picture taken of the cavity type band stop filter according to the present invention,

5 is a state diagram of the insertion loss and the standing wave ratio in the CDMA transmission band using the cavity type band stop filter according to the present invention.

6 is a state diagram of the insertion loss and the standing wave ratio in the CDMA reception band using the cavity type band stop filter according to the present invention.

** Explanation of symbols on the main parts of the drawing **

5: 1st screw 6: 2nd screw 7: 3rd screw

8: fourth screw 10: lid 15: top plate

17 bottom plate 20 terminal 30 body portion

40: cavity 50: pupil resonator 60: pupil cavity

70: hole 80: adjusting rod 90: center line

95 open stub 100 waveguide 110 dielectric

200: cavity bandstop filter

Hereinafter, a cavity type band stop filter according to the present invention will be described with reference to the accompanying drawings.

1 is a three-dimensional perspective view of a cavity band blocking filter according to the present invention, and FIG. 2 is a frontal tomographic configuration diagram of the cavity band blocking filter according to the present invention. 4 is a cross-sectional configuration diagram of a cavity type band stop filter according to the present invention, and FIG. 4 is a real photograph of the cavity type band stop filter according to the present invention, and FIG. 5 is a CDMA using the band type band stop filter according to the present invention. Fig. 6 is a state diagram of the insertion loss and the standing wave ratio in the transmission band, and Fig. 6 is a state diagram of the insertion loss and the standing wave ratio in the CDMA reception band using the cavity type band stop filter according to the present invention.

2 and 3, the cavity type band stop filter 200 according to the present invention,

In band rejection filters that prevent high frequency (RF) signals of certain bands from passing through,

A center line 90 for transmitting a high frequency (RF) signal constitutes a waveguide 100 fixed therein by the dielectric 110, and forms a plurality of Halls 70; Each of the holes 70 is fixed by screwing the adjusting rod (80) consisting of an INVAR (Invar); For example, 12 mm (mm) thickness, the upper plate 15 and the lower plate 17 of the same size is integrally fastened by the third screw (7), for example, with a predetermined depth of 8 millimeters (mm) Grooves having continuous length form a deformed " d " shaped waveguide 100; The center of the waveguide 100 transmits a signal, and a metallic center line 90 plated with silver of 10 micrometers (um) on a brass wire having a diameter of 3 millimeters (mm) is a dielectric having a predetermined size ( The center line 90 is integrally formed by an insulating state, and the center line 90 is a predetermined length at intervals corresponding to one quarter wavelengths of the band stopping center frequency and is open stub of the same material as the center line 90. Lid 10 for attaching and fixing the 95 in the direction of the cavity 40,

The plurality of N-type terminals 20 which are integrally fixed by the lid part 10 and the fourth screw 8 and electrically connected to the center line 90 to input or output signals, are reversible. )Wow,

A plurality of cavities 40 of the same size are formed, and the cavity resonators 50 are fixed to the bottom of the center of each cavity 40 by the first screw 5, respectively; Made of aluminum (DL) material; Each cavity 40 is configured at intervals corresponding to 1/4 wavelengths of the band rejection center frequency; Each cavity resonator 50 is 15 mm (mm) in diameter and 55 mm (mm) in length using an INVAR material, which is a kind of synthetic metal material, and at the same time, the center of the cavity is empty. It consists of.

Hereinafter, the cavity type band stop filter 200 according to the present invention having the above configuration will be described in detail with reference to FIGS. 1 to 3.

The body portion 30 is formed by using an aluminum (Al) material, and as an example, the cavity using aluminum having a width of 246 mm (mm), a length of 198 mm (mm), and a thickness of 75.5 mm (mm). 20 are formed, and each cavity 40 is formed at an interval corresponding to a quarter wavelength of the band stopping center frequency, and forms five horizontally and four vertically.

At the center point of each cavity 40, a cavity resonator 50 made of INVAR, which is a synthetic metal material, is installed, and the body part 30 and the first screw 5 are used. Fastened and fixed.

In more detail, the pupil resonator 50 is formed in a cylindrical shape using an INVAR material, for example, having a diameter of 15 millimeters (mm) and a length of 55 millimeters (mm). As the cavity 60 is formed, it is located at the center of each cavity 40 formed in the body portion 30 while being empty cylindrical and fastened integrally with the body portion 30 by the first screw 5. Is fixed.

As the cavity 40 of the body portion 30 as described above, the lid portion 10 is mounted, and is fastened and fixed to the body portion 30 by a plurality of second screws (6).

The lid portion 10 is composed of the upper plate 15 and the lower plate 17, each made of aluminum (Al) and fastened by a plurality of third screws (7), the thickness is one example, 12 Millimeters (mm).

In the lid portion 10, holes 70 are formed in portions corresponding to the cavity resonators 50 respectively fixed to the cavity 40 of the body portion 30 to be fastened.

The hole 70 penetrates the upper plate 15 completely, extends to a part of depth to the lower plate 17, and is formed at the center of the hole 70 extending to the lower plate 17. The adjusting rod 80 made of a screw or a skew type penetrates by using an invar (INVAR), which is a metal material, is inserted into the center of the cavity cavity 60 of the pupil resonator 50. Is controlled by.

The lower plate 17 of the lid portion 10 forms a deformed “d” shaped waveguide (Wave Guide) 100, and the waveguide 100 has a depth, for example, 8 millimeters (mm). Is formed.

The waveguide 100 passes through a plurality of, for example, 20 cavities 40 formed in the body portion 30.

Inside the waveguide 100, a center line 90 is formed by electroplating a silver having a diameter of 3 millimeters (mm) and electroplating silver having excellent electrical conductivity to a thickness of 10 micrometers (um) or more.

In order to prevent electrical contact between the center line 90 and the waveguide 100, for example, a dielectric 110 made of Teflon having a dielectric constant of 2 and manufactured in a small size is inserted.

As described above, the center line 90 inserted into the waveguide 100 in an insulated state by the dielectric 110 may have an open stub 95 having a predetermined length in units of a quarter wavelength. , For example, by using a solder or the like.

Made of the same material as the center line 90 as described above, the open stub 95 attached to the center line 90 at 1/4 wavelength intervals is extended to each cavity 40 is inserted, the pupil resonator ( Resonate of 50 prevents unnecessary band signals, and since there are 20 open stubs 95 inserted into the cavity 40 and the cavity 40, the cavity band The stop filter 200 has a 20-pole characteristic.

In the center line 90 inserted into the waveguide 100 and insulated by the dielectric 110 as described above, the terminals 20 by the N-type connectors are electrically connected to both ends thereof, and the terminal 20 ) Is fastened to the lid portion 10 by the fourth screw (8).

The lid 10 is completed by fastening and fixing the upper plate 15 of the same material and size by the third screw 7 in order to protect the lower plate 17 of the above configuration.

Therefore, the dielectric 110 and the center line (20) inserted into the waveguide 100 and the waveguide 100 formed in the 20 cavity 40 and the cavity resonator 50, the lower plate 17 formed in the body portion 30 ( 90) by screwing the open stub 95 and the hole 70 attached to the center line 90, the adjustment rod 80 for adjusting the resonance characteristics of the cavity resonator 50, the external mechanical charge and It protects from foreign materials and shields from external electrical influences.

4 is a real photograph taken of the cavity type band stop filter to which the present invention is applied.

5 is a state diagram of insertion loss and standing wave ratio due to the center frequency of the transmission (Tx) band of the cavity type band stop filter to which the present invention is applied.

5, the insertion loss (S21) and the standing wave ratio (S22) are measured at 869 MHz to 894 MHz, which is a transmission band frequency allocated to the CDMA scheme.

The measuring equipment used HP8753D VNA, and the insertion loss (S21) characteristic is -0.12 dB in the CDMA dedicated band, and ripple occurs at -1.68 dB at the frequency of 889 MHz. As can be seen, this is caused by a sudden attenuation characteristic at 889 MHz.

The standing wave ratio (VSWR) is less than 25 dB, and the attenuation characteristic in the band stopping band 890.2 MHz shows -46.0 dB.

6 is a state diagram in which the insertion loss and the standing wave ratio due to the center frequency of the reception (Rx) band of the cavity-type band stop filter to which the present invention is applied are measured using the HP8753D VNA equipment as described above.

6, the insertion loss (S21) and the standing wave ratio (S22) are measured at 820 MHz to 845 MHz, which is the reception band frequency allocated to the CDMA scheme. Is -0.17 dB and standing wave ratio (VSWR) is also 19 dB or less.

Therefore, in the cavity type band stop filter 200 according to the present invention, the insertion loss (Insertion Loss) is 0.2 dB or less at the center frequency of the transmission band frequency, the magnitude of the input / output standing wave ratio is 1.1 or less, and the attenuation characteristic is also It can be seen that it is excellent at 40 dB or more, and the insertion loss and standing wave ratio characteristics are excellent compared to the band stop filter using a conventional coaxial resonator.

The present invention having the above configuration has the effect of improving the characteristics of the insertion loss and the standing wave ratio of the cavity type band stop filter.

In addition, it is excellent in thermal stability and stable to changes in external temperature and vibration, thereby improving the reliability and performance of the base station equipment.

Claims (7)

In high frequency bandstop filter, A lid portion configured to form a waveguide in which a center line transmitting a high frequency signal is fixed by a dielectric; A plurality of N-type terminals which are integrally formed by the lid and the screw and connected to the center line to input and output signals; A cavity-type bandstop filter, characterized in that a plurality of cavities of the same size are formed and a cavity is respectively fixed to the cavity bottom by a first screw at the center bottom of each cavity. The method of claim 1, wherein the lid portion, Form a plurality of holes corresponding to the plurality of cavity numbers formed in the body portion, Each hole is a cavity band stop filter, characterized in that for fixing by screwing the control rod for adjusting the resonant frequency of the cavity resonator. The method of claim 1, wherein the lid portion, Consist of the same size top and bottom plate, The bottom plate is fixed to the body portion by a plurality of second screws, And the upper plate and the lower plate are fixed by a plurality of third screws. The method of claim 3, wherein the bottom plate, Grooves having a predetermined depth are continuously formed to form a deformed r-shaped waveguide, In the center of the waveguide, a metallic center line transmitting a signal is integrally formed in an insulated state by a dielectric having a predetermined size. The adjusting rod is made of Invar material is fixed to the screw coupled to the center of the hole, And the center line attaches and forms an open stub of a predetermined length in the cavity direction at intervals corresponding to a quarter wavelength of a band stop center frequency. The method of claim 4, wherein The bottom plate is made of aluminum with a constant thickness of 12 millimeters, The waveguide formed on the bottom plate is formed to a depth of 8 millimeters, The center line and the open stub is a hollow band-stop filter, characterized in that the silver plated with a thickness of 10 micrometers in brass of 3 millimeters in diameter. According to claim 1, The body portion is made of aluminum, Each cavity is configured at intervals corresponding to a quarter wavelength of the band stop center frequency, Each cavity resonator is a cavity-type band stop filter, characterized in that the center to be empty at the same time as 15 mm in diameter, 55 mm in length using an Invar material. The method of claim 6, The cavity and the cavity resonator filter, characterized in that composed of 20 each of the cavity.