KR100258788B1 - Microwave band pass filters made with an half-cut coaxial resonators - Google Patents

Abstract

PURPOSE: A band pass filter using the half structure of a coaxial line resonator is provided which reduces the weight and volume of the coaxial line by half while maintaining the electrical characteristic of the coaxial line without any change. CONSTITUTION: A band pass filter using the half structure of a coaxial line resonator includes a plurality of resonators(11,12,13,14) each of which has a semicircular groove formed at the top opening, input/output ports(4,5) included in the resonators, and an electrode separating dielectric(6) capacitive-coupling the resonators with the input/output ports. The band pass filter further has a metal cover plate(3) placed on the outer surfaces of the resonators, a dielectric substrate(2) located between the resonators and the metal cover plate, and a coupling window(7) for providing additional electromagnetic coupling among the resonators.

Description

Bandpass Filter Using Half Structure of Coaxial Resonator

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a band pass filter applied to a terminal of a mobile station for Code Division Multiple Access Personal Communication Service (CDMA PCS) and a mobile station for a CDMA Digital Cellular System (DCS). A band pass filter using a half structure of the present invention.

In general, comb-line bandpass filters using conventional ceramic coaxial resonators are widely used as filter devices for transmitting and receiving antennas of U.S. Patent No. 5,374,906, Japanese Patent Application Laid-Open No. 5-55811, and the like. It is well introduced in the literature.

The conventional band pass filters are small filters widely applied to a mobile terminal or a repeater in a wireless communication field, and are mainly electrically obtained through a line coupling or a capacitive or inductive coupling of a coaxial resonance period.

However, the conventional filters as described above have a limitation in reducing the overall size and weight due to the structural characteristics of the coaxial resonator employed, which makes it difficult to miniaturize them. The problem was that the amount of tuning was difficult.

Accordingly, the present invention has been made to solve the above problems, while maintaining the electrical characteristics of the coaxial resonator as it is, while reducing the weight and volume to almost half, and can easily tune the coupling of the resonance period and the resonance frequency. The purpose of the present invention is to provide a band pass filter using a half structure of a coaxial resonator.

1 is an exploded perspective view showing an embodiment of a band pass filter using a half structure of a coaxial resonator according to the present invention;

2 is an equivalent circuit diagram of FIG.

3 is a graph showing the frequency response characteristics of the bandpass filter of FIG.

Explanation of symbols on the main parts of the drawings

2: dielectric substrate 3: metal cover

4: Input terminal 5: Output terminal

6: dielectric for electrode separation 7: bonding window

8: bonded conductor

11, 12, 13, and 14: first to fourth resonators

The present invention for achieving the above object, the semi-circular groove is formed in the upper opening surface, the inner surface and both sides of the semi-circular groove is plated with a metal, the plurality of resonators the upper opening and the front surface is treated with a dielectric; An input / output terminal mounted on both side semicircular grooves of the plurality of resonators to input and output an ultra high frequency signal; An electrode separation dielectric for performing a mediating function of capacitive coupling between semicircular grooves at both ends of the plurality of resonators and input and output terminals; A metal cover plate fitted to an outer surface of the entirety of the plurality of resonators; Band pass filter using half of a coaxial resonator including a dielectric substrate mounted between the plurality of resonators and the metal cover plate to provide electrical shielding and inductive coupling, and a coupling window to provide additional electromagnetic coupling of the plurality of resonance periods. To provide.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings of FIGS. 1 to 3.

The bandpass filter of the present invention takes only half of a conventional cylindrical coaxial resonator, while maintaining its electrical characteristics and insertion loss while maintaining the volume and weight in half.

1 is an exploded perspective view showing an embodiment of a band pass filter using a half structure of a coaxial resonator according to the present invention. As shown in FIG. 1, the four-stage pass-pass filter according to the present invention is parallel to the first to fourth ceramic resonators 11, 12, 13, and 14 having semi-cylindrical grooves 11a, 12a, 13a, and 14a, respectively. And semi-cylindrical electrode separation dielectrics 6 are provided in the semi-cylindrical grooves 11a, 12a, 13a, and 14a of the first to fourth ceramic resonators 11, 12, 13, and 14, respectively. do.

Here, each of the first to fourth ceramic resonators (11, 12, 13, 14) is the Q value of the resonator metal-plated on the low loss ceramic due to the energy of the electric and magnetic fields in the resonator and the resistivity of the plated metal Since most of it is determined by the loss, it is a structure cut in half along the magnetic field wall, considering that the ratio of surface area and volume is an important factor.

In addition, the first to fourth ceramic resonators 11, 12, 13, and 14 have both sides thereof and the inner surfaces of the semi-cylindrical grooves 11a, 12a, 13a, and 14a plated with a conductor, and the top and front surfaces have a dielectric. It has a cuboid shape treated with.

On the electrode separation dielectric 6, a coupling conductor 8 and input / output conductors 4 and 5 for inputting and outputting high frequency signals are provided, and the coupling conductor 8 has a cylindrical structure located at the center thereof. The conductors are connected to each other while being positioned on the dielectric 6, and the input and output conductors 4 and 5 are respectively located on the cylindrical dielectric 6 positioned at both edges.

In the coupling structure as described above, the coupling conductor 8 directly provides capacitive coupling in the concept of a flat plate capacitor during two resonance periods, thereby directly adjusting C ₂₃ in the equivalent circuit diagram of FIG. Accordingly, in the equivalent circuit diagram shown in FIG. 2, notch can be given to the resonant frequencies of L ₂₃ and C ₂₃ , thereby realizing better asymmetric filter characteristics.

In addition, the input and output terminals 4 and 5 and the semicircular grooves 11a and 14a of the first and fourth ceramic resonators 11 and 14 are connected to the electrode separation dielectric 6 mounted therebetween. Capacitive coupling is achieved, indicated by C ₁ and C ₄₅ in the equivalent circuit diagram of FIG.

On the side of the open end of each of the ceramic resonators 11, 12, 13 and 14, a coupling window 7 having a predetermined size formed of a dielectric material is provided to enable electromagnetic coupling of an additional resonance period.

In the semi-cylindrical grooves of the first to fourth ceramic resonators 11, 12, 13, and 14, the dielectric 6, the input / output conductors 4, 5, and the coupling conductor 8 are overlapped with each other. The dielectric substrate 2 is provided to cover the upper portion. The dielectric substrate 2 forms an additional inductive coupling with the electrical shield, and the outer surface of the dielectric substrate 2 is provided with a metal cover 3 bent at both sides to cover the entire filter structure.

In this embodiment, an example of forming the dielectric substrate 2 is shown as the inductive coupling means. It is well known that the present invention is not limited thereto, and may be formed of a printed circuit board (PCB).

Referring to the working state of the present invention configured as described above are as follows.

First, when two common ceramic coaxial resonators are cut in half in the longitudinal direction, that is, in the direction of the magnetic field wall, four resonators 11, 12, 13, and 14 are formed and configured as an extra filter, additional resonance The coupling window 7 is opened on the side of each resonator open end to enable electromagnetic field coupling in the period.

When an ultrahigh frequency signal is input to the input terminal 4 from the outside, capacitive coupling is performed with the first resonator 11 through the electrode separation dielectric 6, and an output terminal 5 in which the ultra high frequency signal is outputted as well. ) Is capacitively coupled through the dielectric 6 to form C ₁ and C ₄₅ as shown in the equivalent circuit diagram of FIG. 2.

In addition, in the equivalent circuit diagram of FIG. 2, the intermediate couplings (L _nm and C _nm ) are formed by the line coupling via the dielectric substrate 2 between the cut open surfaces of the resonators. In the example structure, the amount of coupling by the inductive component prevails at the center frequency of the filter. Therefore, in order to adjust the bandwidth of the filter as in the structure of the present embodiment, additional coupling is performed by using the coupling windows 7, and the thickness of the dielectric substrate 2 and the size of the coupling windows 7 are changed. Adjust In addition, the coupling conductor 8 is provided on the dielectric 6 placed in the semi-circular grooves 12a and 13a of the second and third resonators 12 and 13 so that capacitive coupling of the two resonance periods 12 and 13 is achieved. Is directly provided to adjust C ₂₃ of the equivalent circuit diagram of FIG. 2 directly. Accordingly, the notch can be notched at a desired point (resonant frequency of L ₂₃ and C ₂₃ ) to realize better asymmetric filter characteristics. The frequency response characteristic diagram of this invention which implemented such an example is shown in FIG.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described above, when comparing the half ceramic resonator and the conventional cylindrical coaxial resonator according to the present invention, since the ratio of the volume and surface area of the resonator is the same, in theory, they have the same Q value. Although reduced in half, the insertion loss of the filter is almost the same as that of a conventional coaxial resonator.

In addition, in the conventional small ceramic filter, a dielectric substrate or PCB is introduced and added to the open access surface, which is often used for coupling resonance periods and replaces the functions of intensive devices that increase insertion loss and manufacturing difficulty. By adopting the coupling window and the coupling conductor as a conventional coupling method, it has the effect of achieving a variety of characteristics and miniaturized filter easily.

Claims (7)

A plurality of resonators in which a semicircular groove is formed in an upper open surface, the inner surface and both sides of the semicircular groove are plated with metal, and the upper open surface and the front surface are treated with a dielectric; An input / output terminal mounted on both side semicircular grooves of the plurality of resonators to input and output an ultra high frequency signal; An electrode separation dielectric for performing a mediating function of capacitive coupling between semicircular grooves at both ends of the plurality of resonators and input and output terminals; A metal cover plate fitted to an outer surface of the entirety of the plurality of resonators; Inductive coupling means mounted between the plurality of resonators and the metal cover plate to provide electrical shielding and inductive coupling; And Electromagnetic coupling means for providing additional electromagnetic coupling of the plurality of resonance periods Band pass filter using half of the coaxial resonator comprising a. The method of claim 1, And a plurality of resonators using a half structure of a coaxial resonator including a ceramic resonator. The method according to claim 1 or 2, A band pass filter using a half structure of a coaxial resonator in which the resonator has a shape in which a half is cut along a magnetic field wall of a known cylindrical coaxial resonator. The method according to claim 1 or 2, A band pass filter using a half structure of a coaxial resonator in which the inductive coupling means is formed of a dielectric substrate. The method according to claim 1 or 2, Band-pass filter using the half structure of the coaxial resonator of the inductive coupling means is a printed circuit board. The method according to claim 1 or 2. And said electromagnetic field coupling means is formed on the side of an open end of each of said plurality of resonators and uses a half structure of a coaxial resonator composed of a coupling window of a predetermined size treated with a dielectric. The method according to claim 1 or 2. A bandpass filter using half of a coaxial resonator further comprising a coupling conductor mounted on an electrode separation dielectric positioned at an intermediate side of the resonator to directly provide capacitive coupling between two resonance periods.