KR20040058602A - Radio frequency filter with dielectric part having high dielectric constant and high quality factor(q) - Google Patents

Abstract

PURPOSE: A radio frequency filter having a dielectric of high dielectric constant and high selectivity is provided to lower a resonant frequency by using the dielectric. CONSTITUTION: A radio frequency filter having a dielectric of high dielectric constant and high selectivity includes a coaxial resonant metal bar, a tuning screw, and a dielectric. The coaxial resonant metal bar(720) is fixed at an inside of a storage region of a metal housing. The tuning screw(770) is installed at a predetermined of a cover corresponding to the coaxial resonant metal bar in order to tune a resonant frequency of a wireless frequency filter. The dielectric(800) is coupled to an upper end of the coaxial resonant metal bar. The dielectric has the high dielectric constant and the high selectivity in order to lower the resonant frequency of the wireless frequency filter to a predetermined frequency band.

Description

RADIO FREQUENCY FILTER WITH DIELECTRIC PART HAVING HIGH DIELECTRIC CONSTANT AND HIGH QUALITY FACTOR (Q)}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency filter, and more particularly to a radio frequency filter having a smaller size and a lower resonance frequency.

Typically, radio frequency filters are used to pass, stop, and time delay signal frequency bands. The resonance frequency of the radio frequency filter is adjusted by adjusting means such as a tuning screw, thereby adjusting the characteristics of the radio frequency filter.

Hereinafter, the conventional radio frequency filter 100 will be described with reference to FIGS. 1 to 6.

1 is a perspective view illustrating a radio frequency filter 100 having a disc-shaped resonant metal rod 120 according to an exemplary embodiment. As shown in FIG. 1, the radio frequency filter 100 according to an exemplary embodiment includes a metal housing 110, a disc-shaped resonant metal rod 120, a cover 160, and tuning screws 170 and 175. It is configured to include.

The metal housing 110 includes an input terminal 111 and an output terminal 113, the inside of which is separated into a plurality of receiving spaces by the diaphragm 130, so that the disc-shaped resonant metal rods 120 each receive. Housed in space. The input terminal 111 and the output terminal 113 are provided on the same side of the metal housing 110, respectively, and are connected to one selected accommodation space. In addition, the diaphragm 130 has coupling windows 131, 132, 133, 134 and 135 connected in series from the accommodation space to which the input terminal 111 is connected to the accommodation space to which the output terminal 113 is connected. Is formed. The upper surface of the metal housing 110 is open, and the upper end of the metal housing 110 is sealed by the cover 160 when the disc-shaped resonant metal rod 120 is accommodated in each receiving space.

The disc-shaped resonant metal rod 120 includes a resonant metal rod 121 extending from the bottom surface of the metal housing 110 and a disc 122 extending in the radial direction along the upper outer peripheral surface of the resonant metal rod 121. do.

The radio frequency filter 100 provided with the disk 122 on the top of the resonant metal rod 120 assembled to the metal housing 110 is another type of radio frequency filter provided with a straight resonant metal rod. Compared with, there is a characteristic of operating for a relatively low resonance frequency.

Referring to FIGS. 3, 4, and 12, the correlation between the resonant frequency and the metal housing 110, the disc-shaped resonant metal rod 120, the diaphragm 130, and the cover 160 will be described.

In general, as shown in the circuit diagram shown in FIG. 12, the resonant frequency F ₀ is the capacitive component 17 and the inductive component 19 that constitute the resonant circuit, that is, the metal housing 110 and the disc-shaped resonant metal rod 120. , And the capacitance C ₀ and inductance L ₀ formed between the diaphragm 130 and the cover 160 are determined by Equation 1 below.

Here, F ₀ represents a resonant frequency, L ₀ represents an inductance, and C ₀ represents a capacitance. As shown in Equation 1, the resonance frequency F ₀ is inversely proportional to the product of the inductance L ₀ and the capacitance C ₀ . In other words, the resonant frequency F ₀ is greatly influenced by the inductance L ₀ as the inductive component and the capacitance C ₀ as the capacitive component.

Hereinafter, the elements for determining the capacitance C ₀ will be described and a method for adjusting the resonance frequency F ₀ will be described.

Capacitance C ₀ is defined by Equation 2 below.

Where ε ₀ is the permittivity, D is the distance between electrodes, and A is the active area forming a capacitive bond. According to Equation 2, the capacitance C ₀ is in proportion to the dielectric constant ε ₀ , the active area A, and inversely proportional to the distance D between electrodes.

The active area A is defined by Equation 3 on the radio frequency filter 100.

A is the area of the disk 122 of the coaxial resonant metal rod 120, Φ A1 is the outer diameter of the disk 122, Φ A2 is the inner diameter of the disk 122.

The resonant frequency F ₀ and the capacitance C ₀ is the inverse relationship, the capacitance C ₀ is the resonance of the disc, since a proportional relationship to the area of 122, the disk 122 is the larger area the radio frequency filter 100 of the It can be seen that the frequency F ₀ is lowered. Thus, the resonant frequency F ₀ of the radio frequency filter 100 is inversely proportional to the dielectric constant ε ₀ of the medium present between the disk 122 and the cover 160 (172 (shown in FIG. 3)), and the distance thereof. It can be seen that it is proportional to D.

On the other hand, the inductance L ₀ in inverse relationship with the resonant frequency F _{0 is} in proportion to the length L of the disc-shaped resonant metal rod, and inversely related to the outer diameters Φ D1 and Φ A1 of the disc-shaped resonant metal rod 120. have.

As described above, the desired resonance frequency F ₀ can be obtained by adjusting the capacitance C ₀ and the inductance L ₀ values by adjusting the length, outer diameter, etc. of the disc-shaped resonant metal rod.

Meanwhile, referring to FIGS. 5 and 6, the input terminal 111 and the output terminal 113 are connected to the disc-shaped resonant metal rod 120 by an input end coupling copper wire 115 and an output end coupling copper wire 117, respectively. do.

The resonant frequency F ₀ of the radio frequency filter 100 configured as described above is adjusted through the length, outer diameter, etc. of the disc-shaped resonant metal rod 120, but is more precisely controlled using a separate tuning screw.

Referring to FIG. 1, the tuning screws 170 and 175 are fastened to the cover 160 in correspondence with the positions of the disc-shaped resonant metal rods 120 accommodated in the metal housing 110, and also to the diaphragm 130. It is also fastened to a position corresponding to the coupling window (131 to 135) is formed. The tuning screws 170 and 175 are used to adjust the resonance characteristics and coupling characteristics of the radio frequency filter 100, and after adjusting the resonance characteristics and coupling characteristics, to prevent the flow of the tuning screws 170 and 175. It is fixed by the nut 171. A fastening hole 169 for the screw 179 is formed in the cover 160, and a fastening tab 180 is formed at an upper end of the metal housing 110, so that the cover 160 is formed of the metal housing. It is fixed to the top of 110.

The tuning screws 170 and 175 are fastened to a screw hole (not shown) formed in the cover 160 and used to adjust the resonance frequency, inductance or capacitance. That is, the radio frequency filter 100 is tuned by tightening or releasing the tuning screws 170 and 175 to obtain desired resonance characteristics and coupling characteristics. When the tuning of the radio frequency filter 100 is completed, the tuning screw 170, 175 flows so that the tuning screw using a nut 171 or the like to prevent the resonance frequency, resonance characteristics and coupling characteristics from changing. Fixes 170 and 175 on the cover 160.

On the other hand, the tuning screw 170, 175 is fixed to a position corresponding to the disc-shaped resonant metal rod 120 and the first tuning screw 170 used to adjust the resonance characteristics, and the coupling window (131 to 135) and The second tuning screw 175 is fixed to the corresponding position and used for adjusting the coupling characteristics. The first and second tuning screws 170 and 175 may have different roles depending on their positions.

Hereinafter, the operation of the radio frequency filter 100 will be described with reference to FIGS. 1 and 12.

First, the input end coupling copper wire 115 and the output end coupling copper wire 117 provide inductive couplings 52 and 58, and the metal housing 110, the disc-shaped resonant metal rod 120, and the cover 160. Parallel LC resonant circuits (10, 11, 12, 13, 14, 15) are formed by the respective resonant circuits (10 to 15) are adjacent to each other disk-shaped resonant metal rods 120 Between the disc-shaped resonant metal rod 120 and the metal housing 110, the coupling window (131 to 135) by the mutual relationship of each of the capacitive (17) or inductive (19) coupling is provided.

When a radio frequency signal is applied to the input terminal 111, electric field energy is formed while current flows through the input end coupling copper wire 115. The electromagnetic energy is transferred to the parallel LC resonant circuit 10 including the metal housing 110, the disc-shaped resonant metal rod 120, and the cover 160. The electromagnetic energy transmitted to the parallel LC resonant circuit 10 is transmitted to the next parallel LC resonant circuit 11 adjacent only to the frequency energy corresponding to the resonance frequency F ₀ of the parallel LC resonant circuit 10, and other frequencies. Energy is grounded (G). An inductive coupling 53 is provided between the parallel LC resonant circuit 10 and the next parallel LC resonant circuit 11 adjacent to transmit frequency energy corresponding to the resonance frequency F ₀ . As described above, the radio frequency filter 100 is configured in series with alternating parallel LC resonant circuits 10 to 15 and inductive or capacitive coupling between the input terminal 111 and the output terminal 113. .

Therefore, only the signal corresponding to the resonant frequency F ₀ of the parallel LC resonant circuits 10 to 15 is output through the output terminal 113 in the frequency signal applied to the input terminal 111.

On the other hand, miniaturization and integration of radio frequency filters are increasingly required, and for the design of miniaturization of radio frequency filters, the length of the resonant metal rod should be short. However, as mentioned above, if the length of the metal resonant rod is shortened for miniaturization of the radio frequency filter, there is a problem in that the resonant frequency increases and it is difficult to obtain the resonant frequency in the low frequency band.

In order to obtain the resonant frequency F ₀ in the low frequency band, the resonant metal rod is designed in the shape of a disc. The area of the top surface of the resonant metal rod 121 defined by Eq. The A and the resonance frequency F ₀ can be lowered by designing the distance D with the inner surface of the cover 160 corresponding to the area formed by the disc-shaped resonant metal rod 120 very close. At this time, the medium 172 between the cover 160 and the top of the disc-shaped resonant metal rod 120 is air, the dielectric constant of the air is 1.

As described above, in the prior art, a disk-type resonant metal rod is used to reduce the size of the radio frequency filter while lowering the resonance frequency, and the gap between the disc-shaped resonant metal rod and the cover is designed to be very close.

However, in a radio frequency filter using a disc-shaped resonant metal rod, reducing the size and reducing the resonance frequency is a peak in the trend of increasing the number of applied power and carriers because the distance between the cover and the disc-shaped resonant metal rod is designed to be very close. The power (Peak Power) is further increased, there is a problem that the arc discharge occurs, and can not be used in the base station transmission frequency band.

In addition, in order to reduce the manufacturing cost, the housing and the resonant metal rods are designed as an integrated die casting mold. In the case of a disc type resonant metal rod, a mold in which the resonant metal rod and the housing are integrated cannot be manufactured due to the mold structure.

In addition, since the resonant characteristics are very sensitive to the radio frequency filter using the disc-shaped resonant metal rod, there is a problem that the characteristics of the product vary greatly according to assembly tolerances and processing tolerances during product implementation and manufacturing.

In addition, as the resonance characteristic of the radio frequency filter is sensitive, there is a disadvantage that the defect rate is very high and the characteristics of each individual product are different from each other in the production of the product.As the product is sensitive, the tuning time is long and the production time increases. There is this.

Furthermore, when the frequency is reduced while reducing the filter size, there is a problem in that the selectivity (Q) value actually implemented at the corresponding frequency decreases at the corresponding frequency, thereby failing to realize desired electrical characteristics.

In order to solve the above problems, an object of the present invention is to provide a radio frequency filter that can reduce the resonant frequency while reducing the size of the filter compared to the frequency used.

It is still another object of the present invention to provide a radio frequency filter capable of implementing stable characteristics at high peak power while reducing the size of a transmission filter.

Another object of the present invention is to provide a radio frequency filter capable of sufficiently securing the selectivity (Q) value while reducing the size of the filter compared to the frequency used.

Still another object of the present invention is to provide a radio frequency filter which can be manufactured through a die casting process by integrally designing the housing and the resonant metal rod while reducing the size of the filter compared to the use frequency.

Still another object of the present invention is to provide a radio frequency filter that is easy to adjust its electrical characteristics while reducing the size of the filter compared to the frequency used.

In order to achieve the above object, the present invention is provided with a metal housing having an upper end and at least two receiving spaces by a predetermined diaphragm, coupled to the metal housing to form each of the receiving spaces. A radio frequency filter having a cover to seal,

A coaxial resonant metal rod fixed in the accommodation space of the metal housing;

A tuning screw fastened to the cover at a position corresponding to the coaxial resonant metal rod and used to tune the resonant frequency of the radio frequency filter; And

Disclosed is a radio frequency filter including a dielectric material coupled to an upper end of the coaxial resonant metal rod and having a dielectric constant having a high dielectric constant and a high selectivity (Q) value that lowers the resonance frequency of the radio frequency filter to a predetermined use frequency band.

1 is a perspective view showing a radio frequency filter with a disc-shaped resonant metal rod according to a conventional embodiment;

FIG. 2 is a partially cutaway perspective view illustrating a configuration of the radio frequency filter illustrated in FIG. 1;

3 is a side cross-sectional view showing a cut part in the configuration of the radio frequency filter shown in FIG.

4 is a plan view showing an open state of the upper end of the housing in the configuration of the radio frequency filter shown in FIG.

5 is a perspective view illustrating the inside of an input terminal of a radio frequency filter by cutting along the line B shown in FIG. 1;

6 is a perspective view showing the inside of the output terminal of the radio frequency filter by cutting along the line C shown in FIG.

7 is a perspective view showing a radio frequency filter having a dielectric according to a preferred embodiment of the present invention;

FIG. 8 is a view showing top, side and bottom surfaces respectively showing the dielectric of the radio frequency filter shown in FIG. 7;

9 is a partially cutaway perspective view illustrating a configuration of the radio frequency filter illustrated in FIG. 7;

FIG. 10 is a side cross-sectional view of a portion cut away in the configuration of the radio frequency filter shown in FIG. 9; FIG.

FIG. 11 is an exploded perspective view illustrating a state in which a dielectric is assembled in the radio frequency filter shown in FIG. 9;

12 is an equivalent circuit diagram for describing an operation of the radio frequency filter illustrated in FIG. 7.

13 is a side cross-sectional view showing a configuration of a radio frequency filter according to another embodiment of the present invention;

14 is a side cross-sectional view showing a configuration of a radio frequency filter according to another embodiment of the present invention.

<Description of Major Symbols in Drawing>

700: radio frequency filter 710: metal housing

711: input terminal 713: output terminal

720: coaxial resonant metal rod 730: diaphragm

731 to 735: bonding window 760: cover

770: tuning screw 800: dielectric

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

FIG. 7 is a perspective view showing a radio frequency filter 700 having a dielectric 800 according to a preferred embodiment of the present invention, and FIG. 8 shows the dielectric 800 of the radio frequency filter 700 shown in FIG. 9 is a partial cutaway perspective view showing the configuration of the radio frequency filter 700 shown in FIG. 7, and FIG. 10 is a view of the radio frequency filter 700 shown in FIG. FIG. 11 is an exploded perspective view illustrating a state in which the dielectric material 800 is assembled in the radio frequency filter 700 illustrated in FIG. 9. As shown in FIGS. 7 to 11, the radio frequency filter 700 according to the preferred embodiment of the present invention includes a dielectric 800 having a high dielectric constant ε ₀ and a selectivity (Q) value. Will lower the value to _zero .

The radio frequency filter 700 includes a metal housing 710, a coaxial resonant metal rod 720, a cover 760, and tuning screws 770 and 775, and each of the coaxial resonant metal bars 720. ) And the cover 760 is provided with the dielectric 800.

The metal housing 710 is provided with an input terminal 711 and an output terminal 713, the inside of which is separated into a plurality of receiving spaces by a diaphragm 730 and coaxial with the coaxial resonant metal rod 720. Dielectrics 800 fastened to the metal rods 720 are respectively received. The input terminal 711 and the output terminal 713 are provided on the same side of the metal housing 710, and are connected to one selected accommodation space, respectively. In addition, the diaphragm 730 has coupling windows 731, 732, 733, 734, and 735 connecting in series from the accommodation space to which the input terminal 711 is connected to the accommodation space to which the output terminal 713 is connected. It is provided. The upper surface of the metal housing 710 is open, the cover 760 is coupled. A plurality of fastening tabs 780 are formed at upper ends of the metal housing 710 and the diaphragm 730, respectively.

The input terminal 711 and the output terminal 713 are respectively connected to the coaxial resonant metal rod 720 of the accommodation space by an input end coupling copper wire (not shown) and an output end coupling copper wire (not shown), respectively. This is easily understood through the configuration of the conventional input and output terminals 111 and 113 shown in Figs. 5 and 6, respectively.

Tuning screws 770 and 775 are assembled to the cover 760 corresponding to the coaxial resonant metal rod 720 and the dielectric 800 positioned in the metal housing 710, and are formed in the diaphragm 730. It is also assembled to a position corresponding to the engaging windows (731 to 735). The tuning screws 770 and 775 adjust the resonance characteristics and coupling characteristics of the radio frequency filter 700, and then nuts 771 are coupled to prevent the flow. A screw 779 is fastened to the fastening hole 769 formed in the cover 760 so that the cover 760 is fixed to the fastening tab 780 at the top of the metal housing 710.

The tuning screws 770 and 775 are fastened to a screw hole (not shown) formed in the cover 760 to be used to adjust the resonance frequency F ₀ (inductance L ₀ or capacitance C ₀ ), inductance L or capacitance C. do. That is, tuning the radio frequency filter 700 by adjusting or tightening the tuning screws 770 and 775, that is, adjusting the resonant frequency F ₀ (inductance L ₀ or capacitance C ₀ ), inductance L or capacitance C. It is. When the tuning of the radio frequency filter 700 is completed, the tuning screws 770 and 775 may flow to change characteristics of resonance frequency F ₀ (inductance L ₀ or capacitance C ₀ ), inductance L, or capacitance C, and the like. In order to prevent this, the tuning screws 770 and 775 are fixed on the cover 760 by using a nut 771 or the like.

Meanwhile, the tuning screws 770 and 775 are fixed at positions corresponding to the coaxial resonant metal rod 720 and the dielectric 800, and are used to adjust the resonance frequency F ₀ (inductance L ₀ or capacitance C ₀ ). It is divided into a tuning screw 770 and a second tuning screw 775 fixed to a position corresponding to the coupling windows 731 to 735 and used to adjust the inductance L or the capacitance C. The first and second tuning screws 770 and 775 have different roles depending on their positions.

As shown in FIGS. 8 and 11, the dielectric 800 has a protrusion formed at a predetermined height on one surface thereof and is coupled to a recess formed on an upper portion of the coaxial resonant metal rod 720, whereby the dielectric 800 is coaxial. It is fixed to the type resonant metal rod 720. A predetermined screw 850 is used to secure the coupling between the dielectric 800 and the coaxial resonant metal rod 720. The screw 850 is manufactured using a material selected from iron (Fe), stainless (Sus), brass (Brass), polycarbonate, MC nylon, or pick. In the case of the metallic material such as iron (Fe), stainless steel (Sus), brass (Brass) among the materials of the screw 850, silver plating (Ag Plating) to meet the characteristics of the radio frequency filter 700 It is desirable to.

Hereinafter, the operation of the radio frequency filter 700 configured as described above will be described with reference to FIG. 12. 12 is a diagram illustrating an equivalent circuit of the radio frequency filter 700.

In the radio frequency filter 700, the input coupling copper wire and the output coupling copper wire provide inductive couplings 52 and 58. The parallel LC resonant circuits 10 to 15 are formed by the resonant metal rod 720 and the dielectric 800, the metal housing 710, and the cover 760. Resonance characteristics such as the resonance frequency F ₀ are adjusted by the first tuning screw 770. The resonant metal bars 720, the dielectric 800, or the metal housing 710 between the respective resonant metal bars 720 and the dielectric 800, which are adjacent to each other of the resonant circuits 10 to 15. Each other, each of the coupling windows 731 to 735 is provided with an inductive or capacitive coupling 53 to 57. Coupling characteristics of the inductive or capacitive coupling 53 to 57 are controlled by the second tuning screw 775.

When a radio frequency signal is applied to the input terminal 711 in the radio frequency filter 700, electric field energy is formed while current flows through the input end coupling copper wire. The electromagnetic energy is transferred to the parallel LC resonant circuit 10 formed by the resonant metal rod 720 and the dielectric 800, the metal housing 710, and the cover 760. Of the electromagnetic energy transmitted to the resonant circuit 10, the frequency energy corresponding to the resonant frequency F ₀ of the resonant circuit 10 is transmitted to the next parallel LC resonant circuit 11, and the other frequency energy is grounded ( To G). Between the parallel LC resonant circuit 10 and the next parallel LC resonant circuit 11 adjacent to each other, a configuration relationship between the resonant metal rod 720 and the dielectric 800, the metal housing 710, and the coupling window 731 is provided. Frequency energy is transferred through an inductive or capacitive coupling 53 formed by. That is, the frequency energy filtered by the parallel LC resonant circuit 10 is adjacent to the next parallel LC resonant circuit 11 through the inductive or capacitive coupling 53 between the resonant circuit 10 and the resonant circuit 11. Will be delivered to.

Through the above process, the frequency energy corresponding to the resonant frequency F ₀ of the resonant circuits 10 to 15 is transferred to the resonant circuit 15 connected to the output end coupling copper wire. The frequency energy transferred to the resonant circuit 15 connected to the output end coupling copper wire generates a current by the inductive coupling 58 of the output end coupling copper wire, and thus, to the resonant frequencies of the resonant circuits 10 to 15. Only the corresponding signal is output to the output connector 713.

Referring to FIGS. 8 to 11, the configuration of the LC resonant circuit 10 to 15 may be described. A coaxial resonant metal rod 720 integrally formed in the metal housing 710 and the coaxial resonant metal rod 720 may be described. It is composed of a screw 850 for fixing the dielectric 800 and the coaxial resonant metal rod 720 and the dielectric 800 assembled on the top.

The resonance frequency F ₀ of the LC resonant circuit as described above is defined by Equations 1 and 2, and the active area A of Equation 2 may be defined as the following active area B: .

Here, B is the area of the upper end of the coaxial resonant metal rod 720, Φ B1 is the outer diameter of the coaxial resonant metal rod 720, Φ B2 is the inner diameter of the coaxial resonant metal rod 720.

An inductance L ₀ value that is inversely related to the resonant frequency F ₀ is directly proportional to the length L1 of the coaxial resonant metal rod 720 and inversely related to the area B of the upper end of the coaxial resonant metal rod 720.

According to Equation 2, the capacitance C _{0 which} is inversely related to the resonant frequency F ₀ is _equal to the distance d2 or D3 between the top of the coaxial resonant metal rod 720 and the cover at a corresponding position. Fixed variable) and an inverse relationship with the area B of the upper end of the coaxial resonant metal rod 720 defined by Equation (4). In addition, the dielectric constant ε ₀ of the dielectric 800 provided between the coaxial resonant metal rod 720 and the cover 760 is directly proportional to each other.

In particular, as the dielectric constant ε ₀ of the medium 772 filling the coaxial resonant metal rod 720 and the cover 760 increases, the value increases proportionally, which is very useful as a means of lowering the resonance frequency F ₀ . Therefore, unlike the conventional radio frequency filter, the radio frequency filter 700 according to the present invention has a structure in which a dielectric material 800 having a high dielectric constant ε ₀ is interposed between the coaxial resonant metal rod 720 and the cover 760. .

The dielectric material 800 uses a ceramic having a dielectric constant ε ₀ of 38. Since the dielectric constant of air is 1, the same effect as the capacitance C ₀ increases by 38 times.

By shortening the length of the coaxial resonant metal rod 720, miniaturization of the radio frequency filter 700 is easily achieved. On the other hand, as mentioned above, if the length of the coaxial resonant metal rod 720 is shortened, the inductance component L ₀ is reduced, the resonance frequency F ₀ is very high. By installing a dielectric having a high dielectric constant between the coaxial resonant metal rod 720 and the cover 760 according to the present invention, the capacitance C ₀ value is remarkably reduced while the length of the coaxial resonant metal rod 720 is shortened. This increases the offset value of the resonance frequency F ₀ as the inductance L ₀ decreases. As a result, by providing a dielectric material 800 having a high dielectric constant between the coaxial resonator rod 720 and the cover 760, the miniaturization of the radio frequency filter 720 is achieved, and at the same time, a low frequency is achieved. The resonant frequency F ₀ can be secured in the band.

In addition, the tuning screw 770 may be inserted into the dielectric 800 by forming a space having an inner diameter Φ E2 in the dielectric 800 so that the tuning screw 770 may vary up and down. Therefore, the variable amount of capacitance C ₀ becomes much larger than that of air having a dielectric constant of 1. That is, the depression formed on the top of the coaxial resonant metal rod 720 not only provides the fixing means of the dielectric 800, but also the tuning screw 770 to vary the capacitance C ₀ using the inside of the depression. It can be.

On the other hand, when the resonance frequency F ₀ generally decreases, the selectivity Q value of the radio frequency filter also decreases.

The Q · f of the dielectric constant 38 dielectric 800 used in the present invention is about 50,000. Here, Q refers to the unloaded Q, f is the lowest resonant frequency that can be realized by the dielectric 800, and the unit is GHz.

If the dielectric constant is more than 9 and the selectivity (Q) value is not sufficiently secured, even if the size of the radio frequency filter is reduced, the insertion loss of the radio frequency filter is increased, and the application to the system is restricted.

As a method of increasing the capacitance C ₀ value, a thicker portion T1 of the dielectric 800 or a larger outer diameter Φ E3 of the dielectric 800 may be made in FIG. 8 or 10. have. In addition, there may be a method of reducing the distance D3 between the cover 760 and the coaxial resonant metal rod 720 and the distance d2 between the cover 720 and the dielectric 800. That is, by using not only the dielectric constant of the dielectric 800 but also a change in mechanical dimensions, a change in shape, and the like, a sufficient capacitance C ₀ value can be secured to reduce the resonance frequency to a desired use frequency band.

13 and 14 are side cross-sectional views illustrating a configuration of a radio frequency filter including a dielectric according to another embodiment of the present invention.

Referring to FIG. 13, the dielectric is fixed in a state in which the dielectric 800B is sandwiched between the coaxial resonant metal rod 720B and the cover 760, and the tuning screw 770 passes through the dielectric 800B. Through-holes are formed.

14 is a view in which the dielectric 800C is fixed to the lower end of the tuning screw 770C by using a predetermined screw 850C. The dielectric 800C is variable according to the rotation of the tuning screw 770C between the tuning screw 770C and the coaxial resonant metal rod 720C.

The radio frequency filter manufactured under the above conditions is smaller in size than the conventional disk type resonant metal rod type radio frequency filter in the 50MHz to 2000MHz band, thereby achieving better performance. In addition, since the gap between the tuning screw and the coaxial resonant metal rod is relatively far apart, the dielectric voltage of the dielectric is higher than that of air, thereby reducing the risk of arc discharge at higher peak power. It became.

In addition, since the coaxial resonant metal rod can be used without using the disc resonant metal rod, the metal housing and the resonant metal rod can be manufactured integrally through the die casting process, thereby contributing to cost reduction.

On the other hand, although not shown, if the metal housing and the resonant metal rods are not manufactured integrally, and manufactured separately, the disk-type resonant metal rods can be applied to maintain the resonance frequency lower. When the disc-shaped resonant metal rod is applied, it is apparent that the dielectric 800 is coupled to the top surface of the disc of the disc-shaped resonant metal rod.

In the foregoing detailed description of the present invention, specific embodiments have been described. However, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the present invention.

As described above, the radio frequency filter according to the present invention contributes to the miniaturization of the size of the filter compared to the frequency used, and it is possible to lower the resonance frequency by using a dielectric. In addition, by using a dielectric having a larger insulation voltage than air between the cover and the coaxial resonant metal rod, it is possible to realize stable characteristics at high peak power. Furthermore, since the selectivity (Q) value can be sufficiently secured while the resonance frequency is lowered, it contributes to the improvement of the performance of the radio frequency filter. In addition, the conventional disc-shaped resonant metal rods have to be manufactured and assembled separately from the metal housing and the resonant metal rods, but the radio frequency filter according to the present invention can manufacture the metal housing and the resonant metal rods integrally through a die casting process, thereby reducing processing costs. In addition, productivity is improved by simplifying the assembly process, and manufacturing costs such as other logistics costs can be reduced. In addition, by using a dielectric having a high dielectric constant, it becomes easier to control electrical characteristics.

Claims (12)

A radio frequency filter having a metal housing having an upper end and provided with at least two accommodation spaces by a predetermined diaphragm, and having a cover coupled to the metal housing to seal the respective accommodation spaces, A coaxial resonant metal rod fixed in the accommodation space of the metal housing; A tuning screw fastened to the cover at a position corresponding to the coaxial resonant metal rod and used to tune the resonant frequency of the radio frequency filter; And And a dielectric material coupled to an upper end of the coaxial resonant metal rod and having a dielectric constant having a high dielectric constant and a high selectivity (Q) that lowers the resonance frequency of the radio frequency filter to a predetermined use frequency band. According to claim 1, Wherein said dielectric has a selectivity (Q) value such that the product of selectivity (Q) and use frequency (GHz) is greater than or equal to 20,000. According to claim 1, Radio frequency filter, characterized in that the material of the dielectric is manufactured using a ceramic. According to claim 1, The shape of the dielectric is a radio frequency filter, characterized in that the disk shape having a predetermined thickness. According to claim 1, Fixing protrusions are formed on one surface of the dielectric, And a depression in which the protrusion of the dielectric is inserted at an upper end of the coaxial resonant metal rod. According to claim 1, The protrusion of the dielectric is provided with a screw hole, The recess of the coaxial resonant metal rod is provided with a fastening hole, And said dielectric is fixed to said coaxial resonant metal rod by a screw. The method of claim 6, The material of the screw that provides a fastening force to couple and fix the dielectric to the coaxial resonant metal rod, Radio frequency filter, characterized in that made using a material selected from iron (Fe), stainless (Sus), brass (Brass), polycarbonate, M.C Nylon or Peak (Peek). The method of claim 7, wherein The metal screw made of iron (Fe), stainless steel (Sus) or brass (Brass) is a radio frequency filter, characterized in that produced by silver plating (Ag Plating). The method of claim 1, And the metal housing and the coaxial resonant metal rod are integrally manufactured through a die casting process. According to claim 1, The dielectric is fixed at the same time as being sandwiched between the cover and the coaxial resonant metal rod, And a through hole through which the tuning screw passes. According to claim 1, The dielectric is fastened to the lower end of the tuning screw by a predetermined screw, And a position thereof varies between the cover and the coaxial resonant metal rod. According to claim 1, And a disk extending in the radial direction of the coaxial resonant metal rod from an outer circumferential surface of the upper end of the coaxial resonant metal rod, and having a dielectric fixed thereon.