Radio frequency filter

Abstract

The invention relates to a radio frequency filter, which belongs to the technical field of wireless communication, and comprises a first filter, a second filter and a third filter, the first filter is used for filtering in an HF wave band, the second filter is used for filtering in a VHF wave band and / or a UHF wave band, and the third filter is used for filtering in an L wave band; the radio frequency filter comprises a plurality of independent cavities, each cavity is internally provided with a band-pass filter, the outer side of the section of the main body of each cavity is rectangular, and the inner side of the section of the main body of each cavity is a rounded rectangle. According to the radio frequency filter, the working wave band is widened, frequency resources of different wave bands can be effectively utilized, and the communication capacity is improved. Each band-pass filter is arranged in an independent cavity, the cavity is made of copper alloy, and four corners of the inner side of the cavity are arc-shaped, so that the reflection efficiency of signals is improved, signal leakage to adjacent wave bands is reduced, and interference among different wave bands is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a radio frequency filter. Background Art

[0002] In wireless communication devices, radio frequency filters are indispensable key components. Especially in the radio frequency front end of the target analog payload, it is necessary to perform processing such as power amplification, filtering, and power detection on broadband radio frequency signals.

[0003] In the prior art, radio frequency filters generally process single-band radio frequency signals to achieve amplification and filtering of a certain band, and do not have the ability to work with multi-band signals simultaneously. At the same time, at the end of the radio frequency path, the power is large. The corresponding filter not only requires a large power capacity, but the final-stage filter also needs to do a good job in electromagnetic shielding to solve the crosstalk between filters of different frequency bands. When multiple band signals are transmitted simultaneously, the spurs and noise between multiple bands are large, and there will be significant interference between different bands, which cannot meet the market demand for multi-band simultaneous communication. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the purpose of the invention is to provide a radio frequency filter, which broadens the working band, enables it to effectively utilize the frequency resources of different bands, and improves the communication ability.

[0005] The radio frequency filter of the present invention includes: A first filter, a second filter, and a third filter; The first filter is used for filtering the HF band and includes N1 HF band band-pass filters; The second filter is used for filtering the VHF band and / or UHF band and includes N2 V / UHF band band-pass filters; The third filter is used for filtering the L band and includes N3 L band band-pass filters; The radio frequency filter further includes N independent cavities, and one band-pass filter is arranged in each cavity; Each cavity includes a cover plate and a cavity body. The outer side of the cross-section of the cavity body is rectangular, and the inner side of the cross-section of the cavity body is a rounded rectangle; Wherein, N1 is an integer greater than or equal to 7, N2 is an integer greater than or equal to 6, N3 is an integer greater than or equal to 2, and N is an integer and N = N1 + N2 + N3.

[0006] The radio frequency filter of the present invention is provided with Furthermore, the radio frequency filter of the present invention further includes: A filter switching circuit; The filter switching circuit includes an HF band filter switching circuit, a V / UHF band filter switching circuit, and an L band filter switching circuit; The HF band filter switching circuit includes N1 double-pole double-throw electromagnetic relays; The V / UHF band filter switching circuit includes N2 PIN diode switches; The L band filter switching circuit includes N3 PIN diode switches; Each HF band filter switching circuit is connected to an HF band bandpass filter; Each V / UHF band filter switching circuit is connected to a V / UHF band bandpass filter; Each L band filter switching circuit is connected to an L band bandpass filter.

[0007] Further, the four arc-shaped regions of the rounded rectangle are each a quarter circle with a radius of R, the length of the rounded rectangle is greater than 2*R, and the width of the rounded rectangle is greater than or equal to 2*R; Each arc-shaped region is coated with a reflective material.

[0008] Further, On the inner side of the cavity, an absorbing material is provided in the region other than the arc-shaped regions.

[0009] Further, When N1 is equal to 7, the N1 HF band bandpass filters are respectively: The first HF band bandpass filter, with a passband frequency of 1.5 MHz to 2 MHz; The second HF band bandpass filter, with a passband frequency of 2 MHz to 3 MHz; The third HF band bandpass filter, with a passband frequency of 3 MHz to 4.5 MHz; The fourth HF band bandpass filter, with a passband frequency of 4.5 MHz to 7 MHz; The fifth HF band bandpass filter, with a passband frequency of 7 MHz to 11.5 MHz; The sixth HF band bandpass filter, with a passband frequency of 11.5 MHz to 19 MHz; The seventh HF band bandpass filter, with a passband frequency of 19 MHz to 30 MHz; Among them, each HF band band-pass filter is disposed in a cavity, and seven HF band band-pass filters are disposed in seven adjacent cavities. The arrangement order from left to right is: the first HF band band-pass filter, the fourth HF band band-pass filter, the seventh HF band band-pass filter, the second HF band band-pass filter, the fifth HF band band-pass filter, the third HF band band-pass filter, and the sixth HF band band-pass filter.

[0010] Furthermore, When N2 is equal to 6, the N2 V / UHF band band-pass filters are respectively: The first V / UHF band band-pass filter, with a passband frequency of 30 MHz to 50 MHz; The second V / UHF band band-pass filter, with a passband frequency of 50 MHz to 70 MHz; The third V / UHF band band-pass filter, with a passband frequency of 70 MHz to 110 MHz; The fourth V / UHF band band-pass filter, with a passband frequency of 110 MHz to 180 MHz; The fifth V / UHF band band-pass filter, with a passband frequency of 180 MHz to 300 MHz; The sixth V / UHF band band-pass filter, with a passband frequency of 300 MHz to 450 MHz; Among them, each V / UHF band band-pass filter is disposed in a cavity, and six V / UHF band band-pass filters are disposed in six adjacent cavities. The arrangement order from left to right is: the first V / UHF band band-pass filter, the fourth V / UHF band band-pass filter, the second V / UHF band band-pass filter, the fifth V / UHF band band-pass filter, the third V / UHF band band-pass filter, and the sixth V / UHF band band-pass filter.

[0011] Furthermore, two concave-convex structures are used to connect the cover plate and the cavity body.

[0012] Furthermore, a silver-plated copper mesh is provided to cover the gap between the cover plate and the filter cavity body.

[0013] Furthermore, each HF band band-pass filter includes an inductor. The inductor is mounted on a printed circuit board. A copper plate is provided below the printed circuit board. A heat-conducting pad is provided between the copper plate and the printed circuit board. The heat-conducting pad is made of a soft material; The inductor includes an enameled copper wire and a high-frequency magnetic ring. The operating frequency range of the high-frequency magnetic ring is 1 MHz to 20 MHz, or 20 MHz to 40 MHz.

[0014] Furthermore, the cover plate and the cavity body are made of copper alloy.

[0015] The beneficial effects of the present invention are as follows: The RF filter of the present invention broadens the working frequency band and supports the HF band, V / UHF band, and L band at the same time. It can effectively utilize the frequency resources of different bands and improve the communication ability. Each band-pass filter is arranged in an independent cavity. The cavity is made of copper alloy, and the four corners inside the cavity are arc-shaped, which improves the signal reflection efficiency, reduces the signal leakage to adjacent bands, and reduces the interference between different bands. Absorbing materials are arranged in the area other than the arc-shaped part inside the cavity to improve the absorption of signals in this cavity and reduce the interference to adjacent cavities. The band-pass filters of different frequency bands within the same band are arranged in adjacent cavities, and different frequency bands are staggered. The frequency bands of the band-pass filters in two adjacent cavities are not adjacent, thereby reducing the adjacent-frequency interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are only for the purpose of showing specific embodiments and are not considered as limitations of the present invention. Throughout the drawings, the same reference signs denote the same components. Obviously, the drawings in the following description are only some embodiments described in the embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings.

[0017] Figure 1 One of the schematic diagrams of the RF filter according to the embodiment of the present invention; Figure 2 Another schematic diagram of the RF filter according to the embodiment of the present invention; Figure 3 Schematic diagram of the cavity distribution of the RF filter according to the embodiment of the present invention; Figure 4 One of the schematic diagrams of each independent cavity according to the embodiment of the present invention; Figure 5 Another schematic diagram of each independent cavity according to the embodiment of the present invention; Figure 6 Schematic diagram of the heat dissipation design of the RF filter according to the embodiment of the present invention; Figure 7 Schematic diagram of the HF band filter bank according to the embodiment of the present invention; Figure 8 Schematic diagram of the arrangement order of the HF band filter bank in the cavity according to the embodiment of the present invention; Figure 9 Schematic diagram of the V / UHF band filter bank according to the embodiment of the present invention; Figure 10 Schematic diagram of the arrangement order of the V / UHF band filter bank in the cavity according to the embodiment of the present invention; Figure 11 Schematic diagram of the capacitance and inductance layout for the embodiments of the present invention.

[0018] Reference numerals: 1, cover plate; 2, cavity body; 3, reflective material; 4, wave-absorbing material; 5, concave-convex structure; 6, silver-plated copper mesh; 7, inductor; 8, printed circuit board; 9, copper plate; 10, thermal pad; 11, enameled copper wire; 12, high-frequency magnetic ring; 13, equipment housing; 14, capacitor; 15, cavity; 16, fan; 17, choke coil; 100, RF filter; 101, first filter; 102, second filter; 103, third filter; 200, RF filter; 201, first filter; 202, second filter; 203, third filter; 204, HF band filter switching circuit; 205, V / UHF band filter switching circuit; 206, L band filter switching circuit. Detailed implementation manners

[0019] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. It should be understood that these descriptions are merely exemplary and are not used to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts disclosed in the present invention.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0022] In the present invention, the waveband and frequency band have the same meaning.

[0023] The HF band refers to the radio waveband with a frequency range between 1.8 MHz and 30 MHz. This band is usually called the shortwave band because its wavelength is moderate and can be reflected by the ionosphere to achieve long-distance propagation.

[0024] The V / UHF band refers to the VHF band and / or the UHF band. The frequency range of the VHF band is from 30 MHz to 300 MHz, and the wavelength is between 1 meter and 10 meters. The VHF band is mainly used for short-distance communication. The ionosphere usually does not reflect VHF signals, so it mainly relies on direct waves and reflected waves for line-of-sight propagation. The frequency range of the UHF band is from 225 MHz to 678 MHz, and the wavelength is between 1 meter and 1 decimeter. The UHF band has strong penetration and is suitable for use in urban environments. However, due to its high frequency, the signal attenuation is also large, so it is not suitable for long-distance communication. The UHF band is commonly used in mobile communication, radio and television, satellite communication, radar systems, etc.

[0025] The L band, with a frequency range of 1 - 2 GHz, is one of the commonly used bands in satellite communication. It has the characteristics of low frequency and small propagation loss and is suitable for applications such as satellite navigation systems.

[0026] The V / UHF bandpass filter, which is short for the VHF / UHF bandpass filter, refers to the bandpass filter for the VHF band or the bandpass filter for the UHF band.

[0027] A rounded rectangle means that on the basis of a rectangle, the four right angles are changed to arc-shaped. The length of a rounded rectangle refers to the distance between the two short sides, and the width of a rounded rectangle refers to the distance between the two long sides.

[0028] In the present invention, inductor and inductance represent the same meaning, and capacitor and capacitance represent the same meaning.

[0029] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples of methods and systems consistent with some aspects of the present invention as detailed in the appended claims.

[0030] In view of the technical problems existing in the prior art, the present invention proposes a radio frequency filter to solve the problems that the prior art does not have the ability to work with multiple band signals simultaneously, or when multiple band signals are transmitted simultaneously, the spurious and noise between multiple bands are large, and there will be relatively large interference between different bands.

[0031] As Figure 1 shown, an embodiment of the present invention provides a radio frequency filter 100, which includes a first filter 101, a second filter 102, and a third filter 103, where: The first filter 101 is used for filtering the HF band. The first filter 101 is a filter bank for the HF band, including N1 HF band band-pass filters. In the present invention, the HF band is divided into N1 sub-bands, and each sub-band is processed by an HF band band-pass filter. Among them, the value of N1 is determined by requirements. For example, it can be N1 = 7, that is, the HF band is divided into 7 sub-bands, and each sub-band is processed by a band-pass filter. The frequency range of each sub-band is also determined according to the working range requirements. For example, when the HF band is divided into 7 sub-bands, the frequency ranges of each band from small to large are: 1.5 MHz to 2 MHz, 2 MHz to 3 MHz, 3 MHz to 4.5 MHz, 4.5 MHz to 7 MHz, 7 MHz to 11.5 MHz, 11.5 MHz to 19 MHz, 19 MHz to 30 MHz.

[0032] The second filter 102 is used for filtering the VHF band and / or the UHF band. The second filter 102 is a V / UHF band filter bank, including N2 V / UHF band band-pass filters. In the present invention, the VHF band and the UHF band are divided into N2 sub-bands, and each sub-band is processed by a V / UHF band band-pass filter. The number of sub-bands N2 and the frequency range of each sub-band are also determined according to the working range requirements. For example, the working range requirement of the V / UHF band is 30 MHz to 450 MHz, which is divided into 6 sub-bands, and the frequency range of each sub-band is: 30 MHz to 50 MHz, 50 MHz to 70 MHz, 70 MHz to 110 MHz, 110 MHz to 180 MHz, 180 MHz to 300 MHz, 300 MHz to 450 MHz.

[0033] The third filter 103 is used for filtering in the L band. The third filter 103 is an L-band filter bank, including N3 L-band bandpass filters. In the present invention, the L band is divided into N3 sub-bands, and each sub-band is processed by an L-band bandpass filter. The number N3 of sub-bands and the frequency range of each sub-band are also determined according to the requirements of the working range. For example, if the working range requirement of the L band is from 960 MHz to 1850 MHz, it is divided into two sub-bands: 960 MHz - 1215 MHz and 1350 MHz - 1850 MHz. As a preferred example, a high-power notch filter is provided at the end stage of the 1350 MHz - 1850 MHz bandpass filter to suppress the interference to GPS signals within the frequency band.

[0034] In some embodiments, N1 is an integer greater than or equal to 7, N2 is an integer greater than or equal to 6, and N3 is an integer greater than or equal to 2.

[0035] In some embodiments, as Figure 3 shown, the RF filter of the present invention further includes N independent cavities 15, where N is an integer and N = N1 + N2 + N3, and Figure 3 the front and top of the cavity 15 are covered with copper metal cover plates. A bandpass filter is provided in each cavity 15. That is to say, one of the above-mentioned N1 HF-band bandpass filters, N2 V / UHF-band bandpass filters, and N3 L-band bandpass filters is provided in each cavity 15. The number of cavities 15 is N = N1 + N2 + N3, that is, each of the above-mentioned N1 HF-band bandpass filters, N2 V / UHF-band bandpass filters, and N3 L-band bandpass filters is provided in an independent cavity 15. In this embodiment, in order to prevent signal crosstalk between different frequency bands, a separate cavity design is used for the filters in each frequency band and the segments within the frequency band. That is, each individual bandpass filter uses an independent cavity 15. The separate cavity design can greatly reduce the signal leakage of each filter. The radio frequency signals radiated and conducted are reflected back and forth in the metal shielding cavity and gradually weakened, thereby preventing signal crosstalk between different frequency bands.

[0036] In some embodiments, as Figure 3 shown in the cavity 15, the structure of each cavity 15 is as Figure 4As shown. Each cavity 15 includes a cover plate 1 and a cavity body 2. The outer side of the cross-section of the cavity body 2 is rectangular or a rounded rectangle, and the inner side of the cross-section of the cavity body 2 is a rounded rectangle. Optionally, the circular arcs at the four corners of the rounded rectangle on the inner side of the cross-section of the cavity body 2 are all quarter circles with a radius of R. The length of the rounded rectangle on the inner side of the cross-section is greater than 2*R, and the width of the rounded rectangle on the inner side of the cross-section is greater than or equal to 2*R. For example, if R = 15 cm, then the length of the rounded rectangle on the inner side of the cross-section of the cavity body 2 is greater than 30 cm, such as 40 cm, and the width is greater than or equal to 30 cm, such as 30 cm. In the prior art, both the inner and outer sides of the cross-section of the cavity body are rectangular. The advantage of such a design is that the processing technology is relatively simple and the cost is relatively low, and it can be formed by splicing 4 panels. However, at the joints of the panels, the electromagnetic wave leakage is serious. In this embodiment, according to the principle of electromagnetic wave reflection, the four corners of the inner side of each filter cavity body are designed as circular arcs, and each corner is a quarter circle, so that the electromagnetic wave can be reflected back along the original path, further reducing the electromagnetic wave leakage and avoiding the serious electromagnetic wave leakage problem at the joints of the panels in the prior art.

[0037] In some embodiments, the cover plate 1 and the cavity body 2 of each cavity 15 are made of copper alloy.

[0038] In some embodiments, a reflective material 3 is coated on the circular arc regions at the four corners of the rectangular inner side of the cross-section of the cavity body 2. In this embodiment, in order to further improve the reflection efficiency of the radio frequency signal in the circular arc region, a reflective material 3 is coated on the four circular arc regions on the inner side of the cavity body 2 to improve the reflection efficiency of the electromagnetic radiation in the circular arc region, so that the electromagnetic radiation is continuously reflected in the cavity 15, and finally the electromagnetic radiation reaches the maximum at the top, bottom, left and right positions of the cavity 15, and then absorbing materials are arranged at the top, bottom, left and right positions to absorb the electromagnetic radiation, thereby further reducing the signal leakage to the adjacent cavities and preventing the signal crosstalk between different frequency bands.

[0039] In some embodiments, as Figure 4 shown, the four corners of the rectangular outer side of the cross-section of the cavity body 2 can also be circular arcs.

[0040] In some embodiments, as Figure 5As shown, inside the cavity 15, in the areas other than the arc-shaped area, an absorbing material 4 is provided. In the embodiment of the present invention, the areas other than the arc-shaped area mainly include the top, bottom, left and right sides. Assuming that the length of the rounded rectangle of the inner cross-section of the cavity body 2 is C, and C > 2*R, and the width is K and K > 2*R, then on the left and right sides, except for the arc-shaped area, the remaining length of the long side is C - 2*R, and the absorbing material 4 is provided in this area. Similarly, on the top and bottom, except for the arc-shaped area, the remaining length of the area is K - 2*R, and the absorbing material 4 is provided in this area. For example, if the length of the rounded rectangle of the inner cross-section of the cavity body 2 is 20 cm and the width is 15 cm, and the radius of the arc-shaped areas at the four corners is 5 cm, then on the long sides of the rounded rectangle of the inner cross-section, that is, on the left and right sides, except for the arc-shaped area, there is still a 10 cm area, and the absorbing material 4 is provided in this 10 cm area. And on the wide sides of the rounded rectangle of the inner cross-section, that is, on the top and bottom, except for the arc-shaped area, there is still a 5 cm area, and the absorbing material 4 is provided in this 5 cm area. That is to say, in the embodiment of the present invention, the entire inner surface of the cavity 15 is the absorbing material 4 except for the reflective material 3, so that the electromagnetic radiation reflected from the arc-shaped area is absorbed by the absorbing material 4, preventing the signal in the cavity 15 from leaking to other cavities and interfering with the signals in other cavities.

[0041] In some embodiments, filling the absorbing material 4 at the gap between the metal cover plate 1 and the cavity body 2 can minimize the electromagnetic interference leaking from the gap; in addition, the absorbing material 4 is pasted on the top, bottom, left and right sides of the cavity body 2 (the top of the cavity body 2 is the cover plate 1, and the absorbing material 4 is also pasted on the inner wall of the cover plate 1 facing the cavity side), without pasting on the entire inner wall of the cavity 15. The electromagnetic radiation is finally absorbed by the absorbing material at the top, bottom, left and right positions after reflection, thereby reducing the signal leakage to the adjacent cavity.

[0042] In some embodiments, for the leakage of electromagnetic radiation at the cover plate gap, using a nested concave-convex structure can effectively reduce the intensity of electromagnetic radiation leakage. As Figure 4 shown, two concave-convex structures 5 are used to connect between the cover plate 1 and the cavity body 2.

[0043] In some embodiments, as Figure 5 shown, to further reduce the leakage of electromagnetic radiation at the cover plate gap, a silver-plated copper mesh 6 is used to cover the gap between the cover plate 1 and the cavity body 2 structure, further shielding the internal radio frequency signal from radiating out of the cavity and shielding the external electromagnetic interference from leaking into the cavity. The silver-plated copper mesh 6 has good electrical conductivity and ductility, and the copper mesh 6 is covered at the gap between the cover plate and the housing using fixing parts such as screws and metal pressing plates. As an alternative example, the absorbing material 4 is provided at the contact place between the cover plate 1 and the cavity body 2, and is pressed between the cover plate and the structure to reduce the gap leakage.

[0044] The losses of the filter are concentrated on the inductor. Therefore, it is necessary to dissipate the heat of the inductor well, which can greatly improve the reliability of the filter. For the HF band, in some embodiments, such as Figure 6 shown, an inductor slot is provided on the printed circuit board 8. The inductor 7 is vertically installed in the inductor slot of the printed circuit board 8, and heat-conducting pads 10 are used to cover the upper and lower ends of the inductor. Then, a copper plate 9 is covered and attached to the heat-conducting pad 10, so as to conduct all the heat of the inductor out of the filter module to the external structure. The external structure has a fan 16 that can dissipate heat in real time. That is, as Figure 6 shown, each HF band band-pass filter includes an inductor 7. The inductor 7 is installed on the printed circuit board 8. A copper plate 9 is provided below the printed circuit board 8. A heat-conducting pad 10 is provided between the copper plate 9 and the printed circuit board 8. The heat-conducting pad 10 is made of a soft material. As a preferred example, the inductor 7 of the HF band band-pass filter includes an enameled copper wire 11 and a high-frequency magnetic ring 12. The operating frequency range of the high-frequency magnetic ring 12 is from 1 MHz to 20 MHz, or from 20 MHz to 40 MHz. As an alternative example, the number of high-frequency magnetic rings 12 with an operating frequency range of 1 MHz to 20 MHz is 18, and the number of high-frequency magnetic rings 12 with an operating frequency range of 20 MHz to 40 MHz is 3.

[0045] In some embodiments, in each band-pass filter of the radio frequency filter of the present invention, each capacitor uses two high-Q ceramic capacitors in parallel to increase the Q value of the circuit capacitor, reduce the insertion loss of the filter, and reduce the power consumption of the device. For example Figure 6 shown, the HF band filter requires a large amount of inductance, up to the 10 uH level at most. Therefore, the inductor of the HF band band-pass filter is wound with an enameled copper wire 11 with a diameter of 1.0 mm and a high-frequency magnetic ring 12, taking into account both the size and Q value of the inductor, and also having a large power capacity, resulting in an inductor with a high Q value in the HF band. The inductor of the V / UHF band filter is wound with a hollow coil and a copper post. The inductor of the L band filter is wound with a hollow coil and a copper post or a cavity. In some embodiments, the diameter range of the copper post is greater than or equal to 7.1 mm and less than or equal to 8.1 mm; the diameter of the hollow coil is 1.5 mm - 4.5 mm, and preferably the diameter of the hollow coil is 3 mm.

[0046] In some embodiments, in terms of the layout of capacitors and inductors, the inductors, capacitor matrices, and choke matrices of the present invention adopt a spatial stacked layout, greatly reducing the lateral occupied area of the circuit and reducing the size of the filter. As Figure 11 shown, a choke 17 is provided at the bottom. A capacitor 14 is provided above the choke 17. Above the capacitor 14 is the printed circuit board 8. An inductor 7 is provided above the printed circuit board 8. This spatial stacked layout reduces the lateral area of the circuit and shrinks the size of the filter.

[0047] In some embodiments, the first filter 101 is as Figure 7 shown. When N1 is equal to 7, the N1 HF bandpass filters are respectively: The first HF bandpass filter with a passband frequency from 1.5 MHz to 2 MHz; The second HF bandpass filter with a passband frequency from 2 MHz to 3 MHz; The third HF bandpass filter with a passband frequency from 3 MHz to 4.5 MHz; The fourth HF bandpass filter with a passband frequency from 4.5 MHz to 7 MHz; The fifth HF bandpass filter with a passband frequency from 7 MHz to 11.5 MHz; The sixth HF bandpass filter with a passband frequency from 11.5 MHz to 19 MHz; The seventh HF bandpass filter with a passband frequency from 19 MHz to 30 MHz.

[0048] In the prior art, the above 7 HF bandpass filters are arranged in the order as Figure 7 shown, arranged from top to bottom in sequence. That is, for two adjacent bandpass filters, the passband frequencies are adjacent sub-bands. For example, the passband frequency of the first HF bandpass filter is from 1.5 MHz to 2 MHz, while the passband frequency of the second HF bandpass filter is from 2 MHz to 3 MHz. 1.5 MHz to 2 MHz and 2 MHz to 3 MHz are adjacent sub-bands. The high cut-off frequency of 2 MHz of the first HF bandpass filter is the same as the low cut-off frequency of 2 MHz of the second HF bandpass filter. In the prior art, if these 7 HF bandpass filters are arranged in 7 adjacent cavities 15, then the first HF bandpass filter, the second HF bandpass filter, the third HF bandpass filter, the fourth HF bandpass filter, the fifth HF bandpass filter, the sixth HF bandpass filter, and the seventh HF bandpass filter are arranged in the 7 adjacent cavities 15 from left to right in sequence. That is, from left to right, the working sub-bands of the filters in adjacent cavities are adjacent. The problem with such an arrangement is that the closer the sub-band frequencies of two adjacent cavities are, the more serious the mutual interference is. That is to say, between filters that are physically adjacent and have adjacent working sub-bands, signal coupling and interference often occur, resulting in a decrease in the suppression index of the filter and affecting the harmonic and spurious indexes of the whole machine. To solve the technical problems existing in the prior art, in the embodiments of the present invention, the working frequency bands of the filters arranged in adjacent cavities are staggered, so that the working sub-bands of two physically adjacent cavities are not adjacent, thereby reducing the signal coupling and interference between adjacent cavities. In the present invention, as Figure 8As shown, each HF band bandpass filter is disposed within a cavity 15. Seven HF band bandpass filters are disposed within seven adjacent cavities 15, and the arrangement order from left to right is: the first HF band bandpass filter, the fourth HF band bandpass filter, the seventh HF band bandpass filter, the second HF band bandpass filter, the fifth HF band bandpass filter, the third HF band bandpass filter, and the sixth HF band bandpass filter. The method for disposing the cavities of the HF band bandpass filter of the present invention staggers the frequency positions of the segmented filters, avoiding the situation where the frequency positions of the segmented filters are continuous, such as 1.5 MHz - 2 MHz, 2 MHz - 3 MHz,..., 19 MHz - 30 MHz, reducing the crosstalk between adjacent filters in terms of frequency, and improving the performance of the filters.

[0049] In some embodiments, for the seven HF band bandpass filters, the passband bandwidth design of each bandpass filter mainly considers the second harmonic suppression of the operating frequency points within the passband, and the filters within a segment have an insertion loss of at least -50 dB at the second harmonic of the starting frequency of the segment; at the same time, considering feasibility, the filters are designed as seventh-order elliptical low-pass filters.

[0050] In some embodiments, as Figure 9 shown, the second filter 102 includes: when N2 is equal to 6, the N2 V / UHF band bandpass filters are respectively: The first V / UHF band bandpass filter, with a passband frequency from 30 MHz to 50 MHz; The second V / UHF band bandpass filter, with a passband frequency from 50 MHz to 70 MHz; The third V / UHF band bandpass filter, with a passband frequency from 70 MHz to 110 MHz; The fourth V / UHF band bandpass filter, with a passband frequency from 110 MHz to 180 MHz; The fifth V / UHF band bandpass filter, with a passband frequency from 180 MHz to 300 MHz; The sixth V / UHF band bandpass filter, with a passband frequency from 300 MHz to 450 MHz; Similar to the setting principle of the above HF band bandpass filter, the operating frequency bands of the filters disposed within adjacent cavities 15 of the V / UHF band are staggered, such that the sub-frequency bands of the two adjacent cavities 15 in terms of physics are not adjacent, thereby reducing the signal coupling and interference between adjacent cavities 15. As Figure 10As shown, each V / UHF band pass filter is disposed within a cavity 15. Six V / UHF band pass filters are disposed within six adjacent cavities 15, and their arrangement order from left to right is: the first V / UHF band pass filter, the fourth V / UHF band pass filter, the second V / UHF band pass filter, the fifth V / UHF band pass filter, the third V / UHF band pass filter, and the sixth V / UHF band pass filter.

[0051] As Figure 1 shown, the RF filter of the present invention can support HF band, V / UHF band and L band operation simultaneously, and support N = N1 + N2 + N3 band pass filters to operate simultaneously, broadening the operating frequency band, enabling it to effectively utilize the frequency resources of different frequency bands, and enhancing the communication ability. Moreover, each band pass filter of each sub-band is disposed within an independent cavity 15. When filtering signals in multiple frequency bands simultaneously, interference within different frequency bands is solved, and the communication ability is enhanced. The four corners of the inner profile of the cavity body 2 of each independent cavity 15 are designed to be arc-shaped, which improves the reflection efficiency of the RF signal, reflects the signal back into the cavity, and avoids leakage to adjacent cavities. At the same time, in order to improve the reflection efficiency of the arc-shaped area for the RF signal, a reflective material is coated on the surface of the arc-shaped area to increase the reflection efficiency of the RF signal, further avoiding leakage to adjacent cavities and interference within different frequency bands.

[0052] As Figure 2 shown, an embodiment of the present invention provides another RF filter 200. The filter 200 includes a first filter 201, a second filter 202, a third filter 203, and a filter switching circuit. Among them, the filter switching circuit includes an HF band filter switching circuit 204, a V / UHF band filter switching circuit 205, and an L band filter switching circuit 206. Among them, the HF band filter switching circuit 204 includes N1 double-pole double-throw electromagnetic relays, and each electromagnetic relay is connected to an HF band pass filter for controlling the opening or closing of the input signal of each HF band filter; the V / UHF band filter switching circuit 205 includes N2 PIN diode switches, and each PIN diode switch is connected to a V / UHF band pass filter for controlling the opening or closing of the input signal of each V / UHF band filter; the L band filter switching circuit 206 includes N3 PIN diode switches, and each PIN diode switch is connected to an L band pass filter for controlling the opening or closing of the input signal of each L band filter. In the embodiment of the present invention, the filter switching circuit can switch channels to connect a certain filter or bypass it directly, thereby controlling the access or disconnection of the filter.

[0053] As Figure 2For the RF filter shown, N = N1 + N2 + N3 band-pass filters can be individually connected or disconnected, thus supporting only some of the band-pass filters to work, enabling signal transmission only in some sub-frequency bands, and can work according to different combinations as required, or different filters can work in a time-sharing manner according to different time sequences, thus supporting working modes such as frequency hopping.

[0054] As Figure 2 shown in the RF filter, the first filter 201 is the same as the Figure 1 first filter 101 shown, which will not be elaborated here; the second filter 202 is the same as the Figure 1 second filter 102 shown, which will not be elaborated here; the third filter 203 is the same as the Figure 1 first filter 103 shown, which will not be elaborated here.

[0055] It should be noted that, as Figure 2 shown in the RF filter 200, compared with the RF filter 100 shown in Figure 1 , except for adding a filter switching circuit, other parts are the same as the RF filter shown in Figure 1 , and the same parts will not be elaborated here.

[0056] The applicant of the present invention has made a detailed description and illustration of the embodiments of the present invention in combination with the accompanying drawings of the specification. However, those skilled in the art should understand that the above embodiments are only the preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, rather than a limitation on the protection scope of the present invention. On the contrary, any improvement or modification made based on the spirit of the present invention should fall within the protection scope of the present invention.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A radio frequency filter, characterized in that, Comprising: A first filter, a second filter, and a third filter; The first filter is used for filtering in the HF band and includes N1 HF band band-pass filters; The second filter is used for filtering in the VHF band and / or UHF band and includes N2 V / UHF band band-pass filters; The third filter is used for filtering in the L band and includes N3 L band band-pass filters; The RF filter further includes N independent cavities (15), and one band-pass filter is provided in each cavity (15); Each cavity (15) includes a cover plate (1) and a cavity body (2). The outer side of the cross-section of the cavity body (2) is rectangular, and the inner side of the cross-section of the cavity body (2) is a rounded rectangle; Wherein, N1 is an integer greater than or equal to 7, N2 is an integer greater than or equal to 6, N3 is an integer greater than or equal to 2, and N is an integer and N = N1 + N2 + N3.

2. The radio frequency filter according to claim 1, characterized in that, Further comprising: A filter switching circuit; The filter switching circuit includes an HF band filter switching circuit, a V / UHF band filter switching circuit, and an L band filter switching circuit; The HF band filter switching circuit includes N1 double-pole double-throw electromagnetic relays; The V / UHF band filter switching circuit includes N2 PIN diode switches; The L band filter switching circuit includes N3 PIN diode switches; Each HF band filter switching circuit is connected to an HF band band-pass filter; Each V / UHF band filter switching circuit is connected to a V / UHF band band-pass filter; Each L band filter switching circuit is connected to an L band band-pass filter.

3. The radio frequency filter according to claim 1 or 2, characterized in that, The 4 circular arc regions of the rounded rectangle are all quarter circles with a radius of R. The length of the rounded rectangle is greater than 2*R, and the width of the rounded rectangle is greater than or equal to 2*R; Each circular arc region is coated with a reflective material (3).

4. The radio frequency filter according to claim 3, characterized in that, Inside the cavity (15), in the region other than the circular arc region, an absorbing material (4) is provided.

5. The radio frequency filter according to claim 1 or 2, characterized in that, When N1 is equal to 7, the N1 HF band band-pass filters are respectively: The first HF band band-pass filter, with a passband frequency of 1.5 MHz to 2 MHz; The second HF band band-pass filter, with a passband frequency of 2 MHz to 3 MHz; The third HF band band-pass filter, with a passband frequency of 3 MHz to 4.5 MHz; The fourth HF band band-pass filter, with a passband frequency of 4.5 MHz to 7 MHz; The fifth HF band band-pass filter, with a passband frequency of 7 MHz to 11.5 MHz; The sixth HF band band-pass filter, with a passband frequency of 11.5 MHz to 19 MHz; The seventh HF band band-pass filter, with a passband frequency of 19 MHz to 30 MHz; Among them, each HF band band-pass filter is arranged in a cavity (15), and 7 HF band band-pass filters are arranged in 7 adjacent cavities (15). The arrangement order from left to right is: the first HF band band-pass filter, the fourth HF band band-pass filter, the seventh HF band band-pass filter, the second HF band band-pass filter, the fifth HF band band-pass filter, the third HF band band-pass filter, and the sixth HF band band-pass filter.

6. The radio frequency filter according to claim 1 or 2, characterized in that, When the N2 is equal to 6, the N2 V / UHF band band-pass filters are respectively: The first V / UHF band band-pass filter, with a passband frequency of 30 MHz to 50 MHz; The second V / UHF band band-pass filter, with a passband frequency of 50 MHz to 70 MHz; The third V / UHF band band-pass filter, with a passband frequency of 70 MHz to 110 MHz; The fourth V / UHF band band-pass filter, with a passband frequency of 110 MHz to 180 MHz; The fifth V / UHF band band-pass filter, with a passband frequency of 180 MHz to 300 MHz; The sixth V / UHF band band-pass filter, with a passband frequency of 300 MHz to 450 MHz; Among them, each V / UHF band band-pass filter is arranged in a cavity (15), and 6 V / UHF band band-pass filters are arranged in 6 adjacent cavities (15). The arrangement order from left to right is: the first V / UHF band band-pass filter, the fourth V / UHF band band-pass filter, the second V / UHF band band-pass filter, the fifth V / UHF band band-pass filter, the third V / UHF band band-pass filter, and the sixth V / UHF band band-pass filter.

7. The RF filter according to claim 1 or 2, characterized in that, Two concave-convex structures (5) are used to connect the cover plate (1) and the cavity body (2).

8. The RF filter according to claim 1 or 2, characterized in that, A silver-plated copper mesh (6) is provided to cover the gap between the cover plate (1) and the filter cavity body (2).

9. The RF filter according to claim 1 or 2, characterized in that, Each HF band band-pass filter includes an inductor (7). The inductor (7) is installed on a printed circuit board (8). A copper plate (9) is provided below the printed circuit board (8). A heat-conducting pad (10) made of a soft material is provided between the copper plate (9) and the printed circuit board (8); The inductor (7) includes an enameled copper wire (11) and a high-frequency magnetic ring (12). The operating frequency range of the high-frequency magnetic ring (12) is 1 MHz to 20 MHz, or 20 MHz to 40 MHz.

10. The RF filter according to claim 1 or 2, characterized in that, The cover plate (1) and the cavity body (2) are made of copper alloy.

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