A radio frequency filter

Abstract

The present invention relates to a radio frequency filter, which belongs to the field of wireless communication technology. The radio frequency filter includes: a first filter, a second filter and a third filter; the first filter is used for filtering in the HF band, the second filter is used for filtering in the VHF band and / or the UHF band, and the third filter is used for filtering in the L band; the radio frequency filter of the present invention includes a plurality of independent cavities, each of which is provided with a bandpass filter, 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. The radio frequency filter of the present invention broadens the working band, can effectively utilize the frequency resources of different bands, and improves the communication capability. Each bandpass filter is arranged in an independent cavity, the cavity is made of copper alloy, and the four corners on the inner side of the cavity are arc-shaped, which improves the reflection efficiency of the signal, reduces the signal leakage to adjacent bands, and reduces the interference between different bands.

Description

Technical Field

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

[0002] RF filters are essential components in wireless communication devices, especially in the RF front-end of target analog payloads, where they are required to perform power amplification, filtering, and power detection on broadband RF signals.

[0003] In existing technologies, however, RF filters typically process single-band RF signals to achieve amplification and filtering within a specific band, and lack the ability to operate simultaneously with multiple bands. Furthermore, due to the high power at the final stage of the RF path, the corresponding filter not only requires a large power capacity but also requires effective electromagnetic shielding to mitigate crosstalk between filters in different frequency bands. When multiple bands are transmitted simultaneously, the resulting spurious and noise levels are high, leading to significant interference between the different bands and failing to meet market demand for simultaneous multi-band communication. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a radio frequency filter that broadens the operating band, enables it to effectively utilize frequency resources in different bands, and improves communication capabilities.

[0005] The radio frequency filter of the present invention comprises:

[0006] a first filter, a second filter, and a third filter;

[0007] The first filter is used for filtering in the HF band and includes N1 HF band pass filters;

[0008] The second filter is used for filtering in the VHF band and / or the UHF band, and includes N2 V / UHF band bandpass filters;

[0009] The third filter is used for L-band filtering and includes N3 L-band bandpass filters;

[0010] The radio frequency filter further comprises N independent cavities, each of which is provided with a bandpass filter;

[0011] Each cavity includes a cover plate and a cavity body, wherein the outer side of the cross section of the cavity body is a rectangle, and the inner side of the cross section of the cavity body is a rounded rectangle;

[0012] 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, N is an integer and N=N1+N2+N3.

[0013] The radio frequency filter of the present invention is provided with

[0014] Furthermore, the radio frequency filter of the present invention further includes:

[0015] filter switching circuit;

[0016] 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;

[0017] The HF band filter switching circuit includes N1 double-pole double-throw electromagnetic relays;

[0018] The V / UHF band filter switching circuit includes N2 PIN tube switches;

[0019] The L-band filter switching circuit includes N3 PIN tube switches;

[0020] Each HF band filter switching circuit is connected to an HF band bandpass filter;

[0021] Each V / UHF band filter switching circuit is connected to a V / UHF band bandpass filter;

[0022] Each L-band filter switching circuit is connected to an L-band bandpass filter.

[0023] Furthermore, the four arc-shaped areas of the rounded rectangle are all a quarter of a 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;

[0024] Each arc-shaped area is coated with reflective material.

[0025] Furthermore,

[0026] Wave absorbing material is provided in the area inside the cavity except the arc-shaped area.

[0027] Furthermore,

[0028] When N1 is equal to 7, the N1 HF band pass filters are respectively:

[0029] The first HF band bandpass filter has a passband frequency of 1.5 MHz to 2 MHz;

[0030] The second HF band bandpass filter has a passband frequency of 2MHz to 3MHz;

[0031] The third HF band bandpass filter has a passband frequency of 3MHz to 4.5MHz;

[0032] Fourth HF band bandpass filter, with a passband frequency of 4.5MHz to 7MHz;

[0033] Fifth HF band bandpass filter, with a passband frequency of 7MHz to 11.5MHz;

[0034] 6th HF band bandpass filter, with a passband frequency of 11.5MHz to 19MHz;

[0035] 7th HF band bandpass filter, with a passband frequency of 19MHz to 30MHz;

[0036] Each HF band band-pass filter is arranged in one cavity, and seven HF band band-pass filters are arranged in seven adjacent cavities, and the arrangement order from left to right is: a first HF band band-pass filter, a fourth HF band band-pass filter, a seventh HF band band-pass filter, a second HF band band-pass filter, a fifth HF band band-pass filter, a third HF band band-pass filter and a sixth HF band band-pass filter.

[0037] Furthermore,

[0038] When N2 is equal to 6, the N2 V / UHF band bandpass filters are respectively:

[0039] The first V / UHF band bandpass filter has a passband frequency of 30MHz to 50MHz;

[0040] The second V / UHF band bandpass filter has a passband frequency of 50MHz to 70MHz;

[0041] The third V / UHF band bandpass filter has a passband frequency of 70MHz to 110MHz;

[0042] Fourth V / UHF band bandpass filter, with a passband frequency of 110MHz to 180MHz;

[0043] Fifth V / UHF band bandpass filter, with a passband frequency of 180MHz to 300MHz;

[0044] The sixth V / UHF band bandpass filter has a passband frequency of 300MHz to 450MHz;

[0045] Among them, each V / UHF band band-pass filter is arranged in a cavity, and 6 V / UHF band band-pass filters are arranged in 6 adjacent cavities, and 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.

[0046] Furthermore, the cover plate and the cavity body are connected using two concave-convex structures.

[0047] Furthermore, a silver-plated copper mesh is provided to cover the gap between the cover plate and the filter cavity body.

[0048] Furthermore, each HF band pass filter includes an inductor, which is mounted on a printed circuit board. A copper plate is provided below the printed circuit board, and a thermal pad is provided between the copper plate and the printed circuit board. The thermal pad is made of a soft material.

[0049] 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.

[0050] Furthermore, the cover plate and the cavity body are made of copper alloy.

[0051] The beneficial effects of the present invention are as follows:

[0052] The radio frequency filter of the present invention broadens the working 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 capability. Each bandpass filter is arranged in an independent cavity. The cavity is made of copper alloy. The four corners on the inner side of the cavity are arc-shaped, which improves the reflection efficiency of the signal, reduces the signal leakage to the adjacent bands, and reduces the interference between different bands. In the area other than the arc-shaped area on the inner side of the cavity, absorbing material is provided to improve the absorption of the signal in the cavity and reduce the interference to the adjacent cavity. Bandpass filters of different frequency bands in the same band are arranged in adjacent cavities, and different frequency bands are staggered. The frequency bands of the bandpass filters of the two adjacent cavities are not adjacent, thereby reducing adjacent frequency interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals represent the same components. Obviously, the drawings described below are only some of the embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings.

[0054] Figure 1 This is a schematic diagram of a radio frequency filter according to an embodiment of the present invention;

[0055] Figure 2 This is a second schematic diagram of a radio frequency filter according to an embodiment of the present invention;

[0056] Figure 3 Schematic diagram of cavity distribution of a radio frequency filter according to an embodiment of the present invention;

[0057] Figure 4 is one of the schematic diagrams of each independent cavity in an embodiment of the present invention;

[0058] Figure 5 This is the second schematic diagram of each independent cavity according to an embodiment of the present invention;

[0059] Figure 6 Schematic diagram of heat dissipation design of a radio frequency filter according to an embodiment of the present invention;

[0060] Figure 7 Schematic diagram of an HF band filter bank according to an embodiment of the present invention;

[0061] Figure 8 Schematic diagram of the arrangement order of the HF band filter group in the cavity according to an embodiment of the present invention;

[0062] Figure 9 Schematic diagram of a V / UHF band filter bank according to an embodiment of the present invention;

[0063] Figure 10 Schematic diagram of the arrangement order of the V / UHF band filter group in the cavity according to an embodiment of the present invention;

[0064] Figure 11 FIG. 4 is a schematic diagram of the capacitor and inductor layout according to an embodiment of the present invention.

[0065] Reference numerals:

[0066] 1. Cover plate; 2. Cavity body; 3. Reflective material; 4. 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; 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 DESCRIPTION

[0067] 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 with reference to the accompanying drawings. Obviously, the embodiments described 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 intended 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 work should fall within the scope of protection of the present invention.

[0068] Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention.

[0069] In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 limiting the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The terms "installed", "connected" and "connected" 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 a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of 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 circumstances.

[0070] In the present invention, band and frequency band have the same meaning.

[0071] The HF band refers to the radio frequency range between 1.8 MHz and 30 MHz. This band is often referred to as the shortwave band because its moderate wavelength can be reflected by the ionosphere, allowing long-distance propagation.

[0072] V / UHF band, namely VHF band and / or UHF band. The VHF band has a frequency range of 30 MHz to 300 MHz, and a wavelength of 1 meter to 10 meters. The VHF band is mainly used for short-distance communications. The ionosphere usually does not reflect VHF signals, so it mainly relies on direct waves and reflected waves for line-of-sight propagation. The UHF band has a frequency range of 225 MHz to 678 MHz, and a wavelength of 1 meter to 1 decimeter. The UHF band has strong penetration and is suitable for use in urban environments, but due to its high frequency, the signal attenuation is also large, making it unsuitable for long-distance communications. The UHF band is commonly used in mobile communications, broadcasting and television, satellite communications, and radar systems.

[0073] The L-band, with a frequency range of 1-2 GHz, is one of the commonly used bands in satellite communications. It has the characteristics of low frequency and low propagation loss, and is suitable for applications such as satellite navigation systems.

[0074] V / UHF band bandpass filter is the abbreviation of VHF / UHF band bandpass filter, that is, a bandpass filter for VHF band or a bandpass filter for UHF band.

[0075] A rounded rectangle is a rectangle with four right angles rounded. The length of a rounded rectangle is the distance between its two short sides, and the width is the distance between its two long sides.

[0076] In the present invention, inductance and inductor have the same meaning, and capacitance and capacitor have the same meaning.

[0077] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with certain aspects of the present invention, as detailed in the appended claims.

[0078] In response to the technical problems existing in the prior art, the present invention proposes a radio frequency filter to solve the problem 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 the multiple bands are large, and there will be significant interference between different bands.

[0079] like Figure 1 As 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, wherein:

[0080] The first filter 101 is used for filtering in the HF band. It is an HF band filter bank comprising N1 HF band bandpass filters. In the present invention, the HF band is divided into N1 sub-bands, each of which is processed by an HF band bandpass filter. The value of N1 is determined by requirements. For example, N1 can be 7, meaning the HF band is divided into seven sub-bands, each of which is processed by a bandpass filter. The frequency range of each sub-band is also determined based on operating range requirements. For example, when the HF band is divided into seven sub-bands, the frequency ranges of each band, from smallest to largest, 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, and 19 MHz to 30 MHz.

[0081] The second filter 102 is used for filtering in the VHF band and / or the UHF band. The second filter 102 is a V / UHF band filter bank, comprising N2 V / UHF band bandpass filters. In the present invention, the VHF band and the UHF band are divided into N2 sub-bands, each of which is processed by a V / UHF band bandpass filter. The number N2 of sub-bands and the frequency range of each sub-band are also determined based on the operating range requirements. For example, the operating range requirement for the V / UHF band is 30MHz to 450MHz, which is divided into 6 sub-bands, and the frequency range of each sub-band is: 30MHz to 50MHz, 50MHz to 70MHz, 70MHz to 110MHz, 110MHz to 180MHz, 180MHz to 300MHz, and 300MHz to 450MHz.

[0082] The third filter 103 is used for L-band filtering. The third filter 103 is an L-band filter bank comprising N3 L-band bandpass filters. In the present invention, the L-band is divided into N3 sub-bands, each of which 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 based on the required operating range. For example, the required operating range of the L-band is 960 MHz to 1850 MHz, which 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 final stage of the 1350 MHz-1850 MHz bandpass filter to suppress interference with GPS signals within the frequency band.

[0083] 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.

[0084] In some embodiments, as Figure 3 As shown, the radio frequency filter of the present invention further includes N independent cavities 15, where N is an integer and N=N1+N2+N3, wherein Figure 3 The front and top of the middle cavity 15 are covered with a copper metal cover. Each cavity 15 is provided with a bandpass filter. That is, each cavity 15 is provided with one of the N1 HF band bandpass filters, N2 V / UHF band bandpass filters, and N3 L band bandpass filters. The number of cavities 15 is N=N1+N2+N3, that is, each of the 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 crosstalk between signals in different frequency bands, a cavity design is used for the filters in each frequency band and for the segmentation of the filters within the frequency band. That is, each individual bandpass filter uses an independent cavity 15. The cavity design can greatly reduce signal leakage from each filter. The radiated RF signal is gradually weakened by the back-and-forth reflections in the metal shielding cavity, thereby preventing crosstalk between signals in different frequency bands.

[0085] In some embodiments, as Figure 3 In the cavity 15 shown, the structure of each cavity 15 is as follows Figure 4 As 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 a rectangle or a rounded rectangle, and the inner side of the cross-section of the cavity body 2 is a rounded rectangle. Optionally, the arcs of the four corners of the rounded rectangle on the inner side of the cross-section of the cavity body 2 are all a quarter of a circle 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=15cm, the length of the rounded rectangle on the inner side of the cross-section of the cavity body 2 is greater than 30cm, for example, 40cm, and the width is greater than or equal to 30cm, for example, equal to 30cm. In the prior art, the inner and outer sides of the cross-section of the cavity body are both rectangular. The advantage of this design is that the processing technology is relatively simple and the cost is relatively low. It can be spliced ​​with four panels, but the leakage of electromagnetic waves is serious at the connection between the panels. In this embodiment, based on the principle of electromagnetic wave reflection, the four corners on the inner side of each filter cavity body are designed to be arc-shaped, with each corner being a quarter of a circle, so that the electromagnetic waves can be reflected along the original path, further reducing the leakage of electromagnetic waves and avoiding the serious problem of electromagnetic wave leakage at the connection of the panel in the prior art.

[0086] In some embodiments, the cover plate 1 and the cavity body 2 of each cavity 15 are made of copper alloy.

[0087] In some embodiments, the arc-shaped areas at the four corners of the rectangular inner side of the cross-section of the cavity body 2 are coated with reflective material 3. In this embodiment, to further improve the reflection efficiency of the radio frequency signal in the arc-shaped areas, the four arc-shaped areas on the inner side of the cavity body 2 are coated with reflective material 3. This improves the reflection efficiency of electromagnetic radiation in the arc-shaped areas, causing the electromagnetic radiation to be continuously reflected within the cavity 15, ultimately reaching maximum radiation at the top, bottom, and left and right positions of the cavity 15. Absorbent material is then provided at the top, bottom, and left and right positions to absorb the electromagnetic radiation, thereby further reducing signal leakage to adjacent cavities and preventing crosstalk between signals in different frequency bands.

[0088] In some embodiments, as Figure 4 As shown, the four corners of the outer side of the rectangular cross section of the cavity body 2 may also be arc-shaped.

[0089] In some embodiments, as Figure 5 As shown, the areas inside the cavity 15, excluding the arc-shaped areas, are provided with absorbing material 4. In this embodiment of the present invention, the areas excluding the arc-shaped areas primarily include the top, bottom, and left and right sides. Assuming that the rounded rectangle in the inner cross-section of the cavity body 2 has a length of C, where C > 2*R, and a width of K, where K > 2*R, then on the left and right sides, excluding the arc-shaped areas, the remaining areas of the long sides are C-2*R in length, and absorbing material 4 is provided in each of these areas. Similarly, on the top and bottom, excluding the arc-shaped areas, the remaining areas are K-2*R in length, and absorbing material 4 is provided in each of these areas. For example, if the rounded rectangle in the inner cross-section of the cavity body 2 is 20 cm long and 15 cm wide, and the radius of the arc-shaped areas at each of the four corners is 5 cm, then on the long sides of the rounded rectangle in the inner cross-section, i.e., the left and right sides, excluding the arc-shaped areas, there is a 10 cm area, and this 10 cm area is provided with absorbing material 4. On the wide sides of the rounded rectangle in the inner cross-section, i.e., the top and bottom, there is a 5 cm area in addition to the arc-shaped area, and this 5 cm area is provided with absorbing material 4. In other words, in this embodiment of the present invention, the entire inner surface of cavity 15, except for reflective material 3, is covered with absorbing material 4. This allows electromagnetic radiation reflected from the arc-shaped area to be absorbed by absorbing material 4, preventing the signal within cavity 15 from leaking into other cavities and interfering with the signals therein.

[0090] In some embodiments, filling the gap between the metal cover plate 1 and the cavity body 2 with absorbing material 4 can minimize electromagnetic interference leaked in the gap; in addition, absorbing material 4 is affixed to 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 affixed to the inner wall of the cover plate 1 facing the cavity), and it is not necessary to install the absorbing material on the entire inner wall of the cavity 15. After reflection, the electromagnetic radiation is eventually absorbed by the absorbing material at the top, bottom, left and right positions, thereby reducing signal leakage to adjacent cavities.

[0091] In some embodiments, in order to prevent electromagnetic radiation from leaking through the gaps in the cover plate, a nested concave-convex structure can be used to effectively reduce the intensity of electromagnetic radiation leakage. Figure 4 As shown, the cover plate 1 and the cavity body 2 are connected using two concave-convex structures 5 .

[0092] In some embodiments, as Figure 5 As shown, in order to further reduce the leakage of electromagnetic radiation in the gap of the cover plate, 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 conductivity and ductility. The copper mesh 6 is covered in the gap between the cover plate and the shell using fasteners such as screws and metal pressing plates. As an optional example, an absorbing material 4 is set at the contact point between the cover plate 1 and the cavity body 2, and pressed between the cover plate structure to reduce leakage in the gap.

[0093] The loss of the filter is concentrated on the inductor, so it is necessary to do a good job of inductor heat dissipation, which can greatly improve the reliability of the filter. For the HF band, in some embodiments, such as Figure 6 As shown, an inductor slot is set on the printed circuit board 8, and the inductor 7 is vertically installed in the inductor slot of the printed circuit board 8, and a thermal pad 10 is used to cover the upper and lower ends of the inductor. Then, the thermal pad 10 is covered with a copper plate 9 to adhere to the thermal pad 10, so that all the heat of the inductor is conducted out of the filter module to the external structure. The external structure has a fan 16, which can dissipate heat in real time. Figure 6 As shown, each HF band pass filter includes an inductor 7, which is mounted on a printed circuit board 8. A copper plate 9 is provided below the printed circuit board 8, and a thermal pad 10 is provided between the copper plate 9 and the printed circuit board 8. The thermal pad 10 is made of a soft material. As a preferred example, the inductor 7 of the HF 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 1MHz to 20MHz, or 20MHz to 40MHz. As an optional example, the number of high-frequency magnetic rings 12 with an operating frequency range of 1MHz to 20MHz is 18, and the number of high-frequency magnetic rings 12 with an operating frequency range of 20MHz to 40MHz is 3.

[0094] In some embodiments, each capacitor in each bandpass filter of the radio frequency filter of the present invention uses two high-Q ceramic capacitors in parallel to improve the Q value of the circuit capacitor, reduce the insertion loss of the filter, and reduce the power consumption of the device. Figure 6As shown, the HF band filter requires a large inductance, with a maximum of 10uH. Therefore, the HF band pass filter inductor is wound with a 1.0mm diameter enameled copper wire 11 and a high-frequency magnetic ring 12, which takes into account the size and Q value of the inductor, and also has a large power capacity, thereby obtaining an inductor with a high Q value in the HF band. The V / UHF band filter inductor is wound with a hollow coil and a copper column. The L band filter is wound with a hollow coil and a copper column or a cavity. In some embodiments, the diameter of the copper column ranges from greater than or equal to 7.1mm to less than or equal to 8.1mm; the diameter of the hollow coil is 1.5mm-4.5mm, and the preferred diameter of the hollow coil is 3mm.

[0095] In some embodiments, in terms of the layout of capacitors and inductors, the inductor, capacitor matrix and choke matrix of the present invention adopt a spatial stacking layout, which greatly reduces the horizontal area occupied by the circuit and reduces the size of the filter. Figure 11 As shown, a choke 17 is provided at the bottom, a capacitor 14 is provided above the choke 17, a printed circuit board 8 is provided above the capacitor 14, and an inductor 7 is provided above the printed circuit board 8. This spatial stacking layout reduces the lateral area of ​​the circuit and the size of the filter.

[0096] In some embodiments, the first filter 101 is as follows Figure 7 As shown, when N1 is equal to 7, the N1 HF band pass filters are respectively:

[0097] The first HF band bandpass filter has a passband frequency of 1.5 MHz to 2 MHz;

[0098] The second HF band bandpass filter has a passband frequency of 2MHz to 3MHz;

[0099] The third HF band bandpass filter has a passband frequency of 3MHz to 4.5MHz;

[0100] Fourth HF band bandpass filter, with a passband frequency of 4.5MHz to 7MHz;

[0101] Fifth HF band bandpass filter, with a passband frequency of 7MHz to 11.5MHz;

[0102] 6th HF band bandpass filter, with a passband frequency of 11.5MHz to 19MHz;

[0103] Seventh HF band bandpass filter, with a passband frequency of 19MHz to 30MHz.

[0104] In the prior art, the above 7 HF bandpass filters are arranged in the following order: Figure 7As shown, arranged from top to bottom, the bandpass frequencies of two adjacent bandpass filters are adjacent sub-bands. For example, the bandpass frequency of the first HF bandpass filter is 1.5 MHz to 2 MHz, while the bandpass frequency of the second HF bandpass filter is 2 MHz to 3 MHz. The 1.5 MHz to 2 MHz and 2 MHz to 3 MHz sub-bands are adjacent sub-bands. The high cutoff frequency of the first HF bandpass filter, 2 MHz, is the same as the low cutoff frequency of the second HF bandpass filter, 2 MHz. In the prior art, if these seven HF bandpass filters are placed in seven adjacent cavities 15, then the seven adjacent cavities 15, from left to right, are sequentially arranged as follows: 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. That is, from left to right, the operating sub-bands of the filters in adjacent cavities are adjacent. The problem with this arrangement is that the closer the sub-band frequencies of two adjacent cavities are, the more serious the mutual interference will be. In other words, signal coupling and interference are often prone to occur between filters that are adjacent in physical distance and whose working sub-bands are also adjacent, thereby reducing the suppression index of the filter and affecting the harmonic and spurious index of the whole machine. In order to solve the technical problems existing in the prior art, in an embodiment of the present invention, the working frequency bands of the filters set 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 of adjacent cavities. In the present invention, if Figure 8 As shown, each HF band pass filter is disposed within a cavity 15, and seven HF band pass filters are disposed within seven adjacent cavities 15, and the arrangement order from left to right is: first HF band pass filter, fourth HF band pass filter, seventh HF band pass filter, second HF band pass filter, fifth HF band pass filter, third HF band pass filter, and sixth HF band pass filter. The cavity arrangement method of the HF band pass filter of the present invention staggers the frequency positions of the segmented filters, avoiding the situation where the segmented filter frequency positions are continuous, such as 1.5MHz-2MHz, 2MHz-3MHz, ..., 19MHz-30MHz, thereby reducing crosstalk between filters adjacent in frequency and improving the filter performance.

[0105] In some embodiments, there are 7 HF band bandpass filters, and the passband bandwidth design of each bandpass filter mainly considers the second harmonic suppression of the operating frequency within the passband. The filter in the segment has an insertion loss of at least -50dB at the second harmonic of the starting frequency of the segment; at the same time, considering the feasibility, the filter is designed as a 7th-order elliptical low-pass filter.

[0106] In some embodiments, as Figure 9As shown, the second filter 102 includes: when N2 is equal to 6, the N2 V / UHF band pass filters are respectively:

[0107] The first V / UHF band bandpass filter has a passband frequency of 30MHz to 50MHz;

[0108] The second V / UHF band bandpass filter has a passband frequency of 50MHz to 70MHz;

[0109] The third V / UHF band bandpass filter has a passband frequency of 70MHz to 110MHz;

[0110] Fourth V / UHF band bandpass filter, with a passband frequency of 110MHz to 180MHz;

[0111] Fifth V / UHF band bandpass filter, with a passband frequency of 180MHz to 300MHz;

[0112] The sixth V / UHF band bandpass filter has a passband frequency of 300MHz to 450MHz;

[0113] The same principle as the setting of the HF band bandpass filter mentioned above is used to stagger the operating frequency bands of the filters set in adjacent cavities 15 in the V / UHF band so that the operating sub-bands of two physically adjacent cavities 15 are not adjacent, thereby reducing the signal coupling and interference between adjacent cavities 15. Figure 10 As shown, 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, and 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.

[0114] like Figure 1The radio frequency filter of the present invention shown can simultaneously support HF band, V / UHF band and L band operation, and support N=N1+N2+N3 bandpass filters to operate simultaneously, which broadens the working frequency band, enables it to effectively utilize frequency resources of different frequency bands, and improves communication capabilities. In addition, the bandpass filters of each sub-band are set in an independent cavity 15. When the signals of multiple frequency bands are filtered at the same time, the interference in different frequency bands is resolved, and the communication capability is improved. The four corners of the inner cross-section of the cavity body 2 of each independent cavity 15 are designed to be arc-shaped, which improves the reflection efficiency of the radio frequency 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 radio frequency signal in the arc-shaped area, the surface of the arc-shaped area is coated with a reflective material to increase the reflection efficiency of the radio frequency signal, further avoid leakage to adjacent cavities, and avoid interference in different frequency bands.

[0115] like Figure 2 As shown, an embodiment of the present invention provides another radio frequency filter 200, which includes a first filter 201, a second filter 202, a third filter 203, and a filter switching circuit, wherein 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. The HF band filter switching circuit 204 includes N1 double-pole double-throw electromagnetic relays, each electromagnetic relay is connected to an HF band bandpass filter, and is used to control the opening or closing of the input signal of each HF band filter; the V / UHF band filter switching circuit 205 includes N2 PIN transistor switches, each PIN transistor switch is connected to a V / UHF band bandpass filter, and is used to control the opening or closing of the input signal of each V / UHF band filter; and the L band filter switching circuit 206 includes N3 PIN transistor switches, each PIN transistor switch is connected to an L band bandpass filter, and is used to control 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, allowing a certain section of the filter to be connected or bypassed, thereby controlling the connection or disconnection of the filter.

[0116] like Figure 2 In the RF filter shown, N=N1+N2+N3 bandpass filters can be connected or disconnected individually, thereby supporting only some of the bandpass filters to work, realizing signal transmission only on some sub-bands. It can work in different combinations according to actual needs, or different filters can realize time-sharing work according to different timings, thereby supporting working modes such as frequency hopping.

[0117] like Figure 2 The radio frequency filter shown in FIG. 1 includes a first filter 201 and a second filter 202. Figure 1The first filter 101 is the same as that shown in FIG. 1 , and will not be described in detail here; the second filter 202 is the same as that shown in FIG. Figure 1 The second filter 102 is the same as that shown in FIG. 1 , and will not be described in detail here; the third filter 203 is the same as that shown in FIG. Figure 1 The first filter 103 shown is the same and will not be described again here.

[0118] It should be noted that if Figure 2 The radio frequency filter 200 shown is similar to the Figure 1 The radio frequency filter 100 shown in FIG. 1 is similar to the radio frequency filter 100 shown in FIG. 1 except for the addition of a filter switching circuit. Figure 1 The RF filters shown are the same and the similarities are not repeated here.

[0119] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation plans of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, and is not a limitation on the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

[0120] Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or replacements that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A radio frequency filter, characterized in that: include: The radio frequency filter consists of 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 pass filters; The second filter is used for filtering in the VHF band and / or the UHF band, and includes N2 V / UHF band bandpass filters; The third filter is used for L-band filtering and includes N3 L-band bandpass filters; The radio frequency filter includes N independent cavities, each of which is provided with a bandpass filter; Each cavity is composed of a cover plate (1) and a cavity body (2), the outer side of the cross section of the cavity body (2) is a rectangle, 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=N1+N2+N3; Wherein, the cavity comprises: The four arc-shaped areas of the rounded rectangle are all a quarter of a 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 area is coated with a reflective material (3); Inside the cavity, except for the arc-shaped area, a wave-absorbing material (4) is provided; Each HF band pass filter includes an inductor (7), the inductor (7) is mounted on a printed circuit board (8), a copper plate (9) is provided below the printed circuit board (8), a thermal pad (10) is provided between the copper plate (9) and the printed circuit board (8), and the thermal pad (10) is made of a soft material; The inductor (7) comprises an enameled copper wire (11) and a high-frequency magnetic ring (12), wherein the operating frequency range of the high-frequency magnetic ring (12) is 1 MHz to 20 MHz, or 20 MHz to 40 MHz; An inductor slot is provided on the printed circuit board (8), and the inductor (7) is vertically mounted in the inductor slot of the printed circuit board (8). The inductor (7) passes through the inductor slot, and a thermal pad (10) is used to cover the upper and lower ends of the inductor (7), and then the thermal pad (10) is covered and bonded by a copper plate (9).

2. The radio frequency filter according to claim 1, wherein: Also includes: 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 tube switches; The L-band filter switching circuit includes N3 PIN tube 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.

3. The radio frequency filter according to claim 1 or 2, characterized in that: The first filter comprises: When N1 is equal to 7, the N1 HF band pass filters are respectively: The first HF band bandpass filter has a passband frequency of 1.5 MHz to 2 MHz; The second HF band bandpass filter has a passband frequency of 2MHz to 3MHz; The third HF band bandpass filter has a passband frequency of 3MHz to 4.5MHz; Fourth HF band bandpass filter, with a passband frequency of 4.5MHz to 7MHz; Fifth HF band bandpass filter, with a passband frequency of 7MHz to 11.5MHz; 6th HF band bandpass filter, with a passband frequency of 11.5MHz to 19MHz; 7th HF band bandpass filter, with a passband frequency of 19MHz to 30MHz; Each HF band-pass filter is arranged in a cavity, and seven HF band-pass filters are arranged in seven adjacent cavities, and the arrangement order from left to right is: the cavity of the first HF band-pass filter, the cavity of the fourth HF band-pass filter, the cavity of the seventh HF band-pass filter, the cavity of the second HF band band-pass filter, the cavity of the fifth HF band band-pass filter, the cavity of the third HF band band-pass filter and the cavity of the sixth HF band band-pass filter.

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

5. The radio frequency filter according to claim 1 or 2, characterized in that: The cover plate (1) and the cavity body (2) are connected using two concave-convex structures (5).

6. The radio frequency 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).

7. The radio frequency 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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