Vehicle-mounted wireless communication equipment and band-pass filter thereof

Abstract

The embodiment of the utility model provides a vehicle-mounted wireless communication device and a band-pass filter thereof, the band-pass filter comprises a substrate and a filter circuit arranged on the substrate, and the filter circuit is formed by a microstrip feeder line formed on the substrate. The two ends of the main line are an input end and an output end respectively; the microstrip branches laterally extend from a preset position in the middle of the main line respectively; the tail ends of the microstrip branches are grounded to filter interference signals; each micro-strip branch knot is designed to have adaptive length and width, so that the whole micro-strip feeder line has a matching resistance value matched with the impedance of the predetermined frequency band. According to the embodiment of the utility model, the microstrip feeder is adopted to form the filter circuit, the production cost is saved, the microstrip feeder comprises a main line and a plurality of microstrip branches formed by extending from the side direction of the main line, the tail end of each microstrip branch is correspondingly grounded to filter interference signals, multi-order filtering is formed through combination, and the interference signal filtering effect is good.

Description

Technical Field

[0001] The embodiment of the utility model relates to the technical field of vehicle-mounted wireless communication, and in particular to a vehicle-mounted wireless communication device and a bandpass filter thereof. Background Art

[0002] In-vehicle wireless communication equipment greatly facilitates data transmission during driving. For example, in-vehicle ETC (Electronic Toll Collection) can achieve toll payment without stopping at highways, bridge toll stations, etc. through dedicated short-range communication between the in-vehicle electronic tag installed on the windshield and the microwave antenna on the ETC lane of the toll station, so that vehicles can pass through the toll ramp smoothly and quickly, saving the time of passengers on the vehicle; and in-vehicle DVR (Driving Video Recording) can use wireless communication to control equipment and transmit image data.

[0003] In order to improve the signal transmission quality, a corresponding bandpass filter is usually installed to filter the received signal to retain the signal in the predetermined frequency band. Existing vehicle-mounted bandpass filters usually use LC filter circuits composed of complex electronic components such as resistors, inductors, and capacitors. The assembly space is large, which affects the miniaturization of the overall size of the vehicle-mounted wireless communication equipment; at the same time, the added electronic components are not conducive to the control of production costs. Utility Model Content

[0004] The technical problem to be solved by the embodiments of the utility model is to provide a vehicle-mounted bandpass filter with a simple structure and small assembly space.

[0005] A further technical problem to be solved by the embodiments of the present invention is to provide a vehicle-mounted wireless communication device, wherein the bandpass filter has a simple structure and occupies a small assembly space.

[0006] In order to solve the above-mentioned technical problems, an embodiment of the utility model provides the following technical solutions: a vehicle-mounted bandpass filter for filtering out interference signals and retaining signals in a predetermined frequency band, comprising a substrate and a filtering circuit arranged on the substrate, wherein the filtering circuit is composed of a microstrip feeder formed on the substrate, wherein the microstrip feeder comprises a main line with input and output ends at both ends, and a plurality of microstrip branches extending laterally from predetermined positions in the middle of the main line and having their ends grounded to filter out interference signals, wherein each of the microstrip branches is designed to have an adapted length and width so that the microstrip feeder as a whole has a matching resistance value that matches the impedance of the predetermined frequency band.

[0007] Furthermore, the microstrip branches are an odd number, including a central branch formed by extending from the midpoint of the main line and side branches formed by extending from at least a pair of nodes on the main line that are equidistantly distributed relative to the midpoint.

[0008] Furthermore, the central branch extends from the midpoint toward opposite sides of the main line by the same length, and the side branch extends from the corresponding node toward only one side of the main line.

[0009] Furthermore, the length of the central branch extending on one side of the main line is the same as the length of each of the side branches extending therefrom, and the width of the central branch is the same as the width of the side branches.

[0010] Furthermore, each of the microstrip branches extends laterally from the main line for a predetermined length and then bends vertically to extend parallel to the main line, and sections of each of the microstrip branches parallel to the main line are arranged staggered with each other.

[0011] Furthermore, at least one U-shaped bend is formed in the main line.

[0012] Furthermore, the substrate is a metal-based PCB board, including a metal base plate and a resin panel formed on one side of the metal base plate, the microstrip feeder is formed on the side of the resin panel facing away from the metal base plate, and the end of the microstrip branch is connected to the metal base plate serving as a grounding end through a metal hole passing through the resin panel.

[0013] On the other hand, in order to further solve the above-mentioned technical problems, an embodiment of the utility model provides the following solution: a vehicle-mounted wireless communication device, comprising an antenna module for transmitting and receiving signals and a bandpass filter for filtering out interference signals and retaining signals in a predetermined frequency band, wherein the bandpass filter is a vehicle-mounted bandpass filter as described in any of the above items.

[0014] Furthermore, the median value of the predetermined frequency band is 5.8 GHz.

[0015] Furthermore, the matching resistance of the microstrip feed line is 45-55Ω.

[0016] After adopting the above technical scheme, the embodiment of the utility model has at least the following beneficial effects: the embodiment of the utility model adopts a microstrip feeder to replace complex electronic components such as capacitors and inductors to form a filtering circuit. The microstrip feeder is light in weight, small in size, and low in cost, saving installation space and cost. The microstrip feeder includes a main line and a plurality of microstrip branches extending laterally from predetermined positions in the middle of the main line. The ends of each of the microstrip branches are grounded accordingly and first-order filtering of interference signals is performed accordingly. A combination of multiple microstrip branches constitutes a multi-order filter, which has a good effect on filtering interference signals. On the other hand, by adaptively designing the length and width of the microstrip branches, it is convenient to perform impedance matching on the microstrip feeder, reduce the loss and reflection of the predetermined frequency band signal to be retained in the filtering circuit, and enhance the signal transmission quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a schematic structural diagram of an optional embodiment of the vehicle-mounted bandpass filter of the utility model.

[0018] Figure 2 This is a schematic structural diagram of another optional embodiment of the vehicle-mounted bandpass filter of the utility model.

[0019] Figure 3 The figure is a graph showing the relationship between the standing wave ratio and the signal frequency of an optional embodiment of the vehicle-mounted bandpass filter of the utility model.

[0020] Figure 4 This is a graph showing changes in reflection coefficient and insertion loss versus frequency for an optional embodiment of the vehicle-mounted bandpass filter of the utility model.

[0021] Figure 5 The figure is a cross-sectional schematic diagram of an optional embodiment of the vehicle-mounted bandpass filter of the utility model. DETAILED DESCRIPTION

[0022] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following illustrative embodiments and descriptions are only used to explain the present invention and are not intended to limit the present invention. In addition, the embodiments and features in the embodiments of the present application may be combined with each other without conflict.

[0023] like Figure 1-Figure 5As shown, an optional embodiment of the utility model provides a vehicle-mounted bandpass filter for filtering out interference signals and retaining signals in a predetermined frequency band, including a substrate 1 and a filtering circuit arranged on the substrate 1, wherein the filtering circuit is composed of a microstrip feeder 2 formed on the substrate, wherein the microstrip feeder 2 includes a main line 21 with input ends and output ends respectively, and a plurality of microstrip branches 23 extending laterally from predetermined positions in the middle of the main line 21 and having their ends grounded to filter out interference signals, wherein each of the microstrip branches 23 is designed to have an adapted length and width respectively so that the microstrip feeder 2 as a whole has a matching resistance value that matches the impedance of the predetermined frequency band.

[0024] The embodiment of the utility model adopts a microstrip feeder 2 to replace complex electronic components such as capacitors and inductors to form a filtering circuit. The microstrip feeder 2 is light in weight, small in size, and low in cost, saving space and cost for installation. The microstrip feeder 2 includes a main line 21 and a plurality of microstrip branches 23 extending laterally from predetermined positions in the middle of the main line 21. The ends of each of the microstrip branches 23 are grounded accordingly and first-order filtering of interference signals is performed accordingly. A combination of a plurality of the microstrip branches 23 constitutes a multi-order filter, which has a good effect on filtering interference signals. On the other hand, by adaptively designing the length and width of the microstrip branches 23, impedance matching of the microstrip feeder 2 is facilitated, the loss and reflection of the predetermined frequency band signal to be retained in the filtering circuit are reduced, and the signal transmission quality is enhanced.

[0025] In another optional embodiment of the present invention, Figure 1-Figure 2 As shown, the microstrip branches 23 are an odd number, including a central branch 23a extending from the midpoint 210 of the main line 21 and a side branch 23b extending from at least one pair of nodes 212 on the main line 21 that are equidistantly distributed relative to the midpoint 210. In this embodiment, the microstrip branches 23 are set to an odd number, including the central branch 23a extending from the midpoint 210 of the main line 21 and the side branches 23b extending from at least one pair of nodes 212 on the main line 21 that are equidistantly distributed relative to the midpoint 210, and the side branches 23b are symmetrically distributed, so that the symmetry of the filtering effect is better, so that a waveform diagram with better symmetry can be obtained, the offset of the passband frequency band relative to the predetermined frequency band is reduced, and the passband effect is improved.

[0026] In another optional embodiment of the present invention, Figure 1-Figure 2As shown, the central branch 23a extends from the midpoint 210 to the opposite sides of the main line 21 by the same length, and the side branch 23b extends from the corresponding node 212 only toward one side of the main line 21. In this embodiment, the side branch 23b extends only toward one side of the main line 21, while the central branch 23a extends from the midpoint 210 to the opposite sides of the main line 21 by the same length, which is beneficial for the microstrip branch 23 to maintain symmetry and facilitates compact routing design.

[0027] In another optional embodiment of the present invention, Figure 1-Figure 2 As shown, the length of the central branch 23a extending on one side of the main line 21 is the same as the length of each of the side branches 23b extending, and the width of the central branch 23a is the same as the width of the side branches 23b. In this embodiment, by setting the length and width of the central branch 23a extending on one side to be consistent with the length and width of the side branches 23b, on the one hand, it is convenient to design and produce the microstrip branch 23, and on the other hand, it further enhances the symmetry of the microstrip branch 23 to ensure the bandpass effect.

[0028] In another optional embodiment of the present invention, Figure 1-Figure 2 As shown, each of the microstrip branches 23 extends laterally from the main line 21 for a predetermined length and then bends vertically to extend parallel to the main line 21, and the sections of each of the microstrip branches 23 parallel to the main line 21 are arranged staggered with each other. In this embodiment, each of the microstrip branches 23 is bent and routed to reduce the space occupied by each of the microstrip branches 23 on the substrate 1, which facilitates the miniaturization design of the overall size of the vehicle-mounted wireless communication device, and each of the microstrip branches 23 is arranged staggered with each other to ensure the filtering characteristics of each of the microstrip branches 23.

[0029] In another optional embodiment of the present invention, Figure 1-Figure 2 As shown, at least one U-shaped bend is formed in the main line 21. In this embodiment, by forming at least one U-shaped bend on the main line 21, the layout compactness of the filter circuit is improved and the space occupation is further reduced.

[0030] In another optional embodiment of the present invention, Figure 5As shown, the substrate 1 is a metal-based PCB board, including a metal bottom plate 12 and a resin panel 10 formed on one side of the metal bottom plate 12, the microstrip feed line 2 is formed on the side of the resin panel 10 away from the metal bottom plate 12, and the end of the microstrip branch 23 is connected to the metal bottom plate 12 as a grounding end through a metal hole 230 penetrating the resin panel 10. The substrate 1 in this embodiment includes a metal bottom plate 12 and a resin panel 10 formed on one side of the metal bottom plate 12, and the microstrip feed line 2 is arranged on the resin panel 10, and the metal bottom plate 12 is connected to the metal hole 230 at the end of the microstrip branch 23 to achieve grounding, which has a simple structure and a relatively lower cost.

[0031] On the other hand, in order to further solve the above technical problems, the embodiment of the utility model provides the following solution: a vehicle-mounted wireless communication device, comprising an antenna module for transmitting and receiving signals and a bandpass filter for filtering out interference signals and retaining signals in a predetermined frequency band, wherein the bandpass filter is a vehicle-mounted bandpass filter as described in any of the above embodiments. In this embodiment, a vehicle-mounted bandpass filter that uses a microstrip feeder 2 to form a filter circuit reduces installation space occupancy, reduces production costs, and is more convenient for installation and application.

[0032] In another optional embodiment of the present invention, Figure 3-Figure 4 As shown, the median value of the predetermined frequency band is 5.8 GHz. By setting the median value of the predetermined frequency band to 5.8 GHz, this embodiment can be applied to most application scenarios of vehicle-mounted wireless communication and has a wide range of applications.

[0033] In another optional embodiment of the present invention, the matching resistance of the microstrip feed line 2 is 45-55Ω. In this embodiment, the impedance of the microstrip feed line 2 is matched to form a resistance of 45-55Ω, and the standing wave performance is good. Figure 3 As shown, it can filter the signals outside 4.5GHz~7GHz well, and at the same time greatly reduce the loss and reflection of the filter circuit to the signals in the 5.7GHz~5.9GHz frequency band, and obtain the following Figure 4 The reflection coefficient <-23 and insertion loss <0.23dB shown in the figure achieve effective retention of signals in the 5.7GHz~5.9GHz frequency band, ensuring communication quality.

[0034] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many variations without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A vehicle-mounted bandpass filter, used to filter out interference signals and retain signals in a predetermined frequency band, comprising a substrate and a filter circuit arranged on the substrate, characterized in that: The filtering circuit is composed of a microstrip feed line formed on the substrate, and the microstrip feed line includes a main line with an input end and an output end at both ends, and a plurality of microstrip branches extending laterally from predetermined positions in the middle of the main line and with their ends grounded to filter out interference signals. Each of the microstrip branches is designed to have an adapted length and width so that the microstrip feed line as a whole has a matching resistance value that matches the impedance of the predetermined frequency band.

2. The vehicle-mounted bandpass filter according to claim 1, characterized in that: The microstrip branches are an odd number of branches, including a central branch extending from the midpoint of the main line and side branches extending from at least a pair of nodes on the main line that are equidistantly distributed relative to the midpoint.

3. The vehicle-mounted bandpass filter according to claim 2, characterized in that: The central branch extends from the midpoint toward opposite sides of the main line by the same length, and the side branch extends from the corresponding node toward only one side of the main line.

4. The vehicle-mounted bandpass filter according to claim 3, characterized in that: The length of the central branch extending on one side of the main line is the same as the length of each of the side branches extending therefrom, and the width of the central branch is the same as the width of the side branches.

5. The vehicle-mounted bandpass filter according to claim 1, 2 or 3, characterized in that: Each of the microstrip branches extends laterally from the main line for a predetermined length and then bends vertically to extend parallel to the main line, and sections of each of the microstrip branches parallel to the main line are arranged staggered with each other.

6. The vehicle-mounted bandpass filter according to claim 1, characterized in that: At least one U-shaped bend is formed in the main line.

7. The vehicle-mounted bandpass filter according to claim 1, characterized in that: The substrate is a metal-based PCB board, including a metal base plate and a resin panel formed on one side of the metal base plate. The microstrip feeder is formed on the side of the resin panel facing away from the metal base plate. The end of the microstrip branch is connected to the metal base plate as a grounding end through a metal hole penetrating the resin panel.

8. A vehicle-mounted wireless communication device, comprising an antenna module for transmitting and receiving signals and a bandpass filter for filtering out interference signals and retaining signals in a predetermined frequency band, characterized in that: The bandpass filter is a vehicle-mounted bandpass filter as described in any one of claims 1 to 7.

9. The vehicle-mounted wireless communication device according to claim 8, characterized in that: The median value of the predetermined frequency band is 5.8 GHz.

10. The vehicle-mounted wireless communication device according to claim 9, characterized in that: The matching resistance of the microstrip feed line is 45-55Ω.

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