An octave bandwidth high power short wave filter and short wave broadcast transmitter
By using a parallel main and auxiliary filter module and an air-cooled heat sink design, the problems of heat dissipation and debugging difficulty of high-power shortwave transmitter filters are solved, achieving efficient harmonic suppression and improved signal transmission reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHENGDU HUAQIAN TECH CO LTD
- Filing Date
- 2025-09-15
- Publication Date
- 2026-07-21
AI Technical Summary
The filters of existing high-power shortwave transmitters have heat dissipation problems when processing harmonic power, which leads to severe temperature rise of components, affecting stability and reliability. At the same time, they are difficult to debug, and increase cost and size.
An octave band filter unit is constructed by using a main filter module and a secondary filter module connected in parallel. The main filter module filters useful signals, while the secondary filter module filters harmonic signals and bypasses them to the absorption load. Combined with an air-cooled heat sink, heat dissipation is reduced and the structure is simplified.
It effectively improves out-of-band harmonic suppression, reduces filter temperature rise, enhances reliability and signal transmission quality, simplifies debugging, reduces failure probability, and extends service life.
Smart Images
Figure CN224538169U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of shortwave broadcast transmitter technology, and more specifically, to an octave bandwidth high-power shortwave filter and a shortwave broadcast transmitter. Background Technology
[0002] Currently, vacuum tubes remain the mainstream technology for high-power shortwave transmitters, while all-solid-state technology is rapidly advancing. In this process, the solid-state power amplifiers in shortwave transmitters all employ octave bandwidth designs. While this design improves equipment flexibility, it also presents a key technical challenge: how to ensure the transmitter only outputs signals at the target frequency, avoiding electromagnetic interference to surrounding equipment and the surrounding environment. Against this backdrop, the high suppression, high stability, and high reliability of filters become core elements for ensuring the electromagnetic compatibility of transmitters.
[0003] In practical applications, the fundamental power output of the transmitter's power amplifier is already at a high level, and the accompanying harmonic power often reaches hundreds or even thousands of watts. If traditional filters are used to handle these harmonic powers through reflection and heat dissipation, it will cause a sharp rise in the temperature of the filter components. Excessive temperature will not only cause a sharp decrease in the stability of the filter, but may also directly cause the components to burn out, seriously affecting the normal operation of the transmitter.
[0004] To address the above issues, the current mainstream technical solution is to add a switching filter bank at the output of each power amplifier module to improve harmonic suppression capability. The advantage of this solution is that the output power of a single power amplifier module is relatively low, and the switching filter bank can operate reliably within the power range, while effectively improving the overall harmonic output performance of the transmitter. However, this solution also has significant limitations, specifically in the following three aspects: (1) Size and cost issues: Since a switching filter bank needs to be configured separately for each power amplifier module, taking a typical device as an example, the filter is divided into 6 segments, and the number of synthesis channels is 4. Thus, one shortwave broadcast transmitter needs to be equipped with 4 switching filter banks, with a total of 24 filters. The use of a large number of filters directly leads to an increase in the overall size of the shortwave broadcast transmitter, and at the same time, the equipment procurement and manufacturing costs increase significantly. (2) Increased debugging difficulty: In order to meet the technical requirements of power synthesis, the amplitude-frequency characteristics and phase characteristics of all filters must be highly consistent. This strict requirement greatly increases the debugging difficulty of the shortwave broadcast transmitter, prolongs the equipment debugging cycle, and increases the complexity of technical operation. (3) Insufficient reliability and production adaptability: The consistency requirements of filter characteristics not only raise the debugging threshold, but also reduce the overall reliability of the transmitter. Any deviation in the characteristics of any filter may affect the performance of the whole machine. At the same time, the complex debugging process and strict device requirements also have an adverse effect on the large-scale production of the transmitter, which is not conducive to improving production efficiency and product yield. Utility Model Content
[0005] The purpose of this invention is to provide an octave bandwidth high-power shortwave filter and a shortwave broadcast transmitter to solve the technical problems pointed out in the background art.
[0006] This utility model is achieved through the following technical solution: an octave band bandwidth high-power shortwave filter, including an input switching switch, an output switching switch, a load switching switch, an absorption load, and at least two octave band filtering units; The output terminal of the input switching switch is connected to the input terminal of the octave band filter unit. The octave band filter unit consists of a main filter module and a secondary filter module connected in parallel. The output terminal of the main filter module is connected to the input terminal of the output switching switch, the output terminal of the secondary filter module is connected to the input terminal of the load switching switch, and the output terminal of the load switching switch is connected to the input terminal of the load absorption unit.
[0007] According to a preferred embodiment, the main filtering module and the secondary filtering module are bandpass filters.
[0008] According to a preferred embodiment, the main filter module is composed of a plurality of first inductors and a plurality of first capacitors, wherein the plurality of first inductors are connected in series, the first terminals of the plurality of first capacitors are respectively connected to the lines between adjacent first inductors, and the second terminals of the plurality of first capacitors are grounded. The secondary filter module consists of several second inductors and second capacitors. The several second capacitors are connected in series, the first ends of the several second inductors are respectively connected to the lines between adjacent second capacitors, and the second ends of the several second inductors are grounded.
[0009] According to a preferred embodiment, the number of octave band filtering units is 6, and the input switching switch, output switching switch and load switching switch are all single-pole six-throw switches.
[0010] According to a preferred embodiment, the octave band filter unit is equipped with a heat sink.
[0011] According to a preferred embodiment, the radiator is an air-cooled radiator.
[0012] According to a preferred embodiment, the absorption load is composed of a coupler CP, a resistor R1, a resistor R2, a diode D1, a capacitor C1, a potentiometer RP1, and a connector CZ1. The input terminal of the coupler CP is connected to the output terminal of the load switching switch. The output terminal of the coupler CP is grounded through resistor R2. The coupling terminal of the coupler CP is connected to the positive terminal of diode D1. The isolation terminal of the coupler CP is grounded through resistor R1 and connected to the first terminal of connector CZ1. The negative terminal of diode D1 is connected to the first terminal of potentiometer RP1 and the first terminal of capacitor C1. The second terminal of capacitor C1 is grounded. The second terminal of connector CZ1 is connected to the sliding terminal of potentiometer RP1. The second terminal of potentiometer RP1 is grounded.
[0013] This invention also provides a shortwave broadcast transmitter, including the octave bandwidth high-power shortwave filter as described above.
[0014] According to a preferred embodiment, it also includes an exciter, a driver stage power amplifier module, a distributor, a final stage power amplifier module, a synthesizer, and a directional coupler; The exciter, the driver stage power amplifier module, and the distributor are connected in sequence. The output of the distributor is connected to multiple final stage power amplifier modules. The output of each final stage power amplifier module is connected to the input of the synthesizer. The output of the synthesizer is connected to the input of the input switching switch in the octave bandwidth high-power shortwave filter. The output of the output switching switch in the octave bandwidth high-power shortwave filter is connected to the input of the directional coupler.
[0015] According to a preferred embodiment, the system further includes a water-cooled load, wherein the output of the directional coupler is connected to the input of the water-cooled load.
[0016] The technical solution of the octave band bandwidth high-power shortwave filter and shortwave broadcast transmitter provided by this utility model has at least the following advantages and beneficial effects: (1) By setting the octave band filter unit as a main filter module and a secondary filter module connected in parallel, the main filter module can filter out useful signals and transmit them to subsequent stages through the output switching switch, while the secondary filter module can specifically filter out useless signals such as harmonics and then bypass them to the absorption load through the load switching switch, which can effectively avoid the interference of useless signals with the transmission of useful signals and greatly improve the out-of-band harmonic suppression effect; (2) Since the useless signals such as harmonics are filtered by the secondary filter module and then directed to the absorption load, instead of being released through reflection and heat dissipation like traditional filters, the heat dissipation power generated by the filter due to carrying high-power harmonics is greatly reduced, thereby effectively reducing the temperature rise of the filter and avoiding the instability of the filter due to high temperature. (3) On the one hand, the reduced heat dissipation reduces the risk of high temperature damage to the filter and extends the service life of the filter. On the other hand, compared with the existing technology where each power amplifier module output needs to add a switching filter group to improve the harmonic suppression capability, the present invention can simplify the overall structure, reduce the debugging difficulty and failure probability caused by the inconsistency of the amplitude and phase characteristics of multiple filters, and improve the reliability of the filter and subsequent shortwave broadcast transmitter operation. (4) The input switching switch can accurately control the signal input to the corresponding octave band filter unit. The output switching switch and the load switching switch correspond to the useful signal output and the useless signal bypass, respectively, so that the signal transmission path is clear and controllable, reducing the interference and loss of the signal during transmission, and at the same time helping to improve the standing wave matching with the antenna, further ensuring the signal transmission quality of the shortwave broadcast transmitter. Attached Figure Description
[0017] Figure 1 This is a schematic diagram illustrating the principle of the octave bandwidth high-power shortwave filter provided in Embodiment 1 of this utility model. Figure 2 A schematic diagram of the octave band filter unit provided in Embodiment 1 of this utility model; Figure 3 A schematic diagram of the principle of the absorption load provided in Embodiment 1 of this utility model; Figure 4 This is a schematic diagram of the shortwave broadcast transmitter provided in Embodiment 2 of this utility model. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0019] Example 1 This invention provides an octave bandwidth high-power shortwave filter. Figure 1 The schematic diagram of this octave bandwidth high-power shortwave filter is shown below. Figure 1 As shown, the octave bandwidth high-power shortwave filter includes an input switching switch, an output switching switch, a load switching switch, an absorption load, and at least two octave filtering units.
[0020] The specific structure and connection relationships of each component are as follows: The octave band filtering unit, specifically in this embodiment, refers to... Figure 2 As shown, there are 6 octave band filter units, which correspond to the 6 frequency bands of the shortwave broadcast transmitter.
[0021] Each octave band filter unit consists of a main filter module and a secondary filter module connected in parallel, and both the main filter module and the secondary filter module are bandpass filters. The main filter module consists of several first inductors and first capacitors. The several first inductors are connected in series, the first terminals of the several first capacitors are respectively connected to the lines between adjacent first inductors, and the second terminals of the several first capacitors are grounded.
[0022] In some implementations, the main filtering module includes five first inductors and five first capacitors. The five first inductors are connected in series to form the main signal path. The first terminals of the five first capacitors are respectively connected to the lines between adjacent first inductors, and the second terminals of the five first capacitors are grounded. This structure can efficiently filter out useful fundamental wave signals in the corresponding frequency band.
[0023] The secondary filter module consists of several second inductors and second capacitors. The second capacitors are connected in series, the first ends of the second inductors are connected to the lines between adjacent second capacitors, and the second ends of the second inductors are grounded.
[0024] In some implementations, the secondary filter module comprises five second inductors and five second capacitors. The five second capacitors are connected in series to form a secondary signal path. The first ends of the five second inductors are respectively connected to the lines between adjacent second capacitors, and the second ends of the five second inductors are grounded. This structure can selectively filter out useless signals such as harmonics in this frequency band.
[0025] Specifically, in this embodiment, the octave band filter unit is configured as a main filter module and a secondary filter module connected in parallel. The main filter module can filter out useful signals and transmit them to subsequent stages via an output switching switch. The secondary filter module can selectively filter out useless signals such as harmonics and then bypass them to the absorption load via a load switching switch. This can effectively prevent useless signals from interfering with the transmission of useful signals and significantly improve the out-of-band harmonic suppression effect.
[0026] Furthermore, the octave band filter unit is equipped with a heat sink, preferably an air-cooled heat sink, with the air vents of the air-cooled heat sink facing the octave band filter unit to accelerate heat dissipation through forced airflow; preferably, six octave band filter units share one air-cooled heat sink for heat dissipation, but no specific limitation is made here.
[0027] In this specific example, the input switching switch is a high-power single-pole six-throw switch, which has the ability to withstand high-power signals. The output terminal of the input switching switch is connected to the input terminal of the octave filter unit, which can achieve selective connection with the six octave filter units and ensure that the signal is accurately input to the target octave filter unit.
[0028] In this embodiment, both the output switching switch and the load switching switch are high-power single-pole six-throw switches. The output terminal of the main filter module is connected to the input terminal of the output switching switch, allowing the output switching switch to selectively connect to the main filter module among the six octave band filter units. The output terminal of the secondary filter module is connected to the input terminal of the load switching switch, allowing the load switching switch to selectively connect to the secondary filter module among the six octave band filter units.
[0029] Specifically, the input switching switch can precisely control the signal input to the corresponding octave band filter unit, while the output switching switch and load switching switch correspond to the output of useful signals and the bypass of useless signals, respectively, making the signal transmission path clear and controllable, reducing interference and loss of signals during transmission, and helping to improve the standing wave matching with the antenna, further ensuring the signal transmission quality of the shortwave broadcast transmitter.
[0030] Absorbing load, specifically in this embodiment, see [link to relevant documentation]. Figure 3 As shown, the output terminal of the load switching switch is connected to the input terminal of the absorption load; the absorption load consists of a coupler CP, a resistor R1, a resistor R2, a diode D1, a capacitor C1, a potentiometer RP1, and a connector CZ1. The input terminal of coupler CP is connected to the output terminal of the load switching switch. The output terminal of coupler CP is grounded through resistor R2. The coupling terminal of coupler CP is connected to the positive terminal of diode D1. The isolation terminal of coupler CP is grounded through resistor R1 and connected to the first terminal of connector CZ1. The negative terminal of diode D1 is connected to the first terminal of potentiometer RP1 and the first terminal of capacitor C1. The second terminal of capacitor C1 is grounded. The second terminal of connector CZ1 is connected to the sliding terminal of potentiometer RP1. The second terminal of potentiometer RP1 is grounded. The impedance matching optimization of the absorbed load can be achieved by adjusting potentiometer RP1.
[0031] Specifically, since unwanted signals such as harmonics are filtered by the secondary filter module and directed to the absorption load, rather than being released through reflection and heat dissipation as in traditional filters, the heat dissipation power generated by the filter due to carrying high-power harmonics is greatly reduced. This effectively reduces the temperature rise of the filter, avoids instability or burnout of the filter due to high temperature, and ensures high thermal stability.
[0032] The working principle of the octave bandwidth high-power shortwave filter provided in this embodiment is explained below: When the shortwave radio transmitter is operating, the power signal (containing the fundamental useful signal and harmonic unwanted signals) after being synthesized by the final stage power amplifier is first input to the input switching switch. Based on the current operating frequency of the shortwave radio transmitter, the signal is switched to the corresponding octave band filter unit. After entering this octave band filter unit, the signal is split into two paths. One signal enters the main filtering module, and after being filtered by the first inductor and the grounded first capacitor, only the fundamental useful signal of this frequency band is retained. This fundamental useful signal is transmitted to the input terminal corresponding to the output switching switch. The output switching switch is switched to this path in sync, and the fundamental useful signal is transmitted to the downstream directional coupler, and finally transmitted through the antenna.
[0033] Another signal enters the secondary filter module. After being filtered by the second capacitor in series and the second inductor grounded, the harmonic unwanted signal in this frequency band is screened out and transmitted to the corresponding input terminal of the load switching switch. The load switching switch synchronously switches to this path, transmitting the harmonic unwanted signal to the absorption load. After being distributed by the coupler, part of the power of the harmonic unwanted signal is converted into heat energy and consumed by resistor R2. The other part of the coupled signal is rectified by diode D1 and filtered by capacitor C1. The impedance matching is adjusted by potentiometer RP1 to ensure that the harmonic unwanted signal is efficiently absorbed and to avoid reflection back to the octave band filter unit.
[0034] Meanwhile, the air-cooled radiator continues to work, dissipating the heat generated by the octave band filter unit in a timely manner, and maintaining the temperature stability of the octave band filter unit.
[0035] The following tests compare existing filter modules with the octave bandwidth high-power shortwave filter provided in this embodiment under the same conditions, with a carrier wave of 500W and a modulation power of 2KW. Table 1. Test results of existing filter modules at a carrier power of 500W / modulation power of 2KW (ambient temperature 20℃)
[0036] Table 2. Test results of the octave bandwidth high-power shortwave filter provided in this embodiment at a carrier power of 500W / modulation power of 2KW (ambient temperature 20℃).
[0037] As can be seen from Tables 1 and 2 above, the temperature in this embodiment has been significantly reduced and the power tolerance has been multiplied. Bands 1 to 6 correspond to each octave band filtering unit.
[0038] In summary, the octave bandwidth high-power shortwave filter provided in this embodiment reduces the risk of high-temperature damage to the filter and extends its service life by reducing heat dissipation. On the other hand, compared with the prior art where each power amplifier module output requires an additional switching filter bank to improve harmonic suppression capability, this invention simplifies the overall structure, reduces the debugging difficulty and failure probability caused by the inconsistency of amplitude and phase characteristics of multiple filters, and improves the reliability of the filter and subsequent shortwave broadcast transmitter operation.
[0039] Example 2 This embodiment is based on the technical solution provided in Embodiment 1, and provides a shortwave broadcast transmitter, which includes an octave bandwidth high-power shortwave filter as in Embodiment 1.
[0040] In this embodiment, see Figure 4 As shown, the shortwave broadcast transmitter also includes an exciter, a driver stage power amplifier module, a distributor, a final stage power amplifier module, a synthesizer, and a directional coupler.
[0041] The specific structure and connection relationships of each component are as follows: The exciter uses a dedicated shortwave band excitation module, supports octave band bandwidth signal output, and can generate a stable fundamental excitation signal, providing a high-quality signal source for subsequent power amplification stages.
[0042] The driver stage power amplifier module uses an all-solid-state power amplifier module. Its input is connected to the exciter output, which can amplify the low-power signal output by the exciter. The amplification gain is stable and the linearity is good, which can effectively reduce signal distortion and provide the final stage power amplifier module with a drive signal that meets the power requirements.
[0043] The distributor uses a 4-channel power distribution module. The input port is connected to the output of the driver stage power amplifier module, and the number of output ports is 4. It can evenly distribute the output signal of the driver stage power amplifier to the 4 final stage power amplifier modules, ensuring that the input signal power of each final stage power amplifier module is consistent.
[0044] There are four final stage power amplifier modules, which are connected one-to-one with the four output ports of the distributor to further amplify the signal input to the distributor and meet the high power output requirements of the shortwave broadcast transmitter.
[0045] The synthesizer uses a 4-channel power combining module. The 4 input ports are connected to the outputs of the 4 final stage power amplifier modules, and the output ports are connected to the input switching switch of the shortwave filter. It can efficiently combine the signals output from the 4 final stage power amplifier modules and finally output the total power signal.
[0046] The shortwave filter adopts the structure of Embodiment 1. The function and technical effect of the shortwave filter in this embodiment are the same as those of the embodiment of the octave bandwidth high-power shortwave filter, and will not be repeated here.
[0047] The directional coupler uses a high-power directional coupling module. The input port is connected to the output of the shortwave filter's output switching switch, the direct output port is connected to the input of the water-cooled load, and the coupling output port can be connected to monitoring equipment such as a power meter. It is used to monitor parameters such as the power and VSWR of the shortwave broadcast transmitter's output signal, while also achieving directional signal transmission and reducing signal reflection.
[0048] The water-cooled load uses a closed-loop water circulation cooling system. Its input end is connected to the direct output port of the directional coupler. It can receive and consume the signal power transmitted by the directional coupler. When the shortwave broadcast transmitter is being debugged or the antenna system is malfunctioning, it can serve as a backup load to absorb power and prevent signal reflection from damaging the equipment. At the same time, the water circulation system efficiently dissipates heat and maintains a stable operating temperature of the load.
[0049] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. An octave bandwidth high-power shortwave filter, characterized in that, It includes an input switching switch, an output switching switch, a load switching switch, an absorption load, and at least two octave band filtering units; The output terminal of the input switching switch is connected to the input terminal of the octave band filter unit. The octave band filter unit consists of a main filter module and a secondary filter module connected in parallel. The output terminal of the main filter module is connected to the input terminal of the output switching switch, the output terminal of the secondary filter module is connected to the input terminal of the load switching switch, and the output terminal of the load switching switch is connected to the input terminal of the load absorption unit.
2. The octave band bandwidth high-power shortwave filter as described in claim 1, characterized in that, The main filtering module and the secondary filtering module are bandpass filters.
3. The octave band bandwidth high-power shortwave filter as described in claim 2, characterized in that, The main filter module is composed of several first inductors and first capacitors. The several first inductors are connected in series, the first terminals of the several first capacitors are respectively connected to the lines between adjacent first inductors, and the second terminals of the several first capacitors are grounded. The secondary filter module consists of several second inductors and second capacitors. The several second capacitors are connected in series, the first ends of the several second inductors are respectively connected to the lines between adjacent second capacitors, and the second ends of the several second inductors are grounded.
4. The octave band bandwidth high-power shortwave filter as described in any one of claims 1 to 3, characterized in that, The number of octave band filtering units is 6, and the input switching switch, output switching switch and load switching switch are all single-pole six-throw switches.
5. The octave bandwidth high-power shortwave filter as described in claim 4, characterized in that, The octave band filter unit is equipped with a heat sink.
6. The octave bandwidth high-power shortwave filter as described in claim 5, characterized in that, The radiator is an air-cooled radiator.
7. The octave band bandwidth high-power shortwave filter as described in claim 1, characterized in that, The absorption load consists of a coupler CP, a resistor R1, a resistor R2, a diode D1, a capacitor C1, a potentiometer RP1, and a connector CZ1. The input terminal of the coupler CP is connected to the output terminal of the load switching switch. The output terminal of the coupler CP is grounded through resistor R2. The coupling terminal of the coupler CP is connected to the positive terminal of diode D1. The isolation terminal of the coupler CP is grounded through resistor R1 and connected to the first terminal of connector CZ1. The negative terminal of diode D1 is connected to the first terminal of potentiometer RP1 and the first terminal of capacitor C1. The second terminal of capacitor C1 is grounded. The second terminal of connector CZ1 is connected to the sliding terminal of potentiometer RP1. The second terminal of potentiometer RP1 is grounded.
8. A shortwave broadcast transmitter, characterized in that, Including the octave bandwidth high-power shortwave filter as described in any one of claims 1 to 7.
9. The shortwave broadcast transmitter as described in claim 8, characterized in that, It also includes exciters, driver stage power amplifier modules, distributors, final stage power amplifier modules, synthesizers, and directional couplers; The exciter, the driver stage power amplifier module, and the distributor are connected in sequence. The output of the distributor is connected to multiple final stage power amplifier modules. The output of each final stage power amplifier module is connected to the input of the synthesizer. The output of the synthesizer is connected to the input of the input switching switch in the octave bandwidth high-power shortwave filter. The output of the output switching switch in the octave bandwidth high-power shortwave filter is connected to the input of the directional coupler.
10. The shortwave broadcast transmitter as described in claim 9, characterized in that, It also includes a water-cooled load, and the output of the directional coupler is connected to the input of the water-cooled load.