Integrated multi-frequency adjustable band elimination filter

Abstract

The invention provides an integrated multi-frequency adjustable band elimination filter. The integrated multi-frequency adjustable band elimination filter comprises more than one adjustable band elimination filtering module, each adjustable band elimination filtering module comprises a 90-degree bridge and a frequency hopping combiner; the 90-degree bridge is provided with an input end IN, an isolation end ISO and two coupling ends; the frequency hopping combiner is connected between two coupling ends of the 90-degree bridge; the frequency hopping combiner comprises a combining matching unit and N frequency hopping band-pass filters which are connected in parallel through the combining matching unit, and N is an integer greater than or equal to 2; and the combining matching unit is configured to enable the N frequency hopping band-pass filters which are connected in parallel to have no influence on impedance at a common combining point, so that N independent adjustable band elimination frequencies are realized. The multi-frequency adjustable band elimination filter adopts a parallel structure, and a plurality of frequency hopping band-pass filters are connected in parallel on a shared 90-degree bridge through a frequency hopping combiner, so that multi-frequency band elimination is realized.

Description

Technical Field

[0001] This invention relates to the field of tunable filter technology, and more specifically, to an integrated multi-frequency tunable bandstop filter. Background Technology

[0002] The field of electronic communications is developing rapidly. While the application of various electronic and electrical equipment has improved work, life, and national defense, it has also brought about various complex electromagnetic interference problems. Interference causes a decline in communication quality and even interruptions, with a very significant impact. Therefore, it is crucial to effectively suppress various interference signals.

[0003] Existing technologies, such as the Chinese invention patent "Frequency Hopping Bandstop Filter and Communication Equipment" (publication number: CN117477191A), achieve multi-frequency suppression by cascading multiple independent frequency hopping bandstop modules. Each frequency hopping bandstop module contains a directional coupling unit (such as a 3dB bridge) and a frequency hopping bandpass unit. This series-cascaded architecture essentially connects multiple single-path filter modules in series in the signal path, resulting in the following inherent disadvantages: (i) Large size and low integration: For each additional stopband frequency, a complete module (including a bridge, matching unit, and frequency hopping bandpass unit) needs to be added, resulting in a significant increase in size, weight, and cost; (ii) Accumulated passband loss: Due to the cascaded structure, the signal needs to pass through all modules sequentially, and the passband insertion loss increases exponentially with the number of cascaded modules N, which is fatal to the receiving sensitivity of communication equipment; (iii) Poor flexibility: Current products are limited by loss and size, and can only achieve dual-frequency adjustable bandstop at most, making it difficult to meet the requirements of three or more multi-frequency suppression.

[0004] Therefore, there is an urgent need in this field for a multi-frequency adjustable bandstop filter that can fundamentally overcome the defects of cascaded architecture. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the prior art, the present invention aims to provide an integrated multi-frequency adjustable bandstop filter. This multi-frequency adjustable bandstop filter adopts a parallel architecture, in which multiple frequency-hopping bandpass filters are connected in parallel on a shared 90-degree bridge through a frequency-hopping combiner, thereby realizing multi-frequency bandstop.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: an integrated multi-frequency adjustable bandstop filter, comprising one or more adjustable bandstop filter modules; each adjustable bandstop filter module includes a 90-degree bridge and a frequency hopping combiner; The 90-degree bridge has one input terminal IN, one isolation terminal ISO, and two coupling terminals; The frequency hopping combiner is connected between the two coupling terminals of the 90-degree bridge. The frequency hopping combiner includes a combining matching unit and N frequency hopping bandpass filters connected in parallel through the combining matching unit, where N is an integer greater than or equal to 2; the combining matching unit is configured to ensure that the impedances of the N parallel frequency hopping bandpass filters do not affect each other at a common combining point, thereby realizing N independent adjustable bandstop frequencies.

[0007] Preferably, the combining matching unit includes an input combining matching unit and an output combining matching unit with mutually symmetrical topologies; the input terminals of N frequency-hopping bandpass filters are respectively connected to the input combining matching unit, and the output terminals of N frequency-hopping bandpass filters are respectively connected to the output combining matching unit, so as to realize the N frequency-hopping bandpass filters in parallel; both the input combining matching unit and the output combining matching unit adopt a star network structure; the star network includes a combining point and N branches connected to the combining point; each branch of the star network includes a cable of length L, which is used to perform phase transformation on the signal of the corresponding frequency-hopping bandpass filter.

[0008] Preferably, the cable length L is configured such that the phase transformation provided at the center frequency of the passband of the corresponding frequency hopping bandpass filter is close to 90 degrees.

[0009] Preferably, the cable length L is configured as follows: Determine the common operating frequency band of N frequency-hopping bandpass filters; select an optimal design frequency within the common operating frequency band. f 0 Based on the optimized design frequency f 0 Corresponding guide wavelength λ 0 The calculated length L is: L = (2n+1) × λ 0 / 8.

[0010] Preferably, the merging point is provided with an LC matching network on the side away from the branch; the LC matching network includes a capacitor module and an inductor module; the merging point is connected to the coupling terminal of the 90-degree bridge through the capacitor module; the coupling terminal of the 90-degree bridge is grounded through the inductor module; the capacitor module includes one or more capacitors; when there are two or more capacitors, they are connected in series; the inductor module includes one or more inductors; when there are two or more inductors, they are connected in parallel.

[0011] Preferably, the 90-degree bridge and the frequency hopping combiner are integrated into a single module.

[0012] Preferably, two or more integrated modules are cascaded; the isolation terminal ISO of the previous integrated module is connected to the input terminal IN of the next integrated module.

[0013] Preferably, when there are two or more adjustable bandstop filter modules, the operating frequency bands of the bandpass filters of different frequency hopping combiners are different from each other, partially the same, or completely the same.

[0014] Preferably, in the same frequency hopping combiner, the operating frequency bands of each frequency hopping bandpass filter are different.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. True integration and miniaturization: This invention adopts a parallel structure, connecting N frequency-hopping bandpass filters in parallel on a shared combining matching unit, requiring only one 90-degree bridge; compared with the existing cascaded schemes that require N bridges and N modules, this significantly reduces the number, size and weight of components, achieving a high degree of integration; 2. Fundamentally improved loss characteristics: Since multiple frequency hopping bandpass filters are connected in parallel to the system, the main path of the signal (i.e., the passband) only needs to pass through a 90-degree bridge; therefore, the passband insertion loss of the filter mainly depends on the loss of the 90-degree bridge, and does not increase with the increase of the number N of parallel frequency hopping bandpass filters. This completely solves the inherent defect of loss accumulation in the cascaded scheme. 3. Clear structural advantages: This invention achieves N-frequency notch filtering using a bridge and a frequency hopping combiner through a parallel structure and a star matching network. Compared with existing technologies that require N cascaded modules, it has the advantages of fundamental simplification, higher integration, and lower loss. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the integrated multi-frequency adjustable bandstop filter of the present invention; Figure 2 This is a schematic diagram of the structure of the frequency hopping combiner of the integrated multi-frequency adjustable bandstop filter of the present invention; Figure 3 This is a schematic diagram of the first example of the star network structure of the integrated multi-frequency adjustable bandstop filter of the present invention. Figure 4 This is a schematic diagram of the second example of the star network structure of the integrated multi-frequency adjustable bandstop filter of the present invention; Figure 5 This is a schematic diagram of the third example of the star network structure of the integrated multi-frequency adjustable bandstop filter of the present invention; Figure 6 This is one of the ADS simulation waveform results of the integrated multi-frequency adjustable bandstop filter of this invention; Figure 7 This is the second ADS simulation waveform result of the integrated multi-frequency adjustable bandstop filter of this invention; Figure 8This is a schematic diagram of the integrated multi-frequency adjustable bandstop filter in Embodiment 2; Figure 9 This is one of the ADS simulation waveform results of the integrated multi-frequency adjustable bandstop filter in Example 2; Figure 10 This is the second ADS simulation waveform result of the integrated multi-frequency adjustable bandstop filter in Example 2. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Example 1 This embodiment provides an integrated multi-frequency adjustable bandstop filter, including an adjustable bandstop filter module, such as... Figure 1 As shown; the adjustable band-stop filter module includes a 90-degree bridge and a frequency-hopping combiner. The 90-degree bridge has one input terminal IN, one isolation terminal ISO, and two coupling terminals; the frequency-hopping combiner is connected between the two coupling terminals of the 90-degree bridge. Figure 2 As shown, the frequency hopping combiner includes a combining matching unit and N frequency hopping bandpass filters connected in parallel through the combining matching unit, where N is an integer greater than or equal to 2. The combining matching unit is configured to ensure that the impedances of the N parallel frequency hopping bandpass filters do not affect each other at the common combining point, thereby realizing N independent adjustable bandstop frequencies.

[0019] The combining matching unit includes an input combining matching unit and an output combining matching unit with mutually symmetrical topology; the input terminals of N frequency hopping bandpass filters are respectively connected to the input combining matching unit, and the output terminals of N frequency hopping bandpass filters are respectively connected to the output combining matching unit, so as to realize the parallel connection of N frequency hopping bandpass filters.

[0020] The signal is input through the IN port of the input combiner matching unit, and after being distributed, it enters the input terminals of frequency hopping bandpass filters 1, 2...N respectively. Then, it enters the output combiner matching unit through the output terminals of frequency hopping bandpass filters 1, 2...N for synthesis and finally output through the OUT port.

[0021] like Figure 3 As shown, both the input combining matching unit and the output combining matching unit adopt a star network structure; the star network includes a combining point and N branches connected to the combining point; each branch of the star network contains a cable of length L, which is used to perform phase transformation on the signal of the corresponding frequency hopping bandpass filter.

[0022] By introducing a cable of a specific length L into each frequency-hopping bandpass filter channel, the phase of the output signal is precisely modulated. When these operating channels are connected in parallel in a star network structure, this phase modulation mechanism induces a significant impedance transformation effect. Specifically, at the combining point, any operating channel will present a high input impedance with respect to the passband frequencies of the other operating channels. This high impedance state is equivalent to introducing a high degree of isolation between the operating channels, allowing them to maintain approximately independent electrical characteristics even when physically connected in parallel, thereby ensuring the overall performance of the combining system.

[0023] The cable length L is configured such that the phase shift provided at the center frequency of the passband of the corresponding frequency-hopping bandpass filter is close to 90 degrees. The method for configuring the cable length L is as follows: determine the common operating frequency band of the N frequency-hopping bandpass filters; select an optimized design frequency within the common operating frequency band. f 0 Based on the optimized design frequency f 0 Corresponding guide wavelength λ 0 The calculated length L is: L = (2n+1) × λ 0 / 8.

[0024] like Figure 4 and Figure 5 As shown, an LC matching network is set on the side of the junction point away from the branch; the LC matching network includes a capacitor module and an inductor module; the junction point is connected to the coupling terminal of the 90-degree bridge through the capacitor module; the coupling terminal of the 90-degree bridge is grounded through the inductor module; the capacitor module includes one or more capacitors; when there are two or more capacitors, they are connected in series; the inductor module includes one or more inductors; when there are two or more inductors, they are connected in parallel.

[0025] The 90-degree bridge and the frequency hopping combiner are preferably integrated into a single module. In this frequency hopping combiner, the passband center frequencies of the N frequency hopping bandpass filters can be controlled independently, and the operating frequency bands of each frequency hopping bandpass filter are different.

[0026] The technical advantages of this invention include: The present invention has the following advantages and beneficial effects: 1. True integration and miniaturization: This invention adopts a parallel structure, connecting N frequency-hopping bandpass filters in parallel on a shared combining matching unit, requiring only one 90-degree bridge; compared with the existing cascaded schemes that require N bridges and N modules, this significantly reduces the number, size and weight of components, achieving a high degree of integration; 2. Fundamentally improved loss characteristics: Since multiple frequency hopping bandpass filters are connected in parallel to the system, the main path of the signal (i.e., the passband) only needs to pass through a 90-degree bridge; therefore, the passband insertion loss of the filter mainly depends on the loss of the 90-degree bridge, and does not increase with the increase of the number N of parallel frequency hopping bandpass filters. This completely solves the inherent defect of loss accumulation in the cascaded scheme. 3. Clear structural advantages: This invention achieves N-frequency notch filtering using a bridge and a frequency hopping combiner through a parallel structure and a star matching network. Compared with existing technologies that require N cascaded modules, it has the advantages of fundamental simplification, higher integration, and lower loss.

[0027] Figure 6 The ADS simulation waveform diagram obtained by the frequency hopping combiner is shown in the example of combining two frequency hopping bandpass filters. Figure 7 The following is a simulation waveform diagram of a multi-frequency adjustable bandstop filter, using the synthesis of two frequency-hopping bandpass filters as an example. The simulation results show that this invention can achieve better passband characteristics and frequency selectivity.

[0028] Example 2 This embodiment of an integrated multi-frequency adjustable bandstop filter differs from Embodiment 1 in that it uses multiple adjustable bandstop filter modules, which are cascaded sequentially, such as... Figure 8 As shown in the figure. In this embodiment, there are three adjustable band-stop filter modules; in practical applications, the number of adjustable band-stop filter modules can also be two, four, five, or even more.

[0029] The 90-degree bridge and frequency hopping combiner are preferably integrated into a single module. The isolation terminal ISO of the preceding integrated module is connected to the input terminal IN of the following integrated module.

[0030] The passband center frequencies of N frequency-hopping bandpass filters can be independently controlled. Within the same frequency-hopping combiner, the operating frequency bands of each frequency-hopping bandpass filter are different. The operating frequency bands of the frequency-hopping bandpass filters in different frequency-hopping combiners may be different, partially the same, or all the same.

[0031] In a preferred embodiment of the present invention, by cascading two identical integrated modules, a flexible and diverse adjustable bandstop configuration can be achieved without significantly increasing the passband insertion loss (only introducing the loss of an additional 90-degree bridge).

[0032] Specifically: if each frequency-hopping combiner is a two-way combiner, and the four frequency-hopping bandpass filters are set at different frequencies, then four independent band-stop notch filters can be achieved simultaneously, such as... Figure 9As shown. If three of the frequency-hopping bandpass filters operate at different frequencies, and the third operates at the same frequency, then while achieving three bandstops, the stopband rejection depth at that repetition frequency can be nearly doubled, such as... Figure 10 As shown, if the four frequency-hopping bandpass filters are set at the same frequency in pairs, two stopbands can be formed, and the suppression depth of each stopband is nearly doubled.

[0033] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An integrated multi-frequency adjustable bandstop filter, characterized in that: It includes one or more adjustable band-stop filter modules; each adjustable band-stop filter module includes a 90-degree bridge and a frequency hopping combiner; The 90-degree bridge has one input terminal IN, one isolation terminal ISO, and two coupling terminals; The frequency-hopping combiner is connected between the two coupling terminals of the 90-degree bridge. The frequency hopping combiner includes a combining matching unit and N frequency hopping bandpass filters connected in parallel through the combining matching unit, where N is an integer greater than or equal to 2; the combining matching unit is configured to ensure that the impedances of the N parallel frequency hopping bandpass filters do not affect each other at a common combining point, thereby realizing N independent adjustable bandstop frequencies.

2. The integrated multi-frequency adjustable bandstop filter according to claim 1, characterized in that: The combining matching unit includes an input combining matching unit and an output combining matching unit with mutually symmetrical topologies. The input terminals of N frequency-hopping bandpass filters are respectively connected to the input combining matching unit, and the output terminals of N frequency-hopping bandpass filters are respectively connected to the output combining matching unit to realize N frequency-hopping bandpass filters in parallel. Both the input combining matching unit and the output combining matching unit adopt a star network structure. The star network includes a combining point and N branches connected to the combining point. Each branch of the star network includes a cable of length L, which is used to perform phase transformation on the signal of the corresponding frequency-hopping bandpass filter.

3. The integrated multi-frequency adjustable bandstop filter according to claim 2, characterized in that: The cable length L is configured such that the phase shift provided at the center frequency of the passband of the corresponding frequency hopping bandpass filter is close to 90 degrees.

4. The integrated multi-frequency adjustable bandstop filter according to claim 3, characterized in that: The method for configuring the cable length L is as follows: Determine the common operating frequency band of N frequency-hopping bandpass filters; select an optimal design frequency within the common operating frequency band. f 0 Based on the optimized design frequency f 0 Corresponding guide wavelength λ 0 The calculated length L is: L = (2n+1)× λ 0 / 8。 5. The integrated multi-frequency adjustable bandstop filter according to claim 2, characterized in that: The merging point is provided with an LC matching network on the side away from the branch; the LC matching network includes a capacitor module and an inductor module; the merging point is connected to the coupling terminal of the 90-degree bridge through the capacitor module; the coupling terminal of the 90-degree bridge is grounded through the inductor module; the capacitor module includes one or more capacitors; when there are two or more capacitors, they are connected in series; the inductor module includes one or more inductors; when there are two or more inductors, they are connected in parallel.

6. The integrated multi-frequency tunable bandstop filter according to claim 1, characterized in that: The 90-degree bridge and the frequency hopping combiner are integrated into a single module.

7. The integrated multi-frequency tunable bandstop filter according to claim 6, characterized in that: Two or more integrated modules are cascaded; the isolation terminal ISO of the previous integrated module is connected to the input terminal IN of the next integrated module.

8. The integrated multi-frequency adjustable bandstop filter according to claim 1, characterized in that: When there are two or more adjustable bandstop filter modules, the operating frequency bands of the bandpass filters of different frequency hopping combiners are different, partially the same, or all the same.

9. The integrated multi-frequency adjustable bandstop filter according to claim 1, characterized in that: In the same frequency hopping combiner, the operating frequency bands of each frequency hopping bandpass filter are different.

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