Filter with two-path filtering function

Abstract

The invention discloses a filter with a two-path filtering function, which comprises two electric bridges, two fixed-frequency band-pass filters and a variable-frequency frequency hopping filter, and is characterized in that the two fixed-frequency band-pass filters are respectively connected to a port 0-degree and a port 90-degree as well as a port 90-degree and a port 0-degree of the two electric bridges; the variable frequency hopping filter is connected to ports ISO of the two bridges, and ports IN of the two bridges are respectively used as a signal input end and a signal output end. According to the invention, filters with two paths of frequencies are combined through the 3dB bridge, so that the function of filtering two paths of signals at the same time is achieved.

Description

Technical Field

[0001] The invention relates to a filter with two-way filtering functions, belonging to the technical field of filters. Background Art

[0002] In order to realize the merging of two filters and filter two frequency signals at the same time, see the principle block diagram. Figure 5 One of them is a fixed frequency band pass filter, and the other is a variable frequency frequency hopping filter. The operating frequency of the fixed frequency band pass filter is within the operating frequency range of the variable frequency frequency hopping filter.

[0003] See Figure 5 , assuming that the working frequency of the fixed frequency bandpass filter is F1, and the working frequency of the variable frequency hopping filter is F2; ​​the variable frequency hopping filter is a narrowband bandpass filter, and its adjustable frequency range is set to Fa~Fb. Where Fa≤F1≤Fb.

[0004] To filter the two frequencies F1 and F2 simultaneously, the current conventional approach requires the use of a triplexer. Since F1 is within the frequency range of the variable frequency hopping filter, Fa~Fb needs to be implemented using two variable frequency hopping filters. Figure 6 This approach has the following disadvantages: 1) The frequency hopping filter of Fa~Fb frequency needs to be implemented with two frequency hopping filters, which increases the cost and volume; 2) The triplexer needs to be specially designed and debugged according to the required frequency, and its interchangeability is not high. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a filter with two-way filtering functions to solve the problems existing in the above-mentioned prior art.

[0006] The technical solution adopted by the present invention is: a filter with two-way filtering function, including two bridges, two fixed-frequency band-pass filters and a variable-frequency hopping filter, the two fixed-frequency band-pass filters are respectively connected to port 0° and port 90° and port 90° and port 0° of the two bridges, the variable-frequency hopping filter is connected to port ISO of the two bridges, and ports IN of the two bridges are respectively used as signal input terminals and signal output terminals.

[0007] Furthermore, the above-mentioned bridge adopts a 3dB bridge.

[0008] Furthermore, the fixed frequency bandpass filter adopts a bandpass filter with a frequency of 40.5 MHz, and the variable frequency hopping filter adopts a frequency hopping filter with a frequency of 30-90 MHz.

[0009] Beneficial effects of the present invention: Compared with the prior art, the present invention combines two frequency filters through a 3dB bridge, thereby achieving the function of filtering two signals at the same time, and has the following effects: 1) The bridge used only needs to be within the operating frequency range of the frequency hopping filter, and does not require complicated design and debugging; 2) More flexibility. If the frequency of the fixed-frequency bandpass filter in the simulation experiment is changed to other frequency points between 30 and 90 MHz, the triplexer needs to be redesigned, but the bridge does not need to be redesigned; 3) The use of a triplexer requires the frequency hopping filter to be divided into two frequency bands, which makes the product larger and more expensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of a filter with two-way filtering function; Figure 2 It is a circuit simulation curve graph; Figure 3 These are two 40.5MHz bandpass filters and a frequency hopping filter simulation graph; Figure 4 The center frequency fx of the frequency hopping filter is set as a variable to scan the waveform diagram; Figure 5 It is the principle block diagram of the existing two-way filter; Figure 6 It is a principle block diagram of two-way filters connected by an existing triplexer. DETAILED DESCRIPTION

[0011] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0012] Example 1: Figure 1 As shown, a filter with two-way filtering function includes two bridges, two fixed frequency bandpass filters and a variable frequency hopping filter. The two fixed frequency bandpass filters are respectively connected to the ports 0° and 90° and the ports 90° and 0° of the two bridges. The variable frequency hopping filter is connected to the port ISO of the two bridges. The ports IN of the two bridges are respectively used as the signal input and signal output ends. Two bandpass filters with an operating frequency of F1 are used and connected to the 0° and 90° ports of the 3dB bridge. The frequency hopping filter is connected to the port ISO of the bridge. In this way, two frequency signals can be filtered at the same time.

[0013] Furthermore, the above-mentioned bridge adopts a 3dB bridge.

[0014] Furthermore, the fixed frequency bandpass filter adopts a bandpass filter with a frequency of 40.5 MHz, and the variable frequency hopping filter adopts a frequency hopping filter with a frequency of 30-90 MHz.

[0015] The present invention can meet the filter index requirements: 1. Frequency range: fixed frequency bandpass filter is 40.5MHz, variable frequency hopping filter is 30~90MHz 2. Insertion loss: The loss of a single filter is 3dB, and the loss after the bridge combines the two frequencies is ≤4dB 3.3dB bandwidth: 3%~5% 4. Input and output port impedance: 50Ω 5. It can filter the fixed frequency 40.5MHz and the variable frequency 30~90MHz at the same time.

[0016] The simulation schematic diagram used is shown in Figure 2 Set two 40.5MHz bandpass filters with a 3dB bandwidth of 4% and an insertion loss of 3dB; the frequency hopping filter has an operating frequency range of 30 to 90MHz, a 3dB bandwidth of 4%, and an insertion loss of 3dB. Figure 1 Make the connection and see the simulation results. Figure 3 .

[0017] Set the center frequency fx of the frequency hopping filter as a variable and scan it. The simulation results are shown in Figure 4 Among them, M1, M3, M4, and M5 are the waveforms of the frequency hopping filter working at 30MHz, 50MHz, 70MHz, and 90MHz; M2 is the waveform of the fixed frequency bandpass filter 40.5MHz when the frequency hopping filter works at the above frequencies. From the simulation results, we can see that this solution can filter two frequency signals at the same time. Compared with using a triplexer, this solution has the following advantages: 1) The bridge used only needs to be within the operating frequency range of the frequency hopping filter, and does not require complicated design and debugging.

[0018] 2) Greater flexibility: If the fixed frequency bandpass filter in the example is changed to other frequency points between 30 and 90 MHz, the triplexer needs to be redesigned, but the bridge does not.

[0019] 3) The use of a triplexer requires the frequency hopping filter to be divided into two frequency bands, which makes the product larger and more expensive.

[0020] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A filter with two-way filtering function, characterized in that: It includes two bridges, two fixed frequency band-pass filters and a variable frequency hopping filter. The two fixed frequency band-pass filters are respectively connected to port 0° and port 90° and port 90° and port 0° of the two bridges. The variable frequency hopping filter is connected to port ISO of the two bridges. Port IN of the two bridges serves as a signal input terminal and a signal output terminal respectively.

2. A filter with two-way filtering function according to claim 1, characterized in that: The bridge uses a 3dB bridge.

3. The filter with two-way filtering function according to claim 1, characterized in that: The fixed frequency band pass filter adopts a band pass filter with a frequency of 40.5 MHz, and the variable frequency hopping filter adopts a frequency hopping filter with a frequency of 30 to 90 MHz.

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