Short-wave narrow-band adjustable filter circuit

Abstract

The utility model provides a short-wave narrow-band adjustable filter circuit, which relates to the technical field of filters, and comprises a binary capacitor switching circuit, a resonance matching circuit, a power supply control circuit and a relay driving circuit, the power supply control circuit is electrically connected with the binary capacitor switching circuit and the resonance matching circuit respectively, and the relay driving circuit is electrically connected with the power supply control circuit. The power supply control circuit is used for supplying power to the binary capacitor switching circuit and the resonance matching circuit; the binary capacitor switching circuit is electrically connected with the relay driving circuit, the binary capacitor switching circuit comprises a plurality of capacitors and a plurality of relays, each relay is electrically connected with the corresponding capacitor, and the binary capacitor switching circuit is used for switching on-off states of all the relays. And the inductor in the resonance matching circuit is driven to generate resonance. According to the utility model, the tunable characteristic of the filter circuit can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of filters, in particular to a short-wave narrow-band adjustable filter circuit. Background Art

[0002] In the field of shortwave communications, narrowband tunable filter circuits are a common key technology. Existing shortwave narrowband tunable filter circuits typically employ a resonant circuit structure, utilizing variable inductors or capacitors to adjust the center frequency, thereby tracking changes in the target signal frequency. These filters exhibit high Q characteristics, effectively suppressing interference signals outside the target frequency band and improving the selectivity and signal-to-noise ratio of signal reception. These narrowband tunable filters are widely used in amateur radio receivers, shortwave broadcast receivers, military and aviation communication systems, and operational radio monitoring and test equipment, meeting the technical requirements of shortwave wireless communications for high selectivity, high signal-to-noise ratio, and frequency tunability.

[0003] Chinese patent publication number CN220544985U discloses a 100MHz to 500MHz low rectangular coefficient electrically tunable filter circuit, including a second-order filter first and a second-order filter second. The second-order filter first includes a first capacitor, a third inductor, a first inductor, a second inductor, a fourth inductor, and a second capacitor in sequence. The tap between the third inductor and the first inductor is connected to the fifth inductor, and the tap between the second inductor and the fourth inductor is connected to the sixth inductor and the eighth inductor in sequence. The second-order filter second includes a fourth capacitor, a tenth inductor, a twelfth inductor, an eleventh inductor, a ninth inductor, and a third capacitor connected in series in sequence. The tap between the tenth inductor and the twelfth inductor is connected to the eighth inductor, and the tap between the eleventh inductor and the ninth inductor is connected to the seventh inductor. The first capacitor, the first capacitor, the first capacitor, the first capacitor, the first capacitor, the tap between the first inductor and the second inductor, and the tap between the eleventh inductor and the ninth inductor are all grounded. However, the series inductor structure adopted in the above scheme can only achieve a single frequency tuning range, which cannot meet the wide frequency tuning range requirements of the filter. Therefore, it is very necessary to provide a short-wave narrow-band tunable filter circuit to improve the tunable characteristics of the filter circuit. Utility Model Content

[0004] In view of this, the present invention proposes a shortwave narrowband tunable filter circuit. By providing a binary capacitor switching circuit, the tunability of the filter circuit is enhanced, enabling flexible adjustment of the filter's center frequency. Furthermore, by employing a binary capacitor switching mechanism and switching capacitors via relays, capacitor combinations can be flexibly switched across different frequency bands.

[0005] The utility model provides a short-wave narrow-band adjustable filter circuit, comprising a binary capacitor switching circuit, a resonant matching circuit, a power supply control circuit and a relay drive circuit, wherein:

[0006] The power supply control circuit is electrically connected with the binary capacitor switching circuit and the resonance matching circuit respectively, and is configured to supply power to the binary capacitor switching circuit and the resonance matching circuit.

[0007] The binary capacitor switching circuit is electrically connected with the relay driving circuit, and comprises a plurality of capacitors and a plurality of relays, each of which is electrically connected with a corresponding capacitor, and is configured to switch the on-off state of all the relays to drive the inductor in the resonance matching circuit to resonate.

[0008] On the basis of the above technical solutions, preferably, the binary capacitor switching circuit comprises a first driving sub-circuit, a second driving sub-circuit and a capacitor frequency modulation sub-circuit, the first driving sub-circuit is electrically connected with the second driving sub-circuit, the capacitor frequency modulation sub-circuit and the relay driving circuit respectively, the second driving sub-circuit is electrically connected with the relay driving circuit, and the capacitor frequency modulation sub-circuit is electrically connected with the resonance matching circuit.

[0009] On the basis of the above technical solutions, preferably, the first driving sub-circuit comprises a first relay unit, a second relay unit, a third relay unit, a fourth relay unit, a fifth relay unit, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9 and a capacitor C10, one end of the first relay unit is connected with the capacitor frequency modulation sub-circuit through the capacitor C9 and the capacitor C10, the other end of the first relay unit is connected with the second driving sub-circuit and the relay driving circuit respectively, one end of the second relay unit is connected with the capacitor frequency modulation sub-circuit through the capacitor C7 and the capacitor C8, the other end of the second relay unit is connected with the second driving sub-circuit and the relay driving circuit respectively, one end of the third relay unit is connected with the capacitor frequency modulation sub-circuit through the capacitor C5 and the capacitor C6, the other end of the third relay unit is connected with the second driving sub-circuit and the relay driving circuit respectively, one end of the fourth relay unit is connected with the capacitor frequency modulation sub-circuit through the capacitor C3 and the capacitor C4, the other end of the fourth relay unit is connected with the second driving sub-circuit and the relay driving circuit respectively, one end of the fifth relay unit is connected with the capacitor frequency modulation sub-circuit through the capacitor C1 and the capacitor C2, and the other end of the fifth relay unit is connected with the second driving sub-circuit and the relay driving circuit respectively.

[0010] Further preferably, the second drive subcircuit includes a sixth relay unit, a seventh relay unit, an eighth relay unit, a ninth relay unit, a capacitor C45, a capacitor C46, ​​a capacitor C47, a capacitor C48, a capacitor C49, a capacitor C50, a capacitor C51 and a capacitor C52, one end of the sixth relay unit is connected to the first drive subcircuit through the capacitor C45 and the capacitor C46, ​​and the other end of the sixth relay unit is respectively connected to the first drive subcircuit and the relay drive circuit, one end of the seventh relay unit is connected to the first drive subcircuit through the capacitor C47 and the capacitor C48, and the other end of the seventh relay unit is respectively connected to the first drive subcircuit and the relay drive circuit, one end of the eighth relay unit is connected to the first drive subcircuit through the capacitor C49 and the capacitor C50, and the other end of the eighth relay unit is respectively connected to the first drive subcircuit and the relay drive circuit, one end of the ninth relay unit is connected to the first drive subcircuit through the capacitor C51 and the capacitor C52, and the other end of the ninth relay unit is respectively connected to the first drive subcircuit and the relay drive circuit.

[0011] Further preferably, the capacitor frequency modulation sub-circuit includes a variable capacitor C11, a variable capacitor C12, a capacitor C13 and a capacitor C14, one end of the variable capacitor C11 is respectively connected to the first driving sub-circuit, the second driving sub-circuit, one end of the capacitor C13 and the resonant matching circuit, one end of the variable capacitor C12 is respectively connected to the first driving sub-circuit, the second driving sub-circuit, one end of the capacitor C14 and the resonant matching circuit, and the other end of the variable capacitor C11, the other end of the variable capacitor C12, the other end of the capacitor C13 and the other end of the capacitor C14 are all grounded.

[0012] More preferably, the first relay unit, the second relay unit, the third relay unit, the fourth relay unit, the fifth relay unit, the sixth relay unit, the seventh relay unit, the eighth relay unit and the ninth relay unit each include two capacitors, two relay coils and relay contact switches corresponding to the two relay coils.

[0013] Further preferably, the first relay unit comprises a relay coil K8, a relay coil K10, a relay contact switch K8, a relay contact switch K10, a capacitor C19 and a capacitor C20, one end of the relay coil K8 is connected with the second driving sub-circuit and the relay driving circuit, the other end of the relay coil K8 is connected with the power supply control circuit and one end of the capacitor C19 respectively, the other end of the capacitor C19 is grounded, the first end of the relay contact switch K8 is connected with one end of the capacitor C9, the second end of the relay contact switch K8 is grounded, the third end of the relay contact switch K8 is connected with the air, one end of the relay coil K10 is connected with the second driving sub-circuit and the relay driving circuit, the other end of the relay coil K10 is connected with the power supply control circuit and one end of the capacitor C20 respectively, the other end of the capacitor C20 is grounded, the first end of the relay contact switch K10 is connected with one end of the capacitor C10, the second end of the relay contact switch K10 is grounded, the third end of the relay contact switch K10 is connected with the air.

[0014] Further preferably, the resonance matching circuit comprises a resonance inductor L1, a resonance inductor L2, a tapped matching inductor L3, a tapped matching inductor L4, a radio frequency input interface and a radio frequency output interface, the first end of the resonance inductor L1 and the first end of the resonance inductor L2 are connected with the capacitor frequency modulation sub-circuit, the second end of the resonance inductor L1 is connected with the radio frequency input interface through the tapped matching inductor L3, the third end of the resonance inductor L1 is grounded, the second end of the resonance inductor L2 is connected with the radio frequency output interface through the tapped matching inductor L4, the third end of the resonance inductor L2 is grounded.

[0015] Further preferably, the power supply control circuit comprises a capacitor C53, a capacitor C54, an electrolytic capacitor C55, an electrolytic capacitor C56, a capacitor C57 and a radio frequency choke T1, one end of the electrolytic capacitor C55 is connected with one end of the capacitor C53 and the first end of the radio frequency choke T1 respectively, the other end of the electrolytic capacitor C55, the other end of the capacitor C53 and the second end of the radio frequency choke T1 are grounded together, the third end of the radio frequency choke T1 is connected with one end of the electrolytic capacitor C56, one end of the capacitor C54 and one end of the capacitor C57 respectively, the fourth end of the radio frequency choke T1, the other end of the electrolytic capacitor C56, the other end of the capacitor C54 and the other end of the capacitor C57 are grounded together.

[0016] Further preferably, the relay drive circuit includes a Darlington chip P1, a Darlington chip P2, a terminal J1 and a terminal J2, the Darlington chip P1 is respectively connected to the first drive sub-circuit, the second drive sub-circuit, the terminal J1 and the terminal J2, and the Darlington chip P2 is respectively connected to the first drive sub-circuit, the second drive sub-circuit and the terminal J2.

[0017] The short-wave narrow-band adjustable filter circuit provided by the utility model has the following advantages compared with the prior art:

[0018] Beneficial effects:

[0019] (1) By setting a binary capacitor switching circuit in the shortwave narrowband tunable filter circuit, the tunable characteristics of the filter circuit are realized, and the center frequency of the filter can be flexibly adjusted to track the changes in the frequency of the target signal. At the same time, its narrowband filtering characteristics help to effectively suppress interference signals outside the target frequency band, greatly improving the signal selectivity and signal-to-noise ratio. In addition, the binary capacitor switching mechanism is adopted and the capacitor switching is performed through a relay, which can flexibly switch the capacitor combination in different frequency bands;

[0020] (2) By adopting a multi-stage binary capacitor switching design in the first driving sub-circuit, the binary capacitor switching circuit can achieve a wide frequency tuning range by flexibly switching different relay and capacitor combinations. The design of relay switch switching capacitor enhances the reliability and durability of the circuit, and the parallel connection of each relay unit also improves the fault tolerance and stability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a circuit principle diagram of the shortwave narrowband adjustable filter circuit provided by the utility model.

[0023] Explanation of the accompanying symbols: 1. Binary capacitor switching circuit; 11. First driving sub-circuit; 12. Second driving sub-circuit; 13. Capacitor frequency modulation sub-circuit; 2. Resonant matching circuit; 3. Power supply control circuit; 4. Relay driving circuit. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] See also Figure 1 The utility model provides a shortwave narrowband tunable filter circuit, which includes a binary capacitor switching circuit 1, a resonant matching circuit 2, a power supply control circuit 3 and a relay drive circuit 4, wherein:

[0026] The power control circuit 3 is electrically connected to the binary capacitor switching circuit 1 and the resonant matching circuit 2 respectively. The power control circuit 3 is used to supply power to the binary capacitor switching circuit 1 and the resonant matching circuit 2 .

[0027] In this embodiment, the power control circuit 3 includes a capacitor C53, a capacitor C54, an electrolytic capacitor C55, an electrolytic capacitor C56, a capacitor C57 and a radio frequency choke T1. One end of the electrolytic capacitor C55 is respectively connected to one end of the capacitor C53 and the first end of the radio frequency choke T1, the other end of the electrolytic capacitor C55, the other end of the capacitor C53 and the second end of the radio frequency choke T1 are commonly grounded, the third end of the radio frequency choke T1 is respectively connected to one end of the electrolytic capacitor C56, one end of the capacitor C54 and one end of the capacitor C57, the fourth end of the radio frequency choke T1, the other end of the electrolytic capacitor C56, the other end of the capacitor C54 and the other end of the capacitor C57 are commonly grounded.

[0028] The binary capacitor switching circuit 1 is electrically connected to the relay driving circuit 4. The binary capacitor switching circuit 1 includes multiple capacitors and multiple relays, and each relay is electrically connected to the corresponding capacitor. The binary capacitor switching circuit 1 is used to switch the switching state of all relays to drive the inductor in the resonant matching circuit 2 to generate resonance.

[0029] In this embodiment, the binary capacitor switching circuit 1 includes a first driving sub-circuit 11, a second driving sub-circuit 12 and a capacitor frequency modulation sub-circuit 13. The first driving sub-circuit 11 is electrically connected to the second driving sub-circuit 12, the capacitor frequency modulation sub-circuit 13 and the relay driving circuit 4 respectively. The second driving sub-circuit 12 is electrically connected to the relay driving circuit 4. The capacitor frequency modulation sub-circuit 13 is electrically connected to the resonant matching circuit 2.

[0030] The first driving sub-circuit 11 includes a first relay unit, a second relay unit, a third relay unit, a fourth relay unit, a fifth relay unit, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9 and a capacitor C10. One end of the first relay unit is connected to the capacitor frequency modulation sub-circuit 13 through the capacitor C9 and the capacitor C10, and the other end of the first relay unit is connected to the second driving sub-circuit 12 and the relay driving circuit 4 respectively. One end of the second relay unit is connected to the capacitor frequency modulation sub-circuit 13 through the capacitor C7 and the capacitor C8, and the other end of the second relay unit is connected to the second driving sub-circuit 12 and the relay driving circuit 4 respectively. The actuator circuit 12 is connected to the relay drive circuit 4, one end of the third relay unit is connected to the capacitor frequency modulation sub-circuit 13 through capacitors C5 and C6, and the other end of the third relay unit is connected to the second drive sub-circuit 12 and the relay drive circuit 4 respectively, one end of the fourth relay unit is connected to the capacitor frequency modulation sub-circuit 13 through capacitors C3 and C4, and the other end of the fourth relay unit is connected to the second drive sub-circuit 12 and the relay drive circuit 4 respectively, one end of the fifth relay unit is connected to the capacitor frequency modulation sub-circuit 13 through capacitors C1 and C2, and the other end of the fifth relay unit is connected to the second drive sub-circuit 12 and the relay drive circuit 4 respectively.

[0031] The second driving sub-circuit 12 includes a sixth relay unit, a seventh relay unit, an eighth relay unit, a ninth relay unit, a capacitor C45, a capacitor C46, ​​a capacitor C47, a capacitor C48, a capacitor C49, a capacitor C50, a capacitor C51 and a capacitor C52. One end of the sixth relay unit is connected to the first driving sub-circuit 11 through the capacitor C45 and the capacitor C46, ​​and the other end of the sixth relay unit is respectively connected to the first driving sub-circuit 11 and the relay driving circuit 4. One end of the seventh relay unit is connected to the first driving sub-circuit 11 through the capacitor C47 and the capacitor C48, and the other end of the seventh relay unit is respectively connected to the first driving sub-circuit 11 and the relay driving circuit 4. One end of the eighth relay unit is connected to the first driving sub-circuit 11 through the capacitor C49 and the capacitor C50, and the other end of the eighth relay unit is respectively connected to the first driving sub-circuit 11 and the relay driving circuit 4. One end of the ninth relay unit is connected to the first driving sub-circuit 11 through the capacitor C51 and the capacitor C52, and the other end of the ninth relay unit is respectively connected to the first driving sub-circuit 11 and the relay driving circuit 4.

[0032] The first relay unit, the second relay unit, the third relay unit, the fourth relay unit, the fifth relay unit, the sixth relay unit, the seventh relay unit, the eighth relay unit and the ninth relay unit each include two capacitors, two relay coils and relay contact switches corresponding to the two relay coils.

[0033] In one example, the first relay unit includes a relay coil K8, a relay coil K10, a relay contact switch K8, a relay contact switch K10, a capacitor C19, and a capacitor C20, one end of the relay coil K8 is connected with the second driving sub-circuit 12 and the relay driving circuit 4, the other end of the relay coil K8 is connected with the power supply control circuit 3 and one end of the capacitor C19 respectively, the other end of the capacitor C19 is grounded, the first end of the relay contact switch K8 is connected with one end of the capacitor C7, the second end of the relay contact switch K8 is grounded, the third end of the relay contact switch K8 is connected with the air, one end of the relay coil K10 is connected with the second driving sub-circuit 12 and the relay driving circuit 4, the other end of the relay coil K10 is connected with the power supply control circuit 3 and one end of the capacitor C20 respectively, the other end of the capacitor C20 is grounded, the first end of the relay contact switch K10 is connected with one end of the capacitor C85, the second end of the relay contact switch K10 is grounded, the third end of the relay contact switch K10 is connected with the air.

[0034] The second relay unit includes a relay coil K6, a relay coil K12, a relay contact switch K6, a relay contact switch K12, a capacitor C18, and a capacitor C21, one end of the relay coil K6 is connected with the second driving sub-circuit 12 and the relay driving circuit 4, the other end of the relay coil K6 is connected with the power supply control circuit 3 and one end of the capacitor C18 respectively, the other end of the capacitor C18 is grounded, the first end of the relay contact switch K6 is connected with one end of the capacitor C9, the second end of the relay contact switch K6 is grounded, the third end of the relay contact switch K6 is connected with the air, one end of the relay coil K12 is connected with the second driving sub-circuit 12 and the relay driving circuit 4, the other end of the relay coil K12 is connected with the power supply control circuit 3 and one end of the capacitor C21 respectively, the other end of the capacitor C21 is grounded, the first end of the relay contact switch K12 is connected with one end of the capacitor C10, the second end of the relay contact switch K12 is grounded, the third end of the relay contact switch K12 is connected with the air.

[0035] The third relay unit includes a relay coil K4, a relay coil K14, a relay contact switch K4, a relay contact switch K14, a capacitor C17, and a capacitor C22. One end of the relay coil K4 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K4 is respectively connected to the power control circuit 3 and one end of the capacitor C17, the other end of the capacitor C17 is grounded, a first end of the relay contact switch K4 is connected to one end of the capacitor C5, a second end of the relay contact switch K4 is grounded, and a third end of the relay contact switch K4 is connected to a ground connection. One end of the relay coil K14 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K14 is respectively connected to the power control circuit 3 and one end of the capacitor C22, the other end of the capacitor C22 is grounded, a first end of the relay contact switch K14 is connected to one end of the capacitor C6, a second end of the relay contact switch K14 is grounded, and a third end of the relay contact switch K14 is connected to a ground connection.

[0036] The fourth relay unit includes a relay coil K2, a relay coil K16, a relay contact switch K2, a relay contact switch K16, a capacitor C16, and a capacitor C23. One end of the relay coil K2 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K2 is respectively connected to the power control circuit 3 and one end of the capacitor C16, the other end of the capacitor C16 is grounded, a first end of the relay contact switch K2 is connected to one end of the capacitor C3, a second end of the relay contact switch K2 is grounded, and a third end of the relay contact switch K2 is connected to an empty space. One end of the relay coil K16 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K16 is respectively connected to the power control circuit 3 and one end of the capacitor C23, the other end of the capacitor C23 is grounded, a first end of the relay contact switch K16 is connected to one end of the capacitor C4, a second end of the relay contact switch K16 is grounded, and a third end of the relay contact switch K16 is connected to an empty space.

[0037] The fifth relay unit includes a relay coil K1, a relay coil K18, a relay contact switch K1, a relay contact switch K18, a capacitor C15, and a capacitor C24. One end of the relay coil K1 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K1 is respectively connected to the power control circuit 3 and one end of the capacitor C15, the other end of the capacitor C15 is grounded, a first end of the relay contact switch K1 is connected to one end of the capacitor C1, a second end of the relay contact switch K1 is grounded, and a third end of the relay contact switch K1 is connected to a ground connection. One end of the relay coil K18 is connected to the second drive sub-circuit 12 and the relay drive circuit 4, the other end of the relay coil K18 is respectively connected to the power control circuit 3 and one end of the capacitor C24, the other end of the capacitor C24 is grounded, a first end of the relay contact switch K18 is connected to one end of the capacitor C2, a second end of the relay contact switch K18 is grounded, and a third end of the relay contact switch K18 is connected to a ground connection.

[0038] The sixth relay unit includes a relay coil K3, a relay coil K17, a relay contact switch K3, a relay contact switch K17, a capacitor C25, and a capacitor C39. One end of the relay coil K3 is connected to the first drive sub-circuit 11 and the relay drive circuit 4, the other end of the relay coil K3 is respectively connected to the power control circuit 3 and one end of the capacitor C25, the other end of the capacitor C25 is grounded, a first end of the relay contact switch K3 is connected to one end of the capacitor C45, a second end of the relay contact switch K3 is grounded, and a third end of the relay contact switch K1 is connected to a ground connection. One end of the relay coil K17 is connected to the first drive sub-circuit 11 and the relay drive circuit 4, the other end of the relay coil K17 is respectively connected to the power control circuit 3 and one end of the capacitor C39, the other end of the capacitor C39 is grounded, a first end of the relay contact switch K17 is connected to one end of the capacitor C46, ​​a second end of the relay contact switch K17 is grounded, and a third end of the relay contact switch K17 is connected to a ground connection.

[0039] The seventh relay unit includes a relay coil K5, a relay coil K15, a relay contact switch K5, a relay contact switch K15, a capacitor C31, and a capacitor C38. One end of the relay coil K5 is connected to the first drive sub-circuit 11 and the relay drive circuit 4. The other end of the relay coil K5 is respectively connected to the power control circuit 3 and one end of the capacitor C31. The other end of the capacitor C31 is grounded. A first end of the relay contact switch K5 is connected to one end of the capacitor C47. A second end of the relay contact switch K5 is grounded. A third end of the relay contact switch K5 is connected to a ground connection. One end of the relay coil K15 is connected to the first drive sub-circuit 11 and the relay drive circuit 4. The other end of the relay coil K15 is respectively connected to the power control circuit 3 and one end of the capacitor C38. The other end of the capacitor C38 is grounded. A first end of the relay contact switch K15 is connected to one end of the capacitor C48. A second end of the relay contact switch K15 is grounded. A third end of the relay contact switch K15 is connected to a ground connection.

[0040] The eighth relay unit includes a relay coil K7, a relay coil K13, a relay contact switch K7, a relay contact switch K13, a capacitor C34, and a capacitor C37. One end of the relay coil K7 is connected to the first drive sub-circuit 11 and the relay drive circuit 4, the other end of the relay coil K7 is respectively connected to the power control circuit 3 and one end of the capacitor C34, the other end of the capacitor C34 is grounded, a first end of the relay contact switch K7 is connected to one end of the capacitor C49, a second end of the relay contact switch K7 is grounded, and a third end of the relay contact switch K7 is connected to a ground connection. One end of the relay coil K13 is connected to the first drive sub-circuit 11 and the relay drive circuit 4, the other end of the relay coil K13 is respectively connected to the power control circuit 3 and one end of the capacitor C37, the other end of the capacitor C37 is grounded, a first end of the relay contact switch K13 is connected to one end of the capacitor C50, a second end of the relay contact switch K13 is grounded, and a third end of the relay contact switch K13 is connected to a ground connection.

[0041] The ninth relay unit includes a relay coil K9, a relay coil K11, a relay contact switch K9, a relay contact switch K11, a capacitor C35, and a capacitor C36. One end of the relay coil K9 is connected with the first driving sub-circuit 11 and the relay driving circuit 4, and the other end of the relay coil K9 is connected with the power supply control circuit 3 and one end of the capacitor C35 respectively. The other end of the capacitor C35 is grounded. The first end of the relay contact switch K9 is connected with one end of the capacitor C51, the second end of the relay contact switch K9 is grounded, and the third end of the relay contact switch K9 is connected with the air. One end of the relay coil K11 is connected with the first driving sub-circuit 11 and the relay driving circuit 4, and the other end of the relay coil K11 is connected with the power supply control circuit 3 and one end of the capacitor C36 respectively. The other end of the capacitor C36 is grounded. The first end of the relay contact switch K11 is connected with one end of the capacitor C52, the second end of the relay contact switch K11 is grounded, and the third end of the relay contact switch K11 is connected with the air.

[0042] The binary capacitor combination is adopted, and the first relay unit to the ninth relay unit is switched to realize the continuous stepping of the filter frequency by resonating with the inductor in the resonance matching circuit 2. The inductor in the resonance matching circuit 2 is resonated by sequentially closing the first relay unit to the eighth relay unit, and the ninth relay unit is used for testing the carry.

[0043] The capacitor frequency modulation sub-circuit 13 includes a variable capacitor C11, a variable capacitor C12, a capacitor C13, and a capacitor C14. One end of the variable capacitor C11 is connected with the first driving sub-circuit 11, the second driving sub-circuit 12, one end of the capacitor C13, and the resonance matching circuit 2 respectively. One end of the variable capacitor C12 is connected with the first driving sub-circuit 11, the second driving sub-circuit 12, one end of the capacitor C14, and the resonance matching circuit 2 respectively. The other end of the variable capacitor C11, the other end of the variable capacitor C12, the other end of the capacitor C13, and the other end of the capacitor C14 are all grounded.

[0044] The resonance matching circuit 2 includes a resonance inductor L1, a resonance inductor L2, a tap matching inductor L3, a tap matching inductor L4, a radio frequency input interface, and a radio frequency output interface. The first end of the resonance inductor L1 and the first end of the resonance inductor L2 are both connected with the capacitor frequency modulation sub-circuit 13. The second end of the resonance inductor L1 is connected with the radio frequency input interface through the tap matching inductor L3, and the third end of the resonance inductor L1 is grounded. The second end of the resonance inductor L2 is connected with the radio frequency output interface through the tap matching inductor L4, and the third end of the resonance inductor L2 is grounded.

[0045] The relay drive circuit 4 includes a Darlington chip P1, a Darlington chip P2, a terminal J1 and a terminal J2. The Darlington chip P1 is connected to the first drive sub-circuit 11, the second drive sub-circuit 12, the terminal J1 and the terminal J2 respectively. The Darlington chip P2 is connected to the first drive sub-circuit 11, the second drive sub-circuit and the terminal J2 respectively.

[0046] In this embodiment, the Darlington chip P1 and the Darlington chip P2 are both bipolar Darlington chips of model ULN2003A.

[0047] By setting a binary capacitor switching circuit 1 in a shortwave narrowband tunable filter circuit to realize the tunable characteristics of the filter circuit, the center frequency of the filter can be flexibly adjusted to track the changes in the target signal frequency. At the same time, its narrowband filtering characteristics help to effectively suppress interference signals outside the target frequency band, greatly improving the signal selectivity and signal-to-noise ratio. In addition, by adopting a binary capacitor switching mechanism and switching the capacitors through relays, the capacitor combination can be flexibly switched in different frequency bands, reducing the receiving bandwidth and reducing the insertion loss of the filter.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A shortwave narrowband tunable filter circuit, characterized in that: It comprises a binary capacitance switching circuit (1), a resonant matching circuit (2), a power supply control circuit (3) and a relay drive circuit (4), wherein: The power control circuit (3) is electrically connected to the binary capacitor switching circuit (1) and the resonant matching circuit (2), respectively, and the power control circuit (3) is used to supply power to the binary capacitor switching circuit (1) and the resonant matching circuit (2); The binary capacitor switching circuit (1) is electrically connected to the relay driving circuit (4), the binary capacitor switching circuit (1) comprises a plurality of capacitors and a plurality of relays, and each relay is electrically connected to a corresponding capacitor, and the binary capacitor switching circuit (1) is used to switch the switch states of all relays to drive the inductor in the resonant matching circuit (2) to generate resonance.

2. The shortwave narrowband tunable filter circuit according to claim 1, wherein: The binary capacitance switching circuit (1) comprises a first driving subcircuit (11), a second driving subcircuit (12) and a capacitance frequency modulation subcircuit (13); the first driving subcircuit (11) is electrically connected to the second driving subcircuit (12), the capacitance frequency modulation subcircuit (13) and the relay driving circuit (4), respectively; the second driving subcircuit (12) is electrically connected to the relay driving circuit (4); and the capacitance frequency modulation subcircuit (13) is electrically connected to the resonant matching circuit (2).

3. The shortwave narrowband tunable filter circuit according to claim 2, wherein: The first driving subcircuit (11) comprises a first relay unit, a second relay unit, a third relay unit, a fourth relay unit, a fifth relay unit, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9 and a capacitor C10; one end of the first relay unit is connected to the capacitor frequency modulation subcircuit (13) via the capacitor C9 and the capacitor C10; the other end of the first relay unit is connected to the second driving subcircuit (12) and the relay driving circuit (4) respectively; one end of the second relay unit is connected to the capacitor frequency modulation subcircuit (13) via the capacitor C7 and the capacitor C8; the other end of the second relay unit is connected to the second driving subcircuit (12) and the relay driving circuit (4) respectively. The first embodiment of the present invention relates to a first embodiment of the present invention, wherein the first and second relay units are connected to the capacitor frequency modulation subcircuit (13) through the capacitor C5 and the capacitor C6, and the other end of the third relay unit is connected to the second drive subcircuit (12) and the relay drive circuit (4), respectively; the first and second relay units are connected to the capacitor frequency modulation subcircuit (13) through the capacitor C3 and the capacitor C4, and the other end of the fourth relay unit is connected to the second drive subcircuit (12) and the relay drive circuit (4), respectively; the first and second relay units are connected to the capacitor frequency modulation subcircuit (13) through the capacitor C1 and the capacitor C2, and the other end of the fifth relay unit is connected to the second drive subcircuit (12) and the relay drive circuit (4), respectively.

4. The shortwave narrowband tunable filter circuit according to claim 3, wherein: The second driving subcircuit (12) comprises a sixth relay unit, a seventh relay unit, an eighth relay unit, a ninth relay unit, a capacitor C45, a capacitor C46, ​​a capacitor C47, a capacitor C48, a capacitor C49, a capacitor C50, a capacitor C51 and a capacitor C52, one end of the sixth relay unit is connected to the first driving subcircuit (11) through the capacitor C45 and the capacitor C46, ​​the other end of the sixth relay unit is connected to the first driving subcircuit (11) and the relay driving circuit (4) respectively, and one end of the seventh relay unit is connected to the first driving subcircuit (11) through the capacitor C47 and the capacitor C48. 1), the other end of the seventh relay unit is connected to the first drive subcircuit (11) and the relay drive circuit (4), one end of the eighth relay unit is connected to the first drive subcircuit (11) through the capacitor C49 and the capacitor C50, the other end of the eighth relay unit is connected to the first drive subcircuit (11) and the relay drive circuit (4), one end of the ninth relay unit is connected to the first drive subcircuit (11) through the capacitor C51 and the capacitor C52, the other end of the ninth relay unit is connected to the first drive subcircuit (11) and the relay drive circuit (4), respectively.

5. The shortwave narrowband tunable filter circuit according to claim 4, wherein: The capacitor frequency modulation subcircuit (13) comprises a variable capacitor C11, a variable capacitor C12, a capacitor C13 and a capacitor C14; one end of the variable capacitor C11 is respectively connected to the first driving subcircuit (11), the second driving subcircuit (12), one end of the capacitor C13 and the resonant matching circuit (2); one end of the variable capacitor C12 is respectively connected to the first driving subcircuit (11), the second driving subcircuit (12), one end of the capacitor C14 and the resonant matching circuit (2); the other end of the variable capacitor C11, the other end of the variable capacitor C12, the other end of the capacitor C13 and the other end of the capacitor C14 are all grounded.

6. The shortwave narrowband tunable filter circuit according to claim 4, wherein: The first relay unit, the second relay unit, the third relay unit, the fourth relay unit, the fifth relay unit, the sixth relay unit, the seventh relay unit, the eighth relay unit and the ninth relay unit each include two capacitors, two relay coils and relay contact switches corresponding to the two relay coils.

7. The shortwave narrowband tunable filter circuit according to claim 3, wherein: The first relay unit includes a relay coil K8, a relay coil K10, a contact switch of the relay coil K8, a contact switch of the relay coil K10, a capacitor C19, and a capacitor C20. One end of the relay coil K8 is connected to the second drive subcircuit (12) and the relay drive circuit (4). The other end of the relay coil K8 is connected to the power control circuit (3) and one end of the capacitor C19 respectively. The other end of the capacitor C19 is grounded. The first end of the contact switch of the relay coil K8 is connected to one end of the capacitor C9. The contact switch of the relay coil K8 is connected to one end of the capacitor C9. The second end of the contact switch of the relay coil K8 is grounded, the third end of the contact switch of the relay coil K8 is connected to the air gap, one end of the relay coil K10 is connected to the second drive sub-circuit (12) and the relay drive circuit (4), the other end of the relay coil K10 is connected to the power control circuit (3) and one end of the capacitor C20 respectively, the other end of the capacitor C20 is grounded, the first end of the contact switch of the relay coil K10 is connected to one end of the capacitor C10, the second end of the contact switch of the relay coil K10 is grounded, and the third end of the contact switch of the relay coil K10 is connected to the air gap.

8. The shortwave narrowband tunable filter circuit according to claim 3, wherein: The resonant matching circuit (2) comprises a resonant inductor L1, a resonant inductor L2, a tap matching inductor L3, a tap matching inductor L4, a radio frequency input interface, and a radio frequency output interface. The first end of the resonant inductor L1 and the first end of the resonant inductor L2 are both connected to the capacitor frequency modulation subcircuit (13). The second end of the resonant inductor L1 is connected to the radio frequency input interface via the tap matching inductor L3. The third end of the resonant inductor L1 is grounded. The second end of the resonant inductor L2 is connected to the radio frequency output interface via the tap matching inductor L4. The third end of the resonant inductor L2 is grounded.

9. The shortwave narrowband tunable filter circuit according to claim 1, wherein: The power supply control circuit (3) includes a capacitor C53, a capacitor C54, an electrolytic capacitor C55, an electrolytic capacitor C56, a capacitor C57 and a radio frequency choke T1, one end of the electrolytic capacitor C55 is connected to one end of the capacitor C53 and a first end of the radio frequency choke T1 respectively, the other end of the electrolytic capacitor C55, the other end of the capacitor C53 and the second end of the radio frequency choke T1 are commonly grounded, the third end of the radio frequency choke T1 is connected to one end of the electrolytic capacitor C56, one end of the capacitor C54 and one end of the capacitor C57 respectively, and the fourth end of the radio frequency choke T1, the other end of the electrolytic capacitor C56, the other end of the capacitor C54 and the other end of the capacitor C57 are commonly grounded.

10. The shortwave narrowband tunable filter circuit according to claim 4, wherein: The relay drive circuit (4) comprises a Darlington chip P1, a Darlington chip P2, a terminal J1, and a terminal J2; the Darlington chip P1 is respectively connected to the first drive sub-circuit (11), the second drive sub-circuit (12), the terminal J1, and the terminal J2; and the Darlington chip P2 is respectively connected to the first drive sub-circuit (11), the second drive sub-circuit, and the terminal J2.

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