Intermediate frequency antenna impedance matcher control circuit

Abstract

The utility model relates to a control circuit of an intermediate frequency antenna impedance matcher. The control circuit comprises a radio frequency relay main loop, a signal control circuit, a state feedback circuit and a display circuit. The circuit overcomes the long-standing defect that a main radio frequency path of an existing intermediate-frequency antenna impedance matching box is grounded through a signal relay contact for a long time, effectively prevents lightning stroke from generating induction current through an antenna end to damage components such as a capacitor and a relay in a control circuit, and guarantees stable operation of a matching box unit when an intermediate-frequency transmitter operates. The problem that electrical faults of a capacitor, a relay and the like in the matching box occur frequently in recent years is thoroughly solved, stability and reliability of intermediate frequency NAVTEX frequency broadcasting of a coast radio station are guaranteed, meanwhile, the technical scheme can be applied to other types of antenna impedance matchers in an extended mode, and the stability of the antenna impedance matching box is further improved.

Description

Technical Field

[0001] This patent application belongs to the field of antenna impedance matching control technology, and more specifically, relates to an intermediate frequency antenna impedance matching control circuit. Background Technology

[0002] The existing intermediate frequency antenna impedance matching unit (IF antenna) of the coastal radio station has been in use for a long time. During operation, most electrical faults are related to the electrical system within the antenna impedance matching box, commonly including: tuning capacitor breakdown and explosion, channel switching relay contact sticking, and / or misalignment of the actuating mechanism leading to arcing. These faults are caused by design flaws in the control circuitry and functional defects in the electrical components within the existing antenna impedance matching box. Due to the remote location of the antenna site and the frequent occurrence of faults during thunderstorms, the frequency of faults is high, and repair times are long, affecting the coastal radio station's international communication services. Therefore, it is essential to redesign the electrical control circuitry of the matching box to eliminate the shortcomings of the existing circuitry and to select and replace outdated core components with domestically produced ones to improve the overall communication reliability of the equipment. Utility Model Content

[0003] The technical problem this invention aims to solve is to provide an intermediate frequency (IF) antenna impedance matching circuit control circuit. This circuit addresses the increasing number of electrical faults in antenna impedance matching circuits, ensuring stable operation of the antenna impedance matching circuit during IF transmitter broadcasting. The design requires redesigning the electrical control circuit of the matching box to eliminate the shortcomings of existing circuits. This ensures that the corresponding IF transmitter and transmitting antenna maintain good working condition, guaranteeing smooth and efficient IF NAVTEX broadcasting, minimizing the failure rate and failure time, and reducing the frequency of failures caused by the matching box circuit to a minimum. This effectively improves the reliability and stability of the antenna matching circuit during shortwave transmitter operation.

[0004] To solve the above problems, the technical solution adopted by this utility model is as follows:

[0005] A control circuit for an intermediate frequency antenna impedance matching device includes a radio frequency relay circuit, a signal control circuit, a status feedback circuit, and a display circuit. The signal control circuit is connected to the radio frequency relay circuit, and the radio frequency relay circuit is connected to the status feedback circuit and the display circuit.

[0006] The radio frequency relay circuit includes relays K1, K2, and K3. Relays K1, K2, and K3 are all double-pole double-throw (DPDT) high-voltage relays. The output terminals of relays K1, K2, and K3 are all connected to the main radio frequency transmitting circuit.

[0007] The signal control circuit includes a transmitter power amplifier start / stop signal relay K4, a channel control relay K5, and a local / remote toggle switch. The channel control relay K5, the local / remote toggle switch, and the transmitter power amplifier start / stop signal relay K4 are connected in sequence. The channel control relay K5 is a single-pole double-throw relay, and the local / remote toggle switch is a double-pole double-throw switch.

[0008] The transmitter power amplifier start / stop signal relay K4 is connected to the local intermediate frequency transmitter and is controlled by the working state of the local intermediate frequency transmitter. Pin 4 of the transmitter power amplifier start / stop signal relay K4 is connected to relays K1 and K2, and pin 7 of the transmitter power amplifier start / stop signal relay K4 is connected to relay K3.

[0009] The channel control relay K5 is connected to the channel switching signal of the intermediate frequency transmitter;

[0010] The status feedback circuit is connected to the auxiliary contacts of relays K1, K2, and K3. The status feedback signal consists of four switching signals: K1 ON (CH2), K1 OFF (CH6), K2 ON (CH2), and K3 ON (CH6).

[0011] The display circuit is connected to the auxiliary contacts of relays K1, K2, and K3. The display circuit is used to display the transmitter channel selection status and the transmitter power amplifier operating status at the matching box.

[0012] Furthermore, relays K1, K2, and K3 are all domestically produced ceramic high-voltage vacuum relays GL12SP, which are specifically designed for radio frequency.

[0013] Furthermore, the main RF transmitting circuit includes inductors L1, L2, L3, and capacitor Cs. Relay K1 is connected to inductor L1, relay K2 is connected to inductor L2, and relay K3 is connected to inductor L3. Inductors L2, L3, and capacitor Cs are connected in series. Inductor L1 is connected to inductors L2 and L3 respectively through the auxiliary contacts of relay K2 and relay K3.

[0014] Furthermore, the display circuit uses light-emitting diodes (LEDs).

[0015] Furthermore, in the RF relay circuit, when the intermediate frequency transmitter power amplifier is loaded with high voltage and starts transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is energized, and the two pairs of normally open contacts of K4 close, connecting the control circuit; when the intermediate frequency transmitter stops transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is de-energized, and the corresponding two pairs of contacts of K4 open, at which time the coils of relays K1, K2, and K3 are disconnected from the signal control circuit.

[0016] Furthermore, in the signal control circuit, when the transmitter selects channel CH2 (486KHz), the channel control relay K5 is energized, its contacts 3 and 4 are turned on, and relays K1 and K2 are energized. The impedance matching network operates in an impedance environment corresponding to the CH2 (486KHz) frequency. When the transmitter selects channel CH6 (518KHz), the channel control relay K5 is de-energized, its contacts 2 and 3 are turned on, and relay K3 is energized. The impedance matching network operates in an impedance environment corresponding to the CH6 (518KHz) frequency.

[0017] Furthermore, it also includes a dual-output switching power supply, which is connected to the RF relay circuit, signal control circuit, and display circuit. The dual-output switching power supply is used to provide a stable DC voltage power supply to the circuit.

[0018] Furthermore, the dual-output switching power supply is a power supply module.

[0019] The beneficial effects achieved by this utility model due to the adoption of the above technical solution are as follows:

[0020] This control circuit redesigns the intermediate frequency antenna impedance matching circuit, innovatively introducing a transmitter-side power amplifier start / stop signal (PAON) (the original circuit lacked this PAON design, resulting in a constant short circuit in the relay coil during equipment operation, causing the contacts to remain closed for an extended period) as a precondition for relay activation. It is further enhanced by a new type of RF relay and local / remote toggle switch logic control. This patent replaces the old-style mechanical relay with a new GL12SP RF-specific relay, offering stable and reliable performance. It resolves the long-standing defect in existing intermediate frequency antenna impedance matching boxes where the main RF path is constantly grounded through the signal relay contacts. This effectively prevents damage to capacitors, relays, and other components in the control circuit from lightning strikes that induce current at the antenna end. It ensures stable operation of the matching box unit during intermediate frequency transmitter operation and completely solves the frequent electrical faults in matching boxes caused by capacitors and relays in recent years. This guarantees the stable and reliable broadcasting of the NAVTEX frequency by the coastal radio station. Furthermore, this technical solution can be extended to other types of antenna impedance matching devices to further improve the stability of the antenna impedance matching box. Attached Figure Description

[0021] Figure 1 This is the schematic diagram of the control circuit of this utility model.

[0022] Figure 2 The values ​​are the inductance and capacitance values ​​corresponding to the 518kHz intermediate frequency antenna of the Guangzhou Coast Radio Station, calculated by the simulation software in this embodiment.

[0023] Figure 3 Wiring for this utility model Figure 1 .

[0024] Figure 4 Wiring for this utility model Figure 2 . Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments.

[0026] An intermediate frequency antenna impedance matching control circuit, such as Figure 1 The Guangzhou Coast Radio Station's intermediate frequency NAVTEX antenna impedance matching device shown here consists of a control circuit mainly composed of an RF relay circuit, a signal control circuit, a status feedback circuit, and a display circuit. The signal control circuit is connected to the RF relay circuit, and the RF relay circuit is connected to the status feedback circuit and the display circuit.

[0027] This RF relay circuit consists of relays K1, K2, and K3, along with their auxiliary circuitry. The three relays, K1, K2, and K3, are domestically produced ceramic high-voltage vacuum relays (GL12SP) specifically designed for RF applications. These relays utilize wear-resistant tungsten contacts and a fully enclosed vacuum medium, effectively extinguishing arcs when disconnected under load. They are compact double-pole double-throw (DPDT) high-voltage relays. The outputs of relays K1, K2, and K3 are all connected to the main RF transmitting circuit. By controlling relays K1, K2, and K3, different inductor series and parallel values ​​in the main RF transmitting circuit are selected to achieve the appropriate impedance selection for the corresponding transmitting frequency antenna. This ensures that the impedance of the transmitting feed cable matches the impedance of the transmitting antenna, allowing for effective RF signal transmission.

[0028] The main RF transmitting circuit includes inductors L1, L2, L3, and capacitor Cs. Relay K1 is connected to inductor L1, relay K2 is connected to inductor L2, and relay K3 is connected to inductor L3. Inductors L2, L3, and capacitor Cs are connected in series. Inductor L1 is connected to inductors L2 and L3 respectively through the auxiliary contacts of relay K2 and relay K3.

[0029] Impedance matching is a crucial task in practical radio frequency signal transmission circuits, typically achieved using an L-type matching circuit. An L-type matching circuit, composed of an inductor and a capacitor, effectively adjusts an impedance (IF antenna impedance) to a target impedance value (usually 50Ω). On a Smith chart, the appropriate combination of inductor and capacitor can be selected based on the location of the complex impedance. The actual impedance matching network configuration process is as follows:

[0030] 1) Measure the impedance parameters of the transmitting antenna (the intermediate frequency antenna of Guangzhou Coast Radio Station was found to be an inductive load);

[0031] 2) Determine the matching network based on the parameter requirements of the inductor and capacitor components (considering the actual matching box volume to avoid selecting large-size components);

[0032] 3) The parameters of the inductor coil are continuously variable, so it is easy to match the capacitive region and adjust the inductive point to the capacitive region of the Smith chart.

[0033] 4) The capacitor parameters are limited by the actual set value and need to be adjusted by connecting the inductors in series or parallel.

[0034] Figure 2 To obtain the corresponding inductor and capacitance values ​​for the 518kHz intermediate frequency antenna of the Guangzhou Coast Radio Station calculated using the Smith Circle simulation software: To transform the actual impedance of the antenna at point 1 to 50 ohms at point 4, a 2000pF capacitor needs to be connected in series from point 1 to point 2, followed by a 26.7μH inductor connected in series to make the 0.02 green admittance circle between points 2 and 3 complete. Finally, a 6.7μH inductor is connected in parallel to bring the antenna impedance at point 3 to the matching state of point 4, i.e., changing the original impedance from 8+j45 ohms to 50+j0 ohms. The above steps from point 1 to point 4 are... Figure 2 Points 1 to 4 in the right-hand figure. Figure 2 The DP-Nr values ​​from point 1 to point 4 in the lower left table correspond to the impedance values ​​from point 1 to point 4 in the right-hand graph.

[0035] By following the steps above, we can finally obtain the series and parallel values ​​of the inductor and capacitor corresponding to the frequencies CH2 (486kHz) and CH6 (518kHz), that is... Figure 1 The corresponding values ​​for L1, L2, L3, and Cs are given. The same steps described above can also be used to obtain the inductor and capacitance values ​​corresponding to another frequency of 486kHz.

[0036] The signal control circuit consists of a transmitter power amplifier start / stop signal relay K4, a channel control relay K5, a local / remote toggle switch, and their auxiliary circuitry. The channel control relay K5, the local / remote toggle switch, and the transmitter power amplifier start / stop signal relay K4 are connected sequentially. The channel control relay K5 is a single-pole double-throw relay, and the local / remote toggle switch is a double-pole double-throw switch. The transmitter power amplifier start / stop signal relay K4 is connected to the local intermediate frequency transmitter and is controlled by the local intermediate frequency transmitter's operating state. Pin 4 of the transmitter power amplifier start / stop signal relay K4 is connected to relays K1 and K2, and pin 7 of the transmitter power amplifier start / stop signal relay K4 is connected to relay K3.

[0037] In the RF relay circuit, when the intermediate frequency transmitter power amplifier is loaded with high voltage and starts transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is energized, and the two pairs of normally open contacts of K4 close, connecting the control circuit. When the intermediate frequency transmitter stops transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is de-energized, and the corresponding two pairs of contacts of K4 open. At this time, the coils of relays K1, K2, and K3 are disconnected from the control circuit, ensuring that the RF transmission path is isolated from the control circuit when the transmitter is not working, and preventing the path formed by the RF transmitting antenna terminal RF OUT and the tuning capacitor Cs, inductors L1, L2, and L3 from reaching ground.

[0038] The channel control relay K5 receives the channel switching signal from the intermediate frequency transmitter. When the transmitter selects channel CH2 (486KHz), the single-pole double-throw channel control relay K5 is energized, contacts 3 and 4 are closed, and relays K1 and K2 are energized. The impedance matching network operates in an impedance environment corresponding to the CH2 (486KHz) frequency. When the transmitter selects channel CH6 (518KHz), the single-pole double-throw channel control relay K5 is de-energized, contacts 2 and 3 are closed, and relay K3 is energized. The impedance matching network operates in an impedance environment corresponding to the CH6 (518KHz) frequency.

[0039] The local / remote toggle switch is used for maintenance and repair of the matching box. When the toggle switch is in the Local position, the control status of relays K1, K2, and K3 is not affected by the transmitter power amplifier start / stop signal relay K4.

[0040] In terms of selection, the transmitter power amplifier start / stop signal relay K4 and channel control relay K5 are selected as TQ2-12VATQ203.

[0041] The status feedback circuit is used to feed back the operating status of relays K1, K2, and K3 to the control panel in real time via signal lines. The signal lines are connected to the auxiliary contacts of relays K1, K2, and K3, respectively. The status feedback signal consists of four switching signals: K1 ON (CH2), K1 OFF (CH6), K2 ON (CH2), and K3 ON (CH6). Please refer to... Figure 1 When the K1 2 / 2 contact is closed, it is the K1ON (CH2) signal, which is low; when the K1 2 / 2 contact is open, it is the K1OFF (CH6) signal, which is high. The status feedback signal of K1 is transmitted through a single signal line. Figure 1 The K1 ON signal line on the left side is actually K1 ON / OFF.

[0042] The display circuit is connected to the auxiliary contacts of relays K1, K2, and K3. The display circuit is used to display the transmitter channel selection status and the transmitter power amplifier operating status at the matching box. It mainly consists of light-emitting diodes and auxiliary circuits.

[0043] In addition, to ensure stable operation of the matching box control circuit, a dual-output switching power supply is installed inside the matching box to provide a stable DC voltage to the circuit. This dual-output switching power supply uses a commercially available regulated power supply module, outputting 12V and 5V to the matching box control circuit. It is not part of the control circuit of this patent, therefore no circuit diagram is provided. The dual-output switching power supply is connected to the RF relay circuit, signal control circuit, and display circuit. The dual-output switching power supply outputs stable +12V and +5V voltages to these three circuits. The +12V voltage is used to engage the coils of relays K1, K2, K3, K4, and K5 in the RF relay circuit and signal control circuit, while the +5V voltage powers the LEDs in the display circuit.

[0044] In terms of selection, dual-output switching voltage regulators are used as regulated power supply modules, but other power supply modules can also be used. The choice is based on specific needs and there are no restrictions.

[0045]

[0046] Table 1. Logic State Table of Matching Box Control Circuit

[0047] Table 1 shows the logic state table of the matching box control circuit, which reflects the logical relationship between each signal and relay in the control circuit. As shown in Table 1, the entire RF main circuit will only be activated when the control circuit receives the transmitter-side power amplifier start / stop signal (PAON) and the local / remote toggle switch is in the Remote position within the matching box. Only then can the intermediate frequency (IF) signal be transmitted from the transmitter through the antenna impedance matching box and then through the antenna. This control circuit innovatively introduces the transmitter-side power amplifier start / stop signal (PAON) as a precondition for relay activation, supplemented by a new type of RF relay and local / remote toggle switch logic control. This solves the long-standing defect in existing IF antenna impedance matching boxes where the main RF path is constantly grounded through the signal relay contacts, effectively preventing damage to capacitors, relays, and other components in the control circuit caused by induced current generated at the antenna end during lightning strikes.

[0048] Figure 3 , Figure 4 For the wiring diagram of the electrical control circuit of the matching box, in which Figure 3 Electrical wiring diagram of main signal switching relay and RF main path. Figure 4 This is the wiring diagram for the signal circuit. Together, these two diagrams constitute the wiring diagram for the electrical control circuit of the intermediate frequency matching box.

[0049] Figure 3 The red line represents the main RF signal path. The RF signal originates from the transmitter, is fed into the RF IN terminal of the matching box via a feed cable, and then outputs to the transmitting antenna from the RF OUT terminal after passing through the impedance matching unit within the matching box. RF relays K1, K2, and K3 are controlled by signals CH2 and CH6 on terminal TB1. The operation commands of these three relays control the inductors connected to the RF path, thereby selecting the impedance of the antenna at the corresponding transmitting frequency. Simultaneously, the feedback signals from the operation of RF relays K1, K2, and K3 are transmitted through terminal TB2 to… Figure 3 .

[0050] Figure 4 In the process, the control signals CH2 and PA ON from the transmitter, drawn from terminal P1, are sent to relays K4 and K5 via an isolation circuit (composed of optocouplers U1 and U2, MOSFETs Q2 and Q3, and relays K6 and K7), and then output to terminal TB1. Terminal TB2 will... Figure 2 The feedback signals from the operation of RF relays K1, K2, and K3 are sent to CH2R1, CH2R2, CH6R1, and CH6R2 of terminal block P1 via four isolation relays K8-K11, and then returned to the transmitter via the communication cable.

[0051] In summary, by redesigning the original control circuit of the intermediate frequency antenna matching box and replacing core components such as RF relays with domestically sourced ones, and by creatively introducing transmitter start / stop signals as pre-action parameters, the matching box unit operates smoothly during intermediate frequency transmitter operation. This completely solves the problem of frequent electrical faults such as capacitors and relays in the matching box in recent years, ensuring the stable and reliable broadcasting of the NAVTEX intermediate frequency by the coastal radio station. At the same time, this technical solution can be extended to other types of antenna impedance matching devices to further improve the stability of the antenna impedance matching box.

Claims

1. A control circuit for an intermediate frequency antenna impedance matching device, characterized in that: It includes an RF relay circuit, a signal control circuit, a status feedback circuit, and a display circuit. The signal control circuit is connected to the RF relay circuit, and the RF relay circuit is connected to the status feedback circuit and the display circuit. The radio frequency relay circuit includes relays K1, K2, and K3. Relays K1, K2, and K3 are all double-pole double-throw (DPDT) high-voltage relays. The output terminals of relays K1, K2, and K3 are all connected to the main radio frequency transmitting circuit. The signal control circuit includes a transmitter power amplifier start / stop signal relay K4, a channel control relay K5, and a local / remote toggle switch. The channel control relay K5, the local / remote toggle switch, and the transmitter power amplifier start / stop signal relay K4 are connected in sequence. The channel control relay K5 is a single-pole double-throw relay, and the local / remote toggle switch is a double-pole double-throw switch. The transmitter power amplifier start / stop signal relay K4 is connected to the local intermediate frequency transmitter and is controlled by the working state of the local intermediate frequency transmitter. Pin 4 of the transmitter power amplifier start / stop signal relay K4 is connected to relays K1 and K2, and pin 7 of the transmitter power amplifier start / stop signal relay K4 is connected to relay K3. The channel control relay K5 is connected to the channel switching signal of the intermediate frequency transmitter; The status feedback circuit is connected to the auxiliary contacts of relays K1, K2, and K3. The status feedback signal consists of four switching signals: K1ON, K1OFF, K2ON, and K3ON. The display circuit is connected to the auxiliary contacts of relays K1, K2, and K3. The display circuit is used to display the transmitter channel selection status and the transmitter power amplifier operating status at the matching box.

2. The intermediate frequency antenna impedance matching control circuit according to claim 1, characterized in that: Relays K1, K2, and K3 are all domestically produced ceramic high-voltage vacuum relays GL12SP.

3. The intermediate frequency antenna impedance matching control circuit according to claim 2, characterized in that: The main RF transmitting circuit includes inductors L1, L2, L3, and capacitor Cs. Relay K1 is connected to inductor L1, relay K2 is connected to inductor L2, and relay K3 is connected to inductor L3. Inductors L2, L3, and capacitor Cs are connected in series. Inductor L1 is connected to inductors L2 and L3 respectively through the auxiliary contacts of relay K2 and relay K3.

4. The intermediate frequency antenna impedance matching control circuit according to claim 1, characterized in that: The display circuit uses light-emitting diodes (LEDs).

5. The intermediate frequency antenna impedance matching control circuit according to claim 1, characterized in that: In the RF relay circuit, when the intermediate frequency transmitter power amplifier is loaded with high voltage and starts transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is energized, and the two pairs of normally open contacts of K4 close, connecting the control circuit; when the intermediate frequency transmitter stops transmitting, the coil of the transmitter power amplifier start / stop signal relay K4 is de-energized, and the corresponding two pairs of contacts of K4 open. At this time, the coils of relays K1, K2, and K3 are disconnected from the signal control circuit.

6. The intermediate frequency antenna impedance matching control circuit according to claim 5, characterized in that: In the signal control circuit, when the transmitter selects channel CH2, the channel control relay K5 is energized, its contacts 3 and 4 are turned on, and relays K1 and K2 are energized. The impedance matching network operates in an impedance environment corresponding to the CH2 frequency. When the transmitter selects channel CH6, the channel control relay K5 is de-energized, its contacts 2 and 3 are turned on, and relay K3 is energized. The impedance matching network operates in an impedance environment corresponding to the CH6 frequency.

7. A control circuit for an intermediate frequency antenna impedance matching device according to any one of claims 1-6, characterized in that: It also includes a dual-output switching power supply, which is connected to the RF relay circuit, signal control circuit, and display circuit.

8. The intermediate frequency antenna impedance matching control circuit according to claim 7, characterized in that: The dual-output switching regulated power supply is a regulated power supply module.

Images