RU2477565C1 - Centimetre-range microwave transmitter - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: centimetre-range microwave transmitter has a decoupling device, a p-i-n attenuator, a microwave amplifier, a load, a power supply and a modulator, as well as a waveguide for feeding the input microwave signal, a frequency code decoder, a connector pin for feeding the carrier-frequency code, a connector pin for connecting a mechanical interface, a connector pin for feeding commands for switching on-board radar modes. The frequency code decoder includes series-connected matching device, control device, digital-to-analogue converter (DAC), controlled current source, and the microwave amplifier includes series connected first travelling-wave tube (TWT1), intermediate path, second travelling-wave tube (TWT2), output path.

EFFECT: providing maximum output power of the centimetre-range transmitter at carrier frequencies by using two travelling-wave tubes and providing optimum matching of operating modes thereof.

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Description

The invention is intended to work on flying objects as part of microwave power transmitters of radar stations using Doppler signal processing.

The microwave transmitter is known from the prior art (patent RU No. 2208909, publ. 2003.07.20, IPC Н04В 1/00, H05K 7/20). The microwave transmitter contains a master oscillator, a decoupling device, a p-i-n attenuator, a microwave amplifier, a load, a current source, a discriminator, a power source and a modulator, and a closed-loop cooling system. This microwave transmitter can improve operating efficiency by improving the heat removal from the transmitter units and improving the overall dimensions, but it does not solve the problem of obtaining a significant amount of output power at the output of the microwave transmitter.

A well-known pulse microwave power amplifier (Utility Model No. 16238, publ. 2000.12.10, IPC H03F 3/58) containing a traveling wave lamp (TWT), the collector terminal of which is connected to the positive bus of the collector power source, and the negative bus of the collector source the power supply is connected to the TWT cathode, the anode power supply, the negative bus of the anode power supply is connected to the positive bus of the collector power supply, the positive bus of the anode power supply is connected to the positive terminal of the control the cascade of the high-voltage stabilizer, the negative output of which is connected to the housing, and the control input with the regulating output of the voltage divider, one output of which is connected to the TWT cathode, and the second to the housing, the common output of the modulator power supply is connected to the TWT cathode, negative bus of the modulator power supply connected to the output of the first key, and the positive bus to the inputs of the second and third keys, the input of the first key is connected to the output of the third key, the second TWT control grid and through the dividing a diode with a first TWT control grid, which is connected to the anode of the separation diode, with the output of the second key and through a discharge resistor with the output of the first key, the control input of the first key is connected to the output of the first starting device, the input of which is connected to the output of the switch, the control input of the second key is connected with the output of the second starting device, the input of which is connected to the first input of the switch and the connector of "short" pulses, the control input of the third key is connected to the output of the third starting device, input which is connected to the output of the inverter, the input of the inverter is connected to the trigger connector "long" pulses and the second input of the switch. This pulsed microwave power amplifier expands the functionality of the amplifier, but does not provide increased reliability of the TWT as part of the microwave amplifier.

Closest to the claimed technical essence is the microwave transmitter (patent RU No. 2187880, publ. 2002.08.20, IPC: Н03В 9/06). A microwave transmitter between the second output of the master oscillator and the control input p-i-n of the attenuator includes a frequency discriminator and a current source controlled from the discriminator. The current source provides direct current stabilization through the p-i-n attenuator and, as a result, stabilizes the input power and reduces the noise level of the microwave amplifier. The current source is controlled by a discriminator, which generates a frequency-dependent voltage control current p-i-n attenuator.

The disadvantages of this microwave transmitter can be attributed to the fact that, using a single traveling wave lamp (TWT) in the microwave amplifier, it is not possible to obtain a significant output power and provide optimal input power at the carrier frequencies.

In order to obtain long-range detection of an airborne radar station (RLS), a transmitter with a large output pulse power is required. To obtain a significant value of the output pulse power in the transmitter, two traveling wave tubes are used, connected in series.

One of the ways to ensure noise immunity of radar is the possibility of its operation at several carrier frequencies. Carrier frequency switching is automatic. Therefore, the transmitter actually works on several tens of carrier frequencies in a wide frequency range. In the prototype, a wide frequency range is divided into several narrow frequency subbands and the average input optimal power for this frequency subband is set. But in the frequency sub-band there may appear two or several carrier frequencies, therefore, at one carrier frequency the input power is insufficient, and on the other it is redundant.

The technical result of the proposed technical solution is aimed at significantly improving the characteristics of the microwave transmitter for radars: ensuring maximum output power of the microwave transmitter at carrier frequencies, reducing noise, ensuring coordination of the operation modes of two TWTs in the transmitter, increasing the reliability of the TWT in the microwave transmitter of the centimeter range.

The specified technical result is achieved in that the microwave transmitter of the centimeter range contains a decoupling device, a p-i-n attenuator, a microwave amplifier, a load, a power source and a modulator. At the same time, it differs from the prototype in that it additionally contains a waveguide for supplying an input microwave signal, a frequency code decoder, a connector pin for supplying a carrier frequency code, a connector pin for connecting a technological interface, a connector pin for sending radar command switching commands.

Moreover, the frequency code decoder includes a serially connected matching device, a control device, a digital-to-analog converter (DAC), a controlled current source, and a microwave amplifier includes a serially connected first traveling wave lamp (LBV1), an intermediate path, a second traveling wave lamp (LBV2), and an output path .

The input microwave signal supply waveguide is connected to the input of the decoupling device, the output of the decoupling device is connected to the first input p-i-n of the attenuator, the second input p-i-n of the attenuator is connected to the output of the controlled current source of the frequency code decoder. The output p-i-n of the attenuator is connected to the first input of the TWT1 microwave amplifier, the first output of the power source and modulator is connected to the second input of the TWT1 microwave amplifier. The contact of the connector for connecting the technological interface is connected to the second input of the frequency code decoder control device. The contact of the connector for supplying the carrier frequency code is connected to the first input of the matching device of the frequency code decoder. The contact of the connector for the submission of commands for switching radar modes is connected to the second input of the matching device of the frequency code decoder and to the input of the power source and modulator. The second output of the power source and modulator is connected to the second input of TWT2. The output path of the microwave output amplifier is connected to the load input.

The figure shows the structural diagram of the proposed microwave centimeter range transmitter, which includes: a waveguide for supplying an input microwave signal 1, a connector pin for supplying a carrier frequency code 2, a decoupling device 3, a pin attenuator 4, a microwave amplifier 5, a load 6, a power supply, and a modulator 7 , frequency code decoder 8, connector pin for connecting the technological interface 9.

The frequency code decoder 8 contains a matching device 10, a control device 11, a digital-to-analog converter (DAC) 12, a controlled current source 13.

The microwave amplifier 5 contains LBV1 14, the intermediate path 15, LBV2 16, the output path 17.

The transmitter also contains a connector pin for issuing commands switching modes of the radar 18.

In this case, the waveguide for supplying the input microwave signal 1 is connected to the input of the decoupling device 3, the output of the decoupling device 3 is connected to the first input p-i-n of the attenuator 4, the second input p-i-n of the attenuator 4 is connected to the output of the controlled current source 13 of the frequency code decoder 13.

The pin output of the attenuator 4 is connected to the first input of the TWT1 14 of the microwave amplifier 5, the first output of the power supply and modulator 7 is connected to the second input of the TWT1 14 of the microwave amplifier 5. The contact of the connector for connecting the technological interface 9 is connected to the second input of the control device 11 of the frequency code decoder 11. The contact of the connector for supplying the carrier frequency code 2 is connected to the first input of the matching device 10 of the frequency code decoder 8.

The contact of the connector for issuing radar switching commands 18 is connected to the second input of the matching device 10 of the frequency code decoder 8 and the input of the power source and modulator 7. The second output of the power source and modulator 7 is connected to the second input of TWT2 16. The output of the output path of the microwave amplifier 5 is connected with load input 6.

The operation of the microwave centimeter range is as follows. On command from the on-board digital computer (BCM), a microwave carrier frequency signal is generated in the master radar generator. From the master oscillator through the waveguide of the input signal microwave 1, through the decoupling device 3 and p-i-n attenuator 4, the microwave signal is fed to the microwave amplifier 5 for amplification and then to the load 6.

Microwave amplifier 5 is made on two TWTs connected in series through the intermediate 15. The traveling-wave tubes combine the most important parameters — the operating frequency bandwidth, gain, average power, efficiency, high frequency and phase stability, low noise level, significant attenuation of the output level the signal in the pause between pulses, the strength and compactness of the structure are superior to other types of microwave amplifying devices (Kukarin S.V. Electronic microwave devices - M., Radio and communications, 1981, p. 64-100; Katsman Yu.A. Pribo s microwave - M., Graduate School, 1983 s.196-264; edited by M. Skolnik radar Guide, v.3, M., Soviet Radio, 1979 s.7-127). Therefore, the Chadra 100SG06-014TU integrated product consisting of two TWTs connected in series through an intermediate 15 path with low-voltage control was used as the output amplifier stage of the transmitter.

The radar has a long-range combat mode (high output power of the transmitter) and close combat (low output power of the transmitter). In the mode of low output power of the radar, one LBV1 14 is operating in the transmitter, and in the mode of large output power of the radar station there are two traveling wave lamps in the transmitter - LBV1 14 and LBV2 16.

Commands for switching radar modes are received from the digital computer on the transmitter, to the terminal connector for issuing commands for switching radar 18. From the terminal connector for issuing commands for switching radar 18, the signal is supplied to the power source and modulator 7, which provides power and control of the TWT 1 14 and TWT 16.

The microwave signal received at the input of TWT1 14 is amplified in TWT1 14 and from the output of TWT1 14 through an intermediate path 15 is fed to the input of TWT 16.

LBV2 16 works as a radiolucent device in the mode when a large output power is not required, and with amplification when a large output power is required. The TWT operation modes are determined by the control voltages supplied to the TWT1 14 and TWT 16 control electrodes from the power source and modulator 7.

According to the OST 11 0348-86 p.7 TWT application manual, when cascading a TWT, it is necessary to coordinate the values of the output power of each previous TWT with the maximum input power of the subsequent TWT.

Failure to comply with this condition can lead to the second TWT working behind the saturation point, to reducing the output power and to distorting the shape of the envelope of the output microwave signal in a pulsed mode.

Non-optimal tuning of the TWT set according to the output power and currents of the slowdown system leads to an increase in the spectral density level of amplitude and phase noise, which is unacceptable in radars using Doppler signal processing.

To coordinate the value of the output power LBV1 14 with the value of the input power LBV2 16, the manufacturer of the Chadra 100SG06-014TU integrated product indicates in the passport the optimal level of input power LBV1 14 in the mode of low output power and the optimal level of input power LBV1 14 in the mode of high output power.

Failure to comply with this requirement leads to overheating of the slowdown system due to the phenomenon of dynamic defocusing and a decrease in the operating frequency range due to the phenomenon of undersaturation or oversaturation with the input signal (OST 110348-86 p.17).

At the input of TWT1 14, the microwave signal has a small pulsed power, so setting the optimal input power of TWT114 can be done using the pin attenuator 4. At the output of TWT114, the pulse output power is significant (3000 W) and setting the optimal input power of TWT 16 16 using pin attenuator 4 is not possible.

Therefore, a frequency code decoder 8 is used, which, together with a pin attenuator 4, is designed to set the input optimal power at all carrier frequencies at the input of TWT1 14 in the low output power mode and at all carrier frequencies at the input of TWT1 14 in the high output power mode, thereby optimal input power for TWT2 16.

In the process of adjusting the transmitter to the control device 11 from the computer, which is part of the workplace, through the contact of the connector for connecting the technological interface 9, the current control codes of the diode p-i-n of the attenuator 4 are received.

For each carrier frequency, a code is selected that ensures the optimal operation mode of TWT1 14 and TWT 16 in terms of output power and currents of the retarding system. These codes are stored in the internal FLASH memory of the control device 11. Codes are selected in the process of adjustment in such a way as to ensure that the input optimal power is installed at all carrier frequencies at the input LBV1 14 according to the specifications for the Chadra integrated product and radar mode.

From the output of the control device 11, the codes are transmitted via a serial data line to a digital-to-analog converter (DAC) 12. The voltage from the output of the DAC 12 is supplied to a controlled current source 13, which converts the voltage into current to control the p-i-n attenuator 4.

In the normal mode, from the contact of the connector for supplying the code of the carrier frequency 2 to the control device 11, through the matching device 10, codes of the carrier frequency number are received, which determine the addresses of the FLASH memory cells in which the corresponding control codes are stored. Matching device 10 is designed to convert the input signal decoder levels of frequency code 8 to LVTTL levels necessary for operation of control device 11. Matching device 10 is made on SN74AHC14PWRG4 chips, control device 11 is on EPM1270T144I5 chip, DAC 12 is on AD5320BRTZ chip, controlled current source 13 - on microcircuits 140UD20B (Antonov A.P. Language for the description of digital devices Altera HDL. M., Radio Soft, 2001, p. 69-171, J. Kar. Design and manufacture of electronic equipment. M., Mir, 1980 city, p.126-135).

For the optimal operation of two series-connected TWTs, it is necessary to coordinate the output of TWT1 14 and the input of TWT2 16, as well as matching the output of TWT 16 to load 6.

The intermediate path 15 serves to coordinate the output of TWT1 14 and the input of TWT2 16. A radical way to eliminate the influence of TWT 16 to TWT 14 is to include an intermediate 15 in the path. The circulator protects the TWT 1 14 from the backward wave reflected from the TWT input 16.

The decoupling device 3 is a circulator and serves to protect the radar driver from the backward wave reflected from the input of the TWT1 14 (Vambersky M.V. Microwave Transmitters. - M., Higher School, 1984, p. 404-430; under edited by A.M. Chernushenko. The design of microwave devices and screens. M., Radio and communications, 1983, p.78-207).

The power source and modulator 7 generates all the supply voltages for the microwave amplifier 5 and controls LBV1 14 and LBV2 16 of the microwave amplifier 5 by the control electrode (G. N. Naivelt. Power sources of REA. - M., Radio and communication, 1986, p.121-208, Minaev MI Radio-transmitting devices of superhigh frequencies - Minsk, Higher School, 1978, pp. 40-93, edited by Skolnik M. Radar Reference, vol. 3, M., Soviet Radio , 1979, p. 7-127).

The output channel 17 ensures matching of TWT 16 with load 6 and also contains a circulator that protects TWT 16 from the backward wave reflected from load 6 (Vambersky M.V. Microwave Transmitters. - M., Higher School, 1984, p. 406 -430; edited by A.M. Chernushenko. The design of microwave devices and screens. M., Radio and communications, 1983, p.78-207).

The P-i-n attenuator 4 is made on the basis of the microwave p-i-n diode (Vaysblat A.V. Microwave Switching Devices on Semiconductor Diodes. - M., Radio and Communications, 1987, pp. 5-116).

The technical parameters of the transmitter are obtained by:

- the use of the Chadra integrated product, consisting of two TWTs, providing a large output pulse power, low noise level, a significant attenuation of the output signal level in the pause between pulses;

- setting the optimal input power on both TWTs at carrier frequencies;

- ensuring coordination of both TWTs on entry and exit.

Based on the proposed technical solution, prototypes of the transmitter were manufactured. The microwave centimeter range transmitter provides an output pulse power in the ranged mode of not less than 14500 W, in the melee mode of not less than 2500 W, the spectral density of amplitude noise (in the 1 Hz band) with a detuning of 0.3-35 kHz is 105 dB. Technical parameters are confirmed by the positive results of acceptance tests and preliminary tests.

Claims (1)

A centimeter-wave microwave transmitter comprising a decoupling device, a pin attenuator, a microwave amplifier, a load, a power source, and a modulator, further comprising a waveguide for supplying an input microwave signal, a frequency code decoder, a connector pin for supplying a carrier frequency code, a connector connector for connecting the technological interface, the contact of the connector for issuing commands for switching radar modes, and the frequency code decoder includes serially connected matching device, control device , a digital-to-analog converter (DAC), a controlled current source, and the microwave amplifier includes a first traveling wave lamp (LBV1) connected in series, an intermediate path, a second traveling wave lamp (LBV2), an output path, while the input microwave signal supply waveguide is connected to the decoupling input device, the output of the decoupling device is connected to the first input of the attenuator pin, the second input of the attenuator pin is connected to the output of the controlled current source, the output of the attenuator pin is connected to the first input of TWT1, the first output of the power source and a modulator is connected to the second input of the TWT1, the contact of the connector for connecting the technological interface is connected to the second input of the control device, the contact of the connector for supplying the carrier code is connected to the first input of the matching device, the contact of the connector for issuing commands for switching radar modes is connected to the second input of the matching device and with the input of the power source and modulator, the second output of the power source and modulator is connected to the second input of TWT2, the output path of the output is connected to the input of the load.