SYSTEM OF AUTOMATIC FREQUENCY CONTROL OF HETERODYNE OF RADAR RECEIVER WITH MAGNETRON TRANSMITTER

• Main Authors: I. M. Mytsenko, D. D. Khalameyda
• Format: Article
• Language: English
• Published: Akademperiodyka 2018-06-01
• Series: Радиофизика и электроника
• Subjects: automatic frequency control; discriminator; magnetron transmitter; radar
• Online Access: http://re-journal.org.ua/sites/default/files/file_attach/2018-2/7.pdf

Subject and purpose. At present, pulsed magnetrons are leaders in the use in the transmitters of radar stations which is caused by the need to generate powerful high-frequency oscillations and to provide a given range of radar. The disadvantages of magnetrons include a significant level of noise and difficulties in implementing frequency control. For this reason, when using automatic frequency control (AFC), problems arise in controlling the frequency of the pulsed magnetron. That is why AFC of heterodyne of the receiver rather than the one of the magnetron is most often used. The heterodyne frequency is maintained such that the receiver is always tuned to the frequency of the received signal. The purpose of this paper is to analyze the existing methods for tuning the heterodyne frequency of pulsed radars with a magnetron transmitter, to develop a concept for constructing a functional scheme and its practical implementation. Results. The functional scheme of the automatic frequency tuning system of heterodyne in radar receiver with a magnetron transmitter is developed. A frequency discriminator is used in AFC. The frequency discriminator combines the advantages of a single-cycle circuit (simplicity of design and tuning) and a two-cycle circuit (an output voltage equal to zero for a given magnetron frequency, as well as compensation of variations in the amplitude of the input voltage and interference). The practical implementation of the developed system is shown by the example of millimeter-wave band radar (40 GHz), where a generator based on a Gunn diode with varactor frequency tuning is used as the receiver heterodyne. In this paper, the electric scheme of a new frequency discriminator and its amplitude-frequency characteristic are shown. Methods and methodology. An intuitive method was used to develop an electrical schematic diagram. The analysis of the developed scheme was carried out using the method of mathematical modeling. Conclusions are made about the novelty of the proposed concept of constructing the AFC of heterodyne radar receivers with a magnetron transmitter and its advantages in comparison with known solutions