The Development of an Input Protective Circuit of the Radio Frequency (RF) Path of the High Frequency (HF) Band Receiver

The article presents the results of the input protection circuitdevelopment, the main purpose of which is to limit the signals of high-power entering the HF receiverRF path on the antenna input. The input protection circuit protects the sensitive components and elements of the receiver from overload and failure.The need to ensure the reliability and safety of complex communication systems and complexes is only increasing every year.The relevance of input circuitprotection may occur at small separation of the receiver and the source of interference, under the conditions of electronic warfare. The principle of the developed circuit is based on the relay switchcontrol.The method for selecting the parameters of circuitcomponents is described.The practicalprototype tests of the input protection circuit were carried out, being installed at the input of the manufactured HF band receiver. During the practical experiment, shortcomings were identified that were not revealed in the simulation model built in the NI Multisim environment.In particular, it is a local heating of the two components on the printed circuit board, caused primarily by capacitive resistance and weak filter attenuation introduced within the range of 23…30 MHz. Theways to improve the existing protection circuit are noted. An important feature of the circuit is that after minor modification of the input detector contour, the developed circuit can be used at VHF frequencies, up to 520 MHz.The advantages of the scheme should also include a short response time - 1.27 ms, insertion attenuation - less than 0.01 dBm. The product remains operational after applying a sinusoidal RF signal on the antenna input for 15 minutes with an EMF of 100V in the operating frequency range.