Specific Features of Designing Microwave Photonic Receiving and Transmitting Channels of Onboard Systems for Communication, Radar and Radio Monitoring

Abstract

Introduction. Designers of modern on-board systems for communication, radar, and radio monitoring face the problem of improving their qualitative characteristics, including the operating frequency, instantaneous bandwidth, receiver sensitivity, and electromagnetic compatibility. In addition, the dimensions, weight, and power of such systems, as well their cost, should be minimized. However, the current semiconductor microwave electronics has reached its limits in terms of frequency and dynamic characteristics. A possible solution consists in the implementation of microwave photonic transmission lines in the design of on-board systems for communication, radar, and radio monitoring on the basis of modulation of laser radiation by means of electro-absorption.Aim. To study the transfer characteristics and noise figure of a microwave photonic transmission line realized based on the modulation of laser radiation by means of electro-absorption. To compare the results of theoretical calculations and experimental investigations.Materials and methods. The research methodology involved external modulation using an electro-absorption modulator (EAM), mathematical representation of the transmission coefficient, as well as comparison of the theoretical and practical results.Results. Theoretical values of the transmission coefficient and noise figure for a microwave photonic transmission line based on the external modulation method using an EAM were obtained. Experimental values of the transmission coefficient and noise figure for a microwave photonic line in the frequency range from 100 MHz to 16 GHz were presented. The obtained data were compared with those of the nearest mass-produced products of foreign production and those presented in domestic publications on microwave photonic signal transmission lines.Conclusion. The use of an EAM, whose main advantage consists in the possibility of integration with a laser emitter, allowed the authors to design and manufacture a small-sized industrial prototype of a radio-photonic transceiver, capable of transmitting a radio signal over tens of kilometers in the frequency range from 100 MHz to 12 GHz with a transmission coefficient of at least −3 dB and a noise figure no more than 36 dB at the upper operating frequency. At the same time, the closest analogue manufactured by Emcore with similar dimensions has a transmission coefficient of −30 dB and uses direct modulation of laser radiation as a transmission method, which significantly reduces the transmission range of the microwave signal.