Analysis of the experience of modern armed struggle shows that timely detection of signals onboard radio sources by radio monitoring systems is an important task. One way to ensure its solution is the use of compact broadband antennas in the centimeter range. Therefore the development and improvement of methods for calculating broadband compact antennas in the centimeter wave range is an important and relevant scientific and practical task. An improved method for calculating a traveling wave antenna based on irregular symmetrical slit lines located arranged on a multilayer dielectric substrate (Vivaldi antennas) is proposed, by taking into account the thickness of the dielectric substrate, the relative effective dielectric constant of the substrate layers and two-way power supply to improve the directional properties of the antenna and its coordination in a given frequency band. In particular, the formulas of the phase multiplier of the system (for two radiating elements) and the resulting pattern of the antenna take into account the two-way power supply and the thickness and relative dielectric constant of the substrate. These advanced formulas for calculating and selecting these options antennas, lengths; maximum and minimum slot width; the coefficient of opening the gap; the width of the strip of symmetrical microstrip power line at the connection of the coaxial power line; the width of the strip at the intersection with the slit line; the width of the symmetrical slit line at the base of the opening; the length of a quarter-wave transformer based on a symmetrical microstrip line; the length of the symmetric microstrip power line; slit length; resonator diameter; the radius of the cover of the structural capacitor. The practical significance of the results obtained lies in the possibility of an approximate calculation of compact broadband antennas in the centimeter wavelength range. The results make it possible to model and manufacture these antennas for radio monitoring systems for onboard radio sources.

The governing documents assume the creation in Ukraine by 2025 of a state integrated system of water surface and underwater environment of the Black and Azov seas and the basins of the Dnipro and Danube rivers, as well as a system of operational (combat) control, communication, intelligence and surveillance (C4ISR) of the Armed Forces of Ukraine. Both systems will function in the interests of the Naval Forces of Ukraine and will enable receiving operational data on the water surface environment for the purpose of protecting the sovereignty and territorial integrity of Ukraine, as well as countering illegal activities within the exclusive (maritime) economic zone of Ukraine. The article considers the possibility of using space systems for moving water surface objects identification as part of the targeted water surface environment detection systems. The mentioned space systems allow to simultaneously solve all three tasks inherent in water surface environment detection systems, i.e. detection, identification and observation of moving water surface objects. In the article, moving water surface objects should be understood as manned or unmanned sea and riverine single and group objects capable of moving on the water surface. Currently, similar space systems are already used by the EU, the USA, as well as other maritime states. The abovementioned systems enable the performance of the tasks of covering the water surface environment at significant distances from the coastline under any weather conditions and at different times of the day. At the same time, there are no risks for personnel and technical means of surveillance. The article contains a description of the specified space systems, as well as an overview of the spacecraft used to relay on-board navigational information. It should be noted that at the current stage, similar space systems are also used to detect, identify and track air and ground moving objects. Keywords: water surface environment; exclusive (maritime) economic zone; space system; radio line; navigation information; AIS; LRIT; COSPAS-SARSAT; SSAS; VMS.

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