Design of a directional dual-band antenna for a ground control station for unmanned aerial systems

The article discusses methods for expanding the operating frequency band of microstrip antennas. The design of a dual-band antenna has been developed using a combination of methods, including the addition of passive elements above and in the same plane as the active emitter and their optimal placement relative to each other. The antenna is matched in two wide subbands in terms of reflection coefficient (module S11) of no more than minus 10 dB: 866–1015 MHz, or 16%, and 2050–2835 MHz, or 32% (one input with a resistance of 50 Ohms). Furthermore, the design allows for the formation of directional radiation with maximum gains ranging from 9 to 11 dBi in the lower frequency subband and from 11 to 14 dBi in the upper frequency subband. Antenna polarization is linear, with a high level of cross-polar discrimination of at least 40 dB. The maximum of the radiation pattern is shifted in the elevation plane, while the shape of the pattern provides coverage in the upper hemisphere. The antenna is highly durable since all of its elements are made of sheet metal (stainless steel) and fastened to one another with steel or brass rucks. The article provides methods for designing the proposed antenna, the results of its modeling, and experimental studies performed on the manufactured prototype. The manufactured antenna weighs no more than 750 g and has a compact size of 0.8λmax×0.8λmax×0.07λmax. In unmanned aircraft systems, the antenna is predominantly used as a ground control station antenna for wireless communication systems.