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80 U ndervaluing the primacy of antennas in operational performance is common among unmanned vehicle developers when designing and building a new vehicle prototype. Engineers often simulate the aerodynamics and propulsion data necessary to construct a UAV with precise flight performance and payload capacity, yet shelve the various mission- critical antenna considerations (apart from size, weight and power usage) until preliminary flight testing. At that point, their importance in command, control, navigation and telemetry becomes abundantly clear. The basic activities of an antenna are driven typically by sending alternating current through it to resonate at the frequency of the desired transmission waves. Radio waves are received when their electromagnetic waves create an alternating voltage at the aerial terminals, which is then amplified and processed within the receiving module. The direction and pattern of the radiated energy can be controlled through judicious selection of antenna type. The most basic and well-known configuration is a monopole antenna, such as the classic whip antenna. This typically consists of a linear metal rod, attached perpendicularly to a comparatively large section of material – usually aluminium or another metal – known as a ground plane, which serves as a reflector to help broadcast the signal from the other antenna elements, Rory Jackson reports on the issues governing the choice of antenna, and explains why their early integration into unmanned systems is key Integrated service April/May 2018 | Unmanned Systems Technology Larger UGVs such as the General Dynamics MUTT (pictured with antenna unit from Southwest Antennas) can support larger omnidirectional antennas, which are necessary for control and data links over 900 MHz or lower bands (Photo: LCpl Daniel Betancourt)