Evaluation of a Thin Wire Shape Variants in Free Space and Inside a Dielectric Shell (An Unmanned Aerial Vehicle Wing) Influence on Radar Visibility

The paper explores a thin wire shape variants in free space and inside a dielectric shell (an unmanned aerial vehicle wing) influence on its effective scattering surface. All the studies were carried out under the assumption that the wires are flat curves. The effective scattering surface dependences on the irradiation angle of a dielectric wing model with different shapes of wires in it were estimated. All calculations were performed at a probing wavelength of 3 cm. The study considers several variants of wire laying between two points located at a distance of 0.5 m from each other, and the effective scattering surface value of the entire dielectric shell-wire system are obtained, depending on the wire laying shape and the irradiation angle. The calculations were based on integral representations obtained using Lorentz's lemma and the Pocklington equation for thin-wire antennas. During secondary radiation characteristics evaluating of a single wire in free space, which has a half-period form of a sinusoid and two half-periods of a sinusoid, it was found that the maximum response level from the wire decreases when it is bent by one and a half magnitude orders. At the same time, the azimuths area with maximum values is wider for the wire bent in the two half-periods forms of a sinusoid, and when the sensing location angle is changed to 20 degrees relative to the wire plane, the dependences do not change significantly either qualitatively or quantitatively. When evaluating the characteristics of the secondary radiation of two wires in free space, which has the form of a half- period sinusoid with a distance between the wires of 0.0075 m and 0.015 m, it was found that the level of maximum reflection from two wires drops with their bending by half to one order of magnitude. This is less than for one wire. The analysis of the results obtained for different forms of wire laying in the dielectric hollow wing of an unmanned aerial vehicle shows that the lowest values of the effective scattering surface of the dielectric shell-wire system are obtained when the wire inside the dielectric shell is shaped as a curved wire with ends at the rear edge of the wing. Such a wire shape use inside the dielectric shell (wing cantilever) allows, on the one hand, to reduce the object of study effective scattering surface to the level of the wing without a wire at zero angles, and, on the other hand, not to significantly increase the object effective scattering surface for azimuths from 30 degrees to 50 degrees.