Conformal Cavity-backed Spiral Antenna for UAV Application

In this paper, a conformal spiral antenna with the standard Archimedean spiral geometry, specifically customized for UAV applications, is presented. The effects of integrating the antenna into a cavity-backed cylinder made up of aluminum are examined. This antenna is fed by the balanced-to-unbalanced (Balun) feeding network. A lossy foam absorber inside the cavity is used to mitigate the effects of metal backing on the performance of the antenna. Mounting a spiral antenna onto a cylindrical conductive structure having absorber results in wider beamwidth while minimizing back radiation and enabling their integration in UA V applications. The antenna functions across a wide frequency spectrum from 2 GHz to 12 GHz, encompassing L-band, S-band, C-band, and X-band frequency ranges. Substrate used for fabrication of antenna is FR4 having a diameter of 0.49 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{0}$</tex> and thickness of 0.00067 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{0}$</tex> with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda_{0}$</tex> optimized for lower cutoff frequency. According to the findings of the measurements, the proposed antenna having a circular polarization characteristic of 169 % in the operational bandwidth (AR<3dB) with a maximum realized gain of 7.6 dBic.