Phase-Compensated Conformal Antennas for Changing Spherical Surfaces

Abstract

Self-adapting conformal antennas for changing spherical surfaces are investigated in this work. More specifically, the theory on the relationship between the radius of the spherical surface, element spacing of the conformal array and required phase compensation is developed. Initially, for theoretical validation, a 4 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\times$</tex></formula> 4 phased array antenna is assembled with individual microstrip antennas used as the radiators at 2.47 GHz. Each antenna is connected to a commercially available voltage controlled phase shifter with identical SMA cables and then each phase shifter is connected to a port on a sixteen-way power divider. This phased-array antenna allows for convenient placement of individual patches on the spherical surface and precise phase control. For further validation, a second 4 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\times$</tex></formula> 4 phased-array antenna with embedded phase shifters and a sensing circuit is manufactured. The sensing circuit is used to measure the radius of curvature of the spherical surface and use this information to autonomously apply the appropriate phase compensation, based on the previous theoretical developments, to recover the radiation pattern of the array for different spherical surfaces at 2.47 GHz. Overall, good agreement between theory, simulation and experimental data is shown and that it is possible to recover the radiation pattern autonomously.