The slots in spiral antennas induce stress concentrations and hence may adversely affect the load-carrying capacity of the structural antenna. To minimise the detrimental effect of the slots, appropriate fillers are required to provide structural reinforcement without compromising the radar performance of the antenna. This paper presents an investigation of the effects of electrical and mechanical properties of potential filler materials on the performance of slot spiral antennas. Finite element analysis is carried out for a slot spiral that is designed to work in the C-Band range of frequencies (4–8 GHz). Computational simulations performed using commercial software packages ANSYS® and HFSS® show that by using commercially available filler materials the stress concentration factor of the spiral slot can be reduced by 20%. The results from this research enhance the previously introduced advantages of this type of conformal load-bearing antenna structure (CLAS). This CLAS concept provides a promising solution of replacing conventional externally mounted antennas, thus reducing aircraft weight and aerodynamic drag.

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