Optimization of ferrite coating for near-ground HF bowtie antenna

A method to enable the implementation of a broadband HF antenna only one meter above a conducting ground plane is proposed in this paper. A bowtie antenna is placed very close (0.033λ_max) to a conducting ground. In order to allow the antenna to radiate efficiently, ferrite tiles are laid over the ground plane. However, these ferrite tiles are extremely costly. Therefore, in this paper, we propose the laying of the ferrite tiles only on regions of the ground plane where high electrical current density occurs. In this way, the number of the ferrite tiles required is significantly reduced. A v-shaped bowtie antenna above conducting ground is simulated. By laying the ferrite tiles only in regions with high current density, the amount of ferrite tiles required is reduced by 78.6%. More importantly, using this technique, the VSWR can be improved at any desired frequencies. In this paper, the ferrite tiles are used to improve the performance of the HF antenna in the range of 15 to 25MHz. The measured results are used to verify the simulation results.