Fabry-Perot Antenna with High-Permittivity Grounded Walls for Side Lobe Level Reduction

In this paper, a compact 3λ×3λ Fabry-Perot antenna with high permittivity grounded walls is proposed. The use of high permittivity materials (HPMs) as the cavity side walls, when backed by an opportune metallic sheet, allows a significant enhancement in the overall radiating performance. In particular, while both gain and Half Power Bandwidth improvements can be achieved also by sealing the cavity with purely metal walls, nevertheless, with grounded HPMs, a dramatic reduction of the Side Lobe Level can be accomplished. Indeed, the high value of the dielectric constant of the walls material makes them closely approximating the behavior of an ideal perfect magnetic conductor at the selected working frequency, with an extremely reduced thickness and large angular stability. To demonstrate this approach, we conceived an accurate numerical test-case with a Fabry-Perot cavity working at 3 GHz and having compact dimensions (3λ×3λ). By comparing the purely metallic with the grounded HPM walls configurations, we observed a maximum reduction in the SLL value for both the E and H planes, respectively of 15.9 and 16.2 dB.