Broadband cloaking of struts using Transmission-Line Networks

In this paper, a broadband cloak designed for an application as an antenna strut is presented. The cloak is using the Transmission-Line Network (TLN) concept introduced in [1–2]. In these papers, cloaking was demonstrated for wide incident angle range. Here, we want to reduce scattering from a strut located in the aperture of a reflector antenna. In this case, the wave field is dominated by rays propagating in the direction perpendicular to the focal plane. Therefore, in this paper we modify and optimize the TLN for a specific angle of incidence (broadside). We also study the combination of transmission-line cloaking with hard surfaces cloaking. Simulation and experimental results are presented and they both verify that the cloak works well. The scattering parameters (transmission and reflection coefficients) of the cloaked object are compared with that of uncloaked object and free space. It is shown that although the cloak does not have the same characteristics as free space, it brings a considerable improvement over the uncloaked object case over a broad frequency range.