Development of scanning single port free space measurement setup for imaging reflection loss of microwave absorbing materials

Paving the Way for Suitable Metasurfaces’ Measurements Under Oblique Incidence: Mono-/Bistatic and Near-/Far-Field Concerns

“… Measurements are conducted with an empty chamber (no prototype on the pylon) [18], after and before the AMC or the metallic plate is placed on the pylon. This will help to ensure that no undesired echo or instrumentation error are introduced in the set-up between measurements.…”

“…Therefore, they do not apply the pertinent near-field to far-field transformation [15], which is not always trivial [16], especially when the metasurface is excited under different incidence angles [17]. An alternative for evaluating large planar structures at distances smaller than the required by the far-field condition is adopted in [18]. In this article, a scanning free-space system is employed to measure the absorption of a microwave absorber.…”

“…These lenses focus most of the energy on the structure, ensuring that a plane wave impinges on it. Moreover, they can also be employed to reduce diffraction from the structure's edges [18]. Nevertheless, these lenses have to be designed and manufactured ad hoc for each application and they can introduce certain uncertainties in the measurements.…”

“…Moreover, the optimum configuration of the measurement setup is of utmost importance in the measurement of the metasurfaces' angular stability. Consequently, considering the AMC introduced in a previous work [23], a significant advances in the state of art, regarding the presented in [11]- [15], [18]- [21], [23], will be introduced in this paper, devoting special attention to the influence of the angular step at which the measurements are retrieved, as well as the necessity of conducting a suitable statistical treatment of the measured data. Therefore, the same prototype as in [23] will be considered and measured under both a quasi-monostatic (as in the cited paper) and bistatic set-up configurations.…”

Flat lens design using phase correction technique for horn antenna applications

“…Recently, the benefit of designing a lightweight and high directivity antenna for various applications such as horn antenna is being explored because of the actively growing number of communication systems at certain frequency. Horn antenna can provide an easy free-space measurement of microwave material [1][2][3], instead of complex measurement setup of waveguide [4][5][6] and resonator techniques [7][8][9]. In conventional approach, the design of high gain antenna is usually heavy and absurd long horn antenna, which is impractical.…”