A broadband, stable, and non-iterative free-space method is proposed for dielectric constant ε ^′ _r determination of low-loss dielectric slabs from reflection-only measurements through simple calibration standards (reflect and air). It is applicable for dispersive samples and does not require thickness information. Simulations of non-disperive and dispersive samples are performed to validate our method. Dielectric constant measurements of polyethylene and Polyoxymethylene samples (9–11 GHz) are carried out to examine the accuracy of our method.

A time-domain free-space technique has been proposed to extract relative permittivity (εr) and effective conductivity (σe) of low-loss dielectric samples using their metal- and air-backed calibration-free reflected powers. Numerical computations and 3D electromagnetic simulations were performed to validate the method. A sensitivity analysis was carried out to examine its accuracy. Calibration-free time-domain free-space measurements over 1-12 GHz were conducted by VNA to extract εr and σ e of polyethylene and polypropylene low-loss samples.

In this study, a low-profile ultra-thin metasurface-based reflection-type polarization converter with enhanced bandwidth for X-band (8.2–12.4 GHz) applications is proposed. The designed converter, which has a cell topology above a substrate (FR-4) material terminated in a metal conductor with overall thickness of 1.2 mm corresponding to a thickness of $0.042\lambda$ in terms of wavelength (ultra-thin), indicates the cross polarization performance with a polarization converter ratio (PCR) value of 90% in a wide (9–12 GHz) frequency range (normal incidence) and linear to circular polarization performance with left-handed circular polarization between 8.44 and 8.58 GHz and between 12.74 and 13.14 GHz. It is observed that the converter has a PCR value of 80% for incidence angles up to ${60}^{\circ }$. Simulations of the designed converter performed by a commercial electromagnetic simulation program (CST Microwave Studio) were validated by free-space measurements.