Design, modeling and fabrication of millimeter-wave metasurface and frequency selective surface devices

THIS doctoral dissertation focuses on millimeter-wave (mm-wave) devices based on metasurfaces and frequency selective surfaces (FSSs). The work is organized around three main categories of devices: wideband electromagnetic (EM) absorbers, leaky-wave antennas (LWAs), and wireless pressure sensors. In the first part, resistive surfaces of tantalum nitride (TaN) are employed to design wideband mm-wave absorbers operating in the E- and D-band frequency ranges. These absorbers are ultrathin, low-profile and utilize an air-cavity-free topology. They are analyzed using an equivalent circuit model (ECM) and fabricated on high-permittivity alumina substrates through thin-film technology. The targeted application of these absorbers is their integration between the transmitter (Tx) and receiver (Rx) in system-in package (SiP) modules to enhance isolation. The second part of this dissertation addresses the design and fabrication of LWAs, presented in two configurations: a narrowband LWA for the E-band spectrum operating at 73.5 GHz and a wideband LWA for the X-band spectrum. The narrowband LWA is realized on an ITERA MT-40 dielectric substrate using a periodic array of grids that function as partially reflective surfaces (PRSs) in the top layer. Unlike conventional LWAs that rely on air-cavity-based configurations, which complicate their integration with planar systems and printed circuit boards (PCBs), the proposed design is more compact and integration-friendly. The wideband LWA utilizes two pairs of complementary partially reflective surfaces (CPRSs) to generate a positive phase gradient for bandwidth enhancement. The antenna features a compact geometry supported by a polylactic acid (PLA) cavity, which provides structural rigidity and compactness, making it suitable for practical applications compared to conventional air-cavity-based LWAs. The structure is fabricated through a novel hybrid process that combines fiber laser technology with 3D printing. The final part of this dissertation introduces passive wireless pressure sensors fabricated using a simple, rapid, and cost-effective fiber-laser machining technique. Two sensor configurations are presented: the first employs narrowband absorbers based on patch and cross geometries, while the second utilizes an anisotropic polarization converting metasurface (PCM) composed of periodic dipole resonators. Both sensors operate on the principle of air-gap modulation, where variations in the gap alter the system capacitance and consequently shift the resonance frequency.