A low-profile, wideband, and high-gain antenna array, based on a novel double-H-shaped slot microstrip patch radiating element and robust against high temperature variations, is proposed in this work. The antenna element was designed to operate in the frequency range between 12 GHz and 18.25 GHz, with a 41.3% fractional bandwidth (FBW) and an obtained peak gain equal to 10.2 dBi. The planar array, characterized by a feed network with a flexible 1 to 16 power divider, comprised 4 × 4 antenna elements and generated a pattern with a peak gain of 19.1 dBi at 15.5 GHz. An antenna array prototype was fabricated, and the measurements showed good agreement with the numerical simulations as the manufactured antenna operated in the range of 11.4–17 GHz, with a 39.4% FBW, and the peak gain at 15.5 GHz was 18.7 dBi. The high-temperature simulated and experimental results, performed in a temperature chamber, demonstrated that the array performance was stable in a wide temperature range, from −50 °C to 150 °C.

The implementation of simple, inexpensive, and mass-production-oriented solutions for smart electromagnetic environments (SEMEs) is dealt with by introducing the concept of "one-time programmable" electromagnetic skins (OTP-EMSs). The simultaneous achievement of modular fabrication, (one-time) configurable reflection properties, passive-static operation, and zero maintenance is yielded by integrating expendable components at the atomic level of EMSs. Towards this end, an OTP meta-atom structure is properly defined and optimized to build EMSs featuring the desired scenario-dependent EM wave manipulation functionalities. In order to illustrate the features as well as to point out the potentialities of OTP-EMSs, a representative set of analytical, numerical, and experimental results is reported by considering different apertures, illuminations, and EM wave manipulation requirements.

An innovative multi-functional static-passive electromagnetic skin (SP-EMS) solution is proposed to simultaneously support, in reflection, two independent wave-manipulation functionalities with a single meta-atoms arrangement on the EMS aperture when illuminated by two EM sources operating at the same frequency, but working in different polarization states. Towards this end, a simple reference meta-atom is designed first to enable an accurate and independent control of each polarization component of the local reflection tensor. Successively, the macro-scale synthesis of multi-polarization (MP) SP-EMSs (MP-SP-EMSs) is carried out by solving a global optimization problem where a cost function, which mathematically codes separate requirements for each polarization, is minimized with a customized version of the system-by-design (SbD) technique. Representative results from a set of numerical and experimental tests are reported to assess the feasibility of a multi-function EMS based on polarization diversity as well as the effectiveness and the robustness of the proposed method for the synthesis of MP-SP-EMSs.