ISSUE 1, January 2022
AWE-Inspiring Electrically Small Antennas
Author: Richard W. Ziolkowski
Anytime-wireless-everywhere (AWE) aspirations for Internet-of-Things (IoT) applications to be enabled through current 5G and evolving 6G and beyond ecosystems necessitate the development of innovative electrically small antennas (ESAs). While a variety of ESA systems are reviewed, those realized from the near-field resonant parasitic (NFRP) antenna paradigm are emphasized. Efficiency, bandwidth and directivity issues are highlighted. Multifunctional, reconfigurable, passive and active systems that have been achieved are discussed and illustrated; their performance characteristics and advantages described. This overview finalizes by going back to the future and considers enterprising research areas of current and forward-looking interest.
The Water Drop Lens: Revisiting the Past to Shape the Future
Author: Nelson J. G. Fonseca
This vision paper provides a brief overview on recent developments related to a new solution of quasi-optical beamformer, referred to as the water drop lens. This parallel plate waveguide beamformer, which is a revisited geodesic lens with a shaped profile, is attracting attention for applications in the millimetre-wave range, where more conventional dielectric lenses prove to be too lossy and standard geodesic lenses are still too bulky. On-going investigations include satellite and terrestrial communication systems, radar systems and imaging systems with wideband operation at centre frequencies ranging from about 20 GHz to over 120 GHz.
Material-based high-impedance surfaces for infrared photonic technologies
Author: Íñigo Liberal, José Manuel Pérez-Escudero
Metamaterial high-impedance surfaces (HISs) are characterized by a boundary condition close to that of a perfect magnetic conductor (PMC). This property has enabled a variety of antenna systems such as low-profile antennas, electromagnetic absorbers and anti-radar systems. Here, we push forward the concept of material-based high-impedance surfaces (MatHISs), where a high-impedance boundary is directly obtained from the material properties of doped semiconductors and polar dielectrics at infrared frequencies. Technological advantages of MatHISs such as fabrication simplicity, large-area deployment and integrability into conformal devices suggest multiple applications for infrared photonic technologies, including dynamical thermal emitters, optoelectronic devices and basic research on atomically-thin materials.
Optomechanical Microwave Oscillators
Author: Laura Mercadé, Alejandro Martínez
Optomechanical interaction in optical dielectric
cavities can be used to generate high-purity microwave tones, giving rise to
optomechanical microwave oscillators. Here, we introduce the main properties of
these devices, which can be implemented in photonic integrated chips, and
envisage its deployment in the mid-term in microwave photonics applications.