Recent advancements in surface plasmon polaritons-plasmonics subwavelength structures in microwave and terahertz regimes

This paper presents a review of recent investigational studies on exciting Surface Plasmon Polaritous (SPPs)in MicroWave (MW)and TeraHertZ (THz)regimes by using subwavelength corrugated patterns on conductive or metal surfaces.This article also describes SPP Microstrip (MS)structures at microwave and terahertz frequencies, and compares their significance with that of conventional MS Transmission Lines (TL),in order to tackle the key challenges of high gain,bandwidth size,compactness,TL losses,and signal integrity in high-end electronic de- vices.Because they have subwavelength properties,surface plasmon polaritous are gaining attention for their improved performance and ability for miniaturization in high-speed dense circuits.They possess comparably minuscule wavelength compared to incident light (photons).Consequently,they can demonstrate stronger spatial confinement and higher local field intensity at optical frequencies.In addition to engineering spoof SPP waveguides,which are created by engraving grooves and slits on metal surfaces to allow operation on at low frequencies (microwave and terahertz),semiconductors with smaller permittivity values and thus lower free charge carrier concentration have been demonstrated as a potential candidate in plasmonic devices.If necessary,further tuning of semiconductor-based SPP structures is aided by controlling the charge carrier concentration through doping,or by external stimuli such as optical illumination or thermal excitation of charge carriers from valence to conduction bands.This article conclusively covers previously elucidated perspectives on manipulating SSPPs in the MW and THz ranges,and emphasizes how these could steer next-generation plasmonic devices.

Electromagnetic spectrum chipless radio frequency identification:A review

Over the past few years,Radio Frequency IDentification(RFID)has stridden significantly due to its adoption in many business and daily life activities.RFID empowers end-to-end and item-by-item visibility,letting the customers or decision-makers effectively trail the personnel and resources for improved management.Significant research and development in this area have transformed the inexpensive,miniaturized technology of RFIDs without chip inside.Chipless Radio Frequency IDentification(CRFID)is a unique wireless technology based on radar principle to sense,identify,and track the objects.CRFIDs are simplified and miniaturized tags of traditional RFID,which can widely be used in small and cheap objects/applications in our daily life.This paper reviews the definition,principle,and most recent development in CRFIDs.Based on the reported researches,the ElectroMagnetic Spectrum(EMS)method is typical,which has been concerned by many RFID researchers.Therefore,this paper reviews different types of EMS CRFID tag and classifies these tags based on structure design emphasizing their significant geometries in comparison with performance parameters.Antenna and coding methods of the EMS CRFID are also elaborated,contrasting the tag capacity and coding performance.Finally,we briefly summarize the challenges and limitations in this emerging field and look forward to the prospects of future CRFID.