Compact Pattern

Abstract: We propose an active intraoral shape measurement scheme to realize a compact intraoral diagnostic system for measuring the three-dimensional shapes of gums and teeth. To measure intraoral surfaces with little texture, compact pattern projectors based on diffractive optical elements are integrated in lens gaps of a compact compound-eye camera called a thin observation module by bound optics (TOMBO). The three-dimensional shape is reproduced on the basis of triangulation using the amount of pattern distortion. A scaled-up prototype system is constructed to verify the measurement scheme using the TOMBO camera and a spatial light modulator. The prototype system demonstrates an rms distance accuracy of 0.46 mm. A temporal change of the shape is quantitatively evaluated with a reference surface based on teeth positions.

Abstract: Over the past decades, orbital angular momentum (OAM) has attracted great interest due to its helical phase characteristics. It has been proved that plane spiral OAM (PSOAM) waves have a potential in azimuthal pattern reconfiguration. PSOAM waves could be termed as a special form of OAM wave, which avoids the inconsistency of the divergent angles for different OAM waves. However, from a practical point of view, such a PSOAM-based pattern reconfiguration scheme badly needs a compact high-purity multimode PSOAM antenna. In this communication, a compact high-purity eight-mode PSOAM antenna consisting of a coaxial resonator group (CRG) and a rotating parabolic reflector (RPR) is fabricated and measured. The prototype is designed for $X$ -band operation with a bandwidth of 140 MHz, and the simulated efficiencies of the PSOAM modes ±1,±2,±3, and ±4 are 88.86%, 92.18%, 90.93%, and 91.25%, respectively. The constructed pattern may have the directivity, vorticity, and nondistortion azimuthal 360° scanning capability. This scheme realizes these pattern characteristics with a simpler algorithm and a lower system complexity compared with the phased array antenna-based pattern reconfiguration scheme. It will have potential in next-generation radar and wireless communication system.

Abstract: With the increasing requirement to mitigate the problems of interference between users and electronic jamming, a reconfigurable pattern antenna is one of the solutions to resolve the problems. To switch radiation pattern in azimuth plane around a flat antenna, a Yagi patch antenna operated at higher mode is proposed. A bidirectional pattern using higher mode square patch is used as a driven element and electromagnetic-coupling with a parasitic element serving as a reflector provides a unidirectional pattern. The radiation pattern can be switched by switching feed-probe positions. Simulations were carried out at 2.45 GHz to find appropriate dimensions and validated by measurements.

Abstract: In [1] , the title of the article was incorrectly stated as “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OA. ” The correct title is: “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OAM. ”