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Maximising the power extracted from UTC photodiodes is central to the successful realisation of photonic terahertz emitters. For antenna integrated UTCs this requires the optimisation of the impedance match between UTCs and antennas. We present a comprehensive investigation of the UTC output impedance up to 400 GHz, by means of a semi-analytical approach and using 3D full-wave modelling. We introduce...
We have published a ground-coupled GPR antenna array, which consists of one transmitter and five receivers, for in situ estimation of the thickness and dielectric permittivity of an asphalt pavement layer [1]. In this paper, we optimize the design of the antipodal Vivaldi antenna to pursue a higher resolution through reducing the late-time ringing. Furthermore, an off-ground antenna array is assembled,...
More than 110 dB isolation is experimentally realized in a narrow band in this work. Multiple varactors based tunable metamaterials were placed between two co-polarized monopole antennas. The metamaterials are controlled using an genetic algorithm (GA) based optimization program. The optimization goal is to minimize the transmission coefficient of a. After 3000 generations of evolution, more than...
A novel method of decoupling two closely placed co-polarized antennas is presented in this work. Two co-polarization monopoles are placed at the same elevation with a distance of 0.8 λ. Eight rows of varactors based tunable resonators are placed between them. By tuning the bias voltage of the eight rows, the amplitude and phase responses are altered. Correspondingly, the near field distribution is...
Radio frequency identification (RFID) technology [1] is a wireless communication technology of automatic identifying the target objects using radio frequency signal. In recent years, RFID technology has been widely used in many areas, such as access control, public transportation systems, libraries and food safety traceability [2]-[5]. RFID system consists of three parts: reader, transponder and antenna...
A full-polarimetric radar system for non-contact, non-destructive high-resolution imaging and inspection of wooden buildings damaged by earthquakes is developed. The stepped frequency continuous wave system is based on a network analyzer and employs a multi-channel antenna array consisting of four linearly polarized Vivaldi antennas operating in an ultra-wideband ranging from 1 GHz to 20 GHz. The...
Ground Penetrating Radar (GPR) has widely been accepted in geoengineering, and recently, many successful applications are reported in archaeological survey. After the East Japan great earthquake and tsunami 2011 which killed more than 15,000 and many houses must be relocated from seashore to inland, and we have many demands of archaeological surveys. In order to solve this problem, we have developed...
This work deals with efficient frequency domain solvers specifically developed to design optical and plasmonic devices. Homogeneous and inhomogeneous objects embedded in multilayered media are analyzed using Method of Moment (MoM) and hybrid MoM-Finite Element Method (FEM), respectively. The capability of working with materials of complex permittivity makes these algorithms valid and useful for both...
The reduction in peak SAR for handset with monopole type antenna using Rcard is investigated numerically and experimentally. Numerical results suggest that implementation of R-card with low impedance levels in a sense to cover the antenna feed can effectively reduce the peak SAR values in the human head for both 1g and 10g cases. Such observation has been validated experimentally, and a peak SAR reduction...
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