Metamaterial Polarization Converter Analysis: Limits of Performance

In this paper we analyze the theoretical limits of a metamaterial converter that allows for linear-to- elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50%, while the realistic re ection configuration can give the conversion efficiency up to 90%. We show that a double layer transmission converter and a single layer with a ground plane can have 100% polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.Comment: 10 pages, 11 figures, 2 table

Design of THz Antennas for a continuous-wave interdigitated electrode photomixer

The design of a dual-slot antenna integrated with an interdigitated electrode (IDE) LT GaAs photomixer together with choke filters and a dielectric lens, optimized for high output power at an operating frequency of 1 THz is proposed. An equivalent-circuit model for determination of coplanar waveguide (CPW) IDE capacitance is suggested, in order to tune it out using a dual-slot antenna. The initial design based on a Smith chart approach has been validated by carrying out exhaustive simulations in CST MicroWave Studio software. The radiation efficiency, incase of a dual-slot antenna integrated with a lumped capacitor element is found to be 81% with a directivity value of 11.47 dBi. The effect of choke filters on different antenna radiation parameters is also investigated. A 3-fan CPW radial stub gives a radiation efficiency of 62% with a directivity of 10.5 dBi and has a potential of providing better performa

Correlation between THz AC and micro-four-point-probe DC conductivity mapping of graphene sheets

We present quantitative correlation mapping of the sheet conductance of large areas of graphene. Terahertz time-domain spectroscopy (THz-TDS) maps the nanoscale conductance averaged over the beam spot size whereas micro four-point probe (M4PP) maps the micro-scale conductance