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We report extreme nonlinear carrier dynamics in highly n-doped In0.53Ga0.47As thin film using terahertz time-domain spectroscopy. We attribute our observations to the dramatic reduction of terahertz photoconductivity induced by strong intervalley scattering effects.
In this paper, we introduce new configuration of ultra compact implantable antenna. The antenna is designed using the inductor loaded composite right left handed geometry in substrate integrated waveguide configuration. The antenna is designed for the IMS biomedical band with center frequency = 2.42 GHz at which the return loss is less than 15 dB. The antenna has small size (15×15 mm2) with 6 mm feed...
A new efficient method-method of moment (MOM) with modal expansion-has been developed to analyzed multilayers dielectric resonators (DR) loaded cavities. The resonant frequencies, convergence, and field distributions are presented. Also the efficiency and accuracy of this new method have been verified.
A new approach for Multi-Port Network Modeling (MNM) of multilayer planar circuits containing slots is introduced. Generalized network formulation for aperture problems is combined with Okoshi's model for planar circuits to obtain a unified circuit model for two planar circuits coupled through a slot of arbitrary shape in their common ground plane. The methodology, which can be easily generalized...
A new multi-band microstrip patch antenna element with three folded shaped slots and two coaxial feeds is presented. The designed antenna covers frequency bands ranging from GPS (1.575 GHz) to WLAN, 5.8 GHz and new DSRC, 5.9 GHz. The antenna design has been optimized to provide desired performance in GPS (1.575) GHZ, GPRS (1.85 GHz), WLAN (2.4 GHz), WLAN (5.8 GHz), and DSRC (5.9 GHz). The antenna...
Radio channel models developed for traditional macro-cellular systems can not be used for micro- and pico-cellular environments of modern wireless personal communication systems (PCS). This is mainly because of distinct differences in propagation characteristics and much smaller outdoor and indoor micro-cell sizes [1]. It is therefore essential to develop site specific models [2], [3] for a realistic...
We studied the influence of the gap-size onto the generation of intense THz pulses from ZnSe interdigitated photoconductive antennas. We demonstrated that the waveform and the peak electric field depend strongly on this parameter.
We study the nonlinear ultrafast carrier dynamics in highly n-doped In0.53Ga0.47As using terahertz (THz) time-domain spectroscopy (THz-TDS). In addition to the bleaching effect, we further observe significant THz waveform modulations and high frequency generations.
We report the generation of asymmetric quasi-half-cycle THz pulses with an energy up to 8.3 J generated from a ZnSe interdigitated Large Aperture Photoconductive Antenna (ILAPCA). The THz peak electric field is 331 kV/cm with a spectrum characterized by a median frequency of 0.28 THz, resulting in ponderomotive energy of 15 eV. We observed that the large capacitance of the LAPCA leads to a decrease...
A scanned beam reflectarray antenna (RA) is theoretically designed and analyzed for Ka-band satellite communications on the move (SOTM). A general theoretical approach is developed where the effect of mutual couplings between elements of the array is reasonably considered, resulting in a good prediction of antenna radiation characteristics. The designed reflectarray is constructed with a new broadband...
Taking advantage of the modal analysis of the surface wave along a conducting cylinder, physical interpretation of the slow wave mode along the Double Defected-Photonic Crystal (DD-PC) based Slow Wave Structure (SWS) is presented in this paper. Using the HFSS analysis along with special excitation Input/output (I/O) circuit, a verification of the existence of both the waveguide mode and the surface...
Engineered material have found many applications in all ranges of frequencies, because new electromagnetic properties can be achieved using these structures. Considering trasnmission of EM wave through a planar 2D periodic structure, some resonances can be seen in the transmitted signal. These resonaces have very low quality factor (Q), because the resonating elements in the structure are strongly...
In this paper, a Silicon-On-Glass (SOG) tapered dielectric antenna is presented. The antenna is made from high-resistivity Si and supported on a glass substrate. To increase the antenna efficiency, the Pyrex substrate below the Si tapered sections is etched. To decrease the antenna size and the Side Lobe Level (SLL), the single tapered section is replaced by two shorter tapered sections coupled to...
Recently dielectric antennas have gained a huge interest in millimeter-wave (mmWave) and THz range of frequencies for a wide range of applications such as wireless communication, imaging, and radioastronomy. The most common type of dielectric antenna is the tapered antenna, which is inherently long and radiates in the endfire direction. To realize a down-sized antenna for radiating in a tilted angle,...
This paper proposes a new wide-band phase shifter for mmWave phased array applications. The proposed phase shifter is compact and has both a low absolute insertion loss and low insertion loss variation. The wide-band frequency characteristics is obtained by simple but effective matching technique. The phase shifter is based on loading a CPW line with a high dielectric constant BLT ceramic. For a sample...
An all metallic Axial load Double Defected-Photonic Crystal (ADD-PC) with a cylindrical beam channel, suitable for use as a Slow Wave Structure (SWS) in Cherenkov radiation-based oscillator/amplifier, is introduced. The design of a metallic SWS high power millimeter/THz source, with a superior thermal conductivity and the dimensions, which are full realizable using existing fabrication technique,...
A new Silicon-on-Glass (SOG) technology for millimeter-wave (mmW) /Terahertz (THz) integrated circuits is presented. The main characteristics and advantages of the proposed technology are discussed and compared with the state of the art. Novel mmW high-performance phase shifter and 3-dB in-phase power divider, implemented in the proposed low-loss and low-cost integrated technology platform, are presented...
A novel Backward Wave Oscillator (BWO) suitable for work at millimeter Wave/THz regime, based on the Axial loaded Double Defected-Photonic Crystal (ADD-PC) Slow Wave Structure (SWS), is proposed. With the advantage of the excellent mode selectivity of the PC and the power handling capability of the metallic SWS, the ADD-PC is an ideal structure for Cherenkov radiation-based source/amplifier. The performance...
A low-cost and low-loss Silicon-on-Insulator (SOI) integrated platform is proposed for millimeter-wave (mm-wave) applications. The proposed platform supports mm-wave components in the D-band using dielectric image guide structure. The SOI mm-wave integrated platform uses high resistivity Silicon wafers for very low-loss in the D-Band. All passive components can be fabricated on the same platform with...
Leaky wave antennas attract huge attention among the researchers due to beamsteering capability. Leaky wave antennas are categorized as a special case of travelling wave antenna systems. Leaky wave antennas are widely used in new emerging Millimeter-Wave (mmW) technologies, such as Imaging, radar, outdoor short-range secure communication, and sensing. Dielectric Waveguide antennas are one of the major...
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