International Journal of Terahertz Science and Technology
Vol.4, No.1, March 2011. PP.1-41 (4)
date2011-03-31 14:26:40 Click No.5387

TST, Vol. 4, No. 1, PP. 1-8

(Invited Paper) Engineering Approach to Modelling Metal THz Structures

Stepan Lucyszyn* and Yun Zhou
Department of EEE, Imperial College London,
Exhibition Road, London, SW7 2AZ, UK

Received November 28, 2010

Abstract: When compared to the over-simplified classical skin-effect model, the accurate classical relaxation-effect modelling approach for THz structures at room temperature can be mathematically cumbersome and not insightful. This paper briefly introduces various interrelated electrical engineering concepts as tools for characterizing the intrinsic frequency dispersive nature of normal metals at room temperature. This engineering approach dramatically simplifies the otherwise complex analysis and allows for a much deeper insight to be gained into the classical relaxation-effect model. Three example applications are given for the calculation of important parameters and associated errors with hollow metal-pipe rectangular waveguides (MPRWGs), hollow MPRWG cavity resonators and single metal planar shield.

Keywords: Engineering approach, terahertz dispersion, metals

doi: 10.11906/TST.001-008.2011.03.01

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TST, Vol. 4, No. 1, PP. 9-19

(Invited Paper) W-band Gyro-devices Using Helically Corrugated Waveguide and Cusp Gun: Design, Simulation and Experiment

W. He*, C. R. Donaldson, F. Li, L. Zhang, A. W. Cross, A. D. R. Phelps, K. Ronald,
C. W. Robertson, C. G. Whyte, A. R. Young
SUPA, Department of Physics, University of Strathclyde,
Glasgow, G4 0NG, Scotland, UK

(Received November 18, 2010)

Abstract: This paper presents the design and simulation of W-band Gyro-devices using helically corrugated waveguides as the beam-wave interaction region and a cusp gun as the electron beam source. The electron beam system and the beam-wave interaction were optimized through numerical simulations by using a particle-in-cell (PIC) code MAGIC to predict (calculate) the output power and frequency bandwidth. The beam cross sectional measurement using a scintillator plate confirmed that an axis encircling electron beam was achieved with the designed beam parameters of current 1.5 A and energy 40 keV. The W-band helically corrugated interaction region for the gyrotron backward wave oscillator (Gyro-BWO) was manufactured with a dispersion from 80 GHz to 110 GHz measured using a vector network analyser which was found to be in good agreement with simulations and theory. The Gyro-BWO achieved frequency-tuneable operation by adjusting the magnetic field in the interaction cavity. A -3 dB bandwidth of ~84-104 GHz and output power ~10 kW were simulated using the electron beam from the cusp gun. The gyrotron travelling wave amplifier (Gyro-TWA) is designed to have a  3 dB frequency bandwidth of 90-100 GHz, output power of 10 kW and saturated amplification gain of 40 dB.

Keywords: Gyro-devices, Gyro-BWO, Gyro-TWA, Helically Corrugated Waveguide, Cusp Gun

doi: 10.11906/TST.009-019.2011.03.02

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TST, Vol. 4, No. 1, PP. 20-25

(Invited Paper) Tri-reflector Compact Antenna Test Range Design at High Frequency

Xiaoming Liu1, Yuan Mai2, Hansheng Su1, Daohui Li1, Xiaodong Chen1, Rob Donnan1, Clive Parini1, Shaohua Liu2, and Junsheng Yu2
School of Electronic Engineering and Computer Science, Mile End Road, London UK, E1 4NS
2 School of Electronic Engineering, Beijing University of Posts and Telecommunications, 279Box, 10 Xi Tu Cheng Road, Haidian District, 100876, Beijing, China

(Received November 11, 2010)

Abstract: The Compact Antenna Test Range (CATR), which generates a pseudo-plane wave in a very short distance, is commonly employed to measure electrically large aperture antennas. This paper presents the designs of two tri-reflector CATRs operating at 200 GHz: a Cassegrain-Gregorian (CG) configuration and a Double Gregorian (DG) one. Both of the two designs utilise two shaped sub-reflectors and a spherical main reflector. The characteristics of the two designs were verified using a commercial package GRASP9.

Keywords: Compact Antenna Test Range, Tri-reflector, millimeter/sub-millimeter wave

doi: 10.11906/TST.020-025.2011.03.03

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TST, Vol. 4, No. 1, PP. 26-41

Influence of Tunnel current on DC and Dynamic Properties of Si based Terahertz IMPATT source

Aritra Acharyya1*, Moumita Mukherjee2 and J P Banerjee3
Institute of Radio Physics and Electronics, University of Calcutta, 92, APC Road, Kolkata 700009, India.
2Centre of Millimeter wave Semiconductor Devices and Systems, Institute of Radio Physics and Electronics, University of Calcutta, 1, Girish Vidyaratna Lane, Kolkata 700009, India.

(Received December 06, 2010; accepted February 25, 2011)

Abstract: The effect of tunneling current on the high frequency properties of double drift (p+pnn+) IMPATT devices based on silicon designed to operate at 0.3 THz has been investigated by using a modified double iterative simulation technique. Drift-diffusion model and realistic sharp doping profile of MBE grown junction are used for DC and high frequency analysis of DDR IMPATTs operating in mixed tunneling avalanche transit time (MITATT) mode. The actual rise of junction temperature is estimated through heat flow analysis and considered in the present paper. The DC and high frequency properties of the device in both IMPATT and MITATT modes (with tunneling current) operating in THz regime are studied and compared. The results show that the THz performance of the device as regards power delivery and conversion efficiency deteriorates when tunneling is incorporated in the analysis. This modeling will be helpful to realize Si MITATT source for Terahertz communication systems.

Keywords: Terahertz-source, Silicon, IMPATT and MITATT modes, Tunnel Current.

doi: 10.11906/TST.026-041.2011.03.04

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