Broadband Bow-Tie Slot Antenna with Tuning Stub for Resonant Tunnelling Diode Oscillators with Novel Configuration for Substrate Effects Suppression

Radiation from antennas integrated with InP-based resonant tunnelling diode (RTD) oscillators is usually degraded because of the effects of the large dielectric constant substrate. The common solution has been to use hemispherical lenses to extract the signal from the backside of the substrate. In this paper we present a broadband bow-tie slot antenna with tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to air-side direction. The antenna was designed and fabricated using photolithography techniques to offer wide bandwidth (return loss S11 <-10dB) between 200-350 GHz on semi-insulating InP substrate with dielectric constant of ϵr = 12.56. Simulated and measured bandwidth almost extends the frequency range 230-325 GHz. Simulations shows air-side radiation pattern, an antenna gain of around 11 dB at 290 GHz and 98% radiation efficiency

Diced and grounded broadband bow-tie antenna with tuning stub for resonant tunnelling diode terahertz oscillators

Radiation from antennas integrated with indium phosphide (InP)-based resonant tunnelling diode (RTD) oscillators is mainly through the substrate because of the effects of the large dielectric constant. Therefore, hemispherical lenses are used to extract the signal from the backside of the substrate. In this study the authors present a broadband bow-tie slot antenna with a tuning stub which is diced and mounted on a ground plane to alleviate the substrate effects. Here, the large dielectric constant substrate around the antenna conductor is removed. In addition, the ground plane underneath the diced substrate acts as a reflector and, ultimately, the antenna radiates to the air-side direction. Antenna integration with RTD oscillators is described in this study as well. Two-port bow-tie slot antennas were designed and characterised and showed the suitability of integration with power combining RTD oscillator circuits which are based on mutual coupling. The antennas were fabricated using electron beam lithography on a semi-insulating InP substrate. Simulated and measured bandwidth almost extends the entire frequency range 230–325  GHz. Simulations shows air-side radiation pattern and antenna gain of around 11  dB at 280  GHz. Simulations also show that the antenna may be fed with a 50-Ω or 30-Ω feed line, i.e. suitable feed lines, without compromising its performance which may prove beneficial for optimum loading of RTD oscillators

Laser-Plasma Interactions Enabled by Emerging Technologies

An overview from the past and an outlook for the future of fundamental laser-plasma interactions research enabled by emerging laser systems

Comparison of terahertz technologies for detection and identification of explosives

We present results on the comparison of different THz technologies for the detection and identification of a variety of explosives from our laboratory tests that were carried out in the framework of NATO SET-193 THz technology for stand-off detection of explosives: from laboratory spectroscopy to detection in the field under the same controlled conditions. Several laser-pumped pulsed broadband THz time-domain spectroscopy (TDS) systems as well as one electronic frequency-modulated continuous wave (FMCW) device recorded THz spectra in transmission and/or reflection. © 2014 SPIE

Sensing the hygroscopicity of polymer and copolymer materials using terahertz time-domain spectroscopy

We present the hygroscopicity of polymer and copolymer materials in the low terahertz (THz) frequency range using a linear absorption model. We identify COC 6013 and COC 5013 as optimal THz window materials, possessing both low hygroscopicity and high transmission in the THz regime. The correct choice of window material is of significance for transmission THz spectroscopy and of particular interest for THz liquid spectroscopy.Jegathisvaran Balakrishnan, Bernd M. Fischer and Derek Abbot

Terahertz Technology Applications and Electromagnetic Modelling of Terahertz Waves for Wireless Communication

Bu araştırmada 0.1 ile 10 THz aralığında mikrodalga ve kızılötesi arasında uzanan, elektromanyetik spektrumda çıplak gözle görülemeyen Terahertz (THz) frekanslarının farklı ortamlarda nasıl davrandığı incelenmiştir. Makalenin birinci ve ikinci bölümünde, yüksek hızda kablosuz iletişim için, artan talebi karşılamaya yönelik önemli bir teknoloji olarak öngörülmekte olan Terahertz teknolojisi ve uygulamaları hakkında bilgi verilmiştir. Bu araştırma aynı zamanda hava ve doğal gaz ortamları için hesaplanmış kanal modellenmesi sonucu ortaya çıkan yol kaybı ve emilim kaybı hesaplamalarını göstermektedir. Teorik analiz ve benzetim sonuçları, hava ve doğalgazın THz Bant kısa menzilli kablosuz iletişim kurabileceğini göstermiş ve bu alanda birçok önemli yönlerini vurgulamıştır. Son olarak hava ve doğal gaz ortamı için en ideal performansı sağlayan geçiş pencereleri elde edilmiş ve bu bu geçiş pencereleri makaledeki grafiklerde gösterilmiştir.This paper investigates the behavior of different medium of Terahertz frequencies in the electromagnetic spectrum which is invisible to the naked eye, lying between microwave and infrared in the range from 0.1 to 10 THz. First and second part of the paper gives the information of THz communications which have recently gained greater interest and expectation to meet an ever increasing demand for the speed of wireless communications. This paper also shows the calculating of path loss and attenuation loss data in air and natural gas environment which is resulting in channel modeling. The theoretical analysis and the simulation results prove the feasibility of short range wireless communication in the THz Band in air and natural gas and highlight several important aspects in this field. Finally the frequency window, which provides best performance, has been determined for air and natural gas environment and these frequency windows has been showed in the graphics of the paper