Bow-tie antenna for terahertz resonant tunnelling diode based oscillators on high dielectric constant substrate

In this paper, a broadband bow-tie slot antenna is presented. The coplanar waveguide (CPW) fed antenna is fabricated on an InP substrate for same chip integration with the promising resonant tunnelling diode (RTD) terahertz (THz) oscillator which has the capability of room temperature operation and with relative high power. The antenna exhibits a very wide bandwidth (return loss S11 <;-10 dB) around the design frequency (300 GHz). However, the radiation pattern is degraded because of the large dielectric constant of the InP substrate. A technique to overcome this problem employing a reflector ground plane underneath a thin substrate of low dielectric constant is presented. Initial simulation results of this technique are reported and experimental validation at lower frequency (17 GHz) shows the feasibility of the concept.

I. Introduction

Terahertz (THz) radiation, whose frequency range lies between millimetrewaves and infrared light in the electromagnetic spectrum has many potential applications in different scientific fields such as medical diagnostics, security imaging, and wireless communication [1]–[3]. Resonant tunnelling diode (RTD) based THz oscillators in integrated circuit (IC) form have recently been shown to be the technology in which many of these applications could be implemented [4], [5]. They operate at room temperature and have the potential to produce output power of around 1 mW at these frequencies [6].