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 S
₁₁
<;-10dB) between 200-350 GHz on semi-insulating InP substrate with dielectric constant of ε
_r
= 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.