Wideband Multi-Arm Bowtie Antenna for Millimeter Wave Electro-Optic Sensors and Receivers

We propose and demonstrate a novel design of a multi-arm bowtie antenna (MABA) able to provide wideband field enhancement (FE). The FE is a looked-for parameter of antennas in an integrated electro-optic (EO) communication and sensing applications. In the proposed MABA, the paralleled arms with different lengths and flare angles provide multiple resonance frequencies. By tailoring these resonance frequencies adequately close to each other, a wide range of frequencies with high FE is achieved and the intrinsic limitation of conventional bowtie antennas (BAs) in this regard is overcome. The proposed MABA is designed at the center frequency of 66.2 GHz and fabricated on a silicon-on-insulator substrate with 1.69 mm x 0.21 mm dimensions. Simulation and measurement results show about 40 degrees beamwidth and 63.4-dB FE peak with 27 GHz bandwidth, which is three times larger than the bandwidth of a conventional BA, as the most commonly used antenna for this application, on the same substrate. A figure of merit (FoM) is proposed to study the performance of antennas for integrated EO applications approximately independent from the effects of substrate, operating frequency, and optical parts. The FoM is calculated and a comparison is presented for different state-of-the-art antennas in literature showing more than 2 times better performance of the proposed MABA.