Spot Focusing Coma Correction by Linearly Polarized Dual-Transmitarray Antenna in the Terahertz Region

TL;DR

This paper introduces a dual-transmitarray antenna design that significantly reduces coma aberration in off-axis terahertz focusing, enabling high-quality imaging over a wide angular range.

Contribution

A novel dual-transmitarray approach with optimized phase profiles is proposed and experimentally validated for improved off-axis focusing in THz applications.

Findings

Maintains focus up to 50 degrees off-axis

Achieves a -3 dB spot size under 4 mm at 290 GHz

Near-field sidelobes are below -10 dB across the scanning range

Abstract

Focus scanning is critically important in many terahertz (THz) imaging and sensing applications. A traditional single focusing transmitarray can achieve a good focus when the source is on-axis but moving the source off-axis produces a significant aberration. This paper presents a novel approach to reducing coma in off-axis scanning in the THz region. Here, a dual transmitarray solution is proposed, in which a transmitarray with an optimized phase profile is placed behind a regular phase profile transmitarray. A linearly polarized, dual-transmitarray antenna was fabricated for validation, and the focusing performances were experimentally characterized. The measured results are in good agreement with the theoretical ones. The generated spot of the dual-transmitarray antenna remains focused on an angle up to 50deg, with a -3 dB spot size of less than 4 mm at 290 GHz. The measured near-field sidelobes are all below -10 dB within the whole scanning range.