A Simple Method for Folded-Transmitarray Antenna Gain Improvement in Terahertz Frequency Band

This letter introduces a straightforward method to enhance the gain performance of the conventional folded transmitarray (FTA) operating at 250 GHz. Typically, the FTA requires a feeding source (such as a horn or waveguide) to be positioned appropriately on the reflective layer of FTAs. This configuration can result in feed blockage, where reflected waves return to the feeding source, thus reducing the effective radiation aperture of FTAs. To address this issue, we propose a simple approach to mitigate the feed blockage effect, thereby improving the gain to a certain extent. A modified FTA is proposed at a terahertz frequency band using a standard horn as the feeding source. Simulated results indicate that, compared to the initial FTA, the proposed design achieves an approximate gain improvement of 1.4 dB without increasing fabrication costs and design complexity. A prototype has been fabricated and experimentally tested to validate the findings.