A Compact Brick-Type 40GHz-Band DBF Transmit Antenna Module Using Direct Digital RF Technology

In this paper, a scalable mm-wave digital beamforming (DBF) transmit antenna module in the 40GHz-band is proposed. To address the challenges of compact integration in DBF antenna module, the proposed antenna module uses a direct digital RF technology to eliminate the analog RF up-conversion block, achieving a 1-channel RF front-end width equal to the antenna element spacing. A 4-element brick-type DBF antenna module was fabricated and evaluated. Over-the-air measurements at 40 GHz confirmed successful DBF operation by radiation pattern control and modulated signal measurements. Compared to prior brick-type designs, the proposed module achieves a significant reduction in complexity and footprint, demonstrating its potential for scalable mm-wave DBF systems.