D-Band Scalable Phased Array Antenna-in-Package Using Stripline Power Divider-Based Sub-Array

This article presents an overview and recent design for the sub-array antenna-in-package (AiP) structures of scalable phased array for D-band applications. The primary focus is on the benefits and challenges associated with the design of scalable phased arrays at D-band frequencies. Following this, a sub-array structure of stripline power divider (PD)-based AiP is proposed. Initially, an analysis of a dual-polarized antenna element is conducted, employing characteristic modes and equivalent circuits. Subsequently, two distinct PDs are developed to match the antenna elements for sub-array setups. These configurations achieved notable results, including a 42.8% impedance bandwidth, port-to-port isolation exceeding 15 dB, and a 3 dB gain bandwidth exceeding 43%. Furthermore, a 4\times 4 antenna array is designed that attained notable specifications, such as a maximum gain of 16.7 dBi, a radiation efficiency of 80.7%, and a cross-polarization discrimination (XPD) of over 20 dB at 140 GHz. To validate these accomplishments, a measurement setup was established that could be vertically mounted incorporating bulky frequency extension units and waveguides. This setup successfully confirmed the extensive bandwidths and radiation patterns of the 4\times 4 antenna array.