A 27–31-GHz 1024-Element Ka-Band SATCOM Phased-Array Transmitter With 49.5-dBW Peak EIRP, 1-dB AR, and ±70° Beam Scanning

This article presents a wideband scalable 27–31-GHz 1024-element $Ka$ -band SATCOM transmit (TX) phased array with embedded RF drivers and reconfigurable polarization. The phased array uses silicon TX beamformer (BF) chips and printed stacked-patch antennas on an FR-4 based printed circuit board (PCB) to TX either linear, rotated linear, circular clockwise, or anticlockwise polarization. It demonstrates a measured 3.5° half-power beamwidth (HPBW), 35-dB cross-polar discrimination (XPD), sub-1-dB axial ratio (AR), +49.5-dBW peak effective isotropic radiated power (EIRP) on axis, and the ability to scan to ±70° in all planes without grating lobes and $cos^{1-1.1}(\theta)$ scan loss. The measured error vector magnitude (EVM) of less than 2.3% and the adjacent channel power ratio (ACPR) of less than −32 dBc across all scans at $P_{1\,\text{dB}}$ make it suitable as a compact high-efficiency SATCOM transmitter. The array aperture measures 14.9 cm $\times14.9$ cm, and it is scalable to larger phased arrays with 4096 and a higher number of elements. To the best of our knowledge, this represents the highest level of integration at millimeter waves and with the highest measured EIRP from a SATCOM phased array.

I. Introduction

There is renewed interest in global space-based broadband connectivity envisioned by commercial enterprises with SATCOM systems, such as Starlink, OneWeb, and Kuiper [1]–[3], and the new generation of systems promise high-speed, low-latency global coverage using low earth orbit (LEO) and medium-earth orbit (MEO) satellites. The move to lower orbit satellites was also enabled by recent advances of commercial silicon beamforming chipsets and affordable phased arrays. With these chipsets, it is now feasible for user terminals to be outfitted with advanced active electronically scanned phased arrays (AESAs) at relatively low cost (see Fig. 1). Instead of traditional complex mechanical scanning units, the AESAs provide fast electronic beamsteering, which is important for uninterrupted links between user terminals and moving satellites in LEO/MEO. Affordable phased arrays also benefit current geostationary orbit (GEO) SATCOM systems, especially for SATCOM-on-the-move systems [4], [5]. Fig. 1.

(a) Block diagram of the 1024-element phased array. (b) antenna cell with eight channel TX BF. (c) PCB stackup.