Design of a Compact Analog I/Q Type Vector Modulator in S-Band for Phased Array Antennas

This study presents the design of a compact analog I-Q type vector modulator (VM) for phased array systems in the S-band. The design and implementation of the subcomponents of the produced VM, which are a stripline-based symmetric coupled directional coupler, two 0°/180° bi-phase modulators, two analog variable attenuators, and a Wilkinson combiner, are realized in detail. Bi-phase modulators, analog variable attenuators, and a Wilkinson combiner were combined on a single board using RO4003 material. Simulations were performed in the Computer Simulation Technology (CST) and AWR Applied Wave Research (AWR) Design Environments. The measurement results of the produced VM show a dynamic range of around 30 dB, a 360° phase shift range, a phase resolution of 0.5°, 12 dB insertion loss at 3 GHz, and a return loss higher than 10 dB between 2 and 4 GHz. Moreover, in this study, a compact analog I-Q type VM has been designed and fabricated with lower insertion loss than available literature, considering similar operating bands.

Cite this article as: C. Çindaş and S. Şimşek, “Design of a compact analog I/Q type vector modulator in S-band for phased array antennas,” Electrica, 2026, 26, 0293, doi: 10.5152/electrica.2026.25293.