Validation of a Low-Permittivity PCB Substrate for Compact 28-GHz Phased Array Antennas

This letter presents the validation of a low-permittivity (ε<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> = 1.88) PCB substrate for compact, 28-GHz phased-array antennas. A grounded-coplanar-waveguide(CPWG) feed and a three-layer stack-upwere verified using a TRL calibration board, confirming stable performance up to 60 GHz. A single via-fed patch antenna on the new laminate achieved 7.1 dBi gain, 3.2 dB higher than that on Megtron6 (ε<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> = 3.7). A 1 × 4 array was implemented on the same stack-up achieved 9.2 dBi broadside gain and up to 0.8 dB lower scan loss at 60° compared with Megtron6. These results demonstrate the importance of substrate selection and highlight the potential of this laminate for PCB-based millimeter-wave antennas.