Millimeter-Wave Antenna Array Fed by an Insulated Image Guide Operating in Higher-Order $E^{11}_x$ Mode

This communication presents a low-loss hybrid technology for integration of planar circuits with high-efficiency off-chip antennas. A linear antenna array fed by a low-loss synthesized version of insulated image guide operating in $E^{11}_x$ mode (where the electric field is primarily parallel to the ground-plane) is designed and measured. A planar on-chip electric dipole couples fields efficiently from planar circuits to the antenna array feed line. Measured coupling insertion loss is about 0.5 dB at 90 GHz. A broadside gain of 14.9 dBi at 90 GHz is measured for an array with 10 radiating elements.