A Ka-Band Broadband Polyjet 3-D Printed Quasi-Planar End-Fire Antenna With Partially Hollowed Substrate and Gain Compensation

This letter presents a new class of millimeter-wave broadband quasi-planar endfire antenna featuring flexible design and enhanced structural compatibility with additive manufacturing technology. The broadband endfire radiation performance is enabled by a coupling-probe-fed rectangular patch that is vertically attached to the sidewall of the dielectric substrate of the antenna. The patch and ground of the antenna are perpendicular to the plane of the feeding transmission line, and the metal parts of the antenna are embedded into the dielectric substrate. The architecture allows for the excitation of vertically polarized patterns in the patch. More significantly, the dielectric substrate is hollowed selectively to improve the realized gain in the main-lobe orientation, thus enhancing the stability of the radiation patterns over a wide operational bandwidth. A Ka -band prototype of the proposed antenna is shaped into a 3-D-printing-compatible geometry and is monolithically integrated by exploiting the high-precision Polyjet 3-D printing process. The manufactured antenna demonstrates good radiation patterns in a −10-dB impedance bandwidth from 28.8 to 37.0 GHz with in-band realized gains of 2.5–5.0 dBi.