A Compact 3-D-Printing-Compatible Dual-Polarized Spherical Resonator Antenna With Improved Bandwidth and Reliability

In this paper, a size-compact and wideband millimeter-wave dual-polarized (DP) spherical resonator antenna is proposed. The dual-polarization behavior of the antenna is attributed to a highly symmetrical geometry of the spherical resonator and orthogonality of the resonant modes inside. The wideband and stable DP radiation performance is enabled by a single quasicruci-form radiation aperture that is essentially a combination of two orthogonal elliptical slots. The configuration as such enhances mechanical strength of the radiation structure and effectively improves the antenna reliability for applications at millimeter-wave frequencies. A Ka-band DP antenna prototype is demonstrated. The antenna prototype is manufactured monolithically by using polymer-based Polyjet 3-D printing and electroless copper plating processes. The RF-measured result of the antenna in one of the polarization orientations is in good agreement with the simulated one, validating wideband and stable radiation performance from 26.5 to 39 GHz (a relative bandwidth of 38.2%) with an in-band reflection coefficient of less than -10 dB and peak realized gains of 7–9 dBi.