Three-Dimensional Printed, Dual-Band, Dual-Circularly Polarized Antenna Array Using Gap Waveguide Technology

A gap waveguide (GW)-based 4 × 4 dual-band, dual-circularly polarized antenna array is proposed. The antenna is composed of two stacked layers which are responsible for right-handed circularly polarized (RHCP) radiation in K-band and left-handed circularly polarized (LHCP) radiation in Ka-band. Each stacked layer consists of a GW power distribution network to excite 16 radiating units from a single input. A waffle grid is mounted on top of the array structure to increase effective aperture areas and reduce grating lobes. A prototype was fabricated using stereo lithography appearance (SLA) 3D printing and metallization technology, which significantly decreased the fabrication cost and complexity. Measurement results for the antenna prototype demonstrate the operating bandwidths of 19.91–20.52 GHz in K-band and 28.26–29.19 GHz in Ka-band, over which the reflection coefficients of <−10 dB and axial ratios of <3 dB are achieved. The prototype provides peak gains of 20.1 and 20.3 dB with total efficiencies of >90% in the two respective bands. The combination of dual-band, dual-circularly polarized capability, high gain, high efficiency, lightweight, low cost and compact size renders the proposed design a potential candidate for commercial millimeter wave communication applications.