Direct Metal Laser Sintering Conformal Waveguide Array Antenna for Millimeter-Wave 5G Communications

An omnidirectional conformal array antenna has been implemented in air-filled waveguide technology for the 37–40 GHz band. The input port of the antenna is a standard WR28 rectangular waveguide. The TE
₁₀
mode excited in the rectangular waveguide is used to generate the TE
₀₁
mode inside a circular waveguide by means of a TE
₁₀
–TE
₀₁
mode converter. The circular waveguide section is progressively widened, forming a radial waveguide structure, where the TE
₀₁
mode propagates radially through several radiating apertures. Due to the rotational symmetry of the structure, an omnidirectional radiating performance with low ripple can be achieved. This structure has been three-dimentional (3-D) manufactured using the direct metal laser sintering technology. A good agreement between simulations and measurements has been found. A reflection coefficient of below −15 dB, a low-ripple omnidirectional performance in a conical cut plane, a low cross-polar radiation, and a total efficiency higher than 83% are obtained. This conformal antenna design is proposed for fifth generation (5G) New Radio indoor applications.