Development of commercial all-metal 3D printing chnology provides a new fabrication method for wideband millimeter-wave corrugated horns up to 50 GHz. All-metal 3D printing has advantages of low cost, fast delivery, possibility of mass production, flexibility in fabrication of complicated geometries and good mechanical robustness compared with traditional fabrication techniques, such as direct machining or electroforming, or recently developed methods such as those relying on the assembly of platelets. In this letter, we report the development of a wideband millimeter-wave corrugated horn at 30-50 GHz (50% fractional bandwidth) based on commercial allmetal 3D printing technology. Measurement results of return loss and beam patterns show good performance and are also reported in this letter.

Planar near-field measurements are a common method to characterize antenna performance at millimeter and submillimeter wavelengths. Far-field beam patterns are then calculated from those measurements. However, different approximations have been traditionally used for this calculation without careful analysis. In this paper, we derive a Near-field-to-Far-field Transformation (NFT) based on diffraction theory and the full components of electrical fields based on the boundary condition in the far-field region. We analyze the systematic errors introduced by Fourier Transformation (FT) and the probe antenna by comparison with simulations. We further apply our data analysis procedures in the near-field measurement of a corrugated horn. Measurement and simulation results suggest that when all the procedures are conducted accurately, we are able to reconstruct far-field beam patterns from planar near-field measurements with high accuracy.