High-Gain All-Metal 3-D Printed Lens–Horn Antenna for Millimeter-Wave Applications

In this letter, a high-gain all-metal lens–horn antenna for millimeter-wave applications is proposed. Unlike the conventional metal lens horn, the proposed lens horn can theoretically achieve an arbitrary focal-to-diameter (F/D) ratio, which can further shorten the length of the horn antenna. Considering the design difficulty of the feed, in practice, the F/D ratio generally needs to be greater than 0.4. To further reduce the overall height of the antenna, the lens can be kept at a certain thickness according to the Fresnel lens principle. To demonstrate the proposed theory, a lens–horn antenna with an F/D ratio of 0.7 and an aperture area of π×93.75² mm² is designed, fabricated, and tested. In order to reduce the processing costs and difficulties, the antenna is processed by metal 3-D printed technology. The test results indicate that the antenna achieves a peak gain of 30.8 dBi and 3-dB gain bandwidth of 22.5% (28.4–34.5 GHz). The length of the proposed antenna can be reduced by about 68% compared with the horn antennas without lenses. The proposed antenna has the characteristics of high gain, compact structure, and low cost, which is suitable for high-power millimeter-wave applications.