Keywords: RF, antenna, GRIN, lens, additive manufacturing, DLP, manufacturing, electromagnetics
Summary:With the proliferation of RF systems in telecom (5G, mmWave) and defense (enhanced C4ISR, Manned-Unmanned Teaming, datalinks, etc.) there is a demand for improved efficiency and/or FOV (field of view) for antennas and apertures. A passive option that has been demonstrated to increase gain or FOV is a GRIN (Gradient Refractive Index) device placed in line with the RF energy. GRIN devices have long been an inaccessible or uneconomical option for implementation into commercial RF systems. With the genesis of 3D printable dielectric materials and increased accessibility to 3D printers combined with increasing interest in higher frequency bands, academia and industry both are experiencing a dramatic increase in the research and application of GRIN devices as a cost effective solution. One such area of broadening interest is the introduction of GRIN technology for use in dielectric lenses. Using a commercial DLP 3D printing system combined with low loss 3D printable photopolymer dielectric materials, we present how high performance GRIN lenses can be manufactured quickly and economically with high fidelity and accuracy. We also introduce an RF-specific digital workflow, linking common antenna design tools with the ability to quickly and easily manufacture these integrated RF devices. We describe the material characteristics, device design, and device manufacturing process. To validate the technology, a simple cylindrical, radially symmetric GRIN horn lens was designed and printed. The lens was mounted to a standard horn antenna and served to increase gain and reduce side lobes without dramatically increasing the overall horn antenna device size. The device was tested in the K band, and the practical test results are compared against HFSS simulated results.