Realization of modified Luneburg lens antenna using quasi‐conformal transformation optics and additive manufacturing

Abstract

We demonstrate a new method for realizing modified Luneburg lens antennas with nearly continuously graded permittivity profiles in three‐dimensions. The method used a quasi‐conformal transformation optics (QCTO) approach to modify the geometry and permittivity of a spherical Luneburg lens to have a flat surface for convenient integration of antenna feeds. The modified lens was then fabricated using Fused Deposition Modeling (FDM) printing with an effective media approach that employs space‐filling curves. The method was validated by designing and fabricating a modified Luneburg lens antenna designed to operate in the Ka‐band. The antenna performance of the sample was measured experimentally and shown to compare well to predicted results using full wave simulations. The device was able to achieve a reasonably high degree of beam steering (ie, −55° to +55°) over the entire Ka‐band. We believe this new approach provides a cost‐effective and scalable means of realizing practical passive beam steering lenses that operate over a broad range of frequencies.

High gain, wide-angle QCTO-enabled modified Luneburg lens antenna with broadband anti-reflective layer

“…Modern wireless communication systems are increasingly focusing on high gain, agile, wide-angle, multiband and multibeam beamscanning antenna elements for applications in radar, electronic warfare, wireless and satellite communication systems 1 – 4 . Conventionally, these properties have been exclusively achieved by using either electronically steerable phased array antenna technology or mechanically steerable reflector antenna systems.…”

“…waveguides, antenna arrays, detectors) to the lens's spherical surface. To eliminate this feed mismatch problem between the spherical Luneburg lens and planar feed elements, a more convenient approach is to use a modified Luneburg lens antenna in which the lens's spherical feed surface is transformed into a planar surface to successfully integrate the lens with planar feed sources and other external back-end electronics 1,3,4 . To design such a modified Luneburg lens antenna while maintaining the spherical lens's original electromagnetic performances, the recently developed transformation optics method has drawn great interests among the antenna and electromagnetic community 5,6 .…”

“…For example, a two-dimensional modified Luneburg lens using QCTO method was demonstrated in the X-band 3 . A method to extend the two-dimensional QCTO method to design three-dimensional electromagnetic structure was proposed 6 and a three-dimensional realization of QCTO modified Luneburg lens antennas were demonstrated in the Ku-band (12.4-18 GHz) and Ka-band frequency (26-40 GHz) 1,4 .…”

“…To demonstrate the broadband anti-reflective layer enabled new QCTO Luneburg lens design methodology, an example modified lens antenna was designed using quasi-conformal mapping and implemented with the broadband anti-reflective layer to operate in the Ka-band (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40). The modified lens antenna was realized using the fused deposition modeling (FDM) based additive manufacturing technique 4 to operate in the Ka-band frequency range (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40). The electromagnetic performance of the fabricated lens antenna was experimentally measured and compared with the simulated predictions.…”

“…The modified Luneburg antenna designed with quasi-conformal mapping was practically realized using fused deposition modeling (FDM) based additive manufacturing (AM) technique 4,61 . Here, AM is used to generate small scale changes (i.e.…”