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Realization of modified Luneburg lens antenna using quasi-conformal transformation optics and additive manufacturing
摘要： 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.
关键词： additive manufacturing,beamscanning,beamforming,fused deposition modeling,Luneburg lens,transformation optics
更新于2025-09-23 15:22:29
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Post-Processing of FDM 3D-Printed Polylactic Acid Parts by Laser Beam Cutting
摘要： In this paper, the post-processing of 3D-printed poly lactic acid (PLA) parts is investigated. Workpieces are manufactured by fused deposition modeling (FDM) 3D printing, while they may have defects in some areas such as edges. A post-processing is introduced here for 3D-printed samples by low power CO2 laser. The thickness of the FDM samples are 3.2 mm and printed by optimum conditions. Effects of process parameters such as focal plane position (?3.2–3.2 mm), laser power (20–40 W), and laser cutting speed (1–13 mm/s) are examined based on the design of experiments (DOE). Geometrical features of the kerf; top and bottom kerf; taper; ratio of top to the bottom kerf are considered as output responses. An analysis of the experimental results by statistical software is conducted to survey the effects of process parameters and to obtain regression equations. By optimizing of the laser cutting process; an appropriate kerf quality is obtained and also optimum input parameters are suggested. Experimental verification tests show a good agreement between empirical results and statistical predictions. The best optimum sample with 1.19 mm/s cutting speed, 36.49 W power and 0.53 mm focal plane position shows excellent physical features after the laser cutting process when 276.9 μm top and 261.5 μm bottom kerf width is cut by laser.
关键词： fused deposition modeling,laser cutting,3D printing,additive manufacturing,post-processing,design of experiments
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Bochum, Germany (2019.7.16-2019.7.18)] 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Additive Manufacturing of Symmetrical X-Band Waveguide Filters for Wide-Band Applications based on Extracted Pole Filter Design
摘要： In this paper, the realization of X-band waveguide ?lters based on extracted pole design realized with additive manufacturing (AM) techniques is discussed. All ?lters proposed here bene?t from a symmetrical layout and can hence been cut in the E-plane. Design strategies for the proposed ?lter set-up are presented. Measurement results for a four cavity ?lter with up to two real frequency axis transmission zeros (TZs) are discussed. An extension to a higher number of TZs is possible. To reduce the production costs the commonly known fused deposition modelling (FDM) technique is used for the realization of the waveguide ?lters. Subsequent electroplating necessary for implementation of conductive surfaces will be discussed. The insertion loss of the proposed ?lters can drastically be reduced by the use of the E-plane cut.
关键词： Additive Manufacturing,Fused Deposition Modeling (FDM),E-plane waveguide filter,X-band
更新于2025-09-12 10:27:22
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An approach to improve interface healing in FFF-3D printed Ultem 1010 using laser pre-deposition heating
摘要： Fused Filament Fabrication (FFF) 3D printing has become an effective way to fabricate custom parts at low cost and fast speed. However, due to anisotropic properties of FFF 3D printed parts, their mechanical strength is unsatisfactory compared to those of parts made using traditional methods. To address this issue, an in-process laser local pre-deposition heating (LLPH) method is reported to increase thermal relaxation at inter-layer interface, for improvement of inter-layer adhesion, and therefore tensile strength in the build direction. The effect of laser power on tensile strength, and in-depth investigation of polymer relaxation, reptation and entanglement are presented. 178% increase in tensile strength and an isotropy value of 82.8% (build-direction strength divided by build-plane strength) were achieved. Isotropic behavior at inter-layer interface was observed using Scanning Electron Microscope.
关键词： Additive Manufacturing,3D printing,Fused Deposition Modeling,Inter-layer strength,Inter-layer bond
更新于2025-09-12 10:27:22
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3-D Printed Bandpass Filters With Coupled Vertically Extruded Split Ring Resonators
摘要： The additive manufacturing process of multimaterial extrusion offers performance advantages using functional materials including conductors while making accessible the third dimension in the design of electronics. In this work, we show that the additional geometrical freedom offered by this technique can be exploited for the design and realization of filters made of 3-D resonators that exhibit enhanced characteristics. The coupling properties of 3-D grounded square split ring resonators (SRRs) are initially explored. We demonstrate by simulations and experiments that SRRs with finite height display significantly stronger coupling compared to equivalent thin printed circuit structures. The observed trend can be exploited for designing filters with wider operational bandwidths for a given footprint, or miniaturized layouts and enhanced compatibility with fabrication limits for minimum feature size and spacing without performance degradation. This concept is demonstrated by presenting results of full-wave simulations for sample bandpass filters with identical footprint but formed by coupled 3-D square SRRs of different heights, showing that filters with taller resonators exhibit increasingly wider bandwidths. Two filter prototypes with center frequencies at 1.6 and 2.45 GHz are manufactured by multimaterial 3-D printing. The measured characteristics of these prototypes are found to be in good agreement with numerical simulations taking into account the effect of the lossier metallic and dielectric materials used in 3-D printing and confirm the predicted larger bandwidth of the filters made of 3-D SRRs with marginally higher insertion losses.
关键词： Additive manufacturing,resonance,split-ring resonators,filter design,fused deposition modeling (FDM),3-D printing,direct digital manufacturing (DDM),electromagnetic coupling
更新于2025-09-11 14:15:04