Systematic Generation of Arbitrary Antenna Geometries

Abstract

Applications for conformal, wearable antennas are growing for consumer electronics. Hence, it is important to assess to what degree antenna performance can be tolerant to in-situ deformations that can take the form of bending, crumpling and twisting and combinations of these effects. However, generating geometries of arbitrary antenna deformations such as bending, crumpling and twisting, that can be processed by standard electromagnetic software is a major challenge that significantly complicates full assessment of in-situ antenna performance. Constructive Solid Geometry methods of generating geometries is difficult to robustly apply to non-conformal antennas and more flexible techniques required to progress the antenna studies further. To address this challenge, this paper investigates the utility of the Green Coordinate method for spatial manipulation of 3D objects. First a calibration of a straightforward application of the GC method against a reference case of a patch antenna bent over a cylindrical surface, which can also be generated exactly, is undertaken. The paper shows that systemic scaling distortions are introduced by the GC method and introduces a compensation method that can overcome these distortions. Subsequently, the compensated method is used to obtain new predictions of the electromagnetic performance of patch antennas with deformations.

Assessment of the Robustness of Flexible Antennas to Complex Deformations

“…It is commented here that the subsequent choice of modelling method, Finite Elements, Finite Integration Technique, Method of Moments, or their implementation within particular software packages is not the issue, rather it is the geometrical data upon which they operate that has the failing. The main difficulty when generating arbitrary deformations is in obtaining well behaved interfaces between the constitutive parts of the antenna, free of misalignments and microscopic gaps, as discussed in [28][29][30], which can undermine subsequent EM numerical simulations. Our recent work [28] proposed the use of a computer graphics spatial manipulation technique based on Green Coordinates (GC) for generating arbitrary deformations of antennas [31,32].…”

“…The systematic distortions that are introduced by the GC method can be effectively compensated for by using an iterative pre-scaling approach, as shown in [28][29][30], that guarantees physical reality of the final geometries. This approach was calibrated against the simple case of cylindrical bending for which no distortion is expected to occur and proved that the performance of the GC generated cylindrically bent antenna agrees well with the CSG generated antennas opening the way for robust generation of more general antenna deformations [28].…”

Assessing the Impact of Twisting and Bending Deformations on Flexible Interconnect Performance

“…Computational geometrical models of cylindrical deformation are made using standard Boolean CAD approach based on constructive solid geometry (CSG). However, this CAD approach is not reliable for generating twisting deformation as it may result in formation of microscopic gaps between constitutive layers of the interconnect (ie, substrate/ground plane/metallic trace) which can undermine electromagnetic simulations, as discussed in [19]. To overcome this difficulty we apply a computer graphics approach based on Green Coordinate (GC) technique for spatial manipulation of objects to create desired twisting deformation [20,21].…”

“…To overcome this difficulty we apply a computer graphics approach based on Green Coordinate (GC) technique for spatial manipulation of objects to create desired twisting deformation [20,21]. The full description of how GC methodology is implemented for the purposed of electromagnetic (EM) simulations is discussed in detail in [17,19].…”

A Shape Generation Method for 3D Printed Antennas With Unintuitive Geometries

“…All antennas, no matter what their design, have inherent performance constraints based on their geometry [1]. Generally, fewer constraints result in a larger design space which can be exploited to realize antennas with unintuitive and complex geometries that have desirable properties such as wide bandwidth, high gain, strong circular polarization, and compact size [2,3,4]. However, some level of constraints are needed as completely unrestricted antennas may not be fabricable with traditional methods such as CNC machining.…”