An Efficient Framework For Fast Computer Aided Design of Microwave Circuits Based on the Higher-Order 3D Finite-Element Method

In this paper, an efficient computational framework for the full-wave design by optimization of complex microwave passive devices, such as antennas, filters, and multiplexers, is described. The framework consists of a computational engine, a 3D object modeler, and a graphical user interface. The computational engine, which is based on a finite element method with curvilinear higher-order tetrahedral elements, is coupled with built-in or external gradient-based optimization procedures. For speed, a model order reduction technique is used and the gradient computation is achieved by perturbation with geometry deformation, processed on the level of the individual mesh nodes. To maximize performance, the framework is targeted to multicore CPU architectures and its extended version can also use multiple GPUs. To illustrate the accuracy and high efficiency of the framework, we provide examples of simulations of a dielectric resonator antenna and full-wave design by optimization of two diplexers involving tens of unknowns, and show that the design can be completed within the duration of a few simulations using industry-standard FEM solvers. The accuracy of the design is confirmed by measurements

GPU-Accelerated 3D Mesh Deformation for Optimization Based on the Finite Element Method

This paper discusses a strategy for speeding up the mesh deformation process in the design-by-optimization of high-frequency components involving electromagnetic field simulations using the 3D finite element method (FEM). The mesh deformation is assumed to be described by a linear elasticity model of a rigid body; therefore, each time the shape of the device is changed, an auxiliary elasticity finite-element problem must be solved. In order to accomplish this in a very short time numerical integration and the solution of the resulting system of equations are performed using a graphics processing unit (GPU). The performance of the proposed algorithm is illustrated are verified using a complex example involving 3D FEM analysis of a dielectric-resonator filter

Novel MNZ-type microwave sensor for testing magnetodielectric materials

A novel microwave sensor with the mu-near-zero (MNZ) property is proposed for testing magnetodielectric material at 4.5 GHz. The sensor has a double-layer design consisting of a microstrip line and a metal strip with vias on layers 1 and 2, respectively. The proposed sensor can detect a unit change in relative permittivity and relative permeability with a difference in the operating frequency of 45 MHz and 78 MHz, respectively. The MNZ sensor is fabricated and assembled on two layers of Taconic RF-35 substrate, with thicknesses of 0.51 mm and 1.52 mm, respectively, for the measurement of the sample under test using a vector network analyzer. The dielectric and magnetic properties of two standard dielectric materials (Taconic CER-10 and Rogers TMM13i) and of yttrium–gadolinium iron garnet are measured at microwave frequencies. The results are found to be in good agreement with the values available in the literature, which shows the applicability of the prototype for sensing of magnetodielectric materials

A Microwave Sensor with Operating Band Selection to Detect Rotation and Proximity in the Rapid Prototyping Industry

This article presents a novel sensor for detecting and measuring angular rotation and proximity, intended for rapid prototyping machines. The sensor is based on a complementary split-ring resonator (CSRR) driven by a conductor-backed coplanar waveguide (CBCPW). The sensor has a planar topology, which makes it simple and cost-effective to produce and accurate in measuring both physical quantities. The sensor has two components, a rotor and a stator: the first of these (the CSRR) can rotate around its axis and translate along the plane normal to the ground of the CBCPW. A detailed theoretical and numerical analysis, along with a circuit model, of the unique sensor design is presented. The proposed sensor exhibits linear response for measuring angular rotation and proximity in the range of 30°-60° and 0-200 μm, respectively. Another distinctive feature of the rotation and proximity sensor is the wide frequency band of applicability, which is an integral part of its novel design and is implemented through various dielectric material loadings on the CSRR. In the prototype of the proposed device, the stator (CBCPW) is fabricated on a 0.508-mm-thick RF-35 substrate, whereas the CSRR-based rotor is fabricated on TLY-5 and RF-35 substrates. The angular rotation, proximity, operating band selection, and sensitivity are measured using a vector network analyzer and are found to be good matches to the simulated and theoretical results