To meet antenna design specifications under realistic conditions, electromagnetic coupling effects between the antenna and its environment must be considered. In this work, an efficient antenna design optimization methodology that considers the influence of the human head and main mobile handset components on the antenna performance is presented. The computational optimization time is dramatically reduced by exploiting a Broyden-based input space mapping (SM) algorithm. Both coarse and fine models required for the SM algorithm are based on the finite-element method and are implemented in the same simulator; simplifying the modeling process. However, our coarse model does not consider any object of the actual operational environment. In spite of that and other simplifications applied to the coarse model, the proposed optimization scheme is able to find a solution that meets the specifications in a realistic environment by performing an extremely small number of expensive fine model simulations. Our practical illustration opens up the feasibility of using this CAD methodology to optimize other RF devices that operate in close proximity to objects that affect its desired response, as it is the case for many wearable devices.

A practical formulation for EM‐based design optimization of high‐frequency circuits using simple polynomial surrogate functionals is proposed in this paper. Our approach starts from a careful selection of design variables and is based on a closed‐form formulation that yields global optimal values for the surrogate model weighting factors, avoiding a large set of expensive EM model data, and resulting in accurate low‐order low‐dimension polynomials interpolants that are used as vehicles for efficient design optimization. Our formulation is especially suitable for EM‐based design problems with no equivalent circuital models available. The proposed technique is illustrated by the EM‐based design optimization of a Ka‐band substrate integrated waveguide (SIW) interconnect with conductor‐backed coplanar waveguide (CBCPW) transitions, a low crosstalk PCB microstrip interconnect structure with guard traces, and a 10–40‐GHz SIW interconnect with microstrip transitions on a standard FR4‐based substrate. Three commercially available full‐wave EM solvers are used in our examples: CST, Sonnet, and COMSOL. Copyright © 2015 John Wiley & Sons, Ltd.

In this paper a switchable bandstop filter able to switch between two different central frequency states while precisely maintaining a fixed bandwidth is presented. The filter topology allows precise control over the design parameters frequency and bandwidth, achieved by choosing adequate resonator sections which are switched by PIN diodes to obtain two discreet states. The central frequency control was obtained by modifying resonator length. Bandwidth control was achieved by choosing a resonator width and controlling the normalized reactance slope parameter of a decoupling resonator by means of a switchable resonator extension. The filter was designed to have center frequencies of 2 and 1.5 GHz both having an 8% fractional bandwidth. The comparison between simulations and measurements showed a central frequency deviation of 4 MHz for the 2 GHz frequency response, and a deviation of 2 MHz for the 1.5 GHz frequency response. The fractional bandwidth deviation for the 2 GHz filter response was 0.67%, while at 1.5 GHz a 0.4% deviation was observed. The simulation and measured responses are in very good agreement.