We are very pleased to announce that Montaha Bouezzeddine from RheinMain University of Applied Sciences in Germany was selected as runner up winner for her paper titled "Design of 4-port Tunable MIMO Antenna System for a Femto-cell Base-station Using FEKO"
The idea is the design of a 4-port MIMO antenna in the range [470,790] MHz. The antenna system is meant to be used by a base station (femto-cell) and a user equipment, both containing many PCBs. The idea was to use the box as a “radiating support” by exciting the characteristic modes (CMs), as to exploit the full available volume.
The dimensions of the box (3D structure) are comparable to a wavelength (lambda_0) at 500 MHz in the three dimensions. The main solution method that I used is the MoM. For my application, the most important feature provided by Feko is the computation of CMs. It helps me calculate the eigenvalues, charge density and current distributions, the modal near fields as well as the eigenfields. After choosing the CMs to excite, the full antenna structure with the couplers in place is designed (after some trials on the type of couplers, capacitive and inductive couplers, their dimensions and parameters such as the separation from the box).
I tried to use the optimization techniques (GA and PSO) but they did not really lead to significant results and they consume too much time and resources, especially that the structure is bit large (compared to 2D structures, and in view of the potential of the used PC).
A very interesting feature of CMs in the context of MIMO antenna based on CMs is the modal excitation coefficients. It helps predicting the isolation levels at the modal ports (after a decoupling network needed for the excitation of Cms).
I had used different medium to model the box by replacing the PEC (box, couplers, feeding lines) by some other conductors. This has helped me to predict the modal efficiencies.