Equivalent Circuit Model Separating Dissipative and Radiative Losses for the Systematic Design of Efficient Microstrip-Based On-Chip Antennas

This article presents a comprehensive method to efficiently design capacitively enhanced resonant on-chip antennas using an equivalent circuit (EC) model instead of computationally demanding full-wave simulations. To systemize the design process by predicting the radiation efficiency, the input impedance, the current and voltage distributions, and the radiation pattern of the antenna based on an EC, a method to extract both dissipation and radiation mechanisms from full-wave simulation data is described and carried out. Based on this separation of loss mechanisms, an EC-based antenna optimization with respect to the radiation efficiency is conceivably possible. Additional to the EC, which enables this efficient antenna optimization and increases the physical insight in the radiation mechanism, an analytical estimation of key antenna parameters, as the resonant length, is presented. The results from the analytical calculations and the antenna parameters calculated using the EC model are compared with full-wave FDTD simulations and used to discuss the capabilities and limitations of the EC model. Finally, an on-chip antenna of the considered type operating at 290-300 GHz and manufactured with silicon-germanium technology is used to verify the full-wave antenna simulations and the presented approach in general.