A Modular and Compact RF-MEMS Step Attenuator for Beamforming Applications in the Evolving 5G/6G Scenario

The ambitious expectations of 5G/6G paradigms in terms of data rates rely on the ubiquitous coverage offered by various kinds of cells, adopting antenna arrays in massive multiple-input-multiple-output (mMIMO) configuration, and operating at high frequencies. The revolutionary choice of mMIMO systems unleash the potential of beamforming (BF) techniques, performed by hybrid digital-analog architectures, in which components like radio frequency micro-electromechanical-systems (RF-MEMS) attenuators could be an effective building block for such high-performance antenna systems employed in different kinds of cells. In this work, starting from a basic 1-bit attenuation module, different versions are optimized and simulated to be successively combined into a single compound. The development of -1 dB, -2 dB, -3 dB, and -4 dB single modules permits to achieve a compact and modular arrangement with a maximum -10 dB attenuation by -1 dB steps, operating in the 24.25 - 27.5 GHz range, the 5G frequency band to be employed in European countries. The use case is the one of Femtocells, in which the reduced number of users does not require extensive BF capabilities.