Radio Channel Measurements and Modeling: Incorporating Reconfigurable Antennas Into Wireless Propagation Channels

Reconfigurable antennas (RAs) have been a pivotal technology due to their ability to dynamically adjust parameters. This paper underscores the critical need for the radio channel modeling—defined as an integrated framework that captures the full signal transmission chain, encompassing wireless propagation channel characteristics, transmitter antenna parameters, and receiver antenna responses, while quantifying their intrinsic coupling. This stands in contrast to traditional channel models, which treat antennas as ideal transducers and focus solely on the propagation medium, often overlooking the impact of antenna parameters. A measurement framework, featuring a custom-designed 28/5.3 GHz RA with reconfigurable cross-polarization ratio, isolation level, and voltage standing wave ratio, is established. Results from outdoor and indoor measurement scenarios are presented. Experimental analyses reveal that the influence of isolation levels varies significantly, with indoor environments at 28 GHz showing stronger sensitivity to isolation levels compared to outdoor settings. The paper further discusses radio channel modeling methods, including circuit-based, field-based, and unified field-circuit approaches, emphasizing their roles in bridging information theory and electromagnetic physics. Finally, the study identifies the distinctions between traditional and general antenna designs.