Exploring Elemental Properties of Intelligent Reflecting Surfaces

Intelligent Reflecting Surfaces (IRSs), renowned for their ability to reconfigure wireless signals, operate on the principle of dynamic phase tuning. The reflected signals are configured by controlling the induced capacitance at each element, typically through circuit components such as varactor diodes. Beyond the applied voltage, IRS operation is influenced by various aspects such as material selection, switching speed, and circuit-level characteristics, which are often overlooked in favor of wireless performance in existing research. To address this gap, this work explores the circuit properties of IRS unit cells, highlighting its significance and performance impact. Specifically, this work presents an equivalent electrical diagram of the IRS unit cells through transmission line modelling, illustrating its adjustable parameters and dependence on elemental driven circuit. Besides, a comparative analysis has been conducted by modelling the varactor diode, with simulation results demonstrating the effects of material properties and operating frequency for various IRS applications.