Dual-polarised and ultra-thin broadband AAMCs for both P and L bands applications

Conventional artificial magnetic conductor (AMC) suffers from the thick profile and narrow bandwidth in the low-frequency band. Incorporating varactors into a passive AMC can adjust the working frequency dynamically and broaden the operating band range. This study investigates the different incorporation methods of varactors into AMC using the equivalent circuit analysis method. By establishing the equivalent circuit of the whole configuration, the frequency-domain working characteristics of passive AMC and active AMC (AAMC) are theoretically analysed. It reveals that a parallel incorporation of varactors allows lowering the frequency and increase the working bandwidth more efficiently when compared with a series integration. Following this principle, two dual-polarised AAMCs are proposed. Simulations and measurements indicate that both AAMCs elements have an ultra-low profile (0.0035 λ ) and compact size (0.04 λ ). Moreover, the in-phase-reflection frequency bands of both AAMCs cover P and L bands, proving the effectiveness of the proposed design method.