Integrated design, modeling, and manufacturing of rasorber radome composites with electrically tunable transmission and wideband absorption properties

Integrated design, modeling, and manufacturing of rasorber radomes with electrically tunable transmission and wideband absorption properties are studied. The design principle of rasorber radomes is qualitatively analyzed based on the equivalent circuit theory. The prototypes are designed with a multi-layered configuration and constructed using quartz fiber dense skins, polymethacrylimide (PMI) foam cores , PIN diodes, carbon-based films, and the functional layers with copper patterns. The dynamic control of transmission is implemented by applying varying bias voltages to PIN diode elements. To obtain mechanical protection, the delicate PIN diodes are cured together with the preforms and embedded in the matrix. To stabilize the absorption out of the transmission band, the carbon-based films are overprinted at the reserved gaps of the copper patterns. The measured results demonstrate that as the bias voltage varies, within 2–4 GHz, the transmission of the rasorber radome dynamically varies from 0.8 (at 0 V) to 0.05 (at 50 V), while the absorption dynamically varies from 0.05 (at 0 V) to 0.7 (at 40 V). Within 8–22 GHz, the absorption is consistently more than 0.9, which is independent of the variation of bias voltages. The measured results align well with the simulated results. The rasorber radome can function as a radome to ensure normal operations of an enclosed antenna and also function as a radar absorber with variable absorption responses to avoid radar detection and tracking. Therefore, our proposal possesses considerable engineering application potential in stealth radome technology.