  An intelligent radome utilizing composite metamaterial structures is
presented and investigated in this article, which can realize energy isolation
and asymmetric propagation of electromagnetic (EM) wave self-adaptively by
controlling states of PIN diodes. The whole structure mainly consists of a
broadband polarization-sensitive polarization converter (PC) and an active
frequency selective rasorber (AFSR) switching between a transmission mode and
absorption mode which is used as an energy-selective surface (ESS). Among them,
the function of the PC is to make the EM waves transmit asymmetrically, and the
purpose of AFSR is to make the high-power waves be reflected or absorbed, which
depends on the polarization type of the wave. Thus, the radome can realize both
asymmetric propagations of EM wave and electromagnetic shielding. The
equivalent circuit models (ECM) and parametric studies are considered to
explain the physical operating mechanism of PC and AFSR. The fabricated
structure with 7*7 unit cells is experimentally demonstrated and the measured
results agree with simulated results well. Considering the distinctive
characteristic of self-actuation, the presented concept has the potential
application in electromagnetic stealth and HPEMWs shielding to protect
communication devices.
