  This paper proposes a functionally reconfigurable integrated structure of a
Fabry-Perot (FP) antenna and wideband liquid absorber. The partial reflecting
surface (PRS) is elaborately tailored to serve as both a component of the FP
antenna and the metal ground of the broadband liquid absorber. Then the
integrated structure is realized by combining the FP antenna with the liquid
absorber. The PRS is composed of patches on the top layer of the substrate and
the square loop on the bottom and the microstrip patch antenna is used as a
source. The liquid absorber is composed of a 3-D printed container, 45% ethanol
layer, and a metal ground. By this design, the structure can serve as the FP
antenna when the ethanol is extracted or the liquid absorber when the ethanol
is injected. This can be used to switch between detection and stealth mode
which can better adapt to the complex electromagnetic environment. The
simulation results show that the gain of the antenna reaches to 19.7 dBi and
the operating band is 100 MHz when the ethanol is extracted. When the ethanol
is injected, the absorption band of the absorber ranges from 4 GHz to 20 GHz
and the absorption bandwidth is over 133%. The monostatic RCS reduction bands
of the structure with ethanol range from 4 GHz to 20GHz and the average RCS
reduction is 28.4 dB. The measured and simulated results agree well.
