An absorptive/transmissive FSS radome with lumped resistors loaded

Combing FSS technology with absorbing conception, an FSS radome with absorptive and transmissive characteristics is presented in the paper. It can transmit electromagnetic wave at around 20.5 GHZ. And below the transmission band, it can absorb energy at the frequency range of 5~15GHz with Sit and S21 both less than -10dB, and with the absorption rate more than 80% (even up to 95% at some frequency range). When the FSS radome is cooperated with a waveguide horn operating at K band, the mono-static RCS of antenna system can be dramatically reduced in the absorbing band by 10dB, which provides a possibility that this FSS radome can be utilized in the military field to reduce RCS and realize the stealthy capabilities. The unit cell is a hexagon format and is duplicated as a honeycomb formation. The pass band is obtained by a metallic FSS with a wide rejection band. The absorbing performance is realized by a lossy layer with metallic strips and lumped resistors, which utilizes the metallic FSS as the ground plane within the absorbing frequency range. The equivalent circuit is given briefly and the working principle is analyzed clearly.