Design of a low loss and broadband active element of reconfigurable reflectarray antennas

A low loss wideband active reflectarray element (ARE) is designed in this paper. One PIN diode has been loaded into microstrip metal patch, which alters an element resonant property when the PIN diode is ON or OFF. Thus a 1-bit unit cell is generated by controlling the working states of the PIN diode. Besides, two ingenious designs have been employed to reduce the insertion loss of ARE, one is loading a bridging capacitor in parallel with the PIN diode, the other is using an asymmetric design of the position of electronic device and slot. These technologies together enable the ARE to operate from 8.45 to 12.60 GHz with 180°±30° phase difference (the relative bandwidth is up to 40%). The losses of the ARE with ON and OFF states are less than 0.75 dB in aforementioned frequency range. The experimental results are in line with the simulated ones. Compared with other designs, the proposed ARE has advantages of low insertion loss and wide working band, which is very suitable to achieve high performance multifunctional metasurface.