Design of Circularly Polarized Slotted Waveguide Antenna for SAR Application

A circularly polarized antenna constructed by a traditional slotted waveguide antenna loaded with rectangular cavities was presented in this paper. The realization mechanism of circularly polarized wave radiated by the cavity and the effect of dimension of the cavity on the impedance bandwidth of the antenna are also analyzed. The impedance characteristics and the circular polarization characteristics of this type of antenna can be tuned independently. The designed antenna is operated at X frequency band and consists of 1×10 unit cells. The measured result show that the right hand circular polarized gain is about 16.5 dB at the center frequency. The axial ratio is less than 1 dB at the direction of main radiation and the impedance bandwidth (VSWR<;2) is 64 MHz. The measured data agree well with the simulation results.