Figure 5. The modeling of the offset reflector.

The modeling of the offset reflector is shown in Figure5. We focus the bandwidths ranging from 8GHz to 8.5GHz, which the axial ratio and the gain of right-hand and

left-hand at operating band is demonstrated in Figure 6. It shows that in the working band the circularly polarized gain is above 30dB which the antenna efficiency is about 71%. And

the axial ratio of the direction of the maximum radiation is below 1dB.

Figure6. The return loss and isolation between two ports.

Figure7. The radiation pattern at 8 GHz.

Figure8. The axial ratio at 8GHz.

Figure 7 and 8 shows the radiation pattern and the axial ratio at the frequency of 8GHz. The offset reflector has obtained the right-hand circularly polarized gain of 30.1dB, which a low side lobe of less than -24dB.The angle range of -4dB axial ratio is from-8.5°to10°. The measurements show that the dual-circularly polarized offset reflector is working well. The structure is being processed and we will measure this type of antenna subsequently.

4 Conclusions

A novel dual circularly polarized offset reflector with the septum polarizer has been designed by using FEKO of the company of Altair. By applying the septum polarizer, good performance is obtained as predicted in the simulation results. The whole reflector