| The international military competition is increasing,and the phased array radar plays a more and more important role in the military field.As a part of receiving and radiating electromagnetic waves,antenna plays a vital role in phased array radar.Microstrip patch array antenna has the advantages of ultra light,simple structure,easy to be common with the carrier and easy to integrate with the back-end microwave circuit.Moreover,the microstrip antenna is also easier to obtain better circular polarization performance.The development of phased array radar antenna by using low temperature co fired ceramic(LTCC)technology can increase the bandwidth of the antenna,and can integrate the antenna with the back-end microwave circuit,and also can meet the needs of phased array radar's ultra thin,high reliability and high integration.Based on the theory of microstrip antenna,the design method of circular polarized microstrip antenna is introduced in this paper.The impedance bandwidth and the circular polarization bandwidth of the antenna unit are greatly broadened by using the difference sizes of the upper and lower patch and the cutting different sizes of the double-layer patches.The impedance bandwidth of the improved antenna unit is2.33 GHz,and the bandwidth of the axial ratio less than 3dB is 1.47 GHz,and the gain is5.86 dB.Then,a 2×2 similar-element circular polarization array antenna and a 4×4similar-element circular polarization antenna array are composed with the improved antenna element,which are working in the X band,and the electromagnetic simulation software HFSS is used to optimize the array antennas.The impedance bandwidth of2×2 similar-element array antenna is 2.6GHz,and the bandwidth of AR less than 3dB is660 MHz,and the gain is 10.3dB;the impedance bandwidth of 4×4 similar-element array antenna is 2.75 GHz,and the bandwidth of the AR less than 3dB is 670 MHz,and the gain is 16.4dB.In order to further improve the circular polarization performance of the array antenna,a 2×2 rotating circular polarized array antenna and a 4×4 rotating circular polarization array antenna are developed.The impedance bandwidth of the 2×2 rotating array antenna is 2.25 GHz,and the bandwidth of the AR less than 3dB is 1.65 GHz,and the gain is 11.5dB;the impedance bandwidth of the 4×4 rotating array antenna is1.07 GHz,and the bandwidth of the AR less than 3dB is 940 MHz,and the gain is15 dB. |
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