A Series-Fed Broadband Low Sidelobe Microstrip Array at 24GHz

A 24GHz broadband series-fed microstrip array with low sidelobe performance is designed in this paper. The electric field distribution is changed by loading disturbed branches on one side of the microstrip line, and the electric field on both sides of the microstrip line cannot offset each other. At the same time, the disturbed branches will prolong the current path through the microstrip line, resulting in a lower resonant frequency and improving the impedance matching. The antenna array achieves broadband characteristic while structure is compact. Based on the analysis, a 1 × 8 microstrip linear array is designed. The results show that the impedance bandwidth of the array (|S11| ≤ -10dB) is 13.4%, the average gain in the bandwidth can up to 15.37dBi.The sidelobe level can reach -12.5dB, and it can be further reduced to -19.8dB by Chebyshev distribution.