In this paper, a new C and Ku-band antennas arrays design using lumped-element equivalent schematic technique which can cover respectively the band from 3.7 to 4.2GHz devoted to downlink C-band applications and from 10.7 to 12GHz are fabricated and measured. The design is based on an optimization process taking into account an implementation of lumped-element equivalent schematic in ADS of Agilent software in order to conceive logarithmically periodic linear bowtie antennas array. The basic bowtie simple schematic consists of two identical tapers used directly from the transmission line model to compute the input impedance matching at any frequency providing the resonance. The obtained results show the effectiveness of this method to analyze such types of antennas. The measured and simulation given by CST and Momentum software's results proves the effectiveness of the proposed lumped-element equivalent schematic. The results show that bandwidths from 3.7 to 4.14GHz and from 10.78 to 12.01GHz are obtained which can be used for C-band downlink and Ku-band applications.