Analysis and Implementation of Binomial SIW Slot Antenna Array Based on Pascal’s Triangle Using 6-Port SIW Directional Coupler for X-Band Systems

The binomial array is a non-uniform amplitude array in which the amplitude of the antenna elements are arranged depending on the coefficient of the binomial series. This series based on Pascal’s triangle for which the elements are equally spaced with unequal amplitude excitation in such a way that the resultant radiation pattern has reduced side lobes. In this paper investigation and implementation of reduced side lobes of non-uniform substrate integrated waveguide (SIW)slot antenna array have been presented using the binomial excitation of 121 described by Pascal’s triangle using 6-port SIW directional coupler for three sub-arrays. The proposed array consists of three sub arrays of SIW slot antenna including twelve radiating elements of rectangular shape slots distributed equally for each sub-array. The proposed array has been designed and implemented using Roggers 4350 of $\varepsilon_{\mathrm{r}}=3.6, \tan\delta=0.004$ and thickness $\mathrm{h}_{\mathrm{R}}=1.5$ mm.The proposed array has been simulated using HFSS simulator. Results from the proposed binomial SIW antenna array showed agreement between simulation and measurements and giving return loss ($\mathrm{S}_{11}=-37.7{\mathrm dB}$), gain (G = 11dB), HPBW = 45 degree, radiation efficiency of 84.3%,fractional bandwidth ($\mathrm{B}_{\mathrm{f}}= 11.65\%$)and side lobe level (SLL = -21dB) forX-Band missile guidance system applications.