Design and Development of a Vivaldi Antenna Array for Airborne X-Band Applications

In this paper, design analysis of an X-band Vivaldi antenna array for airborne active phased array radar application has been presented. Initially, a parametric study has been conducted to find out the relationship between design characteristics of a Vivaldi antenna array and its performance. Thereafter, a single Vivaldi antenna leading to 1×8 uniform linear array was designed to achieve optimal performance before proceeding to 8×8 antenna array design. Moreover, the tuning and optimization of designed antenna array have also been performed to achieve the desired results. The transition from stripline to slotline in the feeding section was adopted to adhere to the size restrictions of airborne radar system. The designed antenna array operates in X-Band with a center frequency of 10 GHz. It comprises an array of 64-elements (8×8) and achieves a 22 dB gain. The return loss (S11) is better than −10 dB in 2 GHz bandwidth (8.55 – 10.75 GHz). With a transmitted peak power of 640 W, the Azimuth and Elevation coverage is ±60° and beamwidth is 13°. The isolation between two elements is 20 dB and Side Lobe Levels (SLL) are −30 dBc. The designed single-element Vivaldi antenna and uniform linear 1×8 elements Vivaldi array antenna have been fabricated to develop 8×8 elements antenna array. The return loss parameter and radiation patterns of all prototypes have been found in good agreement with simulation results. Rogers 5880 substrate with 1.57 mm thickness has been utilized for fabrication. The design and simulations analysis have been performed in ANSYS HFSS EM simulation platform and Gerber files have been generated through ADS for fabrication.