Characterization of printed podal vivaldi antennas (8-18 Ghz) on rt duroid with single and double cavity

Abstract

In today’s modern communication systems, miniaturized and light weight sub-systems covering broad bandwidth are in much demand as they lead to realization of very compact and light weight systems. To accomplish this, small and light weight antennas which cover wide bandwidth without much degradation in their performance are required to be designed and realized. A printed podal Vivaldi antenna with single as well as double cavities fed with strip line transmission line and operating from X band to KU band (8-18GHz) is proposed. The strip line transmission line is used in order to prevent the propagation of unwanted modes. The current distribution over both the radiating surfaces will be similar thereby maintaining the symmetry in radiation patterns. The comparison of antenna performance for single cavity and double cavity is also reported in this paper. Using double cavity, the miniaturization of antenna is possible as compare to single cavity Vivaldi antenna. The antenna is first designed using conventional theoretical approaches. Later simulated using 3D EM simulation software, CST Microwave Studio™. Optimization of antenna's various parameters are carried out to achieve the optimum values. Finally, the optimum design is physically fabricated using PCB technology for carrying out practical measurement. The antenna's input impedance characteristic is measured in the form of S-parameter and VSWR using Vector Network analyzer. VSWR less than 3:1 is achieved over the band from 8 GHz to 18 GHz. The radiation patterns measurements are carried out in Anechoic chamber. The proposed Vivaldi antenna is used for digital data transmission via satellites and for voice/audio transmissions.