Design and investigation of cavity backed bowtie antenna with unidirectional radiation pattern using characteristic mode analysis

In this work, a novel cavity backed leaf-shaped bowtie antenna is designed using Characteristic Mode Analysis (CMA). An analytical expression is proposed to arrive at the leaf shape of the bowtie antenna using optimization process. The developed antenna is backed by a square-cavity to get unidirectional radiation pattern with high gain and good front-to-back-ratio characteristics. CMA technique is used in the design and optimization of the cavity structure and generalized design equation is proposed to design the cavity for getting good impedance bandwidth and broadside radiation characteristics in the Desired Band of Interest (DBI). The developed antenna resonates from 0.8 to 4.3 GHz with stable and unidirectional radiation characteristics giving maximum gain and FBR of 11.5 dBi and 15.2 dB respectively, making it suitable for Ground Penetrating Radar (GPR) applications.