Characteristic Mode Approach to Understanding a Capacitively Fed Crossed Bow-tie Antenna

The Theory of Characteristic Modes (TCM) is a unique way to analyze antennas. It allows the response of an antenna to be decomposed into the sum of its parts. In this thesis, a bow-tie antenna and a capacitively fed crossed bow-tie antenna are analyzed using TCM. The bow-tie antenna was modified by placing stubs at the location of an eigencurrent minimum for the third order mode close to an eigencurrent maximum for the first order mode which reduced their modal resonances by 1.8 GHz and 25 MHz respectively. Three characteristic modes were found to make up the response of the capacitively fed crossed bow-tie antenna. Each mode was decoupled into auxiliary modes to remove coupling effects from eigenvalue crossing avoidances. The auxiliary modes were described as a ground plane mode, a dipole dominant mode, and a bow-tie dominant mode. The dipole and bow-tie modes were shown to be synchronously coupled.