Influence of PEC Obstacles on Antenna Q-factors

Total and modal Q-factors of PEC antennas in the presence of PEC obstacles are investigated in this paper. The stored energies are computed by using rigorous expressions derived by Vandenbosch. Characteristic currents required in the integrals are obtained by analysis of substructure characteristic modes, which show superiority compared with conventional characteristic modes when other objects are considered in the radiating system. The compared results of a single antenna and the same antenna above a PEC obstacle are presented to verify the necessity of considering the influence of obstacles. The influence of distance between the antenna and obstacles will also be discussed in this paper.