Ratio of the radiated powers derived from the resonance resistances of impedance of power-ground plane of PCB

摘要

In this paper, based on measurements and FDTD (Finite-Difference Time-Domain) analyses we investigated resonance frequencies and resonance resistances at the resonance frequencies for the input impedance of power-ground planes of printed circuit boards (PCBs). The results showed that the peaks of the radiated electric fields from a PCB occur at the frequencies with a large resonance resistance when the internal resistance of the exciting voltage source is large enough compared to the impedance of power-ground planes, while these peaks shift towards the frequencies with a small resonance resistance with decreasing the internal resistance. Moreover, it was also shown that the ratio of the radiated powers at the two resonance frequencies, which could be derived from the resonance resistances and the internal resistance of the exciting source, was identical approximately to the ratio of the squared radiated electric fields at the two resonance frequencies.