Peak and Average Power Handling Capability of Microstrip Filters

In this paper, the power handling capability of microstrip filters is studied in detail. This paper is addressed from two perspectives, depending on the physical phenomenon limiting the maximum power that the microstrip filter can handle. One of these phenomena is air breakdown or corona effect, which is linked to the peak power handling capability (PPHC) of the device, and the other is the self-heating, which limits the device average power handling capability (APHC). The analysis is focused on three kinds of filtering topologies widely used both in academia and industry, such as the coupled-line, stepped impedance resonator and the dual-behavior resonator-based filters. Closed-form expressions are computed to predict both the PPHC and the APHC as a function of the geometrical parameters of the resonators integrating the filter. Guidelines are also given to extrapolate the provided computations to other filtering topologies based on other kinds of resonators. To validate this research study, three bandpass filters centered at 5 GHz have been implemented and fully characterized by means of two measurements campaigns which have been carried out, one for the PPHC and another one for the APHC. The measured results have validated the performed study and corroborated the conclusions obtained throughout this paper.