Increasing Peak Power Handling in Microstrip Bandpass Filters by Using Rounded-End Resonators

This work describes a new strategy for improving the peak power handling capability (PPHC) of microstrip bandpass filters (BPFs) without any degradation in the electrical performance. For this purpose, a new resonator topology with rounded open-circuit terminations is proposed. Using this strategy, sharp edges are avoided, and a reduction of the maximum peak voltage (V
_peak
) is obtained, leading to higher peak power thresholds. An in-depth analysis of the variation of V
_peak
and PPHC as a function of the circle radius is also carried out. As a validation, two microstrip BPFs centered at 1.6 GHz with different end-circle sizes are designed, manufactured, and measured, showing a PPHC enhancement of 2.10 and 1.15 dB, respectively, compared to a standard microstrip BPF.