In-Depth Study of the Corona Discharge Breakdown Thresholds in Groove Gap Waveguides and Enhancement Strategies for Inductive Bandpass Filters

This work focuses on the study of the corona discharge breakdown in groove gap waveguides (GGWs) and inductive bandpass filters (BPFs) based on this technology. With the main aim of improving the peak power handling capability (PPHC), the location of the maximum normalized electric field strength
$(|{\hat {E}}_{\text {MAX}}|)$
as a function of the geometrical parameters is analyzed. First, the research deals with wave-guiding structures, comparing the distribution of the transverse electric TE10-like mode of a GGW to that of an equivalent rectangular waveguide (RW). Next, a design strategy based on the adjustment of the geometrical dimensions of the bed of nails is proposed, thus achieving a considerable reduction of
$|{\hat {E}}_{\text {MAX}}|$
. The second part of this paper aims for vertically polarized GGW BPFs, where the inductive irises become the most critical part of the component. By a simple modification of their dimensions, a second design criterion is suggested for improving the PPHC. Finally, several Ku-band BPFs centered at 14 GHz and 16 GHz have been manufactured and experimentally verified at the European High-Power Radiofrequency Space Laboratory. This measurement campaign shows peak power thresholds up to 1.09 kW and 3.59 kW at 600 mbar for the non- and full-optimized GGW BPFs, respectively, thereby demonstrating a PPHC enhancement up to 5.16 dB in the high-pressure range when both strategies, proposed in this work, are used.