Unconnected pair of planar helices with straight-edge connections for application in TWTs

A planar slow-wave structure (SWS) for application in traveling-wave tubes (TWTs), unconnected pair of planar helices with straight edge connections (PH-SEC), is presented here. Two versions of the unconnected pair, co-wound and contra-wound, are analyzed and compared for the first time. Analysis for both versions is carried out as special cases of a generic structure consisting of 4 parallel unidirectionally conducting (UC) screens. Both versions show similar characteristics with respect to dispersion and coupling impedance and can provide a relatively large electron-beam tunnel. Both versions of the structure are amenable to fabrication using printed circuit or microfabrication techniques. The proposed planar slow-wave structure has a good potential for application in high frequency TWTs.