Synthesis of dielectric helix supports for wideband traveling‐wave tubes

Abstract

An n-dielectric tube prototype structure consisting of a helix surrounded by adjoining dielectric tubes in an o¨erall en¨elope was studied by HFSS for flat-to-negati¨e dispersion characteristics needed for wideband tra¨eling-wa¨e tubes. The prototype structure obtained was then '' synthesized'' to obtain a wedge-shaped n-step staircase dielectric support structure for a helix.ABSTRACT: Using L-probe patch antennas as elements, a dual-polarized antenna array is designed and tested. The antenna is designed for operation at 900 MHz, and is built as a two-element linear array with a coaxial feed. The feeding network is an air transmission line which is ( ) made of aluminum. An impedance bandwidth of 24% SWR F 2 is obtained. The isolation is less than 25 dB across the passband, and an a¨erage gain of 10 dBi is achie¨ed. ᮊ