Study of HV Dielectrics for High Frequency Operation in Linear and Nonlinear Transmission Lines and Simulation and Development of Hybrid Nonlinear Lines for RF Generation
Abstract
Nonlinear transmission lines (NLTL) provide an ingenuous way of generating RF withoutusing vacuum electron tubes. For high peak power (MW) and frequency up to 300 MHz, dielectricor ferrite-segmented lines (aka synchronous wave NLTLs) have been used. Other configuration implemented with higher efficiency (20-40%) and frequency from 400 MHz to 2 GHz, S-band) is a continuous ferrite-loaded coaxial line with an external magnetic bias, a configuration known as gyromagnetic NLTL. In this project, in the past with the support of USAF, we investigated the use of HV new dielectrics such as PZT and conventional BT-based commercial capacitors for use in lumped NLTLs. The best result obtained was with the employment of commercial capacitors for RF generation packets up to tens of MHz. The use of PZT dielectric was discarded because of their weak nonlinearity as well as segmented lines due to the difficulty of finding thicker BT tiles with great nonlinearity in the market, although they have achieved the best performance in terms of frequency (300 MHz) among the dielectric lumped lines built so far. However, to overpass the 300 MHz limit obtained with segmented lines, a good approach for our project seems to be the employment of SiC Schottky or PIN diodes in the lumped line by keeping a minimum inductance on each line section to avoid that RF oscillations die away because of the parasitic inductance. Moreover, the use of an extra nonlinear element such as a ferrite bead inductor (called hybrid line in this case) looks very promising to increase the frequency further. On other hand, with gyromagnetic lines their great prospect for RF generation in the L and S bands has envisaged the use of SPICE simulations based on distributed LC models for the design of such lines. This can represent a great scientific advance since the use of SPICE eases the task of running simulations compared to the numerical methods because of the complexity and the high quantity of code required.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501810111
Entities
People
- J.O. Rossi
Organizations
- Air Force Office of Scientific Research
- United States Air Force