HIGH POWER SOLITON GENERATION USING HYBRID NONLINEAR TRANSMISSION LINES

Nonlinear Transmission lines (NLTLs) have been studied for high power RF generation with good prospects of applications in telecommand systems of small satellites (Cubesats), pulse radars for remote sensing (SARs) and disruption of communications in battlefield, [1], [2] for instance. Usually NLTLs employ barium titanate (BT) ceramic-based capacitors or ferrite bead inductor as nonlinear elements, denominated as capacitive or inductive lines, respectively. On the other hand, a configuration that employs both nonlinear elements (LC), known as hybrid line, is an efficient approach for exciting soliton oscillations more easily than inductive or capacitive lines. Other interesting aspect is that numerous publications on NLTL with only one linear component are easily found in the literature whereas just a few on hybrid lines and only one considering line experimental tests. In view of that, in this work a 30section hybrid NLTL built using inductors and capacitors of strong nonlinearity (2.2 nF BT ceramic capacitors and 10 mu H ferrite bead inductors) will be described. For the test, the line is fed by a negative input pump pulse generated by a 1 kV discharge of a 0.75 mu F storage capacitor via a fast 50 ns switching system composed by an IGBT switch and its gate circuit driver. In the hybrid line tests, the soliton generation packet obtained on the middle section had a frequency of the order 33.0 MHz, peak power of 13.0 kW and voltage modulation depth (VMD) of around 700 V. For each single shot, approximately 10 RF cycles with small damping were noted. The main conclusion from this experiment is that with an improved proper design hybrid lumped NLTLs may be used to achieve RF in the range of 100-200 MHz.