RF Pulse Formation in Nonlinear Transmission Lines

Key issues in design of NLTLs

“…Using ceramic capacitors as nonlinear medium in NLTLs according to [1], these lines have provided a signal of 60 MW peak power in the 100-200 MHz frequency range. On the other hand, as reported in [2], using ferrite-based inductors as nonlinear medium in NLTLs 20 MW peak power was produced at a frequency of the order of 1.0 GHz. A NLTL (consisting of nonlinear capacitors and/or inductors in cascade) produces output oscillations as it follows.…”

“…, (2) where: -tri is the input rise time, -tro is the output rise time, -n is the number of sections of the line, -C0 is the unbiased capacitance, -C(Vmax) is the decreased capacitance at the maximum voltage applied, -∂2 and ∂1 are respectively the propagation delay times of the peak and lower amplitude portion of the input pulse, where ∂1 > ∂2.…”

Characterization of dielectric properties of commercial ceramic capacitors for pulsed power applications

“…If a load such as an antenna is placed at the line output RF extraction and irradiation is possible. This new application has been recently the focus of intense research as described in [11] and is aimed for use in very compact RF pulse generation for space vehicles and defense mobile platforms as conventional RF tubes are of bigger size and require filament heating power. At present, with the use of this technique they [11] demonstrate the feasibility of generating 20 MW of RF power peak at 1 GHz with pulse repetition rate of about 1 kHz.…”

Simulation Studies of Distributed Nonlinear Gyromagnetic Lines Based on <italic>LC</italic> Lumped Model

“…Gyromagnetic nonlinear transmission lines can produce a very broad frequency spectrum, starting from 600 MHz with an RF conversion efficiency of about 10% and at present exceeding frequencies of 3.0 GHz [3]- [7] for potential applications in satellite communications, which require operating frequencies at least in the S-band range. On the other hand, nonlinear LC lines operate at lower frequencies of around 1.0 GHz [8] in the case of inductive lines with saturated inductors, being even worse in the case of capacitive lines because of the losses in the ceramic dielectric, which limit their application in frequencies up to 250-300 MHz. Although Seddon et al [8] have achieved an efficiency of the order of 20% with LC inductive lines at 1.0 GHz, surely the efficiency of capacitive LC lines is far less than 10% because of dielectric losses.…”

“…On the other hand, nonlinear LC lines operate at lower frequencies of around 1.0 GHz [8] in the case of inductive lines with saturated inductors, being even worse in the case of capacitive lines because of the losses in the ceramic dielectric, which limit their application in frequencies up to 250-300 MHz. Although Seddon et al [8] have achieved an efficiency of the order of 20% with LC inductive lines at 1.0 GHz, surely the efficiency of capacitive LC lines is far less than 10% because of dielectric losses. The focus of this paper is on gyromagnetic lines since these lines are capable of generating stronger pulse oscillations at higher frequencies than the first configuration, and have higher RF conversion efficiency.…”