High power microwave beam steering based on gyromagnetic nonlinear transmission lines

Abstract

We demonstrate electronically controlled beam steering by high power RF pulses produced by two gyromagnetic nonlinear transmission lines (NLTLs) connected to a one high voltage driver. Each NLTL is capable of producing several ns RF pulses with peak power from 50 to 700 MW (6% standard deviation) at frequencies from 0.5 to 1.7 GHz (1% standard deviation) with 100 Hz repetition rate. Using a helix antenna allows irradiating of RF pulses with almost circular polarization and 350 MW maximum peak power, which corresponds to 350 kV effective potential of radiation. At the installation of two identical channels, we demonstrate the possibility of beam steering within ±15° in the horizontal plane by coherent RF pulses with circular polarization at 1.0 GHz center frequency. Fourfold increase in the power flux density for in-phase irradiation of RF pulses is confirmed by comparison with one-channel operation.

Analysis of nonlinear gyromagnetic line operation using LLG equation

“…where Ht is the total effective magnetic field, =1.76×10 11 rad/s/T the electron gyromagnetic ratio, 0 = 4 ×10 -7 H/m the free space magnetic permeability, and Ms the medium saturated static magnetization (generally assumed 0.35 T for ferrites). However, as shown in [2][3][4] the NLTL performance does not confirm this result. As not expected, and different from/contrary to what the LLG equation predicts, the experimental trend observed indicates that the center frequency decreases with the static axial magnetic, but increases with the incident input pulse amplitude because of the azimuthal field.…”

“…Nowadays gyromagnetic nonlinear transmission lines (NLTL) have been studied with great interest [1] since they can generate RF up to frequencies of 1-3 GHz at high power (hundreds of MW) as demonstrated recently [2][3][4]. As they are all solid-sate they can be used as compact RF sources.…”

RF pulse formation dynamics in gyromagnetic nonlinear transmission lines

“…The shock wave velocity is changed with the bias magnetic field which is a basis for multichannel NLTL systems with a bias control of phase in each channel [7][8].…”

“…Optimal conditions are found for the generation of rf pulses with frequencies from 0.6 GHz [1] to 5 GHz [5], rf power from tens MW [4] to several hundred MW [2], pulse repetition rate from 800 Hz [6] to 65 MHz [7]. Based on these studies, multichannel rf sources with electronically controlled beam steering are designed and investigated [8][9]. In all experiments with gyromagnetic NLTLs, the traditional experimental method includes registration of the high voltage pulse incident on NLTL and the pulse coming out of the NLTL.…”

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.…”