Bias-field controlled phasing and power combination of gyromagnetic nonlinear transmission lines

Abstract

Gyromagnetic Nonlinear Transmission Lines (NLTLs) generate microwaves through the damped gyromagnetic precession of the magnetic moments in ferrimagnetic material, and are thus utilized as compact, solid-state, frequency agile, high power microwave (HPM) sources. The output frequency of a NLTL can be adjusted by control of the externally applied bias field and incident voltage pulse without physical alteration to the structure of the device. This property provides a frequency tuning capability not seen in many conventional e-beam based HPM sources. The NLTLs developed and tested are mesoband sources capable of generating MW power levels in the L, S, and C bands of the microwave spectrum. For an individual NLTL the output power at a given frequency is determined by several factors including the intrinsic properties of the ferrimagnetic material and the transmission line structure. Hence, if higher power levels are to be achieved, it is necessary to combine the outputs of multiple NLTLs. This can be accomplished in free space using antennas or in a transmission line via a power combiner. Using a bias-field controlled delay, a transient, high voltage, coaxial, three port, power combiner was designed and tested. Experimental results are compared with the results of a transient COMSOL simulation to evaluate combiner performance.

A Review of Nonlinear Transmission Line System Design

“…The combiner joined two 50 Ω coaxial inputs to a single tapered transition with a final output impedance of 50 Ω. The NLTL output frequency was between 1.8 and 2.6 GHz [113]. Another study aligned a coaxial, four-element NLTL antenna array by placing adjustable, temporal ferrimagnetic delay lines serially in front of the main NiZn ferrite loaded gyromagnetic NLTL.…”

High power seven‐port microwave duplexer for monopulse radar tracking applications based on amplitude discriminator

“…In transient analysis, all four input ports are analysed together and the electromagnetic formulation of Kirchoff's current law at the junctions requires that the signal goes through the output. Thus, the structure exhibits no loss at the junctions and all of the power goes to the outputs [35][36][37] [S] = 1 2 0 0 − 1 2 1 2 1 1 1…”

Gyromagnetic nonlinear transmission line generator of high voltage pulses modulated at 4 GHz frequency with 1000 Hz pulse repetition rate

“…At this work, the two-section NLTLs were used [3,[5][6][7]9]. The input section operated as a pulse sharpening device and sharpened a front, sufficient for the second NLTL section operation in the oscillator's mode.…”

“…The external axial magnetic field biased (H z ) coaxial nonlinear transmission lines (NLTL) partially filled with ferrite rings were used as the sources of high-power microwave pulses [3][4][5][6][7][8][9][10]. The source rf modulation frequency was increased to 4 GHz, a fairly high output peak power of hundreds of megawatts, and operated at the maximum pulse repetition frequency (PRF) of 1000 Hz.…”