Optimization of a broadband VHF lumped-element ferrite circulator

A multistage optimization procedure is provided to maximize the operating bandwidth of a very high frequency circulator. We show through hardware validation that bandwidths on the order of 52.3–80.9 MHz are achievable using a 15 dB isolation specification. Simulation studies indicate that bandwidths on the order of 100% are possible, but such wideband performance has not been achieved in hardware to date. The optimization procedure uses both genetic algorithms and orthogonal sweep methods to find the best crossover geometry and ferrite properties, but the outcome of both methods is roughly the same. Matching networks are used to tune the response and to widen the operating frequency band. These networks are optimized using Pareto tradeoff charts in the context of power metrics like return loss, isolation, and insertion loss. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1476–1481, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27654