Research of SRFT improving and antenna broadband matching based on the IWO–LM algorithm

Abstract

This study proposes two modifications to the classical simplified real frequency technique (SRFT). A hybrid algorithm called invasive weed optimisation Levenberg-Marquardt (IWO-LM) algorithm, which combines the IWO and the LM algorithm, is used to optimise the transducer power gain. So the stochasticity of the IWO is introduced to the classical SRFT, the matching result will not be limited by the initial values. Moreover, an additional programme is added to the classical SRFT, which can transform the lumped matching network to the corresponding microstrip circuit. This improved SRFT is used to design a broadband matching network for a printed dipole base station antenna and compared with the classical SRFT, and the corresponding results show that the improved SRFT is less affected by initial values under the similar matching effect. The microstrip matching network and the antenna are integrated together, and then they are fabricated depending on the simulation. The test result of a vector network analyser shows that the bandwidth after matching is 0.728-1.01 GHz and the relative bandwidth is 32.45%, which is improved by 69.98% compared with the unmatched one.