Conventional waveguides are usually made of metallic materials,and they are effective pathways for the transmission of electromagnetic(EM)waves.A "softmaterial waveguide",by contrast,is supposed to be made of dielectric material and ionic fluids.In biosystem,softmaterial waveguide constructed with the lipid layer and bilateral fluids was suggested as the pathway for pulsed neural signals in a form similar to electromagnetic solitons.By performing experiments and computational simulations we have investigated the transmission efficiency of continuous and pulsed EM waves when they propagate through man-made softmaterial waveguide structures which has the configuration of ionic fluids filled in and out of a dielectric tube,and found three basic characteristics of softmaterial waveguides in EM transmission.(1)The results of both approaches were consistent with each other,showing that a dielectric tube with solutions filling both sides works well as an EM waveguide.The energy flux of an EM wave could be confined within the dielectric layer of such a sandwiched structure,resulting in a better transmission efficiency for the EM wave.That is to say,softmeterial waveguides indeed had the confinement effect on EM waves,supporting previous the description of "softmaterial waveguide" in electromagnetic soliton model for neural signal transmission.(2)The experimental phenomena that within certain limits,the transmission efficiency of signals in softmaterial waveguides were inversely proportional to the frequency of the EM waves,demonstrate that the softmaterial waveguides have the low-pass filter property.Coincidentally,scientists found that neurons can respond with low-frequency signals(<100 Hz),but neglect high-frequency signals(>1 k Hz).These facts might have profound interconnections.If the nature did developed a softmaterial waveguide system(e.g.,fluid-membrane-fluid in axons and normal cells)that are in favor of long-duration EM pulses,and transient currents did generate soliton-like EM pulses as previously proposed14-16,then the sensors or ion channels in the neurons and axons should also favor these long-duration,low-frequency EM pulses.(3)The phenomena that the transmission efficiency of EM waves increased with the thickness of the dielectric layer might explain the role of the myelin sheath in nerve signal transmission.The myelinated axons probably serve as a better softmaterial waveguide by adding the thickness of the dielectric layer,i.e.,the lipid layer.The previous calculation from Xu's team in 2012 also showed that the attenuation length L0 of EM waves was proportional to the diameter of the unmyelinated axons,as well as the number of lipid layers wrapped by the Schwann cells in myelinated axons.These three important properties for softmeterial waveguides found here positively support the electromagnetic soliton model,and might shed some light on understanding many electrical communication phenomena in live biosystems.