Technique of fabricating inhomogeneous mediums and the behaviour of a dipole in such a medium

It is shown that an inhomogeneous medium to be used for antenna experiments can be fabricated using the diffusion profile of NaCl into agar agar. Various problems relating to the construction of a 316gal agar agar tank are described. The production of a desired profile of the electrical properties of the medium is discussed, together with the experimentally determined driving-point admittance and current distribution of a dipole antenna when immersed in the inhomogeneous conducting medium. The measured electrical properties of the agar agar when dissolved in tap water are ¿r = 78 and tan ¿ = 0.13 at 114 Mc/s and a conductivity of 0.8 mmho/cm at 1000c/s; the diffusion constant D of NaCl into 1.3% agar agar is 0.8¿2.0 × 10¿5cm2/s at 25°C. The range of change in the loss tangent is large; one profile varied from tan ¿ = 0.13 to tan ¿ = 3.3, which corresponds to a factor of 25 in the distance of a wavelength. The periods of diffusion were 1¿3 weeks. The properties of a dipole antenna measured in an inhomogeneous conducting medium are compared with those in a homogeneous conducting medium.