Accession Number : AD0646592

Title :   A TECHNIQUE OF FABRICATING INHOMOGENEOUS MEDIA AND THE BEHAVIOR OF A DIPOLE IN SUCH A MEDIUM.

Descriptive Note : Interim technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Iizuka,Keigo

Report Date : DEC 1966

Pagination or Media Count : 41

Abstract : 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 380 Gallon 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 epsilon sub r = 78, tan delta = 0. 13 at 114 Mc/s and a conductivity of 0.8 millimhos /cm at 1000 c/s; the diffusion constant D of NaCl into 1.3% agar agar is 0.000008 to 0.00002 sq cm / sec at 25C. The range of change in the loss tangent is large; one profile varied from tan delta = 0.13 to tan delta = 3.3 which corresponds to a factor of twenty six in the distance of a wavelength. The periods of diffusion were one to three weeks. The properties of a dipole antenna measured in an inhomogeneous conducting medium are compared with those in a homogeneous conducting medium. (Author)

Descriptors :   (*DIPOLE ANTENNAS, RADIO TRANSMISSION), (*TEST FACILITIES, ANTENNAS), GELS, ELECTRICAL CONDUCTIVITY, PROPAGATION, ENVIRONMENTAL TESTS, ELECTRICAL PROPERTIES

Subject Categories : Electrical and Electronic Equipment
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE