SUMMARYOne of the approaches to reducing the size of halfwavelength linear dipole antennas is the meander dipole antenna, where the elements form a meander line. This paper presents a formula for the relationship between the geometrical size and the resonant frequency of the meander line dipole antenna, and a calculation formula for the radiative efficiency is derived from the result. It is shown that the geometrical parameters of the meander line dipole antenna can be determined from the specified radiative efficiency.

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One of the approaches to reducing the size of half‐wavelength linear dipole antennas is the meander dipole antenna, where the elements form a meander line. This paper presents a formula for the relationship between the geometrical size and the resonant frequency of the meander line dipole antenna, and a calculation formula for the radiative efficiency is derived from the result. It is shown that the geometrical parameters of the meander line dipole antenna can be determined from the specified radiative efficiency. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 83(1): 52–58, 2000

SUMMARYDue to their great fabrication flexibility, multilayered conductive thin films are used as a shielding material by thin film metal plating on a dielectric body. In the simulation of the shielding effect of these multilayered thin conducting films by the FDTD method, it is necessary to use a cell size less than the conductor thickness in direct modeling. However, since the shield material generally is much thicker than the metal thin film, the number of cells needed in such modeling is prohibitive and calculation becomes difficult. In this paper, as a subcell method in the FDTD approach, an infinitesimally thin resistive film that has a transmission coefficient equivalent to the multilayered conducting thin film is introduced. By this technique, modeling becomes possible without increasing the number of cells unnecessarily.

In this paper, the diffraction by a half‐sheet parallel to a flat earth for H‐ and E‐polarized plane waves are discussed. The half‐sheet is assumed to be perfectly conducting, and the flat earth is an imperfectly conducting dielectric with the complex refractive index n. This problem is solved by using the angular spectrum proposed by Clemmow, which may be also solved by using the Wiener‐Hopf technique. When kd is large, the diffraction fields can be approximated by the geometrical rays even for small r except in the neighborhood of θ = π/2 and 3π/2. Here, r and θ are polar coordinates of the observation point, with the origin as the edge, and d is the distance between the half‐sheet and the flat earth. The far field can be approximated by the simple geometrical rays in all regions (0 < θ < π). The interaction between the edge and the flat earth can be evaluated even for small kd. Exact values by the numerical integration show that these approximate solutions can give very good accuracy even for small r except in the neighborhood of θ = π/2 and 3π/2. These results will give a fundamental concept to the understanding of the diffraction by a finite conducting plane over a flat earth.