DIPOLE ANTENNAS WITH A SECTOR-SHAPED RADIATION PATTERN

Abstract

Subject and Purpose. The directivity characteristics of a dipole antenna when it is placed above and parallel to a perfectly conducting screen of rectangular shape are considered, aiming to theoretically study dipole antennas with sector-shaped radiation patterns (RP) formed by choosing the optimal electrical dimensions of the screen and the distance between the dipole and the screen. Methods and Methodology. The problem of the dipole radiation field diffraction by the edges of a rectangular screen is solved by the method of the uniform geometric theory of diffraction. The diffracted fields developed at the screen edges are calculated using the uniform asymptotics obtained from the rigorous solution of the model problem of the dipole field diffraction by the edge of a perfectly conducting half-plane. Results. The algorithms and calculation programs developed allow studying the electrodynamic characteristics of the antenna over a wide range of screen electrical dimensions and distances between the dipole and the screen. Radiation patterns, directivity in a path normal to the screen and in directions of maximum radiation, radiation resistance, and protective ratio have been calculated across a broad range of screen dimensions and distances between the dipole and the screen. It has been observed that the antenna of the kind forms sector-shaped radiation patterns when the distance between the dipole and the screen is 0.30 to 0.45 of the resonant wavelength of the dipole. The obtained results have been confirmed by the calculations using the FEKO program. Conclusions. It has been shown that the considered dipole antenna forms sector-shaped radiation patterns when the distance between the dipole and the screen is 0.30 to 0.45 of the dipole resonant wavelength depending on the screen dimensions. The obtained calculation results for the maximum achievable electrodynamic characteristics allow us to find optimal geometric parameters of the antenna with a sector-shaped pattern for a particular application.

Keywords

• uniform geometric theory of diffraction
• dipole
• rectangular screen
• diffracted field
• sector-shaped radiation pattern
• directivity
• radiation resistance