Numerical Modeling of Antenna Arrays for Rapidly Deployable Radio Networks (RDRN). Part 1: Far-Field Patterns of a Cylindrical Conformal Array of Axial Electric Dipoles.

Abstract : Futuristic wireless communication systems must perform in environments that generate scattering from various obstacles which in turn cause multipath effects to be dominant. This results in degradation in the overall performance that can be avoided if the antennas have narrow beamwidths and low sidelobes. Advanced designs for Rapidly Deployable Radio Network (RDRN) systems are required to consider transmission at single frequency to several mobile users in a single frequency cell. This in turn requires narrow beam, low-sidelobe antenna patterns in order to obtain diversity between closely located users in a single cell. In this report analysis of an array of lambda/2, axial, electric dipoles radiating in presence of a conducting cylinder is presented. The amplitude excitations are determined by Hamming and Taylor distributions while the phase excitations are determined by using an even symmetric quadratic phase taper. Once the complex excitations were found the far-field patterns were computed via the Numerical Electromagnetics Code - Basic Scattering Code (NEC-BSC). The mutual coupling has not been considered in this report. The results show that an interelement spacing between 0.4 lambda and 0.6 lambda may be chosen in order to avoid appearence of higher peaks close to the boresight mainbeam. This criterion has also been used to propose an algorithm to design the array geometry and the complex excitations. It was found that even symmetric phase taper provided superior pattern topography in addition to the amplitude taper. Indepenent control of the amplitude and phase excitations indicate that the Digital BeamForming (DBF) technique can be used to design high-performance cylindrical arrays.