Study of Beamwidth Variation of Dipole Array Antenna for Microwave Scanning of Biological Target

Abstract

A broadside quarter wave dipole array antenna has been proposed for microwave scanning of biological body with high contrast in complex permittivity in the near field region. The dimension of inhomogeneities in complex permittivity in different cells of biological target is of the order of millimeter, so the spatial resolution required for medical imaging will be at the same millimeter range. Hence to increase the resolution of the microwave imaging system the beamwidth of the interrogating wave should be minimized. Two different approaches have been studied here for the reduction of beamwidth of near field pattern of dipole array antenna. In the first case the operating frequency is kept constant at 2.4 GHz and the variation of beamwidth has been observed for five different sets of dipole array elements. Beamwidth decreases with the increase of number of array elements. In the second approach the variation of beamwidth of antenna field pattern has been studied with different values of operating frequencies from 2 GHz to 5 GHz while number of dipole elements in the array remains fixed. The beamwidth decreases with the increase of operating frequency.