Near Field Focusing of Rectangular Microstrip Patch Antenna Array

Near Field focusing is one of the most demanded current day research study. Microstrip patch antenna arrays are widely used for the purpose of focusing the radiation from an antenna in the near field (Fresnel) region. Several researchers are working to reduce the focused spot size and improve the power density within the focused region. A 44 microstrip patch antenna array has been proposed here to be used as a near field focused array at a distance of 800mm in the space with respect to the reference origin at frequency 2.4GHz . A 36mm28mm inset fed microstrip patch antenna has been used, with dielectric substrate FR4 . The thickness of the substrate is 1.6mm. Radiation from the antenna is focused at the focal point by providing each element with a different phase shift with respect to the reference point. The designed structure is a focused MPA array, having maximum radiation at 350mm away from the aperture. The sport size at the point of maximum radiation is 2 80120mm , while at the focal point the size of spot is 2 260260mm . The structure is furthermore modified, in order to move the main beam of the focused field with variation in the frequency. The movement of the main beam is achieved by introducing extra lengths of microstrip lines which are multiples of wavelengths. The proposed structure is able to vary the position of main beam with variation in frequency. Keywords: Microstrip patch antenna, near field, NFF antennas, phase distribution, return loss, E-Field radiation.