Wireless personal mobile, cellular and satellite communications have enjoyed the fastest growth rate in the telecommunication industry. By providing directional and steerable beams, smart antennas can deliver high gain and interference reduction in these applications. The conventional phased array system for beam steering requires many expensive phase shifters and beam forming networks. The system is very complicated and expensive. Consequently, the use of phased arrays is limited to a few sophisticated military and space systems. To overcome these problems, a simple, low cost approach for steering an antenna beam is proposed. The proposed approach uses an electronically perturbed/tuned transmission line. A dielectric waveguide or image line can be perturbed by the proximity of a movable metal plate. The patch antenna array is fed through apertures by the dielectric waveguide. A small movement of the metal plate can be accomplished electromechanically using a motor or piezoelectric material. A MEMS device can also be used to accomplish this small movement. Unlike the gimbal systems, the proposed approach uses compact, planar and stationary antennas. Compared with conventional phased arrays, the proposed method does not require solid-state or ferrite phase shifters and their associated beam forming circuits. The proposed technique is less complicated and expensive as compared to the traditional methods.
Although hybrid mode analysis has been used for the propagation constant calculation in our preliminary concept development, a three-dimensional full-wave analysis will be developed to analyze the aperture coupling and to design the whole array. Method of Moments, Finite Difference Time Domain Method and an in house developed wavelet analysis program are proposed to analyze the proposed configuration. The analysis will provide design information such as impedance matching, aperture sizes, coupling coefficients, antenna element mutual coupling, array radiation patterns, and scanning angles as a function of various parameters and dimensions. An eight-element linear array and a 4x4 two-dimensional array will be designed and demonstrated based on the 3D full-wave analysis. Active devices will be directly integrated with the image line to form an active antenna. The use of the piezoelectric material or MEMS device to accomplish the required small movement/perturbation will be investigated. The full-wave analysis will also be used to study the limitation and optimization of the array and steering angle. The proposed research will create a new class of compact and low cost beam steering antennas for wireless communications, radar and sensor applications. It should revolutionize the current phased array and beam steering technology. The results would have a far-reaching impact on future communication and radar systems. ***
