چكيده به لاتين
Abstract:
In recent years, by emerging microstrip lens as Beam forming network (BFN), a compact, lightweight, wideband, wide angle beam former with suitable performance has been built. These lenses can be used in many applications such as automobile collision-avoidance, remotely piloted radars, and remote satellite sensor. microstrip lens has created with some beam ports and receiver ports such that by excitation of any beam ports, the power with specified amplitude and phase couple to receiver ports. The receiver ports have been connected to linear array elements with transmission lines.so beam can be created in specific direction proportional to the excited beam port.
For applications that needs 360 scanning of beam and are faced with limitation of size, weight and cost and… these lenses are appropriated alternative. Therefor for 360 scanning can use multiple lenses or rotate one lens mechanically.
Phase error is one of the most important issues in lens designing. After designing rotman lens with three focal ports, 4 focal lenses and none focal lens were designed. In designing of none focal lens, by using the optimization algorithms such as genetic and considering positions of beam ports, transmission line lengths and … as optimization parameters, the average phase error is tried to decrease.
In this dissertation, for scanning 360 degree of beam, a new method is presented. In this method instead of using multiple lenses, one symmetrical, flexible, compact lens is used. Since the lens contour in this method must be symmetric, the 3 focal and 4 focal lens cannot be used. So none focal method is the best solution for achieving low phase error. The average phase error yet obtained for 360 degree scanning none focal lens with circular contour is 3.3 degree. In this dissertation, with none focal lens design method and considering the lens ‘contour as new parameter of optimization, the average phase error reduced. The obtained phase error is 2 degree that 40% is better than lens with circular contour.
Key Words: Microstrip Lens, Beam forming network, 360 degree scanning, optimization, lens contour, phase error
