Cosecant squared radiation pattern is one of the specific radiation patterns which is used for search and surveillance radars . A feature that distinguishes this radiation pattern from others is that the received power from a target with a range-independent radar cross section flying at constant height , is range-independent . The important of using of this radiation pattern is in elevation that has wide beam and is suitable for search radar . Different ways to form cosecant squared radiation pattern are provided . The first method is to form the reflector surface . The second method is to use an array antenna in front of the parabolic reflector , so that the amplitude and phase of each array element is determined . The third method is the use of stacked beams and the parabolic reflector , so that each feed produce a specific beam and finally the beams in a microwave circuit with different weights are combined and cosecant squared pattern is resulted . In this thesis a reflectarray antenna with an open-ended waveguide feed in X-band to produce cosecant squared radiation pattern , is designed and simulated . The design is based on the distribution of non-linear phase of each reflectarray antenna element . Two reflectarrays with two different unit cells as single layer and two-layer , are designed and simulated , the results are satisfactory . Key Words : Cosecant squared Radiation Pattern , Reflectarray , Shaped Parabolic Reflector
