Design Procedure for a Novel LMDS Base Station Reflectarray Antenna

A reflectarray antenna is demonstrated which can operate at X-band as a Local Multipoint Distribution Service (LMDS) base station antenna. The configuration consists of a center-fed single layer reflectarray consisting of ۲۳×۲۷ elements. The unit cell of the reflectarray has linear polarization with morethan ۴۰۰° linear phase shift. The geometrical parameters of the unit cell have been optimized to increase the bandwidth and achieve lower cross polarization (XP) level for the reflectarray. A design procedure, valid for obtaining any arbitrary pattern, has been implemented. In this procedure, to achieve a specifiedradiation pattern over a desired frequency range, a phase-related synthesis method is applied to obtain required phase shift on thereflectarray surface. The method has been successfully applied to a LMDS base station antenna, characterized by a sectorial cosecant squared beam in the frequency range of ۹.۴ GHz - ۱۱.۵ GHz. The simulation results are in a good agreement with the design requirements. The antenna has cosecant squared pattern over the bandwidth of ۲۱%, XP level better than -۳۰ dB, and SLL less than -۲۰ dB in both elevation and azimuth planes. Also, the۲۳×۲۷-element array size is ۲۴۶×۲۸۹ mm۲ which its ۱dB gain bandwidth is higher than ۱۹%.

کلیدواژه ها:

Beam shaping reflectarray ، Microstrip patch ، LMDS base station Antenna ، Cosecant squared pattern