A NOVEL BANDWIDTH ENHANCEMENT TECHNIQUE FOR X-BAND RF MEMS ACTUATED RECONFIGURABLE REFLECTARRAY

In this paper, a wideband microstrip antenna for X-band (8.2 GHz 12.4 GHz) applications is introduced. First, simple patch antennas are studied, and a narrowband reflectarray antenna is designed. The resultant design demonstrates better performance than the previously published narrowband microstrip reflectarray antennas. The important features of the employed elements are simple structure, linear operation, and use of Radio Frequency Micro Electro Mechanical Systems (RF MEMS) switches for programmable pattern control. Next, employing our novel method, the designed narrowband structure is converted to broadband reflectarray antenna that can cover the whole X band. This novel idea is based on introducing several ground plane slots and controlling their electrical lengths by RF MEMS switches. By means of this method, 952 and 587 degree phase swing are achieved for continuous and discrete slot length variations, respectively. Application of this method along with smaller switches results in phase swing improvement of up to 1616 degree. In all structures a RT duroid (5880) substrate is selected to lower the back radiation. The achieved return loss in all cases is less than 0.32 dB. In comparison with the previous publications, our novel bandwidth enhancement technique has more generalization capability and results in single layered broadband reconfigurable microstrip reectarray antennas with linear phase swing, lower cost, and ease of RF MEMS implementation.