Beam- reconfigurable of a planar parasitic pixel antenna for X-band radar application

The research work in this thesis focuses on the reconfigurable beam-steering antenna for the X-Band radar application. This concept gives more flexibility due to their ability to modify the radiation properties and providing multiple functionalities. The research involve the pixel array antenna, where a particular types of reconfigurable antenna with the grid of metallic patches that are interconnected by a RF- switch. The activation and deactivation of these switches can dynamically reshape the antenna properties. This capability provides pixel antennas with an extreme level of reconfigurability, much higher than in other architectures. However, pixel antenna implementation is still very limited due to the large number of required switches. Even the loss of the switches can easily effect the antenna efficiency due to the complex biasing networks. Therefore, this research focuses on reduction of switches in pixel antenna in order to improve the antenna efficiency, cost and reconfiguration speed. First, the concept of driven parasitic is addressed. A circular patch has been selected as driven antenna because of its low profile characteristics, unidirectional radiation pattern and widespread use. The parasitic layer is located on the right and left of the driven antenna in single layer. The mutual coupling between the driven and parasitic is able to steer beam to three different angles of -40º, 0º and +40º in single layer. This driven parasitic patch antenna based on Yagi Uda principle. Secondly, this work continues on designing driven pixel antenna. The pixel layer is located on top of the driven layer with the air gap of 7mm. The strong coupling between the driven antenna and the pixel surface induces significant currents over the pixel layer, therefore affecting the antenna radiation pattern. The beam steering have been achieved by selecting the properly switch configuration. Finally, the combination of driven parasitic antenna with pixel layer has been introduced. The advantages of this approach, where the driven parasitic and combination of the pixel layer can steer the pattern individually. The HPND-4005 PIN diode has used as interconnecting between the pixels in the simulation process and copper switch for measurement process. The diodes have been modelled into two conditions as ON state and OFF state in simulation. The performance of reconfigurable antenna is analyzed in simulated and measured results. The proposed antennas can steer up to -40º, 0º and 40º with approximate gain of 7 to 10 dBi at all desired directions.