Electronically Controlled Frequency Agile Beam Scanning Reflectarray Antenna with Integrated Control Unit

Abstract

This paper reports the design, development, fabrication, and testing of a 225-element reconfigurable reflectarray (RRA) antenna with frequency agility and beam steering capabilities. The 15 15 (18.75 cm) RRA operating in the Ku band downlink frequency range (11.8 -12.2 GHz) of fixed satellite services (FSS) produces dual resonances switched between uplink frequency range (15-18 GHz) of FSS and earth exploration satellite range of 9.5-9.8 GHz (X Band). To attain reconfigurable multiple resonances, the unit cell is designed with a Malta cross of varying slot lengths interconnected to a square ring via a PIN diode. In the OFF state of the PIN diode connected between the concentric elements, a phase variation of 360° is obtained at 12 GHz and 9.5 GHz by varying the size of the Malta cross. By increasing the width of the outer ring in the ON state of the PIN diode, a dual resonance is obtained at 12 GHz and 17 GHz with 360° phase agility. The beam scanning is attempted at X band frequency by controlling the capacitance offered by the varactor diode connected between an inductive element and Malta cross. The proposed RRA offers 22.16 dBi, 24.5 dBi and 18.43 dBi simulated gain at 17 GHz, 12 GHz, and 9.5 GHz respectively. The simulated sidelobe levels (SLLs) and cross-polarization levels are -14.7 dB and less than -32 dB respectively. The proposed compound reconfigurable reflectarray befits fixed and mobile satellites, earth exploration satellites, radiolocation, aeronautical radio navigation, and deep space research.