Capacitive Loading Effect of Dual Element Reconfigurable Reflectarray Unit Cell

This paper presents an analysis of simple dual elements reconfigurable reflectarray unit cell with varying width of 2.0, 2.5 and 3.0 mm of its square ring against capacitive loading effect of a varactor diode from 0.4 pF to 1.3 pF. The operating frequencies intended is in the range of 8.0 to 8.4 GHz for remote sensing satellite data receiving antenna. Analysis is done by using Floquet mode approach in CST commercial software. The objective is to compare and determine an optimum performance of unit cell's reflection coefficient magnitude and phase range. It is demonstrated that at the operating frequencies of 8.0 GHz and 8.2 GHz, unit cell's phase range significantly improved from 107° and 191° to 305° and 294° respectively with width enlargement from 2.0 mm to 3.0 mm. At 8.4 GHz, it fluctuates at around 240° up to 280° concurrent with width enlargement. The reflection coefficient showed a minimum of -3.95 dB and maximum of -8.34 dB at center frequency in a tradeoff of improved phase range of the unit cell.