A reconfigurable decoupling and matching network for a frequency agile compact array

A novel frequency reconfigurable compact array incorporating a reconfigurable decoupling and matching network (DMN) is proposed. The array radiating part consists of two printed monopole antennas. An inductive biasing line is devised to control the PIN diode states so that the array operating frequency is switchable between 2.5 and 3.5 GHz bands. The element spacing is chosen to be as small as 0.05 λ₀ at 2.5 GHz, which leads to a strong mutual coupling between antenna ports. A reconfigurable DMN is proposed to mitigate the mutual coupling effect for both 2.5 and 3.5 GHz bands. Simulation results show that the use of the DMN realizes a well matched (S₁₁ <;= -10 dB) and decoupled (S₂₁ <;= -20 dB) bandwidth of 70 MHz and 120 MHz in the lower and higher bands, respectively. The antenna total efficiency can be substantially affected by the internal resistor when the PIN diodes are in the `ON´ state. The compact size and frequency reconfigurability feature greatly save the antenna real estate. The decoupled array can be useful for a multi-input multi-output (MIMO) diversity system.