A magnetically controlled reconfigurable antenna using a reed switch

A reconfigurable patch antenna using a reed switch to connect the patch with the ground plane is proposed. There are two coils wound together underneath the ground plane, and a permanent magnet is placed coaxially under the coils. Unlike other reconfigurable antennas where the DC bias control circuit usually has adverse effects on the radiation patterns, the coils and the magnet here have the ability to latch the reed switch on and off to change the resonant frequency of antenna without affecting the radiation pattern characteristics. Since the lead of the reed switch is sitting inside the coils where the magnetic field is the strongest in their center, only a low control current is used to latch the reed switch and the reed switch is less sensitive to the magnetic field produced by other coils. The antenna is fabricated, and measured results confirm the concept. The proposed concept is promising for applications in complicated multi-functional reconfigurable antennas and array structures where many switches are employed to connect the radiating structure with the ground plane.