Mode reconfigurable OAM helical array antenna for higher mode generation

In this paper, an orbital angular momentum (OAM) mode reconfigurable antenna based on a uniform circular array (UCA) is presented. The phase superposition method is presented to overcome the limitation of the number of array units on the mode order in the conventional four-element UCA antenna, which is limited to generating first-order OAM beams. The unit phase is introduced by a bifilar helical antenna in this method, and the unit phase is superimposed with the feed phase of the UCA to enable the generation of 3rd-order OAM beams from the four-element UCA. At the same time, the DC signal-controlled feed network assigns three distinct feed phases to the UCA, which realizes the reconfigurability of the three OAM beams. To achieve mode reconfigurability, 20 p-i-n diodes were integrated as switches in the feed network for controlling the ON/OFF status of p-i-n diodes in the feed network using DC signals. Finally, simulated and measured results show that three OAM beams (lz = -1, -2, and -3) have been generated in the frequency band from 10.6 to 11.8 GHz.