[Moved]: Pattern and Frequency Reconfigurable Annular Slot Antenna Using PIN diode

Hi normally we use PIN diodes for pattern reconfigurable antenna. My question is that as the current in antenna is ac how does the PIN diode works. Because diodes only let current flow only in one direction? When a pin diode is forward biased does it allow the ac current to flow in both direction?

When a PIN diode is forward biased it behaves, in AC, like a variable resistor. The value of its resistance depends from the DC current flowing into the diode.