Why reconfigurable antenna?

hello, i am designed dual band patch antenna for WLAN & WIMAX at 2.4-3.5ghz respectively, by slots on patch. I want to develop these antenna to reconfigurable antenna using switch (e.g PIN diode). But there are some questions to be answered...

1- why reconfigurable if the antenna worked at dual frequency at same time?
2- when using pin diode on slot to switch between two frequency, what type of signal sending to diode to forwarding ON/OFF status?

please help me..
Best Regard