wireless interface going up automatically

I have a laptop with Fedora Core 3 and two interfaces, one ethernet,
and a wireless interface, ath0, using madwifi drivers and a DLink
DWL-G650.

Because sometimes I want to access via ethernet or via wlan I don't
start any interface when the system boots, I start the interface I
want in each moment using ifup eth0 or ifup ath0. I don't know why but
sometimes when I am accessing through ethernet, the ath0 interface is
disabled (doesn't appear when I do ifconfig) but the wlan is working
(the AP), the wireless interface goes up automatically, without doing
ifup ath0. Why is this happening ?

I want to disable this feature, any way to do it ?


Thanks