I am reading this article: http://www.gnswireless.com/faq.htm
And for this question: What can I do if I am having wireless connection problems?
"Signal strength drop or fluctuation are common causes of RF interference. Change the channel on your access point or wireless router. Use only channels 1, 6 or 11 for non-overlapping channels. Change the location of your wireless products. Subtle changes (2-3 feet) can make a big difference. Do not put the access point or wireless router in a cabinet or enclosure. 2.4GHz phones, X-10, and Bluetooth devices will interfere with your wireless network. Change the location of the base for your phone, or downgrade to 900MHz phones, or upgrade to 5.8GHz phones. The wireless signal will degrade (or die completely) when going through brick (fireplace), metal (file cabinet), steel, lead, mirrors, water (fish tank), large appliances, glass, etc. If your wireless connection is only dropping during large file transfers or when a large number of wireless clients are connecting, change the preamble on all wireless devices to short."
But, what I really want to know is:
Why if I put wireless access point near water(fish tank) will degrade its signal?