The wi-fi antenna is located in the top of the LCD display housing. It consists of two elements, fed by two cables, a white main designated on the Wi-Fi card by a white triangle, and a black auxillary designated on the Wi-Fi card by a black triangle. Note that the white and black connection locations are reversed for an ATI Mobility Radeon card and a Mobile Intel GMA card. These cables are routed from the bottom of the system up and into the display housing at the hinge points and up along each side of the display housing to the elements along the top of the housing. See this explanation in the Inspiron 1545 Service Manual:
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Hope this information helps.