Macbook pro wireless connection problems

Hello, have a Macbook pro core duo 2.16, 2 gb ram, model number A1150 running Snow Leopard 10.6.8. Recently the wireless connection has become very weak. I have replaced the Airport card twice (just in case the first one was bad) with no change in performance. The transmit rate varies between 1 and 36 and will not connect with a router unless I am within a few feet and generally have a line of sight connection.
At this point I am suspecting the antenna wires may be defective however this seem like a major repair to replace the antenna.

Any advice on what else I should check before replacing the antenna?

Thanks in advance.

Do other devices suffer the same drop offs from the router?

I should have mentioned it does this regardless brand or type of router.