I've upgraded my antenna for my Kansas City Center, STL Approach on line feed.
I was just using a scanner antenna in the attic with RG-58 cable and could barely hear the St. Charles MO, Kansas City Center feed and now am able to hear a lot more.
I upgraded to an all copper J-Pole and it works GREAT! http://kb9vbr.com/products.php
This guy makes them by hand and it's tuned to what band you want to listen too. After that, I simply bought some RG-8 cable and am in love… hehehe