An existing WRT45G box is working fine for signals within a building, but now needs to stretch to a new reception point across a busy road and unfortunately the wrong side of a steel shutter! The idea is to add an external weatherproof antenna, bypassing the shielding effect of the shutter but I'm confused by the functionality of the standard dual antennae. Are the transmit and receive signals combined to both antenna or split? How to configure for both external signals to feed to the "wrong" side of the shielding and maintain the existing distribution inside the building? Possible?