Sorry J, I still don't understand. An ILS localiser is designed to send out a narrow beam in one direction. The reason that the antenna array is so wide is to focus the signal in the desired direction - because of the way that antennas work there is a 'mirror' signal in the opposite direction, the back-beam. In the UK the back-beam is supressed to minimise the signal strength.
Have you got an example of something different to show what you mean?