by 1948, am transmitter powers in australia and new zealand had risen to a level where significant night-time skywave interference was being experienced. meetings were held between the respective administrations and plans were developed to minimise interference by a partial restack of services in both countries. this was achieved though use of some clear channels for high power services and appropriate operating powers for close-spaced co-channel services. the restack was promptly effected and achieved its limited objective. in subsequent decades, use of directional antennas by australia greatly minimised co-channel interference to new zealand services.