The guys over at MetaGeek have just released version 2.1 of their Chanalyzer software for use with the Wi-Spy USB Spectrum Analyser.
Version 2.1 adds support for the upcoming Wi-Spy 2.4x, which incorporates an RPSMA connector for external antennas. Wi-Spy 2.4x ships with a standard “rubber duck” omni-directional antenna.