I need to extend the aerial cable to the Xbee PRO 900HP 200K Radio Module about a meter or so.
Are there extension cables available? if not how do I go about having it extended and will it effect the performance of the module?
If your radio is either the U.FL or RPSMA versions, then yes you can use an LMR 300 or better cable to remote mount the antenna. Just understand that by doing so, you will introduce cable loss which will affect the range. In addition, RF cable generally is considerably more expensive then data cable. If at all possible, it would be far better to extend your serial cable the required distance or the max distance you can take it and have a shorted antenna cable.