The trouble with anorak broadcasting on Medium wave is pretty much everything is against you. As 'out of band' says above it's very hard to make a liable antenna for the band in your back garden. Just a horizontal long wire gives pretty poor results with most of the energy heading skywards. You need a good few feet of vertical to do much good. Some outdoor loop antenna designs are worth a try and can out perform basic wire antennas by a fair bit. Then, after all that it's pretty much impossible to get any listener interest in your station on the band these days apart from any other anoraks in your area. There are a number of low powered AM transmitters available to buy online but they are quite an expensive outlay. Home brew was always the favoured option back when Medium wave was king. As above, some sort of VHF is a much more viable option than MW really.