I recently purchased a 2" replacement antenna from a Mini vendor. It works fine for FM, but the AM reception is problematic, routinely experiencing interference. The performance is notably worse than the oem antenna. I can't say I know much about antennas (are they just metal), but would there be any performance difference b/w 2" versions? Would a 3.5-4" replacement antenna make any difference? Has anyone experimented between the major Mini alternatives (alta, cravenspeed, out motoring, etc)? Any comments or experiences with them would be appreciated.

 

I think the reason FM is unaffected is that the roof antenna is not used for FM, the window antenna is. The wavelength of an AM signal is way too long for a two inch antenna to work no matter what base loading trickery is used unless the signal is very strong.

 

Actually the MINI runs a Diversity Antenna System. This system uses the Roof antenna and Window antenna for FM and chooses which one has the better signal. The same is done for the AM but as ran-o-matic said the short antenna will not be long enough for the AM signal and thus only the window antenna is used and it is not designed for AM pickup. If you are trying to listen to a close AM station there may not be to much difference but on a station more than about 20 miles away there will be a big difference.

BTW the Roof Module that the Antenna goes on also has a Satellite Antenna built in.

 

Any thoughts if the slightly longer 3.5-4" models would make any difference? Is the oem the only alternative if you want good AM reception? Thanks again.

 

The length on the AM antenna is probably the best bet. Even a 4" antenna is not really long enough to do any good. A real good length for AM reception would be about 1000 ft in length as that is the midspan of the AM Radio band fro a full wave antenna. OF course that is not practical so they wind a coil around the antenna mast to make it appear longer to the radio wave but on to the visual.

BTW the AM reception on mine with an OEM antenna is still really not all that good in my area. I live about 50 miles from the closest AM radio station.

 

Do you have a stock antenna to try? If so, check the reception with that, or see if you can get someone to donate their old one to you for testing.

 

@schatzy62,

I thought that the diversity amplifier was just used to combine the signals for the antennas rather than to provide spatial diversity for the same band. Thanks for the clarification.

 

They do the spatial diversity because in cities like Boston, NY, Chicago, LA (where there are tall buildings) the spatial diversity works so much better with the reflections of signals off of buildings.

 

Thanks again for the assistance.