Many types and manufactures have been used over the years.
The most critical factor is the length of the antenna as it has to 'tune' to the transmitters frequency, thus enabling maximum power transfer into the air without damaing any of the transmitters output components. A correct match will produce a low SWR or Standing Wave Ratio.
In general, the longer the antenna, the lower operating frequency. It's easy to start getting techincal about antennas. Many articles and books have been written on the subject, but for our purposes the following should suffice.