A mast can be a busy place, especially if the ship is equipped with complex IFF, ECM, navigation, communications, surface radar, and air-search radar antennas.
Many ships carry back-ups or duplicate systems in case their primary system fails.
Below are most of the antennas found on Destroyer escorts during WW II and into the early 1960s. The collection includes antenna systems for all versions and conversions of the Destroyer Escorts, to include the picket ship conversions. In addition, the USS Francis M. Robinson was used as an experimental platform for a variety of systems. When photographs or information was available, I included those systems as well. Notice the single vertical element and four horizontal elements.