The ADFADF —Automatic Direction Finder has a cardioid polar diagram, which is made by combining the polar diagrams from the loop aerial (a figure 8) and sense aerial (omnidirectional). This has to be the case so it can determine the direction of the incoming NDBNDB —Non-Directional Beacon waves. Do not get this answer confused with the NDBNDB —Non-Directional Beacon (which is omnidirectional) or the VORVOR —VHF Omnidirectional Range (which is a limacon).