The Neumann AK 20 microphone capsule is part of the KM 100 miniature series microphone systems. The AK 20 features a pressure gradient, single diaphragm transducer with a figure 8 polar pattern. The diaphragm diameter is just 16mm and all sound field components reach the diaphragm directly.
The end result is even frequency response and output levels from 0 to 180 degrees in proximity. The figure 8 polar pattern is effective in stereo MS recording (with an AK 40 or other cardioid mic), ambiance capturing or lectures and conferences with 2 speakers at either ends of the microphone.