Polar Charts are intended for using in cases when you need to show something on the polar coordinate system. They are best for displaying mathematical functions, imitating radars or showing anything else that should use this kind of coordinate system.
This Chart shows how different types of microphone directionality look like. Directionality is a microphone sensitivity to sound relative to the direction or angle from where the sound comes. There are three most common directionality types, which are often plotted in polar charts: unidirectional, bidirectional and omnidirectional.
Here you can find three line series, each for a directionality type, all have different stroke settings. Use legend to manage the series (click the legend items to switch series off and on, hover them to highlight the series). The series with two dashes and a dot stands for unidirectional type, which diagram looks like a cardioid – these microphones are most receptive to sound that comes from front and less sensitive in other directions (the angle when the voice would be heard the best is 0 degrees). The series with simple solid series represents bidirectional type. Microphones of this type are very sensitive to the sound that comes from two opposite sides. These microphones can be used for making records from two sources placed opposite to each other. Omnidirectional microphones are those which can capture and record the sound from every direction. This type is represented by a circle-like series with dashed type of stroke.
X-axis is a kind of divided in two parts, both with positive values from 0 to 180 degree. It is done for emphasizing the fact that the sound source is placed in front of the microphone, which is intended to be in the 0 ° point. Note that this chart shows only typical cases, and real microphones might have variations of those diagrams.