Cardioid

A cardioid (from the Greek καρδία "heart") is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It is therefore a type of limaçon and can also be defined as an epicycloid having a single cusp. It is also a type of sinusoidal spiral, and an inverse curve of the parabola with the focus as the center of inversion.

The name was coined by de Castillon in 1741 but had been the subject of study decades beforehand. Named for its heart-like form, it is shaped more like the outline of the cross section of a round apple without the stalk.

A cardioid microphone exhibits an acoustic pickup pattern that, when graphed in two dimensions, resembles a cardioid, (any 2d plane containing the 3d straight line of the microphone body.) In three dimensions, the cardioid is shaped like an apple centred around the microphone which is the "stalk" of the apple.

Read more about Cardioid:  Equations, Metrical Properties, Inverse Curve, Cardioids in Complex Analysis, Caustics

Other articles related to "cardioid, cardioids":

Unusual Sundials - Analog Calculating Sundial
... A horizontal sundial with a face cut on a cardioid keeps clock time, while still resembling a conventional garden sundial ... The cardioid shape connects the intersections between the solar-time marks of a conventional sundial, and the equal-angles of a true clock-time face ... The place where The shadow crosses the cardioid's edge, and the clock time can be read from the underlying clock-time dial ...
Georg Neumann - History - The Eighties and Beyond
... capsules" for various directional patterns), the cardioid TLM 193 (using the capsule of the U 89 and TLM 170), the small-diaphragm KM 180 series, the large-diaphragm cardioid TLM 103, the variable-pattern TLM 127 ... with transformerless output circuitry the multi-pattern M 149 Tube, the cardioid M 147 Tube, and the omnidirectional M 150 Tube (based on the classic M 50 design, with the ...
Centered Trochoid - Examples - Cardioid
... The cardioid is parameterized by ... Take to get ...
Cardioid - Caustics
... Certain caustics can take the shape of cardioids ... circle with respect to a point on the circumference is a cardioid ... line is a surface whose cross section is a cardioid ...
Georg Neumann - History - The Sixties
... In 1964 Neumann developed a small cardioid capsule with considerably improved off-axis linearity it was used in the KM 64 and U 64 microphones ... The first model was the KTM small cardioid, later followed by the "fet 70" series—transistorized versions of small omnidirectional, cardioid and speech cardioid microphones ... series were the KM 84 small diaphragm cardioid and the U 87 three-pattern, large diaphragm successor to the U 67 ...