Design and simulation of miniature ribbon microphones

Traditional ribbon microphones cannot be miniaturized owing to the sensitivity of the microphone in proportion to its ribbon length. A novel symmetrical voice coil instead of the traditional ribbon is proposed, designed, and optimized. The new structure of ribbon microphones was fabricated by microelectromechanical systems (MEMS) technology, which allows increasing the effective coil length while reducing the diaphragm dimension. The obtained results present a voice coil length of 77.5 mm under a limited ribbon length of 17 mm. Compared with the conventional ribbon microphones (with ribbon length 50 mm and voice coil length 50 mm), the diaphragm dimension was reduced but its effective length was increased by about 55%, from 50 mm to 77.5 mm. Moreover, the magnetic flux density in the air gap of the magnetic circuit by simulations and experiments is measured to be at 5.1 and 5 kG, respectively.