# orthogonal

Orthogonal means rectangular or right-angled. The word orthogonal is used in the context of IT knowledge in storage technology, antenna technology, radio technology and computer science.

- In storage technology, orthogonality is used when the magnetic particles of a hard disk are aligned perpendicular to the hard disk surface, as is the case withperpendicular recording to increase storage density.
- Antennas whose radiating elements are perpendicular to each other are called orthogonal. The polarization planes of orthogonal antennas are perpendicular to each other. Orthogonal antennas also include antennas with circular polarization: Right Hand Circular Polarization( RHCP) and Left Hand Circular Polarization( LHCP).
- In radio transmission systems, multiplexing methods are classified according to their orthogonality into time division multiplex, frequency division multiplex and code division multiplex. Time-division multiplexing is concerned with orthogonal functions in the time domain, as in the case of division into time slots. Frequency division multiplexing is concerned with orthogonal shifts in the spectral domain, where the frequency bands of adjacent carrier frequencies are chosen so precisely that they do not interfere with each other. And code division multiplexing is about general orthogonal functions. Orthogonal frequencies are related in such a way that the carrier maximum of one carrier is reached when the neighboring carrier has just zero. Orthogonal Frequency Division Multiplex( OFDM), Orthogonal Frequency Division Multiple Access( OFDMA) or Scalable Orthogonal Frequency Division Multiple Access( SOFDMA) are such multi-carrier methods with orthogonal carrier relationship.
- In computer science, orthogonality is a design concept with arbitrary combinability.