The RF in RFID, 2nd Edition

Appendix 2

Harmonic Functions

A2.1 Sines and Cosines

The archetype of a smooth periodic signal is the sinusoid (Figure A2.1), typically written as the product of the angular frequency ω and time t. The two closely related functions sine and cosine, abbreviated sin(x) and cos(x), where the arguments of the functions are here expressed as radians. The argument can also be expressed in degrees. There are 2π radians in a circle, so one radian=(180/π)≈57 degrees.

Figure A2.1 Sines and Cosines as a Function of Time.

Both functions are periodic with a period of 2π radians, so if we write the sine as sin (2π f t), where t is time, then f=1/period=frequency. ...