Frequency is the number of vibrations per second in a changing electric current Unit of frequency is Hertz abbreviated Hz. If the current move complete one vibration per second, the frequency 1Hz Units of another frequency:

- Kilohertz (kHz)
- Megahertz (MHz)
- Gigahertz (GHz)
- Terahertz (THz)

Wavelength or Wavelength is the distance between two points is equal to one vibration. In a wireless system, usually measured in meters, centimeters or milli-meter.

Frequency and wavelength are described in equation

where: = wavelength in meters f = frequency in Hertz (vibrations per second) c = speed of light (3X108 meters / second)

Comparison of power in logarithmic:

dBm is 10 log value of the signal for 1 milli Watt

value of 10 dBW is the log of the signal to 1 Watt

**Decibels (dB)**Comparison of power in logarithmic:

dBm is 10 log value of the signal for 1 milli Watt

value of 10 dBW is the log of the signal to 1 Watt

**Signal Propagation**

The signal leaving the antenna, it will propagate and disappear in the air. Selection of the antenna will determine how the type of propagation that would occur.

At 2.4 GHz is very important if we put both devices on a path free of obstructions. If the signal propagation is interrupted, then the decrease in signal quality will occur and disrupt communications.

Trees, buildings, water tanks, and the tower is a device that often interfere with signal propagation

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