More Wireless Basics

This article explains the types of wireless signal. What makes these signals different? What is the difference between a transmitter and a receiver? What do you call a device that both transmits and receives? Make sure you can name two types of antennas and the reason for choosing each type.

Definitions


Omnidirectional
When a node has an omnidirectional antenna attached, it can send and receive wireless signals in all directions around it equally. The signal is actually strongest out to the "sides" of the antenna. Very little or no signal comes out of the "ends" of the antenna.


Directional antenna
When a node has a directional antenna attached, the wireless signal is very strong in one direction and has a very weak or no signal in every other direction. This generally forms a cone or wedge-shaped area from the front of the antenna.

 

Receive sensitivity
The minimum level of a received signal required for a device to understand the signal.

 

Access point
A device that allows wireless devices to connect to a wired network using Wi-Fi.

 

Watt
A unit of power, usually written "W". The most common power levels for Wi-Fi devices are in the range of milliwatts - or thousandths of a watt.

 

dBm
An abbreviation for the power ratio in decibels (dB) of the power referenced to one milliwatt (mW). 0 dBm is equal to 1 milliwatt.